Home Abstracts - 2
Abstracts do Europ Hidration Institut - 2

Modificado em 28 de Maio de 2013





Controlling the hydration of the skin though the application of occluding barrier creams.

The skin is a barrier membrane that separates environments with profoundly different water contents. The barrier properties are assured by the outer layer of the skin, the stratum corneum (SC), which controls the transepidermal water loss. The SC acts as a responding membrane, since its hydration and permeability vary with the boundary condition, which is the activity of water at the outer surface of the skin. We show how this boundary condition can be changed by the application of a barrier cream that makes a film with a high resistance to the transport of water. We present a quantitative model that predicts hydration and water transport in SC that is covered by such a film. We also develop an experimental method for measuring the specific resistance to water transport of films made of occluding barrier creams. Finally, we combine the theoretical model with the measured properties of the barrier creams to predict how a film of cream changes the activity of water at the outer surface of the SC. Using the known variations of SC permeability and hydration with the water activity in its environment (i.e. the relative humidity), we can thus predict how a film of barrier cream changes SC hydration.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23269846

[Management of acute diarrhea in children.]

Diarrhea in childhood is very frequent (two episodes/year/children less of 5 years), rarely fatale (mostly mild) and not requiring additional exploration. But it can justify a hospitalization in case of dehydration (delay of care) or risk of dehydration. It is mainly of viral origin (rotavirus +++) and it has for main complication dehydration. Diagnosis and evaluation of the dehydration, in percentage of loss of weight, must be fast and lead (drive) to a premature correction of hypovolumic shock (or to an accurate fluid management). Main treatment is oral rehydration solutions (ORS), which considerably upset the morbi-mortality, associated with a premature refeeding. Breast-feeding must not be interrupted. Symptomatic treatments and especially antibiotics are not recommended. In case of failure of the rehydration by ORS, alternative is nasogastric tube or intraveinous infusion. Prevention includes essentially the respect of hygienic rules and antirotavirus vaccine.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23265760

A rapid beverage intake questionnaire can detect changes in beverage intake.

Attention on beverage intake, specifically sugar-sweetened beverages (SSB), has increased in recent years. A brief valid, reliable and sensitive assessment tool for quantifying beverage consumption and determining its influence on weight status could help to advance research on this topic. The valid and reliable 15-item beverage questionnaire (BEVQ-15) estimates mean daily intake of water, SSB and total beverages (g, kcal) across multiple beverage categories. Objective: to determine the ability of the BEVQ-15 to detect changes in beverage intake over time. Participants (n=70; age=37±2yr; BMI=24.5±0.4kg/m(2)) underwent two randomly assigned 30-day periods (intervention, increased water and fruit juice consumption; control, increased solid fruit consumption), with a 30-day washout phase between feeding periods. The BEVQ-15 was administered at the beginning and end of each period. Reliability was assessed by Pearson's correlations, paired sample t tests and Cronbach's alpha. Paired sample t tests and repeated measures ANOVA were used to evaluate sensitivity to change. Sixty-nine participants completed all study sessions. Reliability was acceptable for most beverages (range: R(2)=0.52-0.95, P<0.001), but not for energy drinks. Increases in water (g), juice (kcal, g) and total beverage (g) were detected during the intervention period (P<0.001); no changes in these variables were detected in the control period. The BEVQ-15 demonstrates the ability to detect changes in beverage intake over time. This brief (~2min), self-administered, valid, reliable and sensitive beverage intake assessment tool may be used by researchers and practitioners who evaluate and intervene upon beverage intake patterns in adults.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23265410

Nutrition and Fluid Optimization for Patients With Short Bowel Syndrome.

Short bowel syndrome (SBS) is characterized by nutrient malabsorption and occurs following surgical resection, congenital defect, or disease of the bowel. The severity of SBS depends on the length and anatomy of the bowel resected and the health of the remaining tissue. During the 2 years following resection, the remnant bowel undergoes an adaptation process that increases its absorptive capacity. Oral diet and enteral nutrition (EN) enhance intestinal adaptation; although patients require parenteral nutrition (PN) and/or intravenous (IV) fluids in the immediate postresection period, diet and EN should be reintroduced as soon as possible. The SBS diet should include complex carbohydrates; simple sugars should be avoided. Optimal fat intake varies based on patient anatomy; patients with end-jejunostomies can tolerate a higher proportion of calories from dietary fat than patients with a remnant colon. Patients with SBS are prone to deficiencies in vitamins, minerals, and essential fatty acids; serum levels should be periodically monitored and supplements provided as needed. Prebiotic or probiotic therapy may be beneficial for patients with SBS, although further research is needed to determine optimal protocols. Patients with SBS, particularly those without a colon, are at high risk of dehydration; oral rehydration solutions sipped throughout the day can help maintain hydration. One of the primary goals of SBS therapy is to reduce or eliminate dependence on PN/IV; optimization of EN and hydration substantially increases the probability of successful PN/IV weaning.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23264168

Promoting healthy drinking habits in children.

Good fluid intake in children is vitally important as they have immature thirst mechanisms, relatively high rates of fluid loss and are physically active. Poor fluid intake may affect children's cognitive functioning as well as bladder control. Research shows that children drink seven times as much soft drink as water. Schools have a vital role to play in ensuring that children develop healthy drinking patterns.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23252101

Nutrition and hydration.


The effect of beverages varying in glycaemic load on postprandial glucose responses, appetite and cognition in 10-12-year-old school children.

Reducing glycaemic index (GI) and glycaemic load (GL) inconsistently improves aspects of cognitive function and appetite in children. Whether altering the GL by lowering carbohydrate relative to protein and fat has a role in these effects is unknown. Therefore, we assessed the differential effects of beverages varying in GL and dairy composition on appetite, energy intake and cognitive function in children. A total of forty children (10-12 years) completed a double-blind, randomised, crossover trial, receiving three isoenergetic drinks (approximately 1100 kJ): a glucose beverage (GI 100, GL 65), a full milk beverage (GI 27, GL 5) and a half milk/glucose beverage (GI 84, GL 35). For 3 h post-consumption, subjective appetite and cognitive performance (speed of processing, memory, attention and perceptual speed) were measured hourly. At completion, each child was provided a buffet-style lunch and energy intake was calculated. Blood glucose was objectively measured using the Continuous Glucose Monitoring System. Blood glucose AUC values were significantly different between the drinks (P < 0·001), but did not sustain above the baseline for 3 h for any drink. Mixed modelling revealed no effect of beverage on subjective appetite or energy intake. Participant sex and drink GL significantly interacted for short-term memory (P < 0·001). When girls consumed either milk-containing beverage, they recalled 0·7-0·8 more words compared with 0·5 less words after the glucose drink (P ≤ 0·014). Altering GL of drinks by reducing carbohydrate and increasing protein did not affect appetite or cognition in children. Girls may demonstrate improved short-term memory after consuming beverages with higher protein and lower GL.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23244339

Effect of Preexercise Soup Ingestion on Water Intake and Fluid Balance During Exercise in the Heat.

PURPOSE: To determine whether chicken noodle soup before exercise increases ad libitum water intake, fluid balance, and physical and cognitive performance compared with water. METHODS: Nine trained men (age: 25±3y; VO2peak: 54.2±5.1ml·kg-1·min-1; mean±SD) performed cycle exercise in the heat (Wet Bulb Globe Temperature=25.9±0.4ºC) for 90min at 50% VO2peak, 45min after ingesting 355ml of either commercially-available bottled water (WATER) or chicken noodle soup (SOUP). The same bottled water was allowed ad libitum throughout both trials. Participants then completed a time trial to finish a given amount of work (10min at 90% VO2peak; n=8). Cognitive performance was evaluated by the Stroop Word/Color task before, every 30 min during, and immediately after the time trial. RESULTS: Ad libitum water intake throughout steady-state exercise (1435±593 vs. 1163±427g, resp.; P<0.03) was greater in SOUP compared with WATER. Total urine volume was similar in both trials (P=0.13) resulting in a trend for greater water retention in SOUP compared with WATER (87.7±7.6 vs. 74.9±21.7%, resp.; P=0.09) possibly due to a change in free water clearance (-0.32±1.22 vs. 0.51±1.06mL/min, resp; P=0.07). Fluid balance tended to be improved with SOUP (-106±603 vs. -478±594g, P=0.05). Likewise, change in plasma volume tended to be reduced in SOUP compared with WATER (P=0.06). Only mild dehydration was achieved (<1%) and physical performance was not different between treatments (P=0.77). The number of errors in the Stroop word/color task was lower in SOUP throughout the entire trial (treatment effect; P=0.04). CONCLUSION: SOUP before exercise increased ad libitum water intake and may alter kidney function.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23239679

Relationship between thirst perception and plasma arginine vasopressin concentration in man.

We examined the possibility that measurements of thirst perception in man using the visual Analogue Scale (VAS) can be used to estimate plasma arginine vasopressin concentration in man. In thirty normal subjects (male=15 and female=15), thirst perception (TP, cm) was rated and 5.0ml blood samples were collected for the measurement of plasma arginine vasopressin (PAVP) using Enzyme Immunoassay kit. Male subjects were statistically significantly older and taller than the females. However, the blood pressures, body weight and body mass index were similar. There was no significant difference, male vs. female in TP (5.26±0.51 vs. 5.39±0.53cm), calculated plasma osmolality from TP, Posm (298.5±1.7 vs. 299.0±1.8mOsm/kgH2O) and measured plasma arginine vasopressin, PAVP (4.85±0.30 vs. 4.71±0.31pg/ml). Furthermore, the calculated PAVP from TP, PAVP-TP was similar (5.40±0.69 vs.5.60 ±0.70pg/ml). When PAVP was calculated from plasma osmolality, PAVP-Posm the values were also similar (6.10±0.70 vs. 6.30±0.80pg/ml). There was no statistically significant difference between the measured PAVP as well as those calculated from TP and from plasma osmolality. It is thus reasonable to conclude that plasma arginine vasopressin concentration maybe estimated using thirst perception and/or plasma osmolality.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23235301

Water-deficit equation: systematic analysis and improvement.

BACKGROUND: The water-deficit equation {WD(1) = 0.6 × B(m) × [1 - (140 ÷ Na(+))]; B(m) denotes body mass} is used in medicine and nutrition to estimate the volume (L) of water required to correct dehydration during the initial stages of fluid-replacement therapy. Several equation assumptions may limit its accuracy, but none have been systematically tested. OBJECTIVES: We quantified the potential error in WD(1) for the estimation of free water (FW) and total body water (TBW) losses and systematically evaluated its assumptions. DESIGN: Thirty-six euhydrated volunteers were dehydrated (2.2-5.8% B(m)) via thermoregulatory sweating. Assumptions within WD(1) were tested by substituting measured euhydrated values for assumed or unknown values. These included the known (premorbid) B(m) (WD(2)), a proposed correction for unknown B(m) (WD(3)), the TBW estimated from body composition (WD(4)), the actual plasma sodium (WD(5)), the substitution of plasma osmolality (Posm) for sodium (WD(6)), and actual Posm (WD(7)). RESULTS: Dehydration reduced TBW by 3.49 ± 0.91 L, 57% of which (2.02 ± 0.96 L) was FW loss, and increased plasma sodium from 139 (range: 135-143 mmol/L) to 143 (range: 141-148 mmol/L) mmol/L. Calculations for WD(1) through WD(7) all underestimated TBW loss by 1.5-2.5 L (P 40%.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23235197

Food consumption and cardiovascular risk factors in European children: the IDEFICS study.

What is already known about this subject: Few studies addressing the relationship between food consumption and cardiovascular disease or metabolic risk have been conducted in children. Previous findings have indicated greater metabolic risk in children with high intakes of solid hydrogenated fat and white bread, and low consumption of fruits, vegetables and dairy products. What this study adds In a large multinational sample of 2 to 9 years old children, high consumption of sweetened beverages and low intake of nuts and seeds, sweets, breakfast cereals, jam and honey and chocolate and nut-based spreads were directly associated with increased clustered cardiovascular disease risk. These findings add new evidence to the limited literature available in young populations on the role that diet may play on cardiovascular health. OBJECTIVE: To investigate food consumption in relation to clustered cardiovascular disease (CVD) risk. METHODS: Children (n = 5548, 51.6% boys) from eight European countries participated in the IDEFICS study baseline survey (2007-2008). Z-scores of individual CVD risk factors were summed to compute sex- and age-specific (2-<6 years/6-9 years) clustered CVD risk scores A (all components, except cardiorespiratory fitness) and B (all components). The association of clustered CVD risk and tertiles of food group consumption was examined. RESULTS: Odds ratio (OR) of having clustered CVD risk A increased in older children with higher consumption of chocolate and nut-based spreads (boys: OR = 0.46; 95% CI = 0.32-0.69; girls: OR = 0.60; 95% CI = 0.42-0.86), jam and honey (girls: OR = 0.45; 95% CI = 0.26-0.78) and sweets (boys: OR = 0.69; 95% CI = 0.48-0.98). OR of being at risk significantly increased with the highest consumption of soft drinks (younger boys) and manufactured juices (older girls). Concerning CVD risk score B, older boys and girls in the highest tertile of consumption of breakfast cereals were 0.41 (95% CI = 0.21-0.79) and 0.45 (95% CI = 0.22-0.93) times, respectively, less likely to be at risk than those in tertile 1. CONCLUSIONS: High consumption of sugar-sweetened beverages and low intake of breakfast cereals, jam and honey, sweets and chocolate and nut-based spreads seem to adversely affect clustered CVD risk.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23225768

Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency.

OBJECTIVE: Many clinicians believe that exercise-associated muscle cramps (EAMC) occur because of dehydration. Experimental research supporting this theory is lacking. Mild hypohydration (3% body mass loss) does not alter threshold frequency (TF), a measure of cramp susceptibility, when fatigue and exercise intensity are controlled. No experimental research has examined TF following significant (3-5% body mass loss) or serious hypohydration (>5% body mass loss). Determine if significant or serious hypohydration, with moderate electrolyte losses, decreases TF. DESIGN: A prepost experimental design was used. Dominant limb flexor hallucis brevis cramp TF, cramp electromyography (EMG) amplitude and cramp intensity were measured in 10 euhydrated, unacclimated men (age=24±4 years, height=184.2±4.8 cm, mass=84.8±11.4 kg). Subjects alternated exercising with their non-dominant limb or upper body on a cycle ergometer every 15 min at a moderate intensity until 5% body mass loss or volitional exhaustion (3.8±0.8 h; 39.1±1.5°C; humidity 18.4±3%). Cramp variables were reassessed posthypohydration. RESULTS: Subjects were well hydrated at the study's onset (urine specific gravity=1.005±0.002). They lost 4.7±0.5% of their body mass (3.9±0.5 litres of fluid), 4.0±1.5 g of Na(+) and 0.6±0.1 g K(+) via exercise-induced sweating. Significant (n=5) or serious hypohydration (n=5) did not alter cramp TF (euhydrated=15±5 Hz, hypohydrated=13±6 Hz; F(1,9)=3.0, p=0.12), cramp intensity (euhydrated= 94.2±41%, hypohydrated=115.9±73%; F(1,9)=1.9, p=0.2) or cramp EMG amplitude (euhydrated=0.18±0.06 µV, hypohydrated= 0.18±0.09 µV; F(1,9)=0.1, p=0.79). CONCLUSIONS: Significant and serious hypohydration with moderate electrolyte losses does not alter cramp susceptibility when fatigue and exercise intensity are controlled. Neuromuscular control may be more important in the onset of muscle cramps than dehydration or electrolyte losses.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23222192

Thirst drives us to drink at least two litres of water a day.


Hydration in Advanced Cancer: Can Bioelectrical Impedance Analysis Improve the Evidence Base? A Systematic Review of the Literature.

CONTEXT: Decisions surrounding the administration of clinically assisted hydration to patients dying of cancer can be challenging because of the limited understanding of hydration in advanced cancer and a lack of evidence to guide health care professionals. Bioelectrical impedance analysis (BIA) has been used to assess hydration in various patient groupings, but evidence for its use in advanced cancer is limited. OBJECTIVES: To critically appraise existing methods of hydration status assessment in advanced cancer and review the potential for BIA to assess hydration in advanced cancer. METHODS: Searches were carried out in four electronic databases. A hand search of selected peer-reviewed journals and conference abstracts also was conducted. Studies reporting (de)hydration assessment (physical examination, biochemical measures, symptom assessment, and BIA) in patients with advanced cancer were included. RESULTS: The results highlight how clinical examination and biochemical tests are standard methods of assessing hydration, but limitations exist with these methods in advanced cancer. Furthermore, there is disagreement over the evidence for some commonly associated symptoms with dehydration in cancer. Although there are limitations with using BIA alone to assess hydration in advanced cancer, analysis of BIA raw measurements through the method of bioelectrical impedance vector analysis may have a role in this population. CONCLUSION: The benefits and burdens of providing clinically assisted hydration to patients dying of cancer are unclear. Bioelectrical impedance vector analysis shows promise as a hydration assessment tool but requires further study in advanced cancer. Innovative methodologies for research are required to add to the evidence base and ultimately improve the care for the dying.\nhttp://www.ncbi.nlm.nih.gov/pubmed/23200189

Origins for the estimations of water requirements in adults.

Water homeostasis generally occurs without conscious effort; however, estimating requirements can be necessary in settings such as health care. This review investigates the derivation of equations for estimating water requirements. Published literature was reviewed for water estimation equations and original papers sought. Equation origins were difficult to ascertain and original references were often not cited. One equation (% of body weight) was based on just two human subjects and another equation (ml water/kcal) was reported for mammals and not specifically for humans. Other findings include that some equations: for children were subsequently applied to adults; had undergone modifications without explicit explanation; had adjusted for the water from metabolism or food; and had undergone conversion to simplify application. The primary sources for equations are rarely mentioned or, when located, lack details conventionally considered important. The sources of water requirement equations are rarely made explicit and historical studies do not satisfy more rigorous modern scientific method. Equations are often applied without appreciating their derivation, or adjusting for the water from food or metabolism as acknowledged by original authors. Water requirement equations should be used as a guide only while employing additional means (such as monitoring short-term weight changes, physical or biochemical parameters and urine output volumes) to ensure the adequacy of water provision in clinical or health-care settings. FREE FULL-TEXT IN PUBMED\nhttp://www.ncbi.nlm.nih.gov/pubmed/23093341


Application of multifrequency bioelectrical impedance analysis method for the detection of dehydration status in professional divers.

BACKGROUND AND OBJECTIVE. The level of dehydration has been known to be a predisposing factor for the development of decompression sickness in divers. The aim of this study was to determine the level of dehydration in divers who dove with heliox and to determine whether the source of this dehydration was intracellular and/or extracellular by means of multifrequency bioelectrical impedance analysis (MF-BIA). MATERIAL AND METHODS. Eleven male professional divers were enrolled in the study. In order to determine the level of dehydration, MF-BIA was carried out (at 5, 50, and 100 kHz) and capillary hematocrit (Hct) was measured two times: one before diving and the other after leaving the pressure room. RESULTS. When prediving and postdiving parameters were compared, significant increases in the resistance at 5 kHz (P<0.001), 50 kHz, (P<0.001), and 100 kHz (P<0.01) and Hct (P<0.01) were observed after the diving. Similarly, a statistically significant fluid shift was found: total body water, -1.30 L (P<0.001), extracellular water, -0.85 L (P<0.001); and intracellular water, -0.45 L (P=0.011). CONCLUSIONS. Our results showed that mild dehydration occurred both in the intracellular and extracellular compartments in divers after deep diving. This study also indicates that MF-BIA could be a reliable new method for determining the dehydration status in divers.

The Impact of Ramadan Observance upon Athletic Performance

Ramadan observance requires a total abstention from food and drink from sunrise to sunset for a period of one month. Such intermittent fasting has only minor effects upon the overall nutrition and physiological responses of the general sedentary population. Larger meals are consumed at night and in the early morning. Body mass usually remains unchanged, the total energy intake remains roughly constant, and there is little alteration in the relative consumption of protein, fats and carbohydrates. However, Ramadan observance may be of greater consequence for the training and performance of the competitive athlete, particularly when the festival is celebrated in the hotter part of the year and daylight hours are long, as is the case for the 2012 Summer Olympic Games in London, England. The normal sleeping time then tends to be shortened, and blood sugar and tissue hydration decrease progressively throughout the hours of daylight. Some limitation of anaerobic effort, endurance performance and muscle strength might be anticipated from the decrease in muscle glycogen and body fluid reserves, and a reduced blood glucose may cause a depressed mood state, an increased perception of effort, and poorer team work. This review considers empirical data on the extent of such changes, and their likely effect upon anaerobic, aerobic and muscular performance, suggesting potential nutritional and behavioral tactics for minimizing such effects in the Muslim competitor.

Fluid balance of elite female basketball players before and during game play

This study determined the fluid balance of elite female basketball players before and during competition. Before and during two international games seventeen national level players (age: 24.2 ± 3 y; height: 180.5 ± 6 cm; mass: 78.8 ± 8 kg) were assessed. Fluid balance assessment included pregame hydration level as determined by urine specific gravity (USG), change in body mass during the game, ad libitum intake of water and/or sports drink, and estimated sweat losses. Mean (± sd) USG prior to game 1 was 1.005 ± 0.002 and before game 2 USG equaled 1.010 ± 0.005. Players lost an average of 0.7 ± 0.8% and 0.6 ± 0.6% of their body mass during games 1 and 2, respectively. In each game, 3 players experienced a fluid deficit > 1% of body mass and one other a fluid deficit > 2%. Sweat losses in both games, from the beginning of the warm-up to the conclusion of the game (~125 min with average playing time 16-17 min), were approximately 1.99 ± 0.75 L. Fluid intake in game 1 and game 2 equaled 77.8 ± 32% and 78.0 ± 21% of sweat losses, respectively. The majority of players were hydrated prior to each game and did not become meaningfully dehydrated during the game. It is possible the players who experienced the highest levels of dehydration also experienced some degree of playing impairment and the negative relationship between change in body mass and shooting percentage in game 2 provides some support for this notion.

Hydration status and fluid and sodium balance in elite Canadian junior women's soccer players in a cool environment.

Dehydration can impair mental and on-field performance in soccer athletes; however, there is little data available from the female adolescent player. There is a lack of research investigating fluid and electrolyte losses in cool temperatures. Therefore, the purpose of this study was to investigate the pretraining hydration status, fluid balance, and sweat sodium loss in 34 female Canadian junior elite soccer athletes (mean age ± SD, 15.7 ± 0.7 years) in a cool environment. Data were collected during two 90 min on-field training sessions (9.8 ± 3.3 °C, 63% ± 12% relative humidity). Prepractice urine specific gravity (USG), sweat loss (pre- and post-training body mass), and sweat sodium concentration (regional sweat patch method) were measured at each session. Paired t tests were used to identify significant differences between training sessions and Pearson's product moment correlation analysis was used to assess any relationships between selected variables (p ≤ 0.05). We found that 45% of players presented to practice in a hypohydrated state (USG > 1.020). Mean percent body mass loss was 0.84% ± 0.07% and sweat loss was 0.69 ± 0.54 L. Although available during each training session, fluid intake was low (63.6% of players consumed <250 mL). Mean sweat sodium concentration was 48 ± 12 mmol·L(-1). Despite low sweat and moderate sodium losses, players did not drink enough to avoid mild fluid and sodium deficits during training. The findings from this study highlights the individual variations that occur in hydration management in athletes and thus the need for personalized hydration guidelines.

Is there a role for parenteral nutrition or hydration at the end of life?

Hydration and nutrition are essential for the maintenance of life. In patients at the end of life, artificial hydration and nutrition pose clinical, ethical, and logistical dilemmas. No strong evidence exists supporting the use of parenteral hydration/nutrition for the majority of terminally ill patients; however, a subset of patients may derive some benefit. Uncertainty about determining prognosis, psychosocial factors, and perceptions of perceived benefits results in artificial nutrition/hydration being initiated in terminally ill patients. Discontinuation of artificial support can result in distress for patients, family members, and healthcare providers

Comparison of Ringers Lactate vs Normal Saline in Children with Acute Diarrhea and Severe Dehydration: A Double Blind Randomized Controlled Trial.

OBJECTIVE: WHO recommends Ringers lactate (RL) and Normal Saline (NS) for rapid intravenous rehydration in childhood diarrhea and severe dehydration. We compared these two fluids for improvement in pH over baseline during rapid intravenous rehydration in children with acute diarrhea. DESIGN: Double-blind randomized controlled trial. SETTING: Pediatric emergency facilities at a tertiary-care referral hospital. INTERVENTION: Children with acute diarrhea and severe dehydration received either RL (RL-group) or NS (NS-group), 100 mL/kg over three or six hours. Children were reassessed after three or six hours. Rapid rehydration was repeated if severe dehydration persisted. Blood gas was done at baseline and repeated after signs of severe dehydration disappeared. OUTCOME MEASURES: Primary outcome was change in pH from baseline. Secondary outcomes included changes in serum electrolytes, bicarbonate levels, and base deficit from baseline; mortality, duration of hospital stay, and fluids requirement. RESULTS: Twenty two children, 11 each were randomized to the two study groups. At primary end point (disappearance of signs of severe dehydration), the improvement in pH from baseline was not significant in RL-group [from 7.17 (0.11) to 7.28 (0.09)] as compared to NS-group [7.09 (0.11) to 7.21 (0.09)], P=0.17 (after adjusting for baseline serum Na/ Cl). Among this limited sample size, children in RL group required less fluids [median 310 versus 530 mL/kg, P=0.01] and had shorter median hospital stay [38 versus 51 hours, P=0.03]. CONCLUSION: There was no difference in improvement in pH over baseline between RL and NS among children with acute diarrhea and severe dehydration.

Improving nutrition and hydration in hospital: the nurse's responsibility.

Ensuring that the nutrition and hydration needs of patients in hospital are met is part of the nurse's role. Adequate nutrition and hydration is vital for good health, from both a physical and psychological perspective, and should be considered a priority by nurses. Actions required by nurses may include addressing potential barriers and obstacles that may prevent patients receiving adequate food and drink. Ensuring patients are comfortable and positioned appropriately in preparation for mealtimes, regularly checking patients while eating and drinking, and conducting ongoing assessment to identify those who require assistance with their meals is also important. Documentation in care plans and appropriate delegation of nutrition-related tasks to team members, such as healthcare assistants, should also be considered.

Detection of Dehydration by Using Volume Kinetics.

Background: Patients admitted to surgery may be dehydrated, which is difficult to diagnose except when it is severe (>5% of the body weight). We hypothesized that modest dehydration can be detected by kinetic analysis of the blood hemoglobin concentration after a bolus infusion of crystalloid fluid.Methods:Four series of experiments were performed on 10 conscious, healthy male volunteers. Separated by at least 2 days, they received 5 or 10 mL/kg acetated Ringer's solution over 15 minutes. Before starting half of the IV infusions, volume depletion amounting to 1.5 to 2.0 L (approximately 2% of body weight) was induced with furosemide. The elimination clearance and the half-life of the infused fluid were calculated based on blood hemoglobin over 120 minutes. The perfusion index and the pleth variability index were monitored by pulse oximetry after a change of body position.Results:Dehydration decreased the elimination clearance of acetated Ringer's solution [median (25th-75th percentile)] from 1.84 (1.23-2.57) to 0.53 (0.41-0.79) mL/kg/min (Wilcoxon matched-pair test P < 0.001) and increased the half-life from 23 (12-37) to 76 (57-101) minutes (P < 0.001). The smaller infusion, 5 mL/kg, fully discriminated between experiments performed in the euhydrated and dehydrated states, whereas the urinary excretion provided a less-reliable indication of hydration status. Dehydration decreased the perfusion index but did not affect the pleth variability index.Conclusion:Dehydration amounting to 2% of the body weight could be detected from the elimination clearance and the half-life of an infusion of 5 mL/kg Ringer's solution.

Effect of exercise-induced dehydration on endurance performance: evaluating the impact of exercise protocols on outcomes using a meta-analytic procedure.

Objective: It is purported that exercise-induced dehydration (EID), especially if ≥ 2% bodyweight, impairs endurance performance (EP). Field research shows that athletes can achieve outstanding EP while dehydrated > 2% bodyweight. Using the meta-analytic procedure, this study compared the findings of laboratory-based studies that examined the impact of EID upon EP using either ecologically valid (EV) (time-trial exercise) or non-ecologically valid (NEV) (clamped-intensity exercise) exercise protocols.MethodsEP outcomes were put on the same scale and represent % changes in power output between euhydrated and dehydrated exercise tests. Random-effects model meta-regressions and weighted mean effect summaries, mixed-effects model analogue to the ANOVAs and magnitude-based effect statistics were used to delineate treatment effects.Main results Fifteen research articles were included, producing 28 effect estimates, representing 122 subjects. Compared with euhydration, EID increased (0.09±2.60%, (p=0.9)) EP under time-trial exercise conditions, whereas it reduced it (1.91±1.53%, (p<0.05)) with NEV exercise protocols. Only with NEV exercise protocols did EID ≥ 2% bodyweight impair EP (p=0.03).ConclusionsEvidence indicates that (1) EID ≤ 4% bodyweight is very unlikely to impair EP under real-world exercise conditions (time-trial type exercise) and; (2) under situations of fixed-exercise intensity, which may have some relevance for military and occupational settings, EID ≥ 2% bodyweight is associated with a reduction in endurance capacity. The 2% bodyweight loss rule has been established from findings of studies using NEV exercise protocols and does not apply to out-of-doors exercise conditions. Athletes are therefore encouraged to drink according to thirst during exercise.

Hypernatremia in critically ill patients.

Hypernatremia is common in intensive care units. It has detrimental effects on various physiologic functions and was shown to be an independent risk factor for increased mortality in critically ill patients. Mechanisms of hypernatremia include sodium gain and/or loss of free water and can be discriminated by clinical assessment and urine electrolyte analysis. Because many critically ill patients have impaired levels of consciousness, their water balance can no longer be regulated by thirst and water uptake but is managed by the physician. Therefore, the intensivists should be very careful to provide the adequate sodium and water balance for them. Hypernatremia is treated by the administration of free water and/or diuretics, which promote renal excretion of sodium. The rate of correction is critical and must be adjusted to the rapidity of the development of hypernatremia.

The effects of Ramadan intermittent fasting on athletic performance: Recommendations for the maintenance of physical fitness.

Abstract. The behavioural modifications that accompany Ramadan intermittent fasting (RIF) are usually associated with some alterations in the metabolic, physiological, and psychological responses of athletes that may affect sport performance. Muslim athletes who are required to train and/or compete during the month-long, diurnal fast must adopt coping strategies that allow them to maintain physical fitness and motivation if they are to perform at the highest level. This updated review aims to present the current state of knowledge of the effects of RIF on training and performance, focusing on key-factors that contribute to the effects of Ramadan on exercise performance: energy restriction, sleep deprivation, circadian rhythm perturbation, dehydration, and alterations in the training load. The available literature contain few studies that have examined the effects of RIF on physical performance in athletes and, to date, the results are inconclusive, so the effects of RIF on competition outcomes are not at present wholly understood. The diverse findings probably indicate individual differences in the adaptability and self-generated coping strategies of athletes during fasting and training. However, the results of the small number of well-controlled studies that have examined the effects of Ramadan on athletic performance suggest that few aspects of physical fitness are negatively affected, and where decrements are observed these are usually modest. Subjective feelings of fatigue and other mood indicators are often cited as implying additional stress on the athlete throughout Ramadan, but most studies show that these factors may not result in decreases in performance and that perceived exercise intensity is unlikely to increase to any significant degree. Current evidence from good, well-controlled research supports the conclusion that athletes who maintain their total energy and macronutrient intake, training load, body composition, and sleep length and quality are unlikely to suffer any substantial decrements in performance during Ramadan. Further research is required to determine the effect of RIF on the most challenging events or exercise protocols and on elite athletes competing in extreme environments.



Too little water or too much: hyponatremia due to excess fluid intake

Hyponatremia associated with diarrhea is usually caused by dehydration, with salt loss accompanying the excessive loss of water. On the other hand, hyponatremia in this setting can occasionally be caused by excess ingestion or administration of hypotonic fluids (1, 2). In this report, we describe the differential diagnosis of hyponatremia in an infant.

Hydration Status of Arabic Adolescents and Young Men: Measurement, Evaluation, and a School-based Initiative to Improve Drinking Behaviour.

BACKGROUND. Despite the importance of hydration, limited research has been undertaken in Arabic populations. METHODS: Study 1: 88 adult military cadets and 32 school-based adolescents provided five sequential daily mid-morning urine samples. Hydration thresholds were produced using percentiles of estimated urine osmolality (Uosm) and urine color (Ucol). Study 2: 120 military cadets and 52 adolescents provided 1077 mid-morning urine samples and the Uosm:Ucol relationship was assessed using regression. Study 3: 21 adolescents participated in a four-week hydration campaign, providing urine samples pre (PreC), at the end of (EndC) and two weeks post (PostC) campaign. RESULTS: Study 1: Euhydration (41-60th percentile) was 881-970 mOsmol·kg-1 (adults) and 821-900 mOsmol·kg-1 (adolescents). Study 2: In both cohorts, Uosm and Ucol were associated (p<0.01): adults R2=0.33; adolescents R2=0.59. Study 3: Urine osmolality was significantly higher PreC compared to EndC and PostC. CONCLUSIONS: Urinary output of Arabic adolescents and military cadets was more concentrated than frequently recommended for euhydration. Further work in similar populations is required to determine if these values represent hypohydration or merely reflect dietary and cultural differences. In Arabic adolescents and adults, Ucol was an adequate indicator of hydration status. Favorable hydration changes were made following a school-based health campaign.

Influence of Beverage Temperature on Palatability and Fluid Ingestion During Endurance Exercise: a systematic review.

BACKGROUND. Beverage palatability is known to influence fluid consumption during exercise and may positively influence hydration status and help to prevent fatigue, heat illness and decreased performance. PURPOSE: The aims of this review were to evaluate the effect of beverage temperature on fluid intake during exercise and investigate the influence of beverage temperature on palatability. METHODS: Citations from multiple databases were searched from the earliest record to November 2010 using the terms 'beverage', 'fluid' or 'water' and 'palatability', 'preference', 'feeding' and 'drinking behaviour' and 'temperature'. Included studies (n=13) needed to use adult (≥18yr) human participants, have beverage temperatures ≤50°C and measure consumption during exercise and/or palatability. RESULTS: All studies (n=8) reporting palatability indicated cold (0- 10°C) or cool (10-22°C) beverages were preferred to warmer (control, ≥22°C). A meta-analysis on studies (n=5) reporting fluid consumption revealed that participants consumed ~50% (effect size=1.4, 0.75 to 2.04, 95% CI) more cold/cool beverages than control during exercise. Sub-analysis of studies assessing hydration status (n=4) when consuming cool/cold compared to warm beverages demonstrated that dehydration during exercise was reduced by 1.3% of body weight (1.6 to 0.9%, 95% CI) (p<0.001). CONCLUSION: Cool beverage temperatures (<22°C) significantly increased fluid palatability, consumption and hydration during exercise compared to control (≥22°C).

Physical signs of dehydration in the elderly.

Objective Dehydration is a common condition and frequent cause of hospitalization in older people, despite the caregiver's high attention in attempt to avoid its occurrence. In this study, various physical signs were examined as clinical signs of dehydration in elderly. Methods A prospective observational study was conducted in an acute care teaching hospital. Consecutive elderly patients who were admitted to the Department of Medicine were evaluated. Dehydration was defined as a calculated serum osmolality above 295 mOsm/L. The patients diagnosed as dehydrated or not dehydrated were observed for physical signs of dehydration. Data of blood and urine chemistry analysis were also compared between the two groups. Results A total of 27 elderly patients admitted with acute medical conditions were included in this study. For the physical signs, dry axilla had moderate sensitivity (44%) and excellent specificity (89%) to detect dehydration. Sunken eyes and delayed capillary refill time also showed relatively good specificity (83%). For laboratory data, the mean concentrations of serum sodium of the dehydrated group (146 mEq/L) was significantly higher (p<0.01) than those of the non-dehydrated group (134 mEq/L). Conclusion Physical signs of dehydration in elderly showed relatively good specificity but poor sensitivity. The evaluation of the axillary moisture could help assess dehydration as well as laboratory data analysis such as serum sodium concentration. FREE FULL TEXT AVAILABLE IN PUBMED

Effects of hydration and water deprivation on blood viscosity during a soccer game in sickle cell trait carriers.

The present study compared the changes in blood viscosity, hydration status, body temperature and heart rate between a group of sickle cell trait (SCT) carriers and a control (Cont) group before and after a soccer game performed in two conditions: one with water offered ad libitum (hydration condition; Hyd) and the other one without water (dehydration condition; Dehyd). Blood viscosity and haematocrit per blood viscosity ratio (HVR; an index of red blood cell oxygen transport effectiveness) were measured before and at the end of each game. Resting blood viscosity was greater in the SCT carriers than in the Cont group. The increase of blood viscosity over baseline at the end of the game in the Cont group was similar in the two conditions. In contrast, the change in blood viscosity occurring in SCT carriers during soccer games was dependant on the experimental condition: (1) in Dehyd condition, blood viscosity rose over baseline; (2) in Hyd condition, blood viscosity decreased below resting level reaching Cont values. The Cont group had higher HVR than SCT carriers at rest. HVR remained unchanged in the Cont group at the end of the games, whatever the experimental condition. Although HVR of SCT carriers decreased below baseline at the end of the game performed in Dehyd condition, it increased over resting level in Hyd condition reaching the values of the Cont group. Our study demonstrated that ad libitum hydration in exercising SCT carriers normalises the blood hyperviscosity.

Dysphagia, Nutrition, and Hydration in Ischemic Stroke Patients at Admission and Discharge from Acute Care.

Dysphagia may predispose stroke patients toward undernutrition and hydration. These comorbidities increase patient risks for reduced functional outcome and short-term mortality. Despite this impact, available information on relationships among dysphagia, nutrition, and hydration status in acute stroke is limited and conflicted. This study evaluated nutrition and hydration status in ischemic stroke patients with versus without clinically significant dysphagia at admission and at discharge from acute care. Sixty-seven patients admitted to the stroke unit in a tertiary-care hospital provided data for this study. On the day of hospital admission and upon discharge or at 7 days post admission, serum biochemical measures were obtained for nutrition (prealbumin) and hydration status (BUN/Cr). Clinical evaluation for dysphagia, nutrition status, and stroke severity were completed an average of 1.4 days following hospital admission. Dysphagia was identified in 37 % of the cohort. At admission 32 % of patients demonstrated malnutrition based on prealbumin levels and 53 % demonstrated evidence of dehydration based on BUN/Cr levels. No differences in nutrition status were attributed to dysphagia. Patients with dysphagia demonstrated significantly higher BUN/Cr levels (greater dehydration) than patients without dysphagia at admission and at discharge. Dehydration at both admission and discharge was associated with dysphagia, clinical nutrition status, and stroke severity. Results of this study support prior results indicating that dysphagia is not associated with poor nutrition status during the first week post stroke. Dehydration status is associated with dysphagia during this period. The results have implications for future confirmatory research and for clinical management of dysphagia in the acute stroke period.

French children start their school day with a hydration deficit.

Background and Aims: Fluid requirements of children vary as a function of gender and age. To our knowledge, there is very little literature on the hydration status of French children. We assessed the morning hydration status in a large sample of 529 French schoolchildren aged 9-11 years. Methods: Recruited children completed a questionnaire on fluid and food intake at breakfast and collected a urine sample the very same day after breakfast. Breakfast food and fluid nutritional composition was analyzed and urine osmolality was measured using a cryoscopic osmometer. Results: More than a third of the children had a urine osmolality between 801 and 1,000 mosm/kg while 22.7% had a urine osmolality over 1,000 mosm/kg. This was more frequent in boys than in girls (p < 0.001). A majority of children (73.5%) drank less than 400 ml at breakfast. Total water intake at breakfast was significantly and inversely correlated with high osmolality values. Conclusions: Almost two thirds of the children in this large cohort had evidence of a hydration deficit when they went to school in the morning, despite breakfast intake. Children's fluid intake at breakfast does not suffice to maintain an adequate hydration status for the whole morning.

Body weight changes in child and adolescent athletes during a triathlon competition.

We examined young athletes during a triathlon performed in a hot climate. Complete or partial data were available for 95 athletes competing in the National Triathlon Championship in Costa Rica. Mean ± SD for age and body weight (BW) were 13.1 ± 2.5 years and 46.3 ± 11.5 kg, respectively. Race requirements included: 500 m swimming, 15 km cycling, 3.5 km running for juniors (9-13 years); 800 m swimming, 30 km cycling, 8 km running for seniors (14-17 years). WBGT on race day was >31 °C. BW recorded pre- and post-race was available for 92 athletes and performance data were available for 83 of these. Information regarding symptoms experienced during the race was available for 95 athletes. Change in BW (%ΔBW) was calculated and ranged from +0.6 to -2.4 % for junior boys (-1.2 ± 0.9 %), +0.7 to -2.5 % for junior girls (-1.3 ± 0.9 %), 0 to -2.8 % for senior girls (-1.3 ± 0.9 %), and +0.6 to -4.5 % for senior boys (-1.7 ± 1.1 %). Eighteen participants reported no medical symptoms. Of 77 participants who reported symptoms, 42.9 % reported exhaustion/fatigue, 36.4 % reported side stitch/cramp, and 23.4 % reported dizziness. Participants reporting no medical symptoms achieved almost identical (P = 0.99) %ΔBW as those reporting at least one symptom. %ΔBW was more negative (P = 0.005) in participants who reported dizziness (-1.9 %ΔBW) compared with those who did not (-1.4 %ΔBW). %ΔBW was associated with performance in junior girls (r = 0.47, P = 0.02) and senior boys (r = 0.51, P = 0.01), with a trend in junior boys (r = 0.41, P = 0.053) but not in senior girls (r = 0.004, P = 0.99). Young athletes participating in a triathlon in a hot climate can tolerate mild to moderate levels of dehydration, without detrimental effects to self-assessed health.

Analysis of dehydration and strength in elite badminton players.

BACKGROUND. The negative effects of dehydration on aerobic activities are well established. However, it is unknown how dehydration affects intermittent sports performance. The purpose of this study was to identify the level of dehydration in elite badminton players and its relation to muscle strength and power production. METHODOLOGY: Seventy matches from the National Spanish badminton championship were analyzed (46 men's singles and 24 women's singles). Before and after each match, jump height and power production were determined during a countermovement jump on a force platform. Participants' body weight and a urine sample were also obtained before and after each match. The amount of liquid that the players drank during the match was also calculated by weighing their individual drinking bottles. RESULTS AND DISCUSSION: Sweat rate during the game was 1.14±0.46 l/h in men and 1.02±0.64 l/h in women. The players rehydrated at a rate of 1.10±0.55 l/h and 1.01±0.44 l/h in the male and female groups respectively. Thus, the dehydration attained during the game was only 0.37±0.50% in men and 0.32±0.83% in women. No differences were found in any of the parameters analyzed during the vertical jump (men: from 31.82±5.29 to 32.90±4.49 W/kg; p>0.05, women: from 26.36±4.73 to 27.25±4.44 W/kg; p>0.05). Post-exercise urine samples revealed proteinuria (60.9% of cases in men and 66.7% in women), leukocyturia (men = 43.5% and women = 50.0%) and erythrocyturia (men = 50.0% and women = 21.7%). CONCLUSIONS: Despite a moderate sweat rate, badminton players adequately hydrated during a game and thus the dehydration attained was low. The badminton match did not cause muscle fatigue but it significantly increased the prevalence of proteinuria, leukocyturia and erythrocyturia. FREE FULL TEXT IN PUBMED.

Bioelectrical impedance analysis in the assessment of hydration status in peritoneal dialysis patients.

Objective: Assessment of fluid status in chronic peritoneal dialysis (PD) patients is complex. Clinical evaluation based solely on body weight, blood pressure, volume of ultrafiltration (UF) and peripheral edema is insufficient. A non-invasive test, bioelectrical impedance analysis (BIA) might be of potential benefit. Aim: To test whether BIA correlates with other ancillary markers of extracellular fluid volume, namely B-type natriuretic peptide (BNP), residual renal function (RRF) and UF, and whether BIA provides complementary information in categorizing PD patients vis-à-vis hydration status. Methods: A cross-sectional study of 61 out-patients on chronic PD. Single-frequency BIA measurements of resistance/height were divided into tertiles (lowest: 253 Ω/m and 316 Ω/m). Results: Compared to patients in the highest tertile of BIA (least fluid), patients in the lowest tertile (most fluid) had highest BNP, RRF and UF (93.5 vs. 55.0 pg/ml, p = 0.029; 850 vs. 300 ml/day, p = 0.05; and 1.75 vs. 1.21 l/day, p = 0.023, respectively). Conclusions: BIA tertiles categorized PD patients who differed in BNP, RRF and UF in a stepwise pattern, suggesting BIA may better inform hydration status, and serve as an additional clinical tool in management of chronic PD patients.

Assessment of fluid status in peritoneal dialysis.

Fluid management is recognized as a basic component of management of patients on dialysis. Fluid overload is an important adverse factor in patient outcomes, and the negative effects of fluid depletion, including on residual renal function, are aIso increasingly being recognized. The complexities of fluid distribution in renal failure need to be understood to inform assessment of hydration. Clinical assessment of hydration is insensitive to abnormalities in hydration. BIA is the most promising technique for objective assessment of fluid status, but it is essential that the underlying principles and limitations are understood, and that results from BIA are utilized in conjunction with clinical assessment rather than in isolation.

Hydration Status, Fluid Intake and Electrolyte Losses in Youth Soccer Players

The purpose of the study was to determine the hydration status, fluid intake and electrolyte losses of 21 male professional youth soccer players (age 17.1 ± 0.7 yr) training in a cool environment. Pre- and post training measurements of body mass, urine (freezing point osmolality method) and sweat concentration (flame emission spectroscopy) were collected. Fourteen players were found to be hypohydrated prior to training. The amount of fluid lost due to exercise equated to a 1.7 % loss in body mass, which equated to a gross dehydration loss of 0.5 %. Overall, the soccer players replaced 46 ¬± 88% of sweat loss during training and only four remained hypohydrated after training. No significant correlations between sweat loss and sweat concentrations of Na+ (r = -0.11, P = 0.67), K+ (r = 0.14, P = 0.58) were found, but there was a significant correlation with Mg2+ (r = -0.58, P < 0.009). This study found large variability in pre-training hydrationstatus which the players were able to rehydrate during the training sessions.However, given the numbers starting training in a hypohydrated state, adequate hydration status prior to training should be considered by youth players, coaches and sports science support staff.

Symptoms of heat illness in surface mine workers.

OBJECTIVE: To assess the symptoms of heat illness experienced by surface mine workers. METHODS: Ninety-one surface mine workers across three mine sites in northern Australia completed a heat stress questionnaire evaluating their symptoms for heat illness. A cohort of 56 underground mine workers also participated for comparative purposes. Participants were allocated into asymptomatic, minor or moderate heat illness categories depending on the number of symptoms they reported. Participants also reported the frequency of symptom experience, as well as their hydration status (average urine colour). RESULTS: Heat illness symptoms were experienced by 87 and 79 % of surface and underground mine workers, respectively (p = 0.189), with 81-82 % of the symptoms reported being experienced by miners on more than one occasion. The majority (56 %) of surface workers were classified as experiencing minor heat illness symptoms, with a further 31 % classed as moderate; 13 % were asymptomatic. A similar distribution of heat illness classification was observed among underground miners (p = 0.420). Only 29 % of surface miners were considered well hydrated, with 61 % minimally dehydrated and 10 % significantly dehydrated, proportions that were similar among underground miners (p = 0.186). Heat illness category was significantly related to hydration status (p = 0.039) among surface mine workers, but only a trend was observed when data from surface and underground miners was pooled (p = 0.073). Compared to asymptomatic surface mine workers, the relative risk of experiencing minor and moderate symptoms of heat illness was 1.5 and 1.6, respectively, when minimally dehydrated. CONCLUSIONS: These findings show that surface mine workers routinely experience symptoms of heat illness and highlight that control measures are required to prevent symptoms progressing to medical cases of heat exhaustion or heat stroke.

Nurse-physician communication concerning artificial nutrition or hydration (ANH) in patients with dementia: a qualitative study.

Aims and objectives. To explore nurses' experiences with nurse-physician communication during artificial nutrition or hydration (ANH) decision-making in hospitalised patients with dementia. Background.  Artificial nutrition or hydration decision-making often occurs in patients with dementia. Effective communication between professionals is extremely challenging in this population, because these patients are unable to communicate their treatment wishes. Design.  Qualitative interview design. Methods.  Between April 2008 and June 2009, we conducted 21 interviews with nurses from nine different hospitals geographically spread throughout Flanders (Belgium). Interviews were audiotaped and later transcribed. Data processing involved (1) simultaneous and systematic data collection and analysis, (2) constant forwards-backwards wave, (3) continuous dialogue with the data and (4) interactive team processes. Results.  The interviews showed that communication with physicians is the central instrument the nurses used in their attempts to realise their perception of 'the best possible care'. From the nurses' perspective, we distinguished three mutually connected factors that affected the effectiveness of nurse-physician communication during artificial nutrition or hydration decision-making: the physicians' attitude towards the nurses, the nurses' attitude towards the physicians and the forms of communication used by the nurses. The complex interaction between these three factors resulted in a range of nurses' perceptions, varying from positive to negative. The direction of their perceptions depended on the extent to which they succeeded or failed to use nurse-physician communication as an instrument to realise the 'best care'. Conclusion.  Nurse-physician communication was the most important instrument determining whether nurses succeeded or failed to actively act as a patient's representative and whether nurses achieved the best possible care in co-operation with physicians. Relevance to clinical practice. To reach optimal care and nurse job satisfaction, nurse-physician communication during artificial nutrition or hydration decision-making should be an open dialogue characterised by mutual respect and understanding.

Hydration, sweat and thermoregulatory responses to professional football training in the heat.

This study examined the relationship between intensity of training and changes in hydration status, core temperature, sweat rate and composition and fluid balance in professional football players training in the heat. Thirteen professional football players completed three training sessions; "higher-intensity" (140 min; HI(140)), "lower-intensity" (120 min; LI(120)) and "game-simulation" (100 min; GS(100)). Movement demands were measured by Global Positioning System, sweat rate and concentration were determined from dermal patches and body mass change. Despite similar environmental conditions (26.9 ± 0.1°C and 65.0 ± 7.0% relative humidity [Rh]), higher relative speeds (m · min(-1)) and increased perceptions of effort and thermal strain were observed in HI(140) and GS(100) compared with LI(120) (P < 0.05). Significantly (P < 0.05) greater sweat rate (L · h(-1)) and electrolyte losses (g) were observed in HI(140) and GS(100) compared with LI(120). Rate of rise in core temperature was correlated with mean speed (r = 0.85), session rating of perceived exertion (sRPE) (r = 0.61), loss of potassium (K(+)) (r = 0.51) sweat rate (r = 0.49), and total sweat loss (r = 0.53), with mean speed the strongest predictor. Sodium (Na(+)) (r = 0.39) and K(+) (r = 0.50) losses were associated with total distance covered. In hot conditions, individualised rehydration practices should be adopted following football training to account for differences in sweat rate and electrolyte losses in response to intensity and overall activity within a session.

Hypertonic Saline and Acute Wheezing in Preschool Children.

BACKGROUND: Most acute wheezing episodes in preschool children are associated with rhinovirus. Rhinovirus decreases extracellular adenosine triphosphate levels, leading to airway surface liquid dehydration. This, along with submucosal edema, mucus plaques, and inflammation, causes failure of mucus clearance. These preschool children do not respond well to available treatments, even oral steroids. This calls for pro-mucus clearance and prohydration treatments such as hypertonic saline in wheezing preschool children. METHODS: Randomized, controlled, double-blind study. Forty-one children (mean age 31.9 ± 17.4 months, range 1-6 years) presented with wheezing to the emergency department were randomized after 1 albuterol inhalation to receive either 4 mL of hypertonic saline 5% (HS) (n = 16) or 4 mL of normal saline (NS) (n = 25), both with 0.5 mL albuterol, twice every 20 minutes in the emergency department and 4 times a day thereafter if hospitalized. The primary outcome measured was length of stay (LOS) and the secondary outcomes were admission rate (AR) and clinical severity score. RESULTS: The LOS was significantly shorter in the HS than in the NS group: median 2 days (range 0-6) versus 3 days (range 0-5) days (P = .027). The AR was significantly lower in the HS than the NS group: 62.2% versus 92%. Clinical severity score improved significantly in both groups but did not reach significance between them. CONCLUSIONS: Using HS inhalations significantly shortens LOS and lowers AR in preschool children presenting with an acute wheezing episode to the emergency department.

Body Mass Change and Ultraendurance Performance: A Decrease in Body Mass Is Associated With an Increased Running Speed in Male 100-km Ultramarathoners.

Body mass change and ultraendurance performance: a decrease in body mass is associated with an increased running speed in male 100-km ultramarathoners. J Strength Cond Res 26(6): 1505-1516, 2012-We investigated, in 50 recreational male ultrarunners, the changes in body mass, selected hematological and urine parameters, and fluid intake during a 100-km ultramarathon. The athletes lost (mean and SD) 2.6 (1.8) % in body mass (p < 0.0001). Running speed was significantly and negatively related to the change in body mass (p < 0.05). Serum sodium concentration ([Na]) and the concentration of aldosterone increased with increasing loss in body mass (p < 0.05). Urine-specific gravity increased (p 2% in body mass leads to dehydration and consequently impairs endurance performance must be questioned for ultraendurance athletes competing in the field. For practical applications, a loss in body mass during a 100-km ultramarathon was associated with a faster running speed.

Hydration and performance during Ramadan.

In the absence of any food or fluid intake during the hours of daylight during the month of Ramadan, a progressive loss of body water will occur over the course of each day, though these losses can be completely replaced each night. Large body water deficits will impair both physical and cognitive performance. The point at which water loss will begin to affect performance is not well defined, but it may be as little as 1-2% of body mass. For resting individuals in a temperate environment, the water loss that occurs during a day without food or fluid will typically amount to about 1% of body mass by the time of sunset. This small loss of body water is unlikely to have a major adverse effect on any aspect of physical or cognitive performance. Larger body water losses will occur, however, in hot weather or if exercise is undertaken. Performance in events lasting about 1 hour or longer may be impaired in the absence of fluid intake during the event. In weight-category sports, there may be difficulties due to the impossibility of restoring body water content between the weigh-in and competition, and athletes will require alternative strategies. Where more than one competition or training session takes place in a single day and where substantial fluid losses are incurred, recovery will be impaired by the absence of fluid intake.

Promoting and maintaining healthy hydration in patients.

Fluid is essential for life and health. Nurses have an important role in helping patients maintain optimal levels of hydration, particularly in hospital or residential settings where access to fluid is less likely to be under the patient's control. This article describes the benefits of healthy hydration, outlines guidelines on fluid requirements for different patient groups and discusses which beverages should be promoted. Myths about caffeine consumption and hydration will also be addressed using new clinical evidence.

Effects of rehydration fluid temperature and composition on body weight retention upon voluntary drinking following exercise-induced dehydration.

The purpose of this study was to determine the effects of beverage temperature and composition on weight retention and fluid balance upon voluntary drinking following exercise induced-dehydration. Eight men who were not acclimated to heat participated in four randomly ordered testing sessions. In each session, the subjects ran on a treadmill in a chamber maintained at 37℃ without being supplied fluids until 2% body weight reduction was reached. After termination of exercise, they recovered for 90 min under ambient air conditions and received one of the following four test beverages: 10℃ water (10W), 10℃ sports drink (10S), 26℃ water (26W), and 26℃ sports drink (26S). They consumed the beverages ad libitum. The volume of beverage consumed and body weight were measured at 30, 60, and 90 min post-recovery. Blood samples were taken before and immediately after exercise as well as at the end of recovery in order to measure plasma parameters and electrolyte concentrations. We found that mean body weight decreased by 1.8-2.0% following exercise. No differences in mean arterial pressure, plasma volume, plasma osmolality, and blood electrolytes were observed among the conditions. Total beverage volumes consumed were 1,164 ± 388, 1,505 ± 614, 948 ± 297, and 1,239 ± 401 ml for 10W, 10S, 26W, and 26S respectively (P > 0.05). Weight retention at the end of recovery from dehydration was highest in 10S (1.3 ± 0.7 kg) compared to 10W (0.4 ± 0.5 kg), 26W (0.4 ± 0.4 kg), and (0.6 ± 0.4 kg) (P < 0.005). Based on these results, carbohydrate/electrolyte-containing beverages at cool temperature were the most favorable for consumption and weight retention compared to plain water and moderate temperature beverages. FREE FULL-TEXT AVAILABLE IN PUBMED.

Water intake and post-exercise cognitive performance: an observational study of long-distance walkers and runners.

PURPOSE: The impact of diet on endurance performance and cognitive function has been extensively researched in controlled settings, but there are limited observational data in field situations. This study examines relationships between nutrient intake and cognitive function following endurance exercise amongst a group of 33 recreational runners and walkers. METHODS: All participants (mean age of 43.2 years) took part in a long-distance walking event and completed diet diaries to estimate nutrient intake across three-time periods (previous day, breakfast and during the event). Anthropometric measurements were recorded. Cognitive tests, covering word recall, ruler drop and trail making tests (TMT) A and B were conducted pre- and post-exercise. Participants rated their exercise level on a validated scale. Nutrient intake data were summarised using principal components analysis to identify a nutrient intake pattern loaded towards water intake across all time periods. Regression analysis was used to ascertain relationships between water intake component scores and post-exercise cognitive function, controlling for anthropometric measures and exercise metrics (distance, duration and pace). RESULTS: Participants rated their exercise as 'hard-heavy' (score 14.4, ±3.2). Scores on the water intake factor were associated with significantly faster TMT A (p = 0.001) and TMT B (p = 0.005) completion times, and a tendency for improved short-term memory (p = 0.090). Water intake scores were not associated with simple reaction time (assessed via the ruler drop test). CONCLUSION: These data are congruent with experimental research demonstrating a benefit of hydration on cognitive function. Further field research to confirm this relationship, supported with precise measures of body weight, is needed.

Body composition and hydration status changes in male and female open-water swimmers during an ultra-endurance event.

Body mass changes during ultra-endurance performances have been described for running, cycling and for swimming in a heated pool. The present field study of 20 male and 11 female open-water swimmers investigated the changes in body composition and hydration status during an ultra-endurance event. Body mass, both estimated fat mass and skeletal muscle mass, haematocrit, plasma sodium concentration ([Na(+)]) and urine specific gravity were determined. Energy intake, energy expenditure and fluid intake were estimated. Males experienced significant reductions in body mass (-0.5 %) and skeletal muscle mass (-1.1 %) (P 0.05). Changes in percent body fat, fat mass, and fat-free mass were heterogeneous and did not reach statistical significance (P > 0.05) between gender groups. Fluid intake relative to plasma volume was higher in females than in males during the ultra-endurance event. Compared to males, females' average increase in haematocrit was 3.3 percentage points (pp) higher, urine specific gravity decrease 0.1 pp smaller, and plasma [Na(+)] 1.3 pp higher. The observed patterns of fluid intake, changes in plasma volume, urine specific gravity, and plasma [Na(+)] suggest that, particularly in females, a combination of fluid shift from blood vessels to interstitial tissue, facilitated by skeletal muscle damage, as well as exercise-associated hyponatremia had occurred. To summarise, changes in body composition and hydration status are different in male compared to female open-water ultra-endurance swimmers.

The effects of dehydration during cycling on skeletal muscle metabolism in females.

INTRODUCTION: This study investigated the effects of progressive dehydration on the time course of changes to whole body substrate oxidation and skeletal muscle metabolism during 120 min of cycling in hydrated females. METHODS: Subjects (n=9) cycled for 120 min at ∼65% VO2peak on two occasions: with no fluid (DEH) and with fluid replacement to match sweat losses (HYD). Venous blood samples were taken at rest and every 20 min and muscle biopsies taken at 0, 60 and 120 min of exercise. RESULTS: DEH subjects lost 0.9% body mass (BM) from 0-60 min and 1.1% from 60-120 min (2.0% total). HR and Tc were significantly greater from 30-120 min, Pvol loss from 40-120 min, and RPE from 60-120 min in the DEH trial. There were no differences in VO2 or sweat loss between trials. RER (HYD 0.85 ± 0.01 vs. DEH 0.87 ± 0.01) and total carbohydrate (CHO) oxidation (175 ± 17 vs. 191 ± 17g) were higher in the DEH trial. Blood [La] was significantly higher in the DEH trial with no change in plasma free fatty acid and epinephrine concentrations. Muscle glycogenolysis was 31% greater in the DEH trial (252 ± 49 vs. 330 ± 33 mmol/kg dm) and muscle [La] was also higher at 60 min. CONCLUSION: Progressive dehydration significantly increased HR, Tc, RPE, Pvol loss, whole body CHO oxidation, and muscle glycogenolysis, and these changes were already apparent in the first hour of exercise when BM losses were ≤1%. The increased muscle glycogenolysis with DEH appeared to be due to increased core and muscle temperature, secondary to less efficient movement of heat from the core to the periphery.

Medical sports injuries in the youth athlete: emergency management.

As the number of youth sports participants continues to rise over the past decade, so too have sports related injuries and emergency department visits. With low levels of oversight and regulation observed in youth sports, the responsibility for safety education of coaches, parents, law makers, organizations and institutions falls largely on the sports medicine practitioner. The highly publicized catastrophic events of concussion, sudden cardiac death, and heat related illness have moved these topics to the forefront of sports medicine discussions. Updated guidelines for concussion in youth athletes call for a more conservative approach to management in both the acute and return to sport phases. Athletes younger than eighteen suspected of having a concussion are no longer allowed to return to play on the same day. Reducing the risk of sudden cardiac death in the young athlete is a multi-factorial process encompassing pre-participation screenings, proper use of safety equipment, proper rules and regulations, and immediate access to Automated External Defibrillators (AED) as corner stones. Susceptibility to heat related illness for youth athletes is no longer viewed as rooted in physiologic variations from adults, but instead, as the result of various situations and conditions in which participation takes place. Hydration before, during and after strenuous exercise in a high heat stress environment is of significant importance. Knowledge of identification, management and risk reduction in emergency medical conditions of the young athlete positions the sports physical therapist as an effective provider, advocate and resource for safety in youth sports participation. This manuscript provides the basis for management of 3 major youth emergency sports medicine conditions. FREE FULL-TEXT AVAILABLE IN PUBMED.

Evaluation of a clinical dehydration scale in children requiring intravenous rehydration.

OBJECTIVES: To evaluate the reliability and validity of a previously derived clinical dehydration scale (CDS) in a cohort of children with gastroenteritis and evidence of dehydration. METHODS: Participants were 226 children older than 3 months who presented to a tertiary care emergency department and required intravenous rehydration. Reliability was assessed at treatment initiation, by comparing the scores assigned independently by a trained research nurse and a physician. Validity was assessed by using parameters reflective of disease severity: weight gain, baseline laboratory results, willingness of the physician to discharge the patient, hospitalization, and length of stay. RESULTS: Interobserver reliability was moderate, with a weighted κ of 0.52 (95% confidence interval [CI] 0.41, 0.63). There was no correlation between CDS score and percent weight gain, a proxy measure of fluid deficit (Spearman correlation coefficient = -0.03; 95% CI -0.18, 0.12). There were, however, modest and statistically significant correlations between CDS score and several other parameters, including serum bicarbonate (Pearson correlation coefficient = -0.35; 95% CI -0.46, -0.22) and length of stay (Pearson correlation coefficient = 0.24; 95% CI 0.11, 0.36). The scale's discriminative ability was assessed for the outcome of hospitalization, yielding an area under the receiver operating characteristic curve of 0.65 (95% CI 0.57, 0.73). CONCLUSIONS: In children administered intravenous rehydration, the CDS was characterized by moderate interobserver reliability and weak associations with objective measures of disease severity. These data do not support its use as a tool to dictate the need for intravenous rehydration or to predict clinical course.

Pilot study: Effects of drinking hydrogen-rich water on muscle fatigue caused by acute exercise in elite athletes.

BACKGROUND: Muscle contraction during short intervals of intense exercise causes oxidative stress, which can play a role in the development of overtraining symptoms, including increased fatigue, resulting in muscle microinjury or inflammation. Recently it has been said that hydrogen can function as antioxidant, so we investigated the effect of hydrogen-rich water (HW) on oxidative stress and muscle fatigue in response to acute exercise. METHODS: Ten male soccer players aged 20.9 +/- 1.3 years old were subjected to exercise tests and blood sampling. Each subject was examined twice in a crossover double-blind manner; they were given either HW or placebo water (PW) for one week intervals. Subjects were requested to use a cycle ergometer at a 75 % maximal oxygen uptake (VO2) for 30 min, followed by measurement of peak torque and muscle activity throughout 100 repetitions of maximal isokinetic knee extension. Oxidative stress markers and creatine kinase in the peripheral blood were sequentially measured. RESULTS: Although acute exercise resulted in an increase in blood lactate levels in the subjects given PW, oral intake of HW prevented an elevation of blood lactate during heavy exercise. Peak torque of PW significantly decreased during maximal isokinetic knee extension, suggesting muscle fatigue, but peak torque of HW didn't decrease at early phase. There was no significant change in blood oxidative injury markers (d-ROMs and BAP) or creatine kinease after exercise. CONCLUSION: Adequate hydration with hydrogen-rich water pre-exercise reduced blood lactate levels and improved exercise-induced decline of muscle function. Although further studies to elucidate the exact mechanisms and the benefits are needed to be confirmed in larger series of studies, these preliminary results may suggest that HW may be suitable hydration for athletes. FREE FULL-TEXT IN PUBMED.

Older persons and heat-susceptibility: the role of health promotion in a changing climate.

ISSUE ADDRESSED: Many studies world wide have provided evidence that older persons are a sub-population at increased risk of heat-related morbidity and mortality. This article gives an overview of the current state of knowledge of risk factors and provides commentary on the role of health promotion in the prevention of a climate change-related increase in elderly heat casualties. METHODS: A search of peer-reviewed medical and epidemiological literature and community health websites was conducted in order to gain an in-depth understanding of heat-susceptibility in the elderly and preventive strategies. Key search words included: elderly, aged, older, heat, thermoregulation, heat wave, mortality, heat effects, dehydration, heat-related illness, adaptation, adaptive capacity. RESULTS: The reasons underlying reduced heat tolerance in this group are multi-faceted, comprising physiological, social and behavioural limitations, with comorbidities and polypharmacy being contributing factors. Additionally, some older persons may be unable or reluctant to undertake adaptations necessary to maintain thermal homeostasis due to diminished awareness of the heat, lowered thirst sensation, mobility or cognitive impairments, a lowered perception of risk, or economic concerns. CONCLUSION: With older persons in poor health being particularly vulnerable to heat, preventive messages need to promote protective behaviours and help build resilience as temperatures rise.

Influence of skin type, race, sex, and anatomic location on epidermal barrier function.

The intact skin represents a barrier to the uncontrolled loss of water, proteins, and plasma components from the organism. Owing to its complex structure, the epidermal barrier with its major layer, the stratum corneum, is the rate-limiting unit for the penetration of exogenous substances through the skin. The epidermal barrier is not a static structure. The status of different functions of the epidermis can be monitored by assessing specific biophysical parameters such as transepidermal water loss, stratum corneum hydration, and skin surface pH. Variables originating from the individual as well as exogenous factors have an important influence on the epidermal barrier parameters.

Medical sports injuries in the youth athlete: emergency management.

As the number of youth sports participants continues to rise over the past decade, so too have sports related injuries and emergency department visits. With low levels of oversight and regulation observed in youth sports, the responsibility for safety education of coaches, parents, law makers, organizations and institutions falls largely on the sports medicine practitioner. The highly publicized catastrophic events of concussion, sudden cardiac death, and heat related illness have moved these topics to the forefront of sports medicine discussions. Updated guidelines for concussion in youth athletes call for a more conservative approach to management in both the acute and return to sport phases. Athletes younger than eighteen suspected of having a concussion are no longer allowed to return to play on the same day. Reducing the risk of sudden cardiac death in the young athlete is a multi-factorial process encompassing pre-participation screenings, proper use of safety equipment, proper rules and regulations, and immediate access to Automated External Defibrillators (AED) as corner stones. Susceptibility to heat related illness for youth athletes is no longer viewed as rooted in physiologic variations from adults, but instead, as the result of various situations and conditions in which participation takes place. Hydration before, during and after strenuous exercise in a high heat stress environment is of significant importance. Knowledge of identification, management and risk reduction in emergency medical conditions of the young athlete positions the sports physical therapist as an effective provider, advocate and resource for safety in youth sports participation. This manuscript provides the basis for management of 3 major youth emergency sports medicine conditions.

"Pilot study: Effects of drinking hydrogen-rich water on muscle fatigue caused by acute exercise in elite athletes."

"BACKGROUND: Muscle contraction during short intervals of intense exercise causes oxidative stress, which can play a role in the development of overtraining symptoms, including increased fatigue, resulting in muscle microinjury or inflammation. Recently it has been said that hydrogen can function as antioxidant, so we investigated the effect of hydrogen-rich water (HW) on oxidative stress and muscle fatigue in response to acute exercise. METHODS: Ten male soccer players aged 20.9 +/- 1.3 years old were subjected to exercise tests and blood sampling. Each subject was examined twice in a crossover double-blind manner; they were given either HW or placebo water (PW) for one week intervals. Subjects were requested to use a cycle ergometer at a 75 % maximal oxygen uptake (VO2) for 30 min, followed by measurement of peak torque and muscle activity throughout 100 repetitions of maximal isokinetic knee extension. Oxidative stress markers and creatine kinase in the peripheral blood were sequentially measured. RESULTS:\nAlthough acute exercise resulted in an increase in blood lactate levels in the subjects given PW, oral intake of HW prevented an elevation of blood lactate during heavy exercise. Peak torque of PW significantly decreased during maximal isokinetic knee extension, suggesting muscle fatigue, but peak torque of HW didn't decrease at early phase. There was no significant change in blood oxidative injury markers (d-ROMs and BAP) or creatine kinease after exercise. CONCLUSION:\nAdequate hydration with hydrogen-rich water pre-exercise reduced blood lactate levels and improved exercise-induced decline of muscle function. Although further studies to elucidate the exact mechanisms and the benefits are needed to be confirmed in larger series of studies, these preliminary results may suggest that HW may be suitable hydration for athletes. FULL--TEXT AVAILABLE IN PUBMED."\n

"Skeletal Muscle Strength and Endurance are Maintained during Moderate Dehydration. "

This study investigated the effects of moderate dehydration (~2.5% body weight) on muscle strength and endurance using percutaneous electrical stimulation to quantify central and peripheral fatigue, and isolate the combined effects of exercise-heat stress and dehydration, vs. the effect of dehydration alone. Force production and voluntary activation were calculated in 10 males during 1 brief and 15 repeated maximal voluntary isometric contractions performed prior to (control) walking in the heat (35°C), immediately following exercise, and the next morning (dehydration). The protocol was also performed in a euhydrated state. During the brief contractions, force production and voluntary activation were maintained in all trials. In contrast, force production decreased throughout the repeated contractions, regardless of hydration status (P<0.001). The decline in force was greater immediately following exercise-heat stress dehydration compared with control and euhydration (P<0.001). When dehydration was isolated from acute post-exercise dehydration, force production was maintained similarly to control and euhydration. Despite the progressive decline in force production and the increased fatigability observed during the repeated contractions, voluntary activation remained elevated throughout each muscle function test. Therefore, moderate dehydration, isolated from acute exercise-heat stress, does not appear to influence strength during a single contraction or enhance fatigability.

Sports nutrition knowledge among collegiate athletes, coaches, athletic trainers, and strength and conditioning specialists.

CONTEXT: Coaches, athletic trainers (ATs), strength and conditioning specialists (SCSs), and registered dietitians are common nutrition resources for athletes, but coaches, ATs, and SCSs might offer only limited nutrition information. Little research exists about sports nutrition knowledge and current available resources for nutrition information for athletes, coaches, ATs, and SCSs. OBJECTIVE: To identify resources of nutrition information that athletes, coaches, ATs, and SCSs use; to examine nutrition knowledge among athletes, coaches, ATs, and SCSs; and to determine confidence levels in the correctness of nutrition knowledge questions within all groups. DESIGN: Cross-sectional study. SETTING: National Collegiate Athletic Association Division I, II, and III institutions across the United States. Patients and Other Participants: The 579 participants consisted of athletes (n = 185), coaches (n = 131), ATs (n = 192), and SCSs (n = 71). Main Outcome Measure(s): Participants answered questions about nutrition resources and domains regarding basic nutrition, supplements and performance, weight management, and hydration. Adequate sports nutrition knowledge was defined as an overall score of 75% in all domains (highest achievable score was 100%). RESULTS: Participants averaged 68.5% in all domains. The ATs (77.8%) and SCSs (81.6%) had the highest average scores. Adequate knowledge was found in 35.9% of coaches, 71.4% of ATs, 83.1% of SCSs, and only 9% of athletes. The most used nutrition resources for coaches, ATs, and SCSs were registered dietitians. CONCLUSIONS: Overall, we demonstrated that ATs and SCSs have adequate sports nutrition knowledge, whereas most coaches and athletes have inadequate knowledge. Athletes have frequent contact with ATs and SCSs; therefore, proper nutrition education among these staff members is critical. We suggest that proper nutrition programming should be provided for athletes, coaches, ATs, and SCSs. However, a separate nutrition program should be integrated for ATs and SCSs. This integrative approach is beneficial for the continuity of care, as both categories of professionals might be developing and integrating preventive or rehabilitative programs for athletes.

Travel-Associated Illness in Older Adults (>60 y).

Background. Older individuals represent a substantial proportion of international travelers. Because of physiological changes and the increased probability of underlying medical conditions, older travelers might be at higher risk for at least some travel-associated diseases. Methods. With the aim of describing the epidemiology of travel-associated diseases in older adults, medical data were prospectively collected on ill international travelers presenting to GeoSentinel sites from 1997 to 2009. Seven thousand thirty-four patients aged 60 years and over were identified as older travelers and were compared to 56,042 patients aged 18-45 years, who were used as the young adult reference population. Results. The proportionate morbidity of several etiological diagnoses was higher in older ill travelers compared to younger ill, including notably lower respiratory tract infections, high-altitude pulmonary edema, phlebitis and pulmonary embolism, arthropod bites, severe malaria, rickettsiosis, gastritis, peptic ulcers, esophagitis and gastroesophageal reflux disease, trauma and injuries, urinary tract infections, heart disease, and death. In contrast, acute diarrhea, upper respiratory tract infections, flu and flu-like illnesses, malaria, dengue, genital infections, sexually transmitted diseases, and schistosomiasis proportionate morbidities were lower among the older group. Conclusion. Older ill travelers are more likely to suffer from certain life-threatening diseases and would benefit from reinforcement of specific preventive measures including use of anti-thrombosis compression stockings and sufficient hydration and exercises during long-distance flights, hand hygiene, use of disposable handkerchiefs, consideration of face-masks in crowded conditions, influenza and pneumococcal vaccines, progressive acclimatization to altitude, consideration of acetazolamide, and use of repellents and mosquito nets. Antibiotics for the presumptive treatment of respiratory and urinary tract infections may be considered, as well as antacid medications. At-risk patients should be referred to a specialist for medical evaluation before departing, and optimal control of co-morbidities such as cardiovascular and chronic obstructive pulmonary diseases should be achieved, particularly for high-altitude travel.

"Older persons and heat-susceptibility: the role of health promotion in a changing climate. "

ISSUE ADDRESSED: Many studies worldwide have provided evidence that older persons are a sub-population at increased risk of heat-related morbidity and mortality. This article gives an overview of the current state of knowledge of risk factors and provides commentary on the role of health promotion in the prevention of a climate change-related increase in elderly heat casualties. METHODS: A search of peer-reviewed medical and epidemiological literature and community health websites was conducted in order to gain an in-depth understanding of heat-susceptibility in the elderly and preventive strategies. Key search words included: elderly, aged, older, heat, thermoregulation, heat wave, mortality, heat effects, dehydration, heat-related illness, adaptation, adaptive capacity. RESULTS: The reasons underlying reduced heat tolerance in this group are multi-faceted, comprising physiological, social and behavioural limitations, with comorbidities and polypharmacy being contributing factors. Additionally, some older persons may be unable or reluctant to undertake adaptations necessary to maintain thermal homeostasis due to diminished awareness of the heat, lowered thirst sensation, mobility or cognitive impairments, a lowered perception of risk, or economic concerns. CONCLUSION: With older persons in poor health being particularly vulnerable to heat, preventive messages need to promote protective behaviours and help build resilience as temperatures rise.

Evaluation of a Clinical Dehydration Scale in Children Requiring Intravenous Rehydration.

OBJECTIVES: To evaluate the reliability and validity of a previously derived clinical dehydration scale (CDS) in a cohort of children with gastroenteritis and evidence of dehydration. METHODS: Participants were 226 children older than 3 months who presented to a tertiary care emergency department and required intravenous rehydration. Reliability was assessed at treatment initiation, by comparing the scores assigned independently by a trained research nurse and a physician. Validity was assessed by using parameters reflective of disease severity: weight gain, baseline laboratory results, willingness of the physician to discharge the patient, hospitalization, and length of stay. RESULTS: Interobserver reliability was moderate, with a weighted κ of 0.52 (95% confidence interval [CI] 0.41, 0.63). There was no correlation between CDS score and percent weight gain, a proxy measure of fluid deficit (Spearman correlation coefficient = -0.03; 95% CI -0.18, 0.12). There were, however, modest and statistically significant correlations between CDS score and several other parameters, including serum bicarbonate (Pearson correlation coefficient = -0.35; 95% CI -0.46, -0.22) and length of stay (Pearson correlation coefficient = 0.24; 95% CI 0.11, 0.36). The scale's discriminative ability was assessed for the outcome of hospitalization, yielding an area under the receiver operating characteristic curve of 0.65 (95% CI 0.57, 0.73). CONCLUSIONS: In children administered intravenous rehydration, the CDS was characterized by moderate interobserver reliability and weak associations with objective measures of disease severity. These data do not support its use as a tool to dictate the need for intravenous rehydration or to predict clinical course.

"Dehydration treatment practices among pediatrics-trained and non-pediatrics trained emergency physicians. "

OBJECTIVES: We sought to survey emergency physicians in the United States regarding the management of pediatric dehydration secondary to acute gastroenteritis. We hypothesized that responses from physicians with dedicated pediatric training (PT), that is, board certification in pediatrics or pediatric emergency medicine, would differ from responses of physicians with no dedicated pediatric training (non-PT). METHODS: An anonymous survey was mailed to randomly selected members of the American College of Emergency Physicians and sent electronically to enrollees of Brown University pediatric emergency medicine listserv. The survey consisted of 17 multiple-choice questions based on a clinical scenario depicting a 2-year-old with acute gastroenteritis and moderate dehydration. Questions asked related to treatment preferences, practice setting, and training information. RESULTS: One thousand sixty-nine surveys were received: 997 surveys were used for data analysis, including 269 PT physicians and 721 non-PT physicians. Seventy-nine percent of PT physicians correctly classified the scenario patient as moderately dehydrated versus 71% of non-PT physicians (P = 0.063). Among those who correctly classified the patient, 121 PT physicians (58%) and 350 non-PT physicians (68%) would initially hydrate the patient with intravenous fluids. Pediatrics-trained physicians were more likely to initially choose oral or nasogastric hydration compared with non-PT physicians (P = 0.0127). Pediatrics-trained physicians were less likely to perform laboratory testing compared with the non-PT group (n = 92, 45%, vs n = 337, 66%; P < 0.0001). CONCLUSIONS: Contrary to established recommendations for the management of moderately dehydrated children, significantly more PT physicians, compared with non-PT physicians, follow established guidelines.

"Dehydration at admission increased the need for dialysis in hemolytic uremic syndrome children."

BACKGROUND: Oligoanuric forms of postdiarrheal hemolytic uremic syndrome (D+ HUS) usually have more severe acute stage and higher risk of chronic sequelae than nonoligoanuric forms. During the diarrheal phase, gastrointestinal losses could lead to dehydration with pre-renal injury enhancing the risk of oligoanuric D+ HUS. Furthermore, it had been shown that intravenous volume expansion during the prodromal phase could decrease the frequency of oligoanuric renal failure. Thus, we performed this retrospective study to determine whether dehydration on admission is associated with increased need for dialysis in D+ HUS patients. CASE-DIAGNOSIS/ TREATMENT: Data from 137 children was reviewed, which were divided into two groups according to their hydration status at admission: normohydrated (n = 86) and dehydrated (n = 51). Laboratory parameters of the dehydrated patients reflected expected deteriorations (higher urea, higher hematocrit and lower sodium, bicarbonate, and pH) than normohydrated ones. Likewise, the dehydrated group had a higher rate of vomiting and need for dialysis (70.6 versus 40.7 %, p = 0.0007). CONCLUSIONS: Our data suggests that dehydration at hospital admission might represent a concomitant factor aggravating the intrinsic renal disease in D+ HUS patients increasing the need for dialysis. Therefore, the early recognition of patients at risk of D+ HUS is encouraged to guarantee a well-hydrated status.

"The epidemiology of hypernatraemia in hospitalised children in Lothian: a 10-year study showing differences between dehydration, osmoregulatory dysfunction and salt poisoning. "

INTRODUCTION: The relative frequencies of the causes of hypernatraemia in children after the neonatal period are unknown. Salt poisoning and osmoregulatory dysfunction are extremely rare and potentially fatal. In this retrospective 10-year study, the incidence, causes and differential biochemistry of hypernatraemia in children is examined. METHODS: Children with hypernatraemia (sodium ≥150 mmol/litre) aged >2 weeks to 17 years were identified from laboratory data of two paediatric departments serving the Lothian region of Scotland. A review of patient notes established time of onset and cause. Denominator data were available from the Scottish Health Service. RESULTS: On admission to hospital, 1 in 2288 children (1:1535 admitted as an emergency) had hypernatraemia. This is 1 in 30 563 Lothian children <17 years. Overall 0.04% hospital stays had an episode of hypernatraemia. In 45 children admitted with 64 separate episodes (11 from a case of salt poisoning), the commonest cause was dehydration secondary to either gastroenteritis or systemic infection; 31% had an underlying chronic neurological disorder. A total of 177 further cases developed hypernatraemia after admission. The commonest causes were dehydration secondary to severe systemic infection and postoperative cardiac surgery. Urine sodium:creatinine ratio and fractional excretion of sodium were both much higher in the salt poisoning case than in a child with osmoregulatory dysfunction or children with simple dehydration. CONCLUSIONS: Hypernatraemia after 2 weeks of age is uncommon, and on admission is usually associated with dehydration. Salt poisoning and osmoregulatory dysfunction are rare but should be considered in cases of repeated hypernatraemia without obvious cause. Routine measurement of urea, creatinine and electrolytes on paired urine and plasma on admission will differentiate these rare causes.

"Effect of intermittent rehydration therapy as an oral and enteral rehydration solution, alone or in combination with intravenous administration on intravascular dehydration. "

Aim: The purpose of this study was to demonstrate the effectiveness of intermittent fluid infusion (intermittent rehydration therapy) to dehydrated elderly patients and the efficacy of Heisei Solution Water (HSW), an oral and enteral rehydration solution developed by our group. Methods: We enrolled 375 elderly patients with suspected dehydration from among 1,921 patients of our hospital and 13 affiliated hospitals. A total of 36 of 375 patients received intermittent rehydration therapy. These patients were then divided into 3 groups according to the method of administration: (1) oral and enteral administration (n=16), (2) intravenous administration only (n=10) and (3) combined oral, enteral and intravenous administration (n=10). We then compared blood urea nitrogen/creatinine (BUN/Cr) ratios among the 3 groups. Results: BUN/Cr ratios were improved in all groups, but there was no statistically significant difference in the degree of improvement of BUN/Cr ratios among the 3 groups. Conclusion: Intermittent rehydration therapy is a highly effective way to manage dehydration. The intermittent oral and enteral administration of HSW demonstrated the same effectiveness as other forms of administration. FULL-TEXT AVAILABLE IN PUBMED.

Does anticipatory sweating occur prior to fluid consumption?

The purpose of this study was to examine if anticipatory sweating occurs prior to fluid consumption in dehydrated subjects. It was hypothesized that there would first be an anticipatory response to the sight of water, and then with drinking, a second response caused by mechanical stimulation of oropharyngeal nerves. Dehydrated subjects (n=19) sat in a heat chamber for 30 minutes. At minute 15, a resistance hygrometer capsule was attached and sweat rate was measured every 3 seconds. At minute 35:00, a researcher entered the room with previously measured water (2 ml/kg euhydrated body weight). At minute 35:30, the subject was allowed to drink. Data collection continued for 5 minutes post consumption. As expected, 16 of the 19 subjects responded to oropharyngeal stimuli with increased sweat rate. However, the new finding was that a majority (12 of 19) also showed an anticipatory sweating response prior to fluid consumption. Subjects were divided into 4 groups based on the magnitude of the sweating response. Strong responders' (n=4) anticipatory response accounted for 50% or more of the total change in sweat rate. Moderate responders' (n=4) anticipatory response accounted for 20%-49%. Weak responders' (n=4) anticipatory response accounted for 6-20%. Finally, non-responders (n=7) showed no anticipatory response. Although previously noted anecdotally in the literature, the current study is the first to demonstrate that measurable anticipatory sweating occurs prior to fluid intake in dehydrated subjects in a significant percentage of the population. Such data suggests that cerebral input, like oropharyngeal stimulation, can temporarily remove the dehydration-induced inhibition of sweating. FULL-TEXT AVAILABLE IN PUBMED.

Hydration and cognitive performance.

A clinical link exists between severe dehydration and cognitive performance. Using rapid and severe water loss induced either by intense exercise and/or heat stress, initial studies suggested there were alterations in short-term memory and cognitive function related to vision, but more recent studies have not all confirmed these data. Some studies argue that water loss is not responsible for the observations made, and studies compensating water losses have failed to prevent the symptoms. Studies in children have suggested that drinking extra water helps cognitive performance, but these data rely on a small number of children. In older adults (mean age around 60) the data are not strong enough to support a relationship between mild dehydration and cognitive function. Data on frail elderly and demented people are lacking. Methodological heterogeneity in these studies are such that the relationship between mild dehydration and cognitive performance cannot be supported.

Hydration assessment using the cardiovascular response to standing.

The cardiovascular response to standing (sit-to-stand change in heart rate; SSΔHR) is commonly employed as a screening tool to detect hypohydration (body water deficit). No study has systematically evaluated SSΔHR cut points using different magnitudes or different types of controlled hypohydration. The objective of this study was to determine the diagnostic accuracy of the often proposed 20 b/min SSΔHR cut point using both hypertonic and isotonic models of hypohydration. Thirteen healthy young adults (8M, 5F) underwent three bouts of controlled hypohydration. The first bout used sweating to elicit large losses of body water (mass) (>3 % sweat). The second two bouts were matched to elicit 3 % body mass losses (3 % diuretic; 3 % sweat). A euhydration control trial (EUH) was paired with each hypohydration trial for a total of six trials. Heart rate was assessed after 3-min sitting and after 1-min standing during all trials. SSΔHR was compared among trials, and receiver operator characteristic curve analysis was used to determine diagnostic accuracy of the 20 b/min SSΔHR cut point. Volunteers lost 4.5 ± 1.1, 3.0 ± 0.6, and 3.2 ± 0.6 % body mass during >3 % sweat, 3 % diuretic, and 3 % sweat trials, respectively. SSΔHR (b/min) was 9 ± 8 (EUH), 20 ± 12 (>3 % sweat; P < 0.05 vs. EUH), 17 ± 7 (3 % diuretic; P < 0.05 vs. EUH), and 13 ± 11 (3 % sweat). The 20 beats/min cut point had high specificity (90 %) but low sensitivity (44 %) and overall diagnostic accuracy of 67 %. SSΔHR increased significantly in response to severe hypertonic hypohydration and moderate isotonic hypohydration, but not moderate hypertonic hypohydration. However, the 20 beats/min cut point afforded only marginal diagnostic accuracy.

"The Meaning of Parenteral Hydration to Family Caregivers and Patients With Advanced Cancer Receiving Hospice Care. "

CONTEXT: In the U.S., patients with advanced cancer who are dehydrated or have decreased oral intake almost always receive parenteral hydration in acute care facilities but rarely in the hospice setting. OBJECTIVES: To describe the meaning of hydration for terminally ill cancer patients in home hospice care and for their primary caregivers. METHODS: Phenomenological interviews were conducted at two time points with 85 patients and 84 caregivers enrolled in a randomized, double-blind, controlled trial examining the efficacy of parenteral hydration in patients with advanced cancer receiving hospice care in the southern U.S. Transcripts were analyzed hermeneutically by the interdisciplinary research team until consensus on the theme labels was reached. RESULTS: Patients and their family caregivers saw hydration as meaning hope and comfort. Hope was the view that hydration might prolong a life of dignity and enhance quality of life by reducing symptoms such as fatigue and increasing patients' alertness. Patients and caregivers also described hydration as improving patients' comfort by reducing pain; enhancing the effectiveness of pain medication; and nourishing the body, mind, and spirit. CONCLUSION: These findings differ from traditional hospice beliefs that dehydration enhances patient comfort, given that patients and their families in the study viewed fluids as enhancing comfort, dignity, and quality of life. Discussion with patients and families about their preferences for hydration may help tailor care plans to meet specific patient needs.

"Decreased lactate and potassium levels in natural moisturizing factor from the stratum corneum of mild atopic dermatitis patients are involved with the reduced hydration state "

BACKGROUND: Atopic dermatitis (AD) shows dry skin. Water-soluble, low molecular weight components, collectively known as natural moisturizing factor (NMF), play an important role in maintaining the stratum corneum (SC) hydration. Previous studies focused on reduced levels of free amino acids (FAAs) in NMF from AD skin. It remains unknown, however, whether other NMF components are also altered in AD. OBJECTIVE: To characterize the levels of various NMF components in the SC of healthy subjects and in mild AD adult patients. METHODS: NMF components were extracted from three sequential tape-stripped SC samples obtained from the volar forearm. NMF components which were decreased in AD skin were topically applied to examine their contribution to SC moisturization in AD skin. RESULTS: We found that although FAAs levels were not remarkably reduced, levels of pyrrolidone carboxylic acid (PCA), lactate, urea, sodium and potassium were significantly decreased in NMF from mild AD skin. Among those components, only the topical application of potassium lactate effectively increased skin surface hydration indicating that reductions of lactate and potassium influence dry skin in mild AD patients. Unlike the distribution of filaggrin-derived FAAs and PCA, lactate, urea, potassium and sodium were abundant in the surface layer of the SC compared with the inner layer of the SC. Such findings strongly suggest that those components are supplied from outside the SC, i.e. they originate from sweat. CONCLUSION: The reduced levels of sweat-derived NMF components in mild AD patients suggests that impaired sweat function might in part result in the SC dryness.



Dipstick measurements of urine specific gravity are unreliable.

AIM:To evaluate the reliability of dipstick measurements of urine specific gravity (U-SG). METHODS: Fresh urine specimens were tested for urine pH and osmolality (U-pH, U-Osm) by a pH meter and an osmometer, and for U-SG by three different methods (refractometry, automatic readout of a dipstick (Clinitek-50), and (visual) change of colour of the dipstick). RESULTS: The correlations between the visual U-SG dipstick measurements and U-SG determined by a refractometer and the comparison of Clinitek((R))-50 dipstick U-SG measurements with U-Osm were less than optimal, showing very wide scatter of values. Only the U-SG refractometer values and U-Osm had a good linear correlation. The tested dipstick wasunreliable for the bedside determination of U-SG, even after correction for U-pH, as recommended by the manufacturer. CONCLUSIONS: Among the bedside determinations, only refractometry gives reliable U-SG results. Dipstick U-SGmeasurements should be abandoned.

Assessing hydration status.

PURPOSE:Understanding the importance of euhydration in humans in order to ensure good health in various situations, the purpose of this review is to examine the available techniques in assessing hydration status. RECENT FINDINGS: During the past 20 years, many indices have been developed to assess hydration levels accurately in humans. Changes in body weight, haematological and urine parameters, bioelectrical impedance, skinfold thickness, heart rate and blood pressure changes are among these indices. Plasma osmolality, urine osmolality and urine specific gravity are the most widely used markers of hydration. However, urine colour has also been used with reasonable accuracy when laboratory analysis is not available or when a quick estimate of hydration is necessary. Some data indicate that urine colour is as good indicator of hydration as plasma or urine osmolality or urine specific gravity. SUMMARY: Although there is no 'gold standard' for assessment of hydration status, it appears that changes in body weight, along with urine osmolality, specific gravity, conductivity and colour are among the most widely used indices. Furthermore, they provide reasonable results, especially when the analysis is based on the first morning urine sample

The Influence of Personality and Health Beliefs on Maintaining Proper Hydration

The present study was designed to examine factors that could facilitate or impede adherence to proper hydration. Forty volunteers (20 male, 20 female) were randomly assigned to one of two groups: Informed Group (n = 20) and Uninformed Group (n = 20). Bioelectrical impedance was used to measure intracellular (ICW) and extracellular (ECW) body water at Time 1 and 2. Personality, health beliefs, and health behaviors inventories were administered at Time 1. A health information brochure on proper hydration and consequences of poor hydration was given to the Informed Group. All participants were given six 1-liter bottles of water and drank two bottles per day. Both ICW, F(1,38) = 4.79, p < .05, and ECW, F(1,38) = 10.12, p < .005, significantly increased for both groups, and females had significantly greater changes than males in ECW, F(1,38) = 4.43, p < .05, and ICW, F(1,38) = 4.48, p < .05. Health information had no significant effect on female adherence but was a significant predictor of male adherence,  = .266, p < .05. Agreeableness, r = .36, p < .05, and social desirability, r = .33, p < .05, were the only personality factors related to change in ECW for the group as a whole. Health beliefs were unrelated to adherence, but general health concern,  = –.–.053, p < .05, was a significant predictor of change in ECW for males, although it was an inverse relationship.

Human hydration indices: acute and longitudinal reference values.

It is difficult to describe hydration status and hydration extremes because fluid intakes and excretion patterns of free-living individuals are poorly documented and regulation of human water balance is complex and dynamic. This investigation provided reference values for euhydration (i.e.; body mass; daily fluid intake; serum osmolality; M +/- SD); it also compared urinary indices in initial morning samples and 24-hr collections. Five observations of 59 healthy; active men (age 22 +/- 3 yr; body mass 75.1 +/- 7.9 kg) occurred during a 12-d period. Participants maintained detailed records of daily food and fluid intake and exercise. Results indicated that the mean total fluid intake in beverages; pure water; and solid foods was >2.1 L/24 hr (range 1.382-3.261; 95% confidence interval 0.970-3.778 L/24 hr); mean urine volume was >1.3 L/24 hr (0.875-2.250 and 0.675-3.000 L/24 hr); mean urine specific gravity was >1.018 (1.011-1.027 and 1.009-1.030); and mean urine color was > or = 4 (4-6 and 2-7). However; these men rarely (0-2% of measurements) achieved a urine specific gravity below 1.010 or color of 1. The first morning urine sample was more concentrated than the 24-h urine collection; likely because fluids were not consumed overnight. Furthermore; urine specific gravity and osmolality were strongly correlated (r2 = .81-.91; p < .001) in both morning and 24-hr collections. These findings provide euhydration reference values and hydration extremes for 7 commonly used indices in free-living; healthy; active men who were not exercising in a hot environment or training strenuously.

Sex difference of urinary osmolality in German children.

BACKGROUND/AIMS: Origin of sex difference in urinary osmolality. METHODS: In 495 healthy children aged 4.0-14.9 years participating in the DONALD (Dortmund Nutritional and Anthropometric Longitudinally Designed) study (247 boys, 248 girls), the water intake recorded in 24-hour weighed dietary records along with urinary volume, osmolality and free water reserve in 24-hour urine samples from the same day as the dietary record were determined. RESULTS: Boys showed a significantly higher energy intake, total water intake, urinary osmolality and osmolar load than girls but no increase in urinary volume. When referred to energy intake, mean urinary volume and mean free water reserve were significantly higher in girls than boys. Girls could have a preference for food with a higher water density and lower non-renal water losses. CONCLUSION: German girls of the DONALD study displayed a lower urinary osmolality than German boys due to a relatively higher urinary volume. The sex difference could be caused by a higher water density of the ingested food (ml/kcal) and a lower insensible water loss (ml/kcal) in girls than boys.

Problem: thirst, drinking behavior, and involuntary dehydration.

The phenomenon of involuntary dehydration, the delay in full restoration of a body water deficit by drinking, has been described extensively but relatively little is known about its physiological mechanism. It occurs primarily in humans when they are exposed to various stresses including exercise, environmental heat and cold, altitude, water immersion, dehydration, and perhaps microgravity, singly and in various combinations. The level of involuntary dehydration is approximately proportional to the degree of total stress imposed on the body. Involuntary dehydration appears to be controlled by more than one factor including social customs that influence what is consumed, the capacity and rate of fluid absorption from the gastrointestinal system, the level of cellular hydration involving the osmotic-vasopressin interaction with sensitive cells or structures in the central nervous system, and, to a lesser extent, hypovolemic-angiotensin II stimuli. Since humans drink when there is no apparent physiological stimulus, the psychological component should always be considered when investigating the total mechanisms for drinking.

Effects of athletes' muscle mass on urinary markers of hydration status.

To determine if athletes' muscle mass affects the usefulness of urine specific gravity (U(sg)) as a hydration index. Nine rugby players and nine endurance runners differing in the amount of muscle mass (42 +/- 6 vs. 32 +/- 3 kg, respectively; P = 0.0002) were recruited. At waking during six consecutive days, urine was collected for U (sg) analysis, urine osmolality (U(osm)), electrolytes (U[Na+], U[K+] and U[Cl-]) and protein metabolites (U([Creatinine]), U([Urea]) and U([Uric acid])) concentrations. In addition, fasting blood serum osmolality (S(osm)) was measured on the sixth day. As averaged during 6 days, U(sg) (1.021 +/- 0.002 vs. 1.016 +/- 0.001), U(osm) (702 +/- 56 vs. 554 +/- 41 mOsmol kg(-1) H(2)O), U([Urea]) (405 +/- 36 vs. 302 +/- 23 mmol L(-1)) and U([Uric acid]) (2.7 +/- 0.3 vs. 1.7 +/- 0.2 mmol L(-1)) were higher in rugby players than runners (P 1.020) despite S (osm) being below 290 mOsmol kg(-1) H(2)O in all participants. A positive correlation was found between muscle mass and urine protein metabolites (r = 0.47; P = 0.04) and between urine protein metabolites and U(sg) (r = 0.92; P < 0.0001). In summary, U(sg) specificity to detect hypohydration was reduced in athletes with large muscle mass. Our data suggest that athletes with large muscle mass (i.e., rugby players) are prone to be incorrectly classified as hypohydrated based on U(sg).

Markers of hydration status.

This paper reviews the literature, describes and discusses methods by which whole body hydration status can be determined in humans. A method of determining whether or not an individual is hypohydrated is of particular significance in an exercise situation as even moderate levels of hypohydration have a negative impact on exercise performance. Inspection of the published literature indicates that a number of methods have been used to determine hydration status. Body mass changes, urinary indices (volume, colour, protein content, specific gravity and osmolality), blood borne indices (haemoglobin concentration, haematocrit, plasma osmolality and sodium concentration, plasma testosterone, adrenaline, noradrenaline, cortisol and atrial natiuretic peptide), bioelectrical impedance analysis, and pulse rate and systolic blood pressure response to postural change are discussed. The urinary measures of colour, specific gravity and osmolality are more sensitive at indicating moderate levels of hypohydration than are blood measurements of hematocrit and serum osmolality and sodium concentration. Currently no "gold standard" hydration status marker exists, particularly for the relatively moderate levels of hypohydration that frequently occur in an exercise situation. The choice of marker for any particular situation will be influenced by the sensitivity and accuracy with which hydration status needs to be established together with the technical and time requirements and expense involved.

Markers of hydration status.

Many indices have been investigated to establish their potential as markers of hydration status. Body mass changes, blood indices, urine indices and bioelectrical impedance analysis have been the most widely investigated. The current evidence and opinion tend to favour urine indices, and in particular urine osmolality, as the most promising marker available.

Biological variation and diagnostic accuracy of dehydration assessment markers.

BACKGROUND: Well-recognized markers for static (one time) or dynamic (monitoring over time) dehydration assessment have not been rigorously tested for their usefulness in clinical, military, and sports medicine communities. OBJECTIVE: This study evaluated the components of biological variation and the accuracy of potential markers in plasma, urine, saliva, and body mass (B(m)) for static and dynamic dehydration assessment. DESIGN: We studied 18 healthy volunteers (13 men and 5 women) while carefully controlling hydration and numerous preanalytic factors. Biological variation was determined over 3 consecutive days by using published methods. Atypical values based on statistical deviations from a homeostatic set point were examined. Measured deviations in body fluid were produced by using a separate, prospective dehydration experiment and evaluated by receiver operating characteristic (ROC) analysis to quantify diagnostic accuracy. RESULTS: All dehydration markers displayed substantial individuality and one-half of the dehydration markers displayed marked heterogeneity of intraindividual variation. Decision levels for all dehydration markers were within one SD of the ROC criterion values, and most levels were nearly identical to the prospective group means after volunteers were dehydrated by 1.8-7.0% of B(m). However, only plasma osmolality (P(osm)) showed statistical promise for use in the static dehydration assessment. A diagnostic decision level of 301 plus mn 5 mmol/kg was proposed. Reference change values of 9 mmol/kg (P(osm)), 0.010 [urine specific gravity (U(sg))], and 2.5% change in B(m) were also statistically valid for dynamic dehydration assessment at the 95% probability level. CONCLUSIONS: P(osm) is the only useful marker for static dehydration assessment. P(osm), U(sg), and B(m) are valid markers in the setting of dynamic dehydration assessment. FULL-TEXT AVAILABLE IN PUBMD

Comparison of 3 Methods to Assess Urine Specific Gravity in Collegiate Wrestlers.

OBJECTIVE: To investigate the reliability and validity of refractometry, hydrometry, and reagent strips in assessing urine specific gravity in collegiate wrestlers. DESIGN AND SETTING: We assessed the reliability of refractometry, hydrometry, and reagent strips between 2 trials and among 4 testers. The validity of hydrometry and reagent strips was assessed by comparison with refractometry, the criterion measure for urine specific gravity. SUBJECTS: Twenty-one National Collegiate Athletic Association Division III collegiate wrestlers provided fresh urine samples. MEASUREMENTS: Four testers measured the specific gravity of each urine sample 6 times: twice by refractometry, twice by hydrometry, and twice by reagent strips. RESULTS: Refractometer measurements were consistent between trials (R =.998) and among testers; hydrometer measurements were consistent between trials (R =.987) but not among testers; and reagent-strip measurements were not consistent between trials or among testers. Hydrometer (1.018 +/- 0.006) and reagent-strip (1.017 +/- 0.007) measurements were significantly higher than refractometer (1.015 +/- 0.006) measurements. Intraclass correlation coefficients were moderate between refractometry and hydrometry (R =.869) and low between refractometry and reagent strips (R =.573). The hydrometer produced 28% false positives and 2% false negatives, and reagent strips produced 15% false positives and 9% false negatives. CONCLUSIONS: Only the refractometer should be used to determine urine specific gravity in collegiate wrestlers during the weight-certification process.


Effect of preexercise electrolyte ingestion on fluid balance in men and women.

PURPOSE: This article aimed to study the effect of preexercise ingestion of an electrolyte-containing beverage and meal on fluid balance during exercise in men and women. METHODS: Twenty healthy, college-aged people (10 males, 10 females; mean +/- SD = 51.2 +/- 9.8 mL x kg x min(-1)) exercised at 58 +/- 4% V O 2 peak for 90 min, 45 min after ingesting 355 mL of chicken noodle soup (SOUP; 167 mmol x L(-1) Na +), carbohydrate-electrolyte beverage (CE; 16 mmol x L(-1) Na+), or water (WATER). After 90 min of exercise, participants completed a physical performance task (PPT) consisting of the calculated work that would be completed in 30 min at 60% V O 2 peak (n = 19). Water was allowed ad libitum throughout all trials. RESULTS: Fluid balance was improved in SOUP compared with WATER (-251 +/- 418 vs -657 +/- 593 g, respectively; P = 0.002) because of greater water intake and retention throughout the trial. Water intake was also greater in CE compared with WATER mostly because of an increase during the PPT. Plasma osmolality increased after ingestion of SOUP and remained elevated throughout exercise compared with both CE and WATER. Men and women had similar fluid balance results, with women having lower relative water intake and evaporative water losses compared with men. Physical performance was similar in all trials. CONCLUSIONS: SOUP ingested before exercise improves fluid balance because of increased ad libitum water intake and reduced proportional urinary water loss. The increase in water intake and, subsequently, the improved fluid balance may be because of a greater plasma osmolality before and throughout exercise.

Voluntary dehydration among elementary school children residing in a hot arid environment

BACKGROUND: Voluntary dehydration is a condition where humans do not drink appropriately in the presence of an adequate fluid supply. This may adversely affect their physical and intellectual performance. The present study aimed to describe the prevalence of voluntary dehydration among elementary school children of different ethnicities and countries of birth. METHODS: Four hundred and twenty-nine elementary school children; aged 8-10 years; from four subpopulations (Israeli-born Jewish and Bedouin-Arab children; and immigrant children who recently arrived to Israel from Eastern Europe and from Ethiopia) were studied. The level of dehydration was determined by noontime urine osmolality; from samples taken over 1 week in mid-summer. Urine osmolality <500 mOsmol kg(-1) H(2)O was considered to be an appropriate level of hydration. RESULTS: Mean urine osmolality was 862 +/- 211 mOsmol kg(-1) H(2)O. Osmolality above 800 mOsmol kg(-1) H(2)O was detected in 67.5% of the urine samples; among these; 25% were above 1000 mOsmol kg(-1) H(2)O. The most dehydrated group was that of Israeli-born Jewish children; whereas the Bedouin-Arab children were the least dehydrated. CONCLUSIONS: A high proportion of children who reside in a hot and arid environment were found to be in a state of moderate to severe dehydration. Bedouin ethnicity was associated with better hydration; whereas Israeli-born Jews were most severely dehydrated. Educational intervention programmes promoting water intake should start in early childhood and continue throughout life.

Effects of Ramadan upon fluid and food intake, fatigue, and physical, mental, andsocial activities: a comparison between the UK and Libya.

Two studies were performed during Ramadan, one in the UK (N=31) and the other in Libya (N=33). The aims were to assess some changes to lifestyle that are produced by fasting as well as effects due to culture. Subjects were studied on eight separate occasions: four control days (two before and two after Ramadan) and four days during the four weeks of Ramadan itself. A questionnaire was answered that asked about naps and fluid and food intake. The questions elicited if an individual had slept, drank, or eaten, plus the reasons for doing or not doing so. Also, subjects were asked to describe their physical, mental, and social activities, their fatigue, and their perceived abilities to perform physical or mental work. The questionnaire was answered five times per day: at sunrise, at 10:00 h, at 14:00 h, at sunset, and on retiring to sleep at night. Urine samples were collected at sunset and measured for osmolality. Differences between control and Ramadan days, as well as between subjects studied in UK and Libya, were assessed by analysis of variance. Correlations between fatigue and physical, mental, and social activities were also assessed, as were differences in urine osmolality. Fasting during Ramadan resulted in fewer activities and increased fatigue and frequency of napping during daytime. Changes in fluid and food intake indicated some degree of preparation for fasting before sunrise and a marked "recuperation" from fasting after sunset. The reasons given for napping in the daytime, for drinking or not drinking, and for eating or not eating, changed during Ramadan compared with control days; as a result, links between fatigue and activities, and fatigue and fluid and food intake, were all altered during Ramadan, particularly after sunset. Subjects become dehydrated during the daytime, but this was not reduced when females who were menstruating drank during this time. Several differences between the two studies were found. There was a greater frequency of napping during the daytime in the Libya study, and evidence for the conservation of energy during the daytime and reduced physical, mental, and social activities. Subjects' preparations for fasting and recovering from it--their fluid and food intakes and associated reasons for these--also differed. Possible explanations of these differences are discussed.

Influence of diuretic-induced dehydration on competitive running performance.

A diuretic drug (40 mg of furosemide) was utilized to study the effects of dehydration (D) on competitive running performance, without prior thermal or exercise stress. Eight men competed in randomized races of 1,500, 5,000, and 10,000 m, while normally hydrated (H) and with mean plasma volume reductions of 9.9, 12.3, and 9.9%, respectively. As a result of the reduced body water (change in body weight = -1.9, -1.6, and -2.1%), mean outdoor performance times on a running track increased 0.16 min, 1.31 min (P less than 0.05), and 2.62 min (P less than 0.05) in the 1,500-m, 5,000-m, and 10,000-m trials. Running performance decrements due to dehydration were more strongly correlated with changes in body weight (r = -0.79, -0.65, and -0.40) than with urine volume or plasma volume differences. In addition, subjects were studied during submaximal and maximal treadmill exercise while H and D (mean change in plasma volume = -7.1%). Neither submaximal nor maximal oxygen uptake was significantly altered (P greater than 0.05) as a consequence of D. Mean treadmill run time to volitional exhaustion was reduced by 41.4 s (P less than 0.05) during the D treadmill trial. Therefore, it appears that competitive performance in trials of long duration (5,000 and 10,000 m) was affected to a greater extent by D than the shorter 1,500-m event, even though submaximal and maximal oxygen uptake was not altered.

Influence of water drinking on resting energy expenditure in overweight children.

BACKGROUND: It was previously demonstrated that drinking water significantly elevates the resting energy expenditure(REE) in adults, and that low water intake is associated with obesity and lesser success in weight reduction. This study addressed the potential of water drinking to increase the REE in children, as an additional tool for weight management. OBJECTIVE: To examine the effect of drinking water on the REE of overweight children. DESIGN: A total of 21 overweight, otherwise-healthy children (age 9.9±1.4 years, 11 males) drank 10 ml kg(-1) cold water (4 °C). REE was measured before and after water ingestion, for 66 min. The main outcome measure was the change in mean REE from baseline values. RESULTS: Immediately after drinking water, there was a transient decrease in REE, from a baseline value of 3.32±1.15 kilojoule (kJ) per min to 2.56±0.66 kJ per min at minute 3 (P=0.005). A subsequent rise in REE was then observed, which was significantly higher than baseline after 24 min (3.89±0.78 kJ/min (P=0.021)), and at most time points thereafter. Maximal mean REE values were seen at 57 min after water drinking (4.16±1.43 kJ per min (P=0.004)), which were 25% higher than baseline. REE was significantly correlated with age, height, weight and fat-free mass; the correlations with maximal REE values after water drinking were stronger than with baseline REE values. CONCLUSIONS: This study demonstrated an increase of up to 25% in REE following the drinking of 10 ml kg(-1) of cold water in overweight children, lasting for over 40 min. Consuming the recommended daily amount of water for children could result in an energy expenditure equivalent to an additional weight loss of about 1.2 kg per year. These findings reinforce the concept of water-induced REE elevation shown in adults, suggesting that water drinking could assist overweight children in weight loss or maintenance, and may warrant emphasis in dietary guidelines against the obesity epidemic.

Drinking water with a meal: a simple method of coping with feelings of hunger,satiety and desire to eat.

This study examined whether drinking of water with breakfast affects the feelings of satiety and hunger, and how long after the meal this effect is maintained. Eight healthy, normal-weight women had three breakfasts with two extra glasses (4 dl) of water and three similar breakfasts without water. The breakfasts were served on three successive mornings during a 2 week period. The subjects filled in forms with visual analogue scales on feelings of hunger, satiety and desire to eat. The forms were filled just before the breakfast, in the middle of the breakfast before and after drinking of water, after finishing the meal, and thereafter every 30 min until 11.15 a.m. The results show that drinking two glasses of water affects subjective feelings of hunger and satiety during the meal, but this effect is not maintained after the meal. It is suggested that during a meal subjective feelings of hunger and satiety change independently of the food energy consumed. This study allows, however, no conclusions on the possible influence of drinking water on actual food intake during and after a meal.

Does the provision of cooled filtered water in secondary school cafeteriasincrease water drinking and decrease the purchase of soft drinks?

BACKGROUND: Secondary school students often do not drink sufficient quantities of water during the school day to prevent dehydration, promote learning and good health. The study aimed to measure the effect of health promotion and the free provision of cooled filtered water on the consumption of water and soft drinks. It also aimed to explore students' views of drinking water provision. METHODS: A study was conducted with three secondary schools in North Tyne side. Over a 3 month period one school was given cooled filtered water and active promotion (W + P), another had water only (W). The control school (C) took part in post-intervention focus group work. RESULTS: The average volume of water drunk by students, in school 'W + P' was greater (P = 0.05) than that drunk in school 'W' and control school 'C'. The volume of soft drinks purchased by students in all three schools before and during the intervention remained static. Focus group data revealed that students viewed their existing water provision as poor and wanted sufficient supplies of cooled filtered water in school. CONCLUSIONS: This pilot study indicates that active promotion of water drinking increased consumption of water by secondary school students. Further developments of the project are suggested.

Promotion and provision of drinking water in schools for overweight prevention:randomized, controlled cluster trial.

OBJECTIVE: The study tested whether a combined environmental and educational intervention solely promoting water consumption was effective in preventing overweight among children in elementary school. METHODS: The participants in this randomized, controlled cluster trial were second- and third-graders from 32 elementary schools in socially deprived areas of 2 German cities. Water fountains were installed and teachers presented 4 prepared classroom lessons in the intervention group schools (N = 17) to promote water consumption. Control group schools (N = 15) did not receive any intervention. The prevalence of overweight (defined according to the International Obesity Task Force criteria), BMI SD scores, and beverage consumption (in glasses per day; 1 glass was defined as 200 mL) self-reported in 24-hour recall questionnaires, were determined before (baseline) and after the intervention. In addition, the water flow of the fountains was measured during the intervention period of 1 school year (August 2006 to June 2007). RESULTS: Data on 2950 children (intervention group: N = 1641; control group: N = 1309; age, mean +/- SD: 8.3 +/- 0.7 years) were analyzed. After the intervention, the risk of overweight was reduced by 31% in the intervention group, compared with the control group, with adjustment for baseline prevalence of overweight and clustering according to school. Changes in BMI SD scores did not differ between the intervention group and the control group. Water consumption after the intervention was 1.1 glasses per day greater in the intervention group. No intervention effect on juice and soft drink consumption was found. Daily water flow of the fountains indicated lasting use during the entire intervention period, but to varying extent. CONCLUSION: Our environmental and educational, school-based intervention proved to be effective in the prevention of overweight among children in elementary school, even in a population from socially deprived areas. FULL TEXT AVAILABLE IN PUBMED

Hydration and disease.

Many diseases have multifactorial origins. There is increasing evidence that mild dehydration plays a role in the development of various morbidities. In this review, effects of hydration status on acute and chronic diseases are depicted (excluding the acute effects of mild dehydration on exercise performance, wellness, cognitive function, and mental performance) and categorized according to four categories of evidence (I-IV). Avoidance of a high fluid intake as a precautionary measure may be indicated in patients with cardiovascular disorders, pronounced chronic renal failure (III), hypoalbuminemia, endocrinopathies, or in tumor patients with cisplatin therapy (IIb) and menace of water intoxication. Acute systemic mild hypohydration or dehydration may be a pathogenic factor in oligohydramnios (IIa), prolonged labor (IIa), cystic fibrosis (III), hypertonic dehydration (III), and renal toxicity of xenobiotica (Ib). Maintaining good hydration status has been shown to positively affect urolithiasis (Ib) and may be beneficial in treating urinary tract infection (IIb), constipation (III), hypertension (III), venous thromboembolism (III), fatal coronary heart disease (III), stroke (III), dental disease (IV), hyperosmolar hyperglycemic diabetic ketoacidosis (IIb), gallstone disease (III), mitral valve prolapse (IIb), and glaucoma (III). Local mild hypohydration or dehydration may play a critical role in the pathogenesis of several broncho-pulmonary disorders like exercise asthma (IIb) or cystic fibrosis (Ib). In bladder and colon cancers, the evidence on hydration status' effects is inconsistent. FULL TEXT AVAILABLE IN PUBMED

Effect of aging on regional cerebral blood flow responses associated with osmoticthirst and its satiation by water drinking: a PET study.

Levels of thirst and ad libitum drinking decrease with advancing age, making older people vulnerable to dehydration. This study investigated age-related changes in brain responses to thirst and drinking in healthy men. Thirst was induced with hypertonic infusions (3.1 ml/kg 0.51M NaCl) in young (Y) and older (O) subjects. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET). Thirst activations were identified by correlating rCBF with thirst ratings. Average rCBF was measured from regions of interest (ROI) corresponding to activation clusters in each group. The effects of drinking were examined by correlating volume of water drunk with changes in ROI rCBF from maximum thirst to post drinking. There were increases in blood osmolality (Y, 2.8 +/- 1.8%; O, 2.2 +/- 1.4%) and thirst ratings (Y, 3.1 +/- 2.1; O, 3.7 +/- 2.8) from baseline to the end of the hypertonic infusion. Older subjects drank less water (1.9 +/- 1.6 ml/kg) than younger subjects (3.9 +/- 1.9 ml/kg). Thirst-related activation was evident in S1/M1, prefrontal cortex, anterior midcingulate cortex (aMCC), premotor cortex, and superior temporal gyrus in both groups. Post drinking changes of rCBF in the aMCC correlated with drinking volumes in both groups. There was a greater reduction in aMCC rCBF relative to water drunk in the older group. Aging is associated with changes in satiation that militate against adequate hydration in response to hyperosmolarity, although it is unclear whether these alterations are due to changes in primary afferent inflow or higher cortical functioning.

Fluid restriction in heart failure patients: is it useful? The design of a prospective, randomised study.

Thirst is a common and troublesome symptom for patients with moderate to severe heart failure. The pharmacological and non-pharmacological treatment as well as the nature of the disease itself causes increased thirst. There is no evidence in the literature about the usefulness of fluid restriction for heart failure patients. Formerly, when very little pharmacological treatment was available, fluid restriction was one of the few interventional options but nowadays when the pharmacological treatment has improved, its importance may be questioned. This article describes the design of an on-going study with the aim to determine if an individualised and less restrictive fluid prescription can improve the quality of life, cardiac function and exercise capacity, and decrease in hospital admissions and thirst. This study will be performed as a two-group, 1:1 randomised cross-over study. In group 1, the patients are instructed to comply with a maximum fluid intake of 1.5 l. This is a standard treatment today. In group 2, the patients are recommended to intake a fluid, based on the physiological need of 30 ml/kg body weight/24 h, and are allowed to increase the fluid intake to a maximum of 35 ml/kg body weight/24 h. After 16 weeks, the patients will cross over to the other intervention strategy and continue for another 16 weeks.

Determinants of the sensation of thirst in terminally ill cancer patients.

While a sensation of thirst causes severe distress for a certain proportion of cancer patients in the terminal stage, the factors contributing to this symptom have not been established. To clarify the association between sensation of thirst and medical factors, especially dehydration, a cross-sectional observational study was performed on terminally ill cancer patients receiving inpatient hospice care. On admission to a palliative care unit, 88 consecutive patients underwent blood sampling and were requested to rate the intensity of thirst on a visual analogue scale (VAS). Physicians prospectively evaluated factors that might potentially be contributing to the symptom. The mean VAS score for thirst was 5.0+/-2.8, and 18% of the patients complained of severe thirst with a VAS score of > or = 8. No significant correlations were observed between the VAS score for thirst and the values of total protein, blood urea nitrogen (BUN), creatinine, sodium, osmolality, hematocrit, atrial natriuretic peptide (ANP), and biochemical dehydration defined by the levels of BUN, creatinine, sodium and osmolality. On the other hand, dehydration defined by ANP level ( or = 300 mosmol/kg), gastrointestinal cancer, survival, performance status, oral intake, vomiting, and stomatitis were significantly associated with the severity of thirst. In addition, mouth breathing and opioids were determined to be a potential clinical cause of severe thirst when a retrospective chart review was carried out. In conclusion, sensation of thirst is a frequent symptom in terminally ill cancer patients and is associated with dehydration, hyperosmolality, poor general conditions, stomatitis, oral breathing, and opioids. Careful assessments and treatment of underlying causes is important to alleviate patients' distress.

Thirst in the elderly with and without heart failure.

Elderly patients with heart failure (HF) may be troubled by thirst, despite the fact that elderly have an impaired ability to sense thirst. The present study was undertaken to compare the intensity of thirst in patients with and without HF and to evaluate how this symptom relates to the health-related quality of life and indices of the fluid balance. Forty-eight patients (mean age 80 years) admitted to hospital with worsening HF (n = 23) or with other acute illness (n = 25) graded their thirst and estimated their health-related quality of life (HRQoL). Serum sodium was measured and urine samples were assessed for color and electrolyte content. The HF patients reported significantly more intensive thirst (median = 75 mm) compared with those in the control group (median = 25 mm; p < 0.0001). There was no statistically significant relationship between thirst and HRQoL, which was low overall. Serum sodium and urine color did not differ significantly between the groups, but the urine of the HF patients had a lower sodium concentration and osmolality. We conclude

Fluid replacement and glucose infusion during exercise prevent cardiovasculardrift.

This study examined the influence of both hydration and blood glucose concentration on cardiovascular drift during exercise. We first determined if the prevention of dehydration during exercise by full fluid replacement prevents the decline in stroke volume (SV) and cardiac output (CO) during prolonged exercise. On two occasions, 10 endurance-trained subjects cycled an ergometer in a 22 degrees C room for 2 h, beginning at 70 +/- 1% maximal O2 uptake (VO2max) and in a euhydrated state. During one trial, no fluid (NF) replacement was provided and the subject's body weight declined 2.09 +/- 0.19 kg or 2.9%. During the fluid replacement trial (FR), water was ingested at a rate that prevented body weight from declining after 2 h of exercise (i.e., 2.34 +/- 0.17 1/2 h). SV declined 15% and CO declined 7% during the 20- to 120-min period of the NF trial while heart rate (HR) increased 10% and O2 uptake (VO2) increased 6% (all P less than 0.05). In contrast, SV was maintained during the 20- to 120-min period of FR while HR increased 5% and thus CO actually increased 7% (all P less than 0.05). Rectal temperature, SV, and HR were similar during the 1st h of exercise during NF and FR. However, after 2 h of exercise, rectal temperature was 0.6 degree C higher (P less than 0.05) and SV and CO were 11-16% lower (P less than 0.05) during NF compared with FR.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary reference intakes for water, sodium, potassium, chloride and sulphate.

This report is one in a series that presents a comprehensive set of reference values for nutrient intakes for healthy U.S. and Canadian individuals and populations. It is a product of the Food and Nutrition Board (FNB) of the Institute of Medicine, working in cooperation with Canadian scientists. The report establishes a set of reference values for dietary electrolytes and water to expand and replace previously published Recommended Dietary Allowances (RDAs) and Recommended Nutrient Intakes (RNIs) for the United States and Canada, respectively. Close attention was given to the evidence relating electrolyte intake to the risk of high blood pressure and hypertension, as well as other diseases, and the amounts of water from beverages and foods needed to maintain hydration. In addition, since requirements for sulphur can be met by inorganic sulfate in the diets of animals, a review of the role in inorganic sulfur in the form of sulfate is included. The group responsible for developing this report, the Panel on Dietary Reference Intakes for Electrolytes and Water, under the oversight and assistance of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (the DRI Committee), has analyzed the evidence on risks and beneficial effects of nutrients included in this review.

Effect of beverage osmolality on intestinal fluid absorption during exercise.

To determine how osmolality of an orally ingested fluid-replacement beverage would alter intestinal fluid absorption from the duodenum and/or jejunum during 85 min of cycle exercise (63.3 +/- 0.9% peak O2 uptake) in a cool environment (22 degreesC), seven subjects (5 men, 2 women, peak O2 uptake = 54.5 +/- 3.8 ml . kg-1 . min-1) participated in four experiments separated by 1 wk in which they ingested a water placebo (WP) or one of three 6% carbohydrate (CHO) beverages formulated to give mean osmolalities of 197, 295, or 414 mosmol/kgH2O. CHO solutions also contained 17-18 meq Na+ and 3.2 meq K+. Nasogastric and multilumen tubes were fluoroscopically positioned in the gastric antrum and duodenojejunum, respectively. Subjects ingested a total of 23 ml/kg body mass of the test solution, 20% (370 +/- 9 ml) of this volume 5 min before exercise and 10% (185 +/- 4 ml) every 10 min thereafter. By using the rate of gastric emptying as the rate of intestinal perfusion (G. P. Lambert, R. T. Chang, D. Joensen, X. Shi, R. W. Summers, H. P. Schedl, and C. V. Gisolfi. Int. J. Sports Med. 17: 48-55, 1996), intestinal absorption was determined by segmental perfusion from the duodenum (0-25 cm) and jejunum (25-50 cm). There were no differences (P > 0.05) in gastric emptying (mean 18.1 +/- 1.3 ml/min) or total fluid absorption (802 +/- 109, 650 +/- 52, 674 +/- 62, and 633 +/- 74 ml . 50 cm-1 . h-1 for WP, hypo-, iso-, and hypertonic solutions, respectively) among beverages; but WP was absorbed faster (P < 0.05) from the duodenum than in the jejunum. Of the total volume of fluid ingested, 82 +/- 14, 74 +/- 6, 76 +/- 5, and 68 +/- 7% were absorbed for WP, hypo-, iso-, and hypertonic beverages, respectively. There were no differences in urine production or percent change in plasma volume among solutions. We conclude that total fluid absorption of 6% CHO-electrolyte beverages from the duodenojejunum during exercise, within the osmotic range studied, is not different from WP. FULL-TEXT AVAILABLE IN PUBMED

Effect of sodium in a rehydration beverage when consumed as a fluid or meal.

To investigate the impact of fluid composition on rehydration effectiveness, 30 subjects (15 men and 15 women) were studied during 2 h of rehydration after a 2.5% body weight loss. In a randomized crossover design, subjects rehydrated with water (H2O), chicken broth (CB: 109.5 mmol/l Na, 25.3 mmol/l K), a carbohydrate-electrolyte drink (CE: 16.0 mmol/l Na, 3.3 mmol/l K), and chicken noodle soup (Soup: 333.8 mmol/l Na, 13.7 mmol/l K). Subjects ingested 175 ml at the start of rehydration and 20 min later; H2O was given every 20 min thereafter for a total volume equal to body weight loss during dehydration. At the end of the rehydration period, plasma volume was not significantly different from predehydration values in the CB (-1.6 +/- 1.1%) and Soup (-1.4 +/- 0.9%) trials. In contrast, plasma volume remained significantly (P < 0.01) below predehydration values in the H2O (-5.6 +/- 1.1%) and CE (-4.2 +/- 1.0%) trials after the rehydration period. Urine volume was greater in the CE (310 +/- 30 ml) than in the CB (188 +/- 20 ml) trial. Urine osmolality was higher in the CB and Soup trials than in the CE trial. Urinary sodium concentration was higher in the Soup and CB trials than in the CE and H2O trials. These results provide evidence that the inclusion of sodium in rehydration beverages, as well as consumption of a sodium-containing liquid meal, increases fluid retention and improves plasma volume restoration. FULL-TEXT AVAILABLE IN PUBMED

Fluid and electrolyte balance in ultra-endurance sport.

It is well known that fluid and electrolyte balance are critical to optimal exercise performance and, moreover, health maintenance. Most research conducted on extreme sporting endeavour (>3 hours) is based on case studies and studies involving small numbers of individuals. Ultra-endurance sportsmen and women typically do not meet their fluid needs during exercise. However, successful athletes exercising over several consecutive days come close to meeting fluid needs. It is important to try to account for all factors influencing bodyweight changes, in addition to fluid loss, and all sources of water input. Increasing ambient temperature and humidity can increase the rate of sweating by up to approximately 1 L/h. Depending on individual variation, exercise type and particularly intensity, sweat rates can vary from extremely low values to more than 3 L/h. Over-hydration, although not frequently observed, can also present problems, as can inappropriate fluid composition. Over-hydrating or meeting fluid needs during very long-lasting exercise in the heat with low or negligible sodium intake can result in reduced performance and, not infrequently, hyponatraemia. Thus, with large rates of fluid ingestion, even measured just to meet fluid needs, sodium intake is vital and an increased beverage concentration [30 to 50 mmol/L (1.7 to 2.9 g NaCl/L) may be beneficial. If insufficient fluids are taken during exercise, sodium is necessary in the recovery period to reduce the urinary output and increase the rate of restoration of fluid balance. Carbohydrate inclusion in a beverage can affect the net rate of water assimilation and is also important to supplement endogenous reserves as a substrate for exercising muscles during ultra-endurance activity. To enhance water absorption, glucose and/or glucose-containing carbohydrates (e.g. sucrose, maltose) at concentrations of 3 to 5% weight/volume are recommended. Carbohydrate concentrations above this may be advantageous in terms of glucose oxidation and maintaining exercise intensity, but will be of no added advantage and, if hyperosmotic, will actually reduce the net rate of water absorption. The rate of fluid loss may exceed the capacity of the gastrointestinal tract to assimilate fluids. Gastric emptying, in particular, may be below the rate of fluid loss, and therefore, individual tolerance may dictate the maximum rate of fluid intake. There is large individual variation in gastric emptying rate and tolerance to larger volumes. Training to drink during exercise is recommended and may enhance tolerance.

Effects of solution osmolality on absorption of select fluid replacement solutionsin human duodenojejunum.

These experiments examined relationships between initial osmolality and carbohydrate (CHO) composition of an infused solution and osmolality and water and CHO absorption in a test segment. A triple-lumen tube with a 10-cm mixing segment and a 40-cm test segment was passed into the duodenojejunum. The infusion port was approximately 10 cm beyond the pyloric sphincter. Perfusion solutions were hypotonic (186 mosmol/kg; solution A), isotonic (283 mosmol/kg; solution B), and hypertonic (403 mosmol/kg; solution C). All solutions contained 18 meq Na+ and 3 meq K+. In the mixing segment, osmolality increased 83 mosmol/kg and decreased 90 mosmol/kg for solutions A and C, respectively. Corresponding changes in the test segment were an increase of 60 mosmol/kg and a decrease of 34 mosmol/kg. The osmolality of solutionB did not change. In the test segment, mean osmolality and water and total solute fluxes were not significantly different among solutions, but solution C produced 27% greater fluid absorption than did solution A. When net fluid movement from mixing and test segments was determined, solution A produced 17% greater fluid absorption than did solution C. The mean increases in plasma and urine volumes over the 80-min test period were not significantly different. In the test segment, water flux correlated with CHO and Na+ fluxes but not with osmolality. In conclusion, 1) significant differences in solution osmolality were eliminated within the proximal duodenum and 2) perfusing 6% CHO solutions with osmolalities ranging from 186 to 403 mosmol/kg did not produce significant differences in fluid homeostasis (plasma volume) at the end of an 80-min test period.

Volume repletion after exercise-induced volume depletion in humans:replacement of water and sodium losses.

Sodium and water loss during, and replacement after, exercise-induced volume depletion was investigated in six volunteers volume depleted by 1.89 +/- 0.17% (SD) of body mass by intermittent exercise in a warm, humid environment. Subjects exercised in a large, open plastic bag, allowing collection of all sweat secreted during exercise. For over 60 min beginning 40 min after the end of exercise, subjects ingested drinks containing 0, 25, 50, or 100 mmol/l sodium (trials 0, 25, 50, and 100) in a volume (ml) equivalent to 150% of the mass lost (g) by volume depletion. Body mass loss and sweat electrolyte (Na+, K+, and Cl-) loss were the same on each trial. The measured sweat sodium concentration was 49.2 +/- 18.5 mmol/l, and the total loss (63.9 +/- 38.7 mmol) was greater than that ingested on trials 0 and 25. Urine production over the 6-h recovery period was inversely related to the amount of sodium ingested. Subjects were in whole body negative sodium balance on trials 0 (-104 +/- 48 mmol) and 25 (-65 +/- 30 mmol) and essentially in balance on trial 50 (-13 +/- 29 mmol) but were in positive sodium balance on trial 100 (75 +/- 40 mmol). Only on trial 100 were subjects in positive fluid balance at the end of the study. There was a large urinary loss of potassium over the recovery period on trial 100, despite a negligible intake during volume repletion. These results confirm the importance of replacement of sodium as well as water for volume repletion after sweat loss. The sodium intake on trial 100 was appropriate for acute fluid balance restoration, but its consequences for potassium levels must be considered to be undesirable in terms of whole body electrolyte homeostasis for anything other than the short term. FULL-TEXT AVAILABLE IN PUBMED

Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat.

PURPOSE: This study was conducted to determine whether preexercise ingestion of a highly concentrated sodium beverage would increase plasma volume (PV) and reduce the physiological strain of moderately trained males running in the heat. METHODS: Eight endurance-trained (.VO2max: 58 mL.kg(-1).min(-1) (SD 5); 36 yr (SD 11)) runners completed this double-blind, crossover experiment. Runners ingested a high-sodium (High Na+: 164 mmol Na+.L(-1)) or low-sodium (Low Na+: 10 mmol Na+.L(-1)) beverage (10 mL.kg(-1)) before running to exhaustion at 70% .VO2max in warm conditions (32 degrees C, 50% RH, V(a) approximately equal to 1.5 m.s(-1)). Beverages (approximately 757 mL) were ingested in seven portions across 60 min beginning 105 min before exercise. Trials were separated by 1-3 wk. Heart rate and core and skin temperatures were measured throughout exercise. Urine and venous blood were sampled before and after drinking and exercise. RESULTS: High Na+ increased PV before exercise (4.5% (SD 3.7)), calculated from Hct and [Hb]), whereas Low Na+ did not (0.0% (SD 0.5); P = 0.04), and involved greater time to exercise termination in the six who stopped because of an ethical end point (core temperature 39.5 degrees C: 57.9 min (SD 6) vs 46.4 min (SD 4); P = 0.04) and those who were exhausted (96.1 min (SD 22) vs 75.3 min (SD 21); P = 0.03; High Na+ vs Low Na+, respectively). At equivalent times before exercise termination, High Na+ also resulted in lower core temperature (38.9 vs 39.3 degrees C; P = 0.00) and perceived exertion (P = 0.01) and a tendency for lower heart rate (164 vs 174 bpm; P = 0.08). CONCLUSIONS: Preexercise ingestion of a high-sodium beverage increased plasma volume before exercise and involved less thermoregulatory and perceived strain during exercise and increased exercise capacity in warm conditions.

Metabolic and thermodynamic responses to dehydration-induced reductions in muscle blood flow in exercising humans

1. The present study examined whether reductions in muscle blood flow with exercise-induced dehydration would reduce substrate delivery and metabolite and heat removal to and from active skeletal muscles during prolonged exercise in the heat. A second aim was to examine the effects of dehydration on fuel utilisation across the exercising leg and identify factors related to fatigue. 2. Seven cyclists performed two cycle ergometer exercise trials in the heat (35 C; 61 +/- 2 % of maximal oxygen consumption rate, VO2,max), separated by 1 week. During the first trial (dehydration, DE), they cycled until volitional exhaustion (135 +/- 4 min, mean +/- s.e.m.), while developing progressive DE and hyperthermia (3.9 +/- 0.3 % body weight loss and 39.7 +/- 0.2 C oesophageal temperature, Toes). On the second trial (control), they cycled for the same period of time maintaining euhydration by ingesting fluids and stabilising Toes at 38.2 +/- 0.1 degrees C. 3. After 20 min of exercise in both trials, leg blood flow (LBF) and leg exchange of lactate, glucose, free fatty acids (FFA) and glycerol were similar. During the 20 to 135 +/- 4 min period of exercise, LBF declined significantly in DE but tended to increase in control. Therefore, after 120 and 135 +/- 4 min of DE, LBF was 0.6 +/- 0.2 and 1.0 +/- 0.3 l min-1 lower (P < 0.05), respectively, compared with control. 4. The lower LBF after 2 h in DE did not alter glucose or FFA delivery compared with control. However, DE resulted in lower (P < 0.05) net FFA uptake and higher (P < 0.05) muscle glycogen utilisation (45 %), muscle lactate accumulation (4.6-fold) and net lactate release (52 %), without altering net glycerol release or net glucose uptake. 5. In both trials, the mean convective heat transfer from the exercising legs to the body core ranged from 6.3 +/- 1.7 to 7.2 +/- 1.3 kJ min-1, thereby accounting for 35-40 % of the estimated rate of heat production ( approximately 18 kJ min-1). 6. At exhaustion in DE, blood lactate values were low whereas blood glucose and muscle glycogen levels were still high. Exhaustion coincided with high body temperature ( approximately 40 C). 7. In conclusion, the present results demonstrate that reductions in exercising muscle blood flow with dehydration do not impair either the delivery of glucose and FFA or the removal of lactate during moderately intense prolonged exercise in the heat. However, dehydration during exercise in the heat elevates carbohydrate oxidation and lactate production. A major finding is that more than one-half of the metabolic heat liberated in the contracting leg muscles is dissipated directly to the surrounding environment. The present results indicate that hyperthermia, rather than altered metabolism, is the main factor underlying the early fatigue with dehydration during prolonged exercise in the heat.

Effect of fluid ingestion on muscle metabolism during prolonged exercise.

Five trained men were studied during 2 h of cycling exercise at 67% peak oxygen uptake at 20-22 degrees C to examine the effect of fluid ingestion on muscle metabolism. On one occasion, the subjects completed this exercise without fluid ingestion(NF) while on the other they ingested a volume of distilled deionized water that prevented loss of body mass (FR). No differences in oxygen uptake during exercise were observed between the two trials. Heart rate was lower (P < 0.01) throughout exercise when fluid was ingested, and rectal temperature after 2 h of exercise was lower (38.0 +/- 0.2 and 38.6 +/- 0.2 degrees C for FR and NF, respectively; P < 0.01), as was muscle (vastus lateralis) temperature (38.5 +/- 0.4 and 39.1 +/- 0.5 degrees C for FR and NF, respectively; P < 0.05). Resting muscle ATP, creatine phosphate, creatine, glycogen, and lactate levels were similar in the two trials, as were the post exercise ATP, creatine phosphate, and creatine levels. In contrast, muscle glycogen was higher (P < 0.05) and muscle lactate was lower (P < 0.05) after 2 h of exercise in FR compared with NF. Net muscle glycogen utilization during exercise was reduced by 16% when fluid was ingested (318 +/- 46 and 380 +/- 53 mmol/kg dry weight for FR and NF, respectively; P < 0.05). These results indicate that fluid ingestion reduces muscle glycogen use during prolonged exercise, which may account, in part, for the improved performance previously observed with fluid ingestion.

American College of Sports Medicine position stand. Exercise and fluidreplacement.

This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least several hours before the activity to enable fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited.

Hydration effects on thermoregulation and performance in the heat.

During exercise, sweat output often exceeds water intake, producing a water deficit or hypohydration. The water deficit lowers both intracellular and extracellular fluid volumes, and causes a hypotonic-hypovolemia of the blood. Aerobic exercise tasks are likely to be adversely effected by hypohydration (even in the absence of heat strain), with the potential affect being greater in hot environments. Hypohydration increases heat storage by reducing sweating rate and skin blood flow responses for a given core temperature. Hypertonicity and hypovolemia both contribute to reduced heat loss and increased heat storage. In addition, hypovolemia and the displacement of blood to the skin make it difficult to maintain central venous pressure and thus cardiac output to simultaneously support metabolism and thermoregulation. Hyperhydration provides no advantages over euhydration regarding thermoregulation and exercise performance in the heat.

Urine specific gravity in exercisers prior to physical training.

Urine specific gravity (USG) is used as an index of hydration status. Many studies have used USG to estimate pre-exercise hydration in athletes. However, very little is known about the pre-exercise hydration status of recreational exercisers. The purpose of the present study was to measure the pre-exercise USG in a large sample of recreational exercisers who attended 2 different fitness centers in the United States. In addition, we wanted to determine if factors such as time of day, geographic location, and gender influenced USG. We tested 166 subjects in Chicago and 163 subjects in Los Angeles. Subjects completed a survey on their typical training regimen and fluid-replacement habits, and thereafter voided and delivered a urine sample to the investigators prior to beginning exercise. Samples were measured on site for USG using a hand-held refractometer. The mean (SD) USG was 1.018 (+/- 0.007) for all subjects. Males had a higher average USG (1.020 +/- 0.007) when compared with females (1.017 +/- 0.008; p = 0.001). Despite differences in climate, no difference in mean USG occurred based on location or time of day. Based on standards used for athletes (USG > or = 1.020), 46% of the exercisers were likely to be dehydrated.

Effect of glycerol-induced hyperhydration on thermoregulation and metabolismduring exercise in heat.

This study examined the effect of glycerol ingestion on fluid homeostasis, thermoregulation, and metabolism during rest and exercise. Six endurance-trained men ingested either 1 g glycerol in 20 ml H2O x kg(-1) body weight (bw) (GLY) or 20 ml H2O x kg(-1) bw (CON) in a randomized double-blind fashion, 120 min prior to undertaking 90 min of steady state cycle exercise(SS) at 98% of lactate threshold in dry heat (35 degrees C, 30% RH), with ingestion of CHO-electrolyte beverage (6% CHO) at 15-min intervals. A 15-min cycle, where performance was quantified in kJ, followed (PC). Pre-exercise urine volume was lower in GLY than CON (1119 +/- 97 vs. 1503 +/- 146 ml x 120 min(-1); p < .05). Heart rate was lower (p < .05) throughout SS in GLY, while forearm blood flow was higher (17.1 +/- 1.5 vs. 13.7 +/- 3.0 ml x 100 g tissue x min(-1); p < .05) and rectal temperature lower (38.7 +/- 0.1 vs. 39.1 +/- 0.1 degrees C; p < .05) in GLY late in SS. Despite these changes, skin and muscle temperatures and circulating catecholamines were not different between trials. Accordingly, no differences were observed in muscle glycogenolysis, lactate accumulation, adenine nucleotide, and phosphocreatine degradation or inosine 5'-monophosphate accumulation when comparing GLY with CON. Of note, the work performed during PC was 5% greater in GLY (252 +/- 10 vs. 240 +/- 9 kJ; p < .05). These results demonstrate that glycerol, when ingested with a bolus of water 2 hours prior to exercise, results in fluid retention, which is capable of reducing cardiovascular strain and enhancing thermoregulation. Furthermore, this practice increases exercise performance in the heat by mechanisms other than alterations in muscle metabolism.

Influence of body temperature on the development of fatigue during prolongedexercise in the heat.

We investigated whether fatigue during prolonged exercise in uncompensable hot environments occurred at the same critical level of hyperthermia when the initial value and the rate of increase in body temperature are altered. To examine the effect of initial body temperature [esophageal temperature (Tes) = 35.9 +/- 0.2, 37.4 +/- 0. 1, or 38.2 +/- 0.1 (SE) degrees C induced by 30 min of water immersion], seven cyclists (maximal O2 uptake = 5.1 +/- 0.1 l/min) performed three randomly assigned bouts of cycle ergometer exercise (60% maximal O2 uptake) in the heat (40 degrees C) until volitional exhaustion. To determine the influence of rate of heat storage (0.10 vs. 0.05 degrees C/min induced by a water-perfused jacket), four cyclists performed two additional exercise bouts, starting with Tes of 37.0 degrees C. Despite different initial temperatures, all subjects fatigued at an identical level of hyperthermia (Tes = 40. 1-40.2 degrees C, muscle temperature = 40.7-40.9 degrees C, skin temperature = 37.0-37.2 degrees C) and cardiovascular strain (heart rate = 196-198 beats/min, cardiac output = 19.9-20.8 l/min). Time to exhaustion was inversely related to the initial body temperature: 63 +/- 3, 46 +/- 3, and 28 +/- 2 min with initial Tes of approximately 36, 37, and 38 degrees C, respectively (all P < 0.05). Similarly, with different rates of heat storage, all subjects reached exhaustion at similar Tes and muscle temperature (40.1-40.3 and 40. 7-40.9 degrees C, respectively), but with significantly different skin temperature (38.4 +/- 0.4 vs. 35.6 +/- 0.2 degrees C during high vs. low rate of heat storage, respectively, P < 0.05). Time to exhaustion was significantly shorter at the high than at the lower rate of heat storage (31 +/- 4 vs. 56 +/- 11 min, respectively, P < 0.05). Increases in heart rate and reductions in stroke volume paralleled the rise in core temperature (36-40 degrees C), with skin blood flow plateauing at Tes of approximately 38 degrees C. These results demonstrate that high internal body temperature per se causes fatigue in trained subjects during prolonged exercise in uncompensable hot environments. Furthermore, time to exhaustion in hot environments is inversely related to the initial temperature and directly related to the rate of heat storage. FULL-TEXT AVAILABLE IN PUBMED

Effect of glycerol- induced hyperhydration on thermoregulatory and cardiovascularfunctions and endurance performance during prolonged cycling in a 25 degrees Cenvironment.

We compared the effect of glycerol-induced hyperhydration (GIH) to that of water-induced hyperhydration (WIH) on cardiovascular and thermoregulatory functions and endurance performance (EP) during prolonged cycling in a temperate climate in subjects consuming fluid during exercise. At weekly intervals, 6 trained male subjects ingested, in a randomized, double-blind, counterbalanced fashion, either a glycerol (1.2 g glycerol/kg bodyweight (BW) with 26 mL/kg BW of water-aspartame-flavored fluid) or placebo solution (water-aspartame-flavored fluid only) over a 2 h period. Subjects then performed 2 h of cycling at 66% of the maximal oxygen consumption (VO(2) max) and 25 degrees C while drinking 500 mL/h of sports drink, which was followed by a step-incremented cycling test to exhaustion. Levels of hyperhydration did not differ significantly between treatments before exercise. During exercise, GIH significantly reduced urine production by 246 mL. GIH did not increase sweat rate nor did it decrease heart rate, rectal temperature, or perceived exertion during exercise as compared with WIH. EP was not significantly different between treatments. Neither treatment induced undesirable side effects. It is concluded that, compared with WIH, GIH decreases urine production, but does not improve cardiovascular orthermoregulatory functions, nor does it improve EP during 2 h of cycling in a 25 degrees C environment in trained athletes consuming 500 mL/h of fluid during exercise.

Circulatory regulation during exercise in different ambient temperatures.

Three relatively fit subjects performed duplicate 20- to 25-min cycle ergometer exercise bouts at moderate and heavy intensities (40% and 70% Vo2 max) in ambient temperatures of 20, 26, and 36 degrees C. They approached a steady state in internal body temperature (Tes) in all but the heavy exercise in the heat, where Tes rose consistently, averaging 38.84 degrees C at the termination of exercise. Cardiac output (Q), estimated by a rebreathing technique, was proportional to Vo2 and independent of the body temperatures, except during the lower exercise intensity in the heart, where Q averaged 1.31 . min -1 higher throughout. In any environment, forearm blood flow was linearly related to Tes above the Tes threshold for vasodilation, but during heavy exercise in the heat this relationship was severely attenuated above a Tes around 38.0 degrees C, when forearm blood flow exceeded 15 ml.min -1 .100 ml -1. Plasma volume decreases during exercise were primarily a function of the intensity of exercise. During heavy exercise in the heat the relative vasconstriction contributes to the maintenance of an adequate stroke volume preventing a fall in Q. In this case, circulatory regulation has precedence over temperature regulation.

Human circulatory and thermoregulatory adaptations with heat acclimation andexercise in a hot, dry environment.

1. Heat acclimation was induced in eight subjects by asking them to exercise until exhaustion at 60% of maximum oxygen consumption rate (VO2) for 9-12 consecutive days at an ambient temperature of 40 degrees C, with 10% relative humidity (RH). Five control subjects exercised similarly in a cool environment, 20 degrees C, for 90 min for 9-12 days; of these, three were exposed to exercise at 40 degrees C on the first and last day. 2. Acclimation had occurred as seen by the increased average endurance from 48 min to 80 min, the lower rate of rise in the heart rate (HR) and core temperature and the increased sweating. 3. Cardiac output increased significantly from the first to the final heat exposure from 19.6 to 21.4 l min-1; this was possibly due to an increased plasma volume and stroke volume. 4. The mechanism for the increased plasma volume may be an isosmotic volume expansion caused by influx of protein to the vascular compartment, and a sodium retention induced by a significant increase in aldosterone. 5. The exhaustion coincided with, or was elicited when, core temperature reached 39.7 +/- 0.15 degrees C; with progressing acclimation processes it took progressively longer to reach this level. However, at this point we found no reduction in cardiac output, muscle (leg) blood flow, no changes in substrate utilization or availability, and no recognized accumulated 'fatigue' substances. 6. It is concluded that the high core temperature per se, and not circulatory failure, is the critical factor for the exhaustion during exercise in heat stress.

Influence of sodium replacement on fluid ingestion following exercise-induceddehydration.

This study investigated the hypothesis that addition of Na+ to a rehydration beverage would stimulate drinking and augment restoration of body water in individuals dehydrated during 90 min of continuous treadmill exercise in the heat. Following a 3.0 +/- 0.2% decrease in body weight (BW), 6 subjects sat in a thermoneutral environment for 30 min to allow body fluid compartments to stabilize. Over the next 3 hr, subjects rehydrated ad libitum using either flavored/artificially sweetened water (H2O-R) or a flavored, 6% sucrose drink containing either 25 (LNa(+)-R) or 50 (HNa(+)-R) mmol/L NaCl. Results demonstrated that rapid removal of the osmotic stimulus, during H2O-R, and the volume-dependent dipsogenic stimuli, during HNa(+)-R, are important factors in limiting fluid intake during rehydration, compared to LNa(+)-R. It was also found that the pattern of fluid replacement and restoration of fluid balance following dehydration is influenced by the dehydration protocol used to induce the loss in total body water and the sodium content of the rehydration beverage.

Rosenbloom C.

Athletes who are properly fueled and hydrated before, during, and after exercise can improve training, increase performance, and decrease fatigue. Many commercial products are marketed to athletes and are designed to be consumed at specific periods: before, during, and after exercise. Are these products really necessary? This article reviews the research on nutrition support for the athlete surrounding exercise and discusses the different nutritional needs of the recreational athlete versus the elite athlete. Guidelines for macronutrient intake before, during, and after exercise are provided along with decision trees to help the practitioner guide the athlete to proper fueling strategies.

Role of osmolality and plasma volume during rehydration in humans.

To determine how the sodium content of ingested fluids affects drinking and the restoration of the body fluid compartments after dehydration, we studied six subjects during 4 h of recovery from 90-110 min of a heat [36 degrees C, less than 30% relative humidity (rh)] and exercise (40% maximal aerobic power) exposure, which caused body weight to decrease by 2.3%. During the 1st h, subjects rested seated without any fluids in a thermoneutral environment (28 degrees C, less than 30% rh) to allow the body fluid compartments to stabilize. Over the next 3 h, subjects rehydrated ad libitum using tap water and capsules containing either placebo (H2O-R) or 0.45 g NaCl (Na-R) per 100 ml water. During the 3-h rehydration period, subjects restored 68% of the lost water during H2O-R, whereas they restored 82% during Na-R (P less than 0.05). Urine volume was greater in H2O-R than in Na-R; thus only 51% of the lost water was retained during H2O-R, whereas 71% was retained during Na-R (P less than 0.05). Plasma osmolality was elevated throughout the rehydration period in Na-R, whereas it returned to the control level by 30 min in H2O-R (P less than 0.05). Changes in free water clearance followed changes in plasma osmolality. The restoration of plasma volume during Na-R was 174% of that lost. During H2O-R it was 78%, which seemed to be sufficient to diminish volume-dependent dipsogenic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Stroke volume during exercise: interaction of environment and hydration.

Euhydrated and dehydrated subjects exercised in a hot and a cold environment with our aim to identify factors that relate to reductions in stroke volume (SV). We hypothesized that reductions in SV with heat stress are related to the interaction of several factors rather than the effect of elevated skin blood flow. Eight male endurance-trained cyclists [maximal O(2) consumption (VO(2 max)) 4.5 +/- 0.1 l/min; means +/- SE] cycled for 30 min (72% VO(2 max)) in the heat (H; 35 degrees C) or the cold (C; 8 degrees C) when euhydrated or dehydrated by 1.5, 3.0, or 4.2% of their body weight. When euhydrated, SV and esophageal temperature (T(es) 38. 2-38.3 degrees C) were similar in H and C, whereas skin blood flow was much higher in H vs. C (365 +/- 64% higher; P < 0.05). With each 1% body weight loss, SV declined 6.4 +/- 1.3 ml (4.8%) in H and 3.4 +/- 0.4 ml (2.5%) in C, whereas T(es) increased 0.21 +/- 0.02 and 0. 10 +/- 0.02 degrees C in H and C, respectively (P < 0.05). However, reductions in SV were not associated with increases in skin blood flow. The reduced SV was highly associated with increased heart rate and reduced blood volume in both H (R = 0.96; P < 0.01) and C (R = 0. 85; P < 0.01). In conclusion, these results suggest that SV is maintained in trained subjects during exercise in euhydrated conditions despite large differences in skin blood flow. Furthermore, the lowering of SV with dehydration appears largely related to increases in heart rate and reductions in blood volume. FULL-TEXT AVAILABLE IN PUBMED



We studied the relationship between plasma osmolality, arginine vasopressin (AVP), and fluid input in patients during the acute phase of a first stroke. Fifteen consecutive patients were studied (median age 79) and their blood sampled on days 0, 1, 2, 3, 7 and 14. Plasma osmolality was related to fluid input over days 0-3 (p = 0.0013) and AVP over 14 days (p less than 0.001). Patients with a poor outcome had higher AVP concentrations (p = 0.02). Those on intravenous fluids received a higher volume (p less than 0.01) and had a lower plasma osmolality (p = 0.04). The results of this preliminary study indicate that a standard regime for fluid input is inappropriate.

Comparison of 3 methods to assess urine specific gravity in collegiate wrestlers.

OBJECTIVE: To investigate the reliability and validity of refractometry, hydrometry, and reagent strips in assessing urinespecific gravity in collegiate wrestlers. DESIGN AND SETTING: We assessed the reliability of refractometry, hydrometry, and reagent strips between 2 trials and among 4 testers. The validity of hydrometry and reagent strips was assessed by comparison with refractometry, the criterion measure for urine specific gravity. SUBJECTS: Twenty-one National Collegiate Athletic Association Division III collegiate wrestlers provided fresh urine samples. MEASUREMENTS: Four testers measured the specific gravity of each urine sample 6 times: twice by refractometry, twice by hydrometry, and twice by reagent strips. RESULTS: Refractometer measurements were consistent between trials (R =.998) and among testers; hydrometer measurements were consistent between trials (R =.987) but not among testers; and reagent-strip measurements were not consistent between trials or among testers. Hydrometer (1.018 +/- 0.006) and reagent-strip (1.017 +/- 0.007) measurements were significantly higher than refractometer (1.015 +/- 0.006) measurements. Intraclass correlation coefficients were moderate between refractometry and hydrometry (R =.869) and low between refractometry and reagent strips (R =.573). The hydrometer produced 28% false positives and 2% false negatives, and reagent strips produced 15% false positives and 9% false negatives. CONCLUSIONS: Only the refractometer should be used to determine urine specific gravity in collegiate wrestlers during the weight-certification process.

Urine test strips: how reproducible are readings?

In an experiment, multiple reagent test strips from 90 urine samples were examined twice: observed visually by one of two persons and analyzed by spectrophotometry. Interobserver and intra-observer agreement were calculated and expressed as Cohen's K. Interobserver and intra-observer agreement were moderate to good, but lower than one might expect. Enhancing discoloration of the test pads could improve reproducibility. FULL-TEXT AVAILABRLE IN PUBMED

Clinical and physical signs for identification of impending and current water-loss dehydration in older people

This is the protocol for a review and there is no abstract. The objectives are as follows: To determine the diagnostic accuracy of state, minimally invasive clinical and physical signs (or sets of signs) to be used as screening tests for detecting impending or current water-loss dehydration, or both, in older people by systematically reviewing studies that have measured a reference standard and at least one index test in people aged 65 years and over. 1. To assess the effect of different cut offs of index test results assessed using continuous data on sensitivity and specificity in diagnosis of impending or current water-loss dehydration. 2. To identify clinical and physical signs that may be used in screening for impending or current water-loss dehydration in older people. 3. To identify clinical and physical signs that are not useful in screening for impending or current water-loss dehydration in older people. 4. To directly compare promising index tests (sensitivity _ 0.60 and specificity _ 0.75) where two or more are measured in a single study (direct comparison). 5. To carry out an exploratory analysis to assess the value of combining the best three index tests where the three tests each have some predictive ability of their own, and individual studies include participants who had all three tests. We will explore sources of heterogeneity of diagnostic accuracy of individual clinical and physical signs that show some evidence of discrimination by the reference standard used, cut off value for tests providing continuous data, type of participants (community dwelling older people, those in residential care, and those in hospital), sex, and baseline prevalence of dehydration.

Hydration in acute stroke: where do we go from here?

Objectives: to examine current practice with regard to hydration in acute stroke (part 1) to identify problem areas, to develop, implement and evaluate an intervention package (part 2). Design: prospective, repeated measures, between subjects Setting: a district general hospital. Participants: consecutive admissions with an acute stroke. Part 1 involved 30 patients, 14 of whom were women whose median age was 73 (45–90), part 2 involved 48 patients, 27 of whom were women whose median age was 73 (47–91). Main outcome measures: amount of fluid prescribed, received and mode of delivery in the first 2 weeks plus standardized swallowing assessments on admission, days 3, 7 and 14. Results: in both parts 1 and 2 of the study patients were appropriately managed according to the results of the SSA. However, in part 1 it was found that patients were documented as, on average, receiving less than 21 (regardless of mode of delivery) and were being prescribed little more than 1.51 per day. In part 2 there was a 33% increase (P<0.005) in fluid prescribed, but no significant increase (P=0.76) in the amount of fluid documented as having been delivered. This was independent of admitting ward. Conclusions: the intervention package had little or no effect on practice. The reasons are discussed and recommendations made. Further interventions are to be explored, implemented and reaudited in the future

Influence of raised osmolarity on clinical outcome after acute stroke.

BACKGROUND AND PURPOSE: Abnormal physiological parameters after acute stroke may induce early neurological deterioration. Studies of the effect of dehydration on stroke outcome are limited. We examined the association of raisedplasma osmolality on stroke outcome at 3 months and the change of plasma osmolality with hydration during the first weekafter stroke. METHODS: Acute stroke patients had their plasma osmolality measured at admission and at days 1, 3, and 7. Maximum plasma osmolality and the area under curve (AUC) were also calculated during the first week. Patients were stratified according to how they were hydrated: orally, intravenously, or both. Outcome included survival at 3 months after stroke. Logistic regression was performed to examine the association between raised plasma osmolality (>296 mOsm/kg) and survival, adjusting for stroke severity. Linear regression was performed to examine the pattern of plasma osmolality across hydration groups. RESULTS: One hundred sixty-seven patients were included. Mean admission (300 mOsm/kg, SD 11.4), maximum (308.1 mOsm/kg, SD 17.1), and AUC (298.3 mOsm/kg, SD 11.7) plasma osmolality were significantly higher in those who died compared with survivors (293.1 mOsm/kg [SD 8.2], 297.7 mOsm/kg [SD 8. 7], and 291.7 mOsm/kg [SD 8.1], respectively; P:296 mOsm/kg was significantly associated with mortality (OR 2.4, 95% CI 1.0 to 5.9). In patients hydrated intravenously, there was no significant fall in plasma osmolality compared with patients hydrated orally (P:=0.68). CONCLUSIONS: Raised plasma osmolality on admission is associated with stroke mortality, after correcting for case mix. Correction of dehydration after stroke requires a more systematic approach. Trials are required to determine whether correcting dehydration after stroke improves outcome. FULL TEXT AVAILABLE IN PUBMED

Urine colour as an index of hydration in critically ill patients

In order to test the hypothesis that urine colour can be used as an index of hydration in critically ill patients, we selected 40 intensive care and high-dependency patients and correlated urine colour (scored on an eight-point scale) with various indices of hydration: urine:plasma sodium, osmolality and urea ratios, urine output and central venous pressure. In addition, we compared the colour-chart score with scores made by intensive care nurses (without the benefit of a colour chart) in order to test subjective assessment of urine colour. There were weak but statistically significant correlations between urine colour andurine output (Spearman's r = - 0.555) and between urine colour and urine:plasma sodium ratio (Spearman's r = - 0.459). Subjective assessment of urine colour appeared to be reliable. Thus, although urine colour does vary with hydration in thecritically ill, assessment of urine colour adds little to the overall assessment of hydration in this group of patients.

Dehydration in the elderly: a short review.

Dehydration is the most common fluid and electrolyte problem among the elderly. The usual causes of water loss are frequently absent in dehydrated elderly patients. Age-related changes in total body water, thirst perception, renal concentrating ability, and vasopressin effectiveness probably predispose to dehydration. Dehydration related to infection, high-protein tube feedings, cerebral vascular accidents, and medication-related hypodypsia are particularly relevant for elderlypatients. Appropriate treatment depends on accurately assessing the water deficit and slowly correcting that deficit. FULL-TEXT AVAILABLE IN PUBMED

Dehydration: biological considerations, age-related changes and risk factors in older adults

Maintenance of water balance is essential to normal physiologic function and vigorous aging. Older adults, however, frequently experience alterations in fluid homeostasis, which result in dehydration. This article describes the physiology of water balance, age-related changes that influence fluid regulation, and associated risk factors for dehydration in older adults. Fluid hygiene is an important health promotion activity for this age group, but when efforts to prevent imbalance are unsuccessful, early identification and intervention to correct problems should be done to minimize adverse consequences. Although much is known about fluid homeostasis, dehydration, and contributory factors in the aging process, water disorders remain prevalent in this group. A great deal of work is still needed to determine "best practices" and creative clinical interventions to support adequate fluid intake behaviors. Both quality management programs and research studies provide avenues for systematic evaluation.

Human hydration indices: acute and longitudinal reference values.

It is difficult to describe hydration status and hydration extremes because fluid intakes and excretion patterns of free-living individuals are poorly documented and regulation of human water balance is complex and dynamic. This investigation provided reference values for euhydration (i.e., body mass, daily fluid intake, serum osmolality; M +/- SD); it also compared urinary indices in initial morning samples and 24-hr collections. Five observations of 59 healthy, active men (age 22 +/- 3 yr, body mass 75.1 +/- 7.9 kg) occurred during a 12-d period. Participants maintained detailed records of daily food and fluid intake and exercise. Results indicated that the mean total fluid intake in beverages, pure water, and solid foods was >2.1 L/24 hr (range 1.382-3.261, 95% confidence interval 0.970-3.778 L/24 hr); mean urine volume was >1.3 L/24 hr (0.875-2.250 and 0.675-3.000 L/24 hr); mean urine specific gravity was >1.018 (1.011-1.027 and 1.009-1.030); and mean urine color was > or = 4 (4-6 and 2-7). However, these men rarely (0-2% of measurements) achieved a urine specific gravity below 1.010 or color of 1. The first morning urine sample was more concentrated than the 24-h urine collection, likely because fluids were not consumed overnight. Furthermore, urine specific gravity and osmolality were strongly correlated (r2 = .81-.91, p < .001) in both morning and 24-hr collections. These findings provide euhydration reference values and hydration extremes for 7 commonly used indices in free-living, healthy, active men who were not exercising in a hot environment or training strenuously.
A complete urinalysis includes physical, chemical, and microscopic examinations. Midstream clean collection is acceptable in most situations, but the specimen should be examined within two hours of collection. Cloudy urine often is a result of precipitated phosphate crystals in alkaline urine, but pyuria also can be the cause. A strong odor may be the result of a concentrated specimen rather than a urinary tract infection. Dipstick urinalysis is convenient, but false-positive and false-negative results can occur. Specific gravity provides a reliable assessment of the patient's hydration status. Microhematuria has a range of causes, from benign to life threatening. Glomerular, renal, and urologic causes of microhematuria often can be differentiated by other elements of the urinalysis. Although transient proteinuria typically is a benign condition, persistent proteinuria requires further work-up. Uncomplicated urinary tract infections diagnosed by positive leukocyte esterase and nitrite tests can be treated without culture. FULL-TEXT AVAILABLE IN PUBMED

Swallowing, nutrition, and hydration during acute stroke care.

Dysphagia occurs in up to half of patients after an acute stroke and may cause dehydration, undernutrition, and aspiration pneumonia. Current evidence suggests that a systematic program of diagnosis and treatment of dysphagia in an acute stroke management plan may yield dramatic reductions in aspiration pneumonia rates. There is also some evidence thatnutritional supplementation and proper hydration may reduce morbidity and mortality in acute stroke patients. This article focuses on the recent advances in the evaluation and management of dysphagia, undernutrition, and dehydration related toacute stroke. A summary of pertinent studies in the area of stroke dysphagia and nutrition is also included. FULL-TEXT AVAILABLE IN PUBMED

Dehydration and venous thromboembolism thromboembolism after acute stroke.

BACKGROUND:Although it is widely assumed that dehydration predisposes to venous thromboembolism (VTE), there are no clinical studies to support this. Aim: To evaluate the relationship between biochemical indices of dehydration and VTEafter acute ischaemic stroke (AIS). DESIGN: Prospective observational study. METHODS: Unselected AIS patients (n = 102) receiving standard thromboprophylaxis with aspirin and graded compression stockings, underwent serial measurements of serum urea, creatinine and osmolality, and were screened for VTE using magnetic resonance direct thrombus imaging. RESULTS: Serum osmolality of >297 mOsm/kg, urea >7.5 mmol/l and urea:creatinine ratio (mmol:mmol) >80 a few days post-AIS were associated with odds ratios for VTE of, respectively, 4.7, 2.8 and 3.4 (p = 0.02, 0.05, 0.02) on multivariable analysis. DISCUSSION: Dehydration after AIS is strongly independently associated with VTE, reinforcing the importance of maintaining adequate hydration in these patients. FULL-TEXT AVAILABLE IN PUBMED

Dehydration in hospital-admitted stroke patients: detection, frequency, andassociation.

BACKGROUND AND PURPOSE:We aimed to determine the frequency of dehydration, risk factors, and associations with outcomes at hospital discharge after stroke.METHODS:\nWe linked clinical data from stroke patients in 2 prospective hospital registers with routine blood urea and creatinine results. Dehydration was defined by a blood urea-to-creatinine ratio >80. RESULTS:\nOf 2591 patients registered, 1606 (62%) were dehydrated at some point during their admission. Independent risk factors for dehydration included older age, female gender, total anterior circulation syndrome, and prescribed diuretics (all P<0.001). Patients with dehydration were significantly more likely be dead or dependent at hospital discharge than those without (χ(2)=170.5; degrees of freedom=2; P<0.0001).CONCLUSIONS:\nDehydration is common and associated with poor outcomes. Further work is required to establish if these associations are causal and if preventing or treating dehydration improves outcomes.

Water: a neglected nutrient in the young child? A South African perspective

Water is considered an essential nutrient because the body cannot produce enough water itself, by metabolism of food, to fulfil its need. When the quantity or quality of water is inadequate, health problems result, most notably dehydration and diarrhoea. As a result of contaminated water and poor hygiene, related infections are still a serious problem. Indeed, in theSouth African setting water availability and sanitation are critical issues because of the prevalence of childhood diarrhoea and also the HIV/AIDS crisis. Though considerable efforts have been made to improve the water and sanitation problems in SouthAfrica - especially with regard to water supply infrastructure - there is still room for much improvement. Water is a healthy alternative to calorie-dense, non-nutritive beverages, such as artificial fruit drinks and soda. The latter should be avoided as they contribute little other than energy and may contribute to overweight and obesity. Also, they displace more nutritious foods from the child's diet. Consumption of fruit juice should also be limited. These issues highlight the need for a specific guideline relating to water intake in the paediatric food-based dietary guidelines.

Diarrhoea in the critically ill

PURPOSE OF REVIEW: The purpose of this review is to update the knowledge on diarrhoea, a common problem in critically ill patients. Epidemiological data will be discussed, with special emphasis on diarrhoea in tube-fed patients and during antibiotic therapy. The possible preventive and therapeutic measures will be presented. RECENT FINDINGS: The need for concise definitions of diarrhoea was recently re-emphasized. The use of pump-driven continuous instead of intermittent enteral feeding is less often associated with diarrhoea. The discontinuation of enteral feeding during diarrhoea is not justified. Clostridium difficile-associated diarrhoea is frequent during antibiotic therapy with quinolones and cephalosporins. Formulas enriched with water-soluble fibres are probably effective to prevent diarrhoea, and promising data on the modulation of gut microflora with probiotics and prebiotics were recently released. SUMMARY: Diarrhoea is common in critically ill patients, especially when sepsis and hypoalbuminaemia are present, and during enteral feeding and antibiotic therapy. The management of diarrhoea includes generous hydration, compensation for the loss of electrolytes, antidiarrheal oral medications, the continuation of enteral feeding, and metronidazole or glycopeptides in the case of moderate to severe C. difficile colitis. The place of enteral formulas enriched with water-soluble fibres, probiotics and prebiotics is not yet fully defined.

Comparison between normal saline and a polyelectrolyte solution for fluid resuscitation in severely dehydrated infants with acute diarrhoea

The optimal intravenous solution for rehydration of infants and children with severe dehydration is debated. AIM: The aim was to compare the efficacy of a polyelectrolyte solution (group PS) with sodium chloride 0.9% solution (group NS) in rapid parenteral rehydration of severely dehydrated infants with acute diarrhoea. METHODS: Primary outcomes were volume and time to hydration. Secondary outcomes were urea, creatinine, electrolytes, glucose, arterial pH and bicarbonate levels. Patients were assigned randomly and openly to one of the two treatment groups. Severe dehydration was defined as one or more of the following associated with any other sign of dehydration: depressed consciousness, a weak or absent pulse or capillary refill time > 10 sec. Peripheral blood samples for chemical pathology were collected before and after rapid fluid therapy. The mean age of the 36 enrolled infants was 9.1 mths. All had depressed consciousness or severe hypotension/shock. The fluid infusion rate was 50 ml/kg/hr until haemodynamic stability was restored (absence of severe hypotension and two urine emissions). Fluid volume, time to rehydration and weight before and after rehydration were recorded. RESULTS: All infants recovered full pulse within 1 hr; most had a better level of consciousness or capillary refill <3 sec. Group NS (15 infants) showed (before and after treatment, respectively) a decrease of plasma potassium (3.4 to 3.1 mmol/L, p=0.07), bicarbonate (13.3 to 12.2 mmol/L, p=0.01) and glucose (8.2 to 5.8 mmol/L, p<0.01). Group PS (21 infants) showed a decrease of potassium (4.4 to 3.2 mmol/L, p<0.01) but an increase in bicarbonate (11.6 to 13.3 mmol/L, p<0.01) and glucose (11.4 to 14.8 mmol/L, p=0.08). CONCLUSION: Polyelectrolyte solution was as effective as normal saline on volume expansion and better for correcting acidosis.


Hydration profile and influence of beverage contents on fluid intake by women during outdoor recreational walking.

This study examined hydration status, sweat losses, and the effects of flavoring and electrolytes on fluid intake for women (n = 27, age = 24 ± 4 years) walking at a self-selected pace for ~1 h on a 1 km outdoor path during summer mornings or evenings. Over five consecutive days, participants consumed ad libitum one non-caloric beverage containing: (1) water (W), (2) acidified water (AW), (3) acidified water with electrolytes (AWE), (4) acidified water with flavor (AWF), and (5) acidified water with flavor and electrolytes (AWFE) in a counter-balanced order during walks and a 1-h recovery period. Walk Wet bulb globe temperature (26.2 ± 1.8 °C) and pace (6.0 ± 0.5 km/h) did not differ among beverages (P > 0.05). Thirty-four percent of pre-walk urine specific gravity samples exceeded 1.020. Flavoring (AWF 700 ± 393 mL; AWFE 719 ± 405 mL) did not result in greater consumption (P > 0.05) over W (560 ± 315 mL), with all three beverages exceeding grand mean sweat losses (528 ± 208 mL). Addition of electrolytes did not influence (P > 0.05) the intake between AW versus AWE or AWF versus AWFE. The results of this study indicate that the majority of women will consume fluids in excess of their sweat losses within 1 h post-walk. Over half of consumption took place during walks, highlighting the importance of fluid availability during exercise. Great among-subjects variability in sweat losses and fluid intake support the need for promoting individualized hydration strategies based on the changes in body mass for athletic populations.

Intestinal Temperature, Heart Rate, and Hydration Status in Multiday Trail Runners

OBJECTIVE: To assess heart rate (HR), intestinal body temperature (Tintest), and hydration status changes and relationships in 12 participants in a 3-day trail run. DESIGN: Descriptive field study. SETTING: Three Cranes Challenge trail run, in Karkloof, KwaZulu-Natal, South Africa. PARTICIPANTS: Twelve (5 men and 7 women) amateur runners. INTERVENTIONS: Trail run of 95 km divided into 3 stages: elevation gains on the 3 days, 1020, 1226, and 680 m, respectively. MAIN OUTCOME MEASURES: Changes in HR, Tintest, serum osmolality, and body mass. RESULTS: Environmental conditions were consistently mild (ambient temperature range, 11.5-22.8°C; maximum relative humidity range, 95%-97%), average running speed varied from 9.00 to 5.14 minutes/km, and distance covered in the 3 stages ranged from 32 (stages 1 and 3) to 40 km (stage 2). Mean HR ranged from 134 to 171 beats per minute in the 12 athletes during the trail events and averaged at 150 beats per minute, whereas Tintest ranged between 36.1 and 40.2°C. The correlation between maximum Tintest and percent age-predicted maximum HR (n = 12) was significant (R = 0.58; P 0.05). CONCLUSIONS: This study provides evidence in support of the contention that maximum Tintest is more closely related to metabolic rate during trail running than percent dehydration. The findings do not support an increase in core body temperature with a change in serum osmolality or body mass.

Effect of ramadan fasting on body water status markers after a rugby sevens match.

PURPOSE: To evaluate the effect of Ramadan fasting on body water status markers of rugby players at basal condition and following a simulation of rugby sevens match. METHODS: TWELVE RECREATIONAL RUGBY SEVENS PLAYERS PLAYED THREE MATCHES: one day before Ramadan (before Ramadan), at the end of the first week of Ramadan (Beg-R) and at the end of Ramadan (End-R). Before and immediately after each match, body weight was determined and blood samples were taken for the measurement of body water status markers. Total body water was measured with an impedancemeter only before matches. RESULTS: At rest, an increase in hematocrit (+4.4%, P=0.03), hemoglobin (+3.4%, P=0.01) and plasma osmolarity (+2.8%, P<0.001) was noticed at End-R compared to before Ramadan. Total body water measured before Ramadan did not differ significantly from that of Ramadan. After the match, values of hematocrit and plasma osmolarity increased significantly at End-R (+1.4%, P=0.02; +3.1%, P<0.001 respectively) compared to before Ramadan. Although, hemoglobin measured after matches occurring during Ramadan did not differ from those of before Ramadan. In response to matches, the change of percentage of body water status markers did not differ during each period of the investigation. CONCLUSIONS: The present results show that Ramadan fasting induces dehydration at basal conditions. Also, rugby sevens match played during Ramadan did not exacerbate the magnitude of responses to matches of blood and body water status markers.

Effects of dehydration on immune functions after a judo practice session.

We investigated the effects of dehydration after a judo practice session on player muscle and immune functions. Subjects included 25 female university judoists. Investigations were performed before and after 2.5 h of regular judo practice. Body composition, serum enzymes (myogenic enzymes, immunoglobulins and complements), neutrophils counts, reactive oxygen species (ROS) production capability, and phagocytic activity (PA) were measured. Subjects were divided into two groups according to level of dehydration after practice (mild dehydration and severe dehydration groups) and results were compared. Creatine kinase was found to increase significantly after practice. In addition, neutrophil count also increased significantly after practice in both groups. The changing ratios of IgA, IgG and C3 observed in the mild dehydration group were significantly higher than those in the severe dehydration group. In the severe dehydration group, post-practice PA/neutrophil had decreased significantly. Significant positive correlations were found between severity of dehydration and changing ratios of IgA, IgG, IgM, C3, C4 and ROS production capabilities, whereas no significant association was seen with PA and/or serum SOD activity. These results suggest that dehydration resulted in immunosuppression, including decreased neutrophil function.

Fluid balance and cycling performance following dehydration and rehydration with a carbohydrate-electrolyte solution.

The effect of ingestion of a 7.6% carbohydrate (CHO)-electrolyte solution (CES) or placebo (P) on rehydration (R) after exercise-induced dehydration and on subsequent time trial (TT) cycling performance was investigated. On four occasions, well-trained participants exercised in the heat (27°C) until ~3% body weight (BW) loss. After exercise, participants sat in a thermo-controlled environment (22°C) and ingested CES or P in a volume equal to 120% of previous BW loss. Fluids were ingested in 3 bolus of 50%, 40% and 30% at 0, 30, 60 min, respectively, during 2 h R period. Then, participants performed a 1 h TT, in which they ingested either no further fluid (in both CES and P trials; n=13) or ingested 2 ml·kg¯1 BW of a 15.3% CHO solution (in CES trial) or P (in P trial) at the start and on achieving 25% and 50% of work (n=6). R with CES (70±3%) was significantly higher compared to P (60±5%; n=13; p<0.01). When no fluid was ingested during TT, no difference in performance between CES and P was observed. When CHO was ingested during TT, performance was significantly improved with CES compared to P (61.2±1.7 vs 65.7±2.5 min, respectively; p<0.05; n=6). It is concluded that CES was more effective than P for rehydration and additional CHO supply just before and during TT improved subsequent cycling performance.



Artificial nutrition and hydration in the last week of life in cancer patients. Asystematic literature review of practices and effects.

BACKGROUND: The benefits and burdens of artificial nutrition (AN) and artificial hydration (AH) in end-of-life care are unclear. We carried out a literature review on the use of AN and AH in the last days of life of cancer patients.MATERIALS AND METHODS:We systematically searched for papers in PubMed, CINAHL, PsycInfo and EMBASE. All English papers published between January 1998 and July 2009 that contained data on frequencies or effects of AN or AH incancer patients in the last days of life were included.RESULTS:Reported percentages of patients receiving AN or AH in the last week of life varied from 3% to 53% and from 12% to 88%, respectively. Five studies reported on the effects of AH: two found positive effects (less chronic nausea, less physical dehydration signs), two found negative effects (more ascites, more intestinal drainage) and four found also no effectson terminal delirium, thirst, chronic nausea and fluid overload. No study reported on the sole effect of AN.CONCLUSIONS:Providing AN or AH to cancer patients who are in the last week of life is a frequent practice. The effects on comfort, symptoms and length of survival seem limited. Further research will contribute to better understanding of this important topic in end-of-life care. FREE FULL-TEXT AVAILABLE IN PUBMED

Hydration in palliative care: when, how and why.

Background: a great majority of patients with end-stage disease experience a severily reduced oral intake before death, which is due to a variety of causes related to their cancer or its treatment. Reduced oral intake is perceived by patients and their families with distress because of implications related to eating and hydration. This perception and the fact that there is no evidence-based research to determine how it is best to proceed sourround this issue of much controversy even among palliative care professionals. Objective: to review the existing literature regarding the assessment of hydration in cancer patients, the process of decision making regarding hydration, and the methods and outcomes of artificial hydration. Material and method: we conducted a narrative review using the Pubmed database as well as references within the identified papers, chapters in textbooks of pallaitive medicine and oncology, and previous issues of Medicina Paliativa. The review was conducted both in English and Spanish. Results: terminal cancer patients need less fluid for adequate hydration; however, they are at increased risk for fluid deficiency, often precipitated by minor variations in fluid intake, infection, and other conditions. Conclusion: the main symptoms of dehydration are difficult to interpret due to the presence of multiple symptoms related to cancer and cancer therapy. A careful assessment is needed before a decision is made regarding fluid administration. In unclear cases a brief trial of parenteral hydration may be useful. The subcutaneous and rectal routes are useful alternatives to the intravenous route, particularly in the community setting. If hydration is not considered appropriate a progressive reduction of drugs likely to accumulate in the presence of dehydration – including opioids – is indicated.

Should we hydrate terminally ill patients?

Terminally ill patients frequently have difficulties with fluid and food intake. The indication of artificial hydration in thesepatients has been subject of intense debate in the past years and the clinical practice widely varies, mostly based on anecdotal data and not on clinical evidence about risks and benefits associated to artificial hydration in terminal patients. There are not only technical questions concerning benefits and risks associated to artificial hydration, but also questions related to the ethical principles and values involved. Several topics, such as the effect of artificial hydration alleviating symptoms or reversing neurological alterations as delirium, its life prolonging effect or if it promotes unnecessary suffering, are discussed. In this review we will analyze clinical benefits and risks associated to artificial hydration in terminal patients, making reference to some ethical principles involved. FREE FULL-TEXT AVAILABLE IN PUBMED

Nutrition and hydration for terminal cancer patients in Taiwan

Many medical professionals are still confused when facing the reduction of food or fluid intake in terminal cancer patients. The aim of this study was to assess the frequency and causes of the inability of eating or drinking in terminal cancer patientsand to investigate the use of artificial nutrition and hydration (ANH); the frequency, type, and the extent to which staff found ANH to be ethically justified. Three hundred forty-four consecutive patients with terminal cancer admitted to a palliative care unit in Taiwan were recruited. A structured data collection form was used daily to evaluate clinical conditions, which were analyzed at the time of admission, 1 week after admission and 48 h before death. One hundred thirty-three (38.7%) of the 344 patients were unable to take water or food orally on admission; the leading cause was GI tract disturbances (58.6%). This impaired ability to eat or drink had become worse 1 week after admission (39.1%, P<0.01) and again 48 h before death (60.1%, P<0.001). The total rate of ANH use declined significantly, from 57.0% to 46.9% 1 week after admission ( P<0.001), but rose again to the same level as at admission in the 48 h before death (53.1%, P=0.169). Parenteral hydratation could be reduced significantly 1 week after admission ( P<0.05), but no reduction was possible in the 48 h before death; nor was it possible to reduce the nutrition administered. Multiple Cox regression analysis shows that the administration of ANH, either at admission or 2 days before death, did not have any significant influence on the patients' survival (HR: 0.88, 95% CI: 0.58-1.07; HR: 1.03, 95% CI: 0.76-1.38). In conclusion, sensitive care and continuous communication will probably lessen the use of ANH in terminal cancer patients. We have found it easier to reduce artificial hydratation than artificial nutrition, which corresponds to local cultural practice. Whether or not ANH was used did not influence survival in this study. Thus, the goals of care for terminal cancer patients should be refocused on the promotion of quality of life and preparation for death, rather than in simply making every effort to improve the status of hydratation and nutrition.

Half-Marathon and Full-Marathon Runners' Hydration Practices and Perceptions

Context: The behaviors and beliefs of recreational runners with regard to hydration maintenance are not well elucidated. Objective: To examine which beverages runners choose to drink and why, negative performance and health experiences related to dehydration, and methods used to assess hydration status. Design: Cross-sectional study. Setting: Marathon registration site. Patients or Other Participants: Men (n = 146) and women (n = 130) (age = 38.3 ± 11.3 years) registered for the 2010 Little Rock Half-Marathon or Full Marathon. Intervention(s): A 23-item questionnaire was administered to runners when they picked up their race timing chips. Main Outcome Measure(s): Runners were separated into tertiles (Low, Mod, High) based on z scores derived from training volume, expected performance, and running experience. We used a 100-mm visual analog scale with anchors of 0 (never) and 100 (always). Total sample responses and comparisons between tertile groups for questionnaire items are presented. Results: The High group (58±31) reported greater consumption of sport beverages in exercise environments than the Low (42 ± 35 mm) and Mod (39 ± 32 mm) groups (P < .05) and perceived sport beverages to be superior to water in meeting hydration needs (P < .05) and improving performance during runs greater than 1 hour (P < .05). Seventy percent of runners experienced 1 or more incidents in which they believed dehydration resulted in a major performance decrement, and 45% perceived dehydration to have resulted in adverse health effects. Twenty percent of runners reported monitoring their hydration status. Urine color was the method most often reported (7%), whereas only 2% reported measuring changes in body weight. Conclusions: Greater attention should be paid to informing runners of valid techniques to monitor hydration status and developing an appropriate individualized hydration strategy. FULL-TEXT FREE AT http://www.ingentaconnect.com/content/nata/jat/2011/00000046/00000006/art00001

Inverse relationship between percentage body weight change and finishing time in 643 forty-two-kilometre marathon runners.

OBJECTIVE: The purpose of this study was to determine the relationship between athletic performance and the change in body weight (BW) during a 42 km marathon in a large cohort of runners. METHODS: The study took place during the 2009 Mont Saint-Michel Marathon (France). 643 marathon finishers (560 males and 83 females) were studied. The change in BW during the race was calculated from measurements of each runner's BW immediately before and after the race. RESULTS: BW loss was 2.3 ± 2.2% (mean±SEM) (p<0.01). BW loss was -3.1 ± 1.9% for runners finishing the marathon in less than 3 h; -2.5 ± 2.1% for runners finishing between 3 and 4 h; and -1.8 ± 2.4% for runners who required more than 4 h to complete the marathon. The degree of BW loss was linearly related to 42 km race finishing time (p3% in runners completing the race in less than 3 h. These data are not compatible with laboratory-derived data suggesting that BW loss greater than 2% during exercise impairs athletic performance. They match an extensive body of evidence showing that the most successful athletes in marathon and ultra-marathon running and triathlon events are frequently those who lose substantially more than 3-4% BW during competition.

hanges in body mass alone explain almost all of the variance in the serum sodium concentrations during prolonged exercise. Has commercial influence impeded scientific endeavour?

In 1991, we provided definitive evidence that exercise-associated hyponatraemia (EAH) is caused by abnormal fluid retention in those who overdrink during prolonged exercise, but this finding was ignored. Instead, in 1996, influential guidelines of the American College of Sports Medicine (ACSM) promoted the concept that athletes should drink 'as much as tolerable' duringexercise. What followed was an epidemic of cases of EAH and its associated encephalopathy (EAHE). A recent study funded by the sports drink industry confirms our 1991 finding by showing that 95% of the variance in the serum sodiumconcentration during exercise can be explained by changes in body mass alone. The possibility is that commercial influencedelayed the acceptance of our findings for two decades.

First reported cases of exercise-associated hyponatremia in Asia.

There are no reported cases of exercise-associated hyponatremia (EAH) in tropical Asia. This study aimed to investigate the incidence of EAH at the on-site medical tent and fluid balance in long distance foot races in a warm and humid environment. Body mass was taken before and after the races (42-km marathon; 84-km ultra-marathon). Blood sodium concentration was measured for symptomatic runners admitted to the medical tent. Mean (SD) dry bulb temperature was 29.0 (0.6)°C, relative humidity 89 (2)% and wind speed 0.3 (0.5) m/s. Three out of the 8 symptomatic runners admitted to the medical tent were diagnosed with hyponatremia, with blood sodium concentrations of 134 mmol/L in a 42-km runner, and 131 and 117 mmol/L in two 84-km runners. In the 42-km race, mean % ΔBM was -1.6 (1.2)%, ranging from -5.7 to 1.4%, and 22 runners (7%) gained weight. In the 84-km race, mean % ΔBM was -2.3 (1.7)%, ranging from -8.0 to 1.4%, and 9 runners (8%) gained weight. In addition to the 3 cases of symptomatic hyponatremia observed, 8% of the 84-km runners and 7% of the 42-km runners gained weight during the race. This indicates the need to disseminate advice for the prevention and treatment of EAH for races held in the tropics.

Exercise-associated hyponatremia during winter sports.

Exercise-associated hyponatremia (EAH) is hyponatremia that occurs

Low prevalence of exercise-associated hyponatremia in male 100 km ultra-marathon runners in Switzerland.

We investigated the prevalence of exercise-associated hyponatremia (EAH) in 145 male ultra-marathoners at the '100-km ultra-run' in Biel, Switzerland. Changes in body mass, urinary specific gravity, haemoglobin, haematocrit, plasma [Na(+)], and plasma volume were determined. Seven runners (4.8%) developed asymptomatic EAH. Body mass, haematocrit and haemoglobin decreased, plasma [Na(+)] remained unchanged and plasma volume increased. Δ body mass correlated with both post race plasma [Na(+)] and Δ plasma [Na(+)]. Δ plasma volume was associated with post race plasma [Na(+)]. The athletes consumed 0.65 (0.30) L/h; fluid intake correlated significantly and negatively (r = -0.50, p < 0.0001) to race time. Fluid intake was neither associated with post race plasma [Na(+)] nor with Δ plasma [Na(+)], but was related to Δ body mass. To conclude, the prevalence of EAH was low at ~5% in these male 100 km ultra-marathoners. EAH was asymptomatic and would not have been detected without the measurement of plasma [Na(+)].

Do male 100-km ultra-marathoners overdrink?

PURPOSE: Fluid overload is considered a main risk factor for exercise-associated hyponatremia (EAH). The aim of this study was to investigate the incidence of EAH in ultra-runners at the 100 km ultra-run in Biel, Switzerland. METHODS: Pre- and postrace, body mass, urinary specific gravity, hemoglobin, hematocrit, plasma [Na+], and plasma volume were determined. RESULTS: Of the 145 finishers, seven runners (4.8%) developed asymptomatic EAH. While running, the athletes consumed a total of (median and interquartile ranges) 6.9 (5.1-8.8) L over the 100 km distance, equal to 0.58 (0.41-0.79) L/h. Fluid intake correlated negatively and significantly with race time (r = -.50, P < .0001). Body mass decreased, plasma [Na+] remained unchanged, hematocrit and hemoglobin decreased, and urinary specific gravity increased. Plasma volume increased by 4.6 (-2.3 to 12.8) %. Change in body mass correlated with both postrace plasma [Na+] and Δ plasma [Na+]. Postrace plasma [Na+] correlated to Δ plasma [Na+]. Fluid intake was associated neither with postrace plasma [Na+] nor with Δ plasma [Na+]. Fluid intake was related to Δ body mass (r = .21, P = .012), but not to postrace body mass. Fluid intake showed no correlation to Δ plasma volume. Change in plasma volume was associated with postrace [Na+]. CONCLUSIONS: Incidences of EAH in 100 km ultra-marathoners were lower compared with reports on marathoners. Body mass decreased, plasma volume increased, and plasma [Na+] was maintained. Since fluid intake was related neither to Δ plasma volume nor to Δ plasma [Na+], we assume that factors other than fluid intake maintained body fluid homeostasis.

Physician nutrition and cognition during work hours: effect of a nutrition based intervention.

BACKGROUND: Physicians are often unable to eat and drink properly during their work day. Nutrition has been linked to cognition. We aimed to examine the effect of a nutrition based intervention that of scheduled nutrition breaks during the workday upon physician cognition, glucose, and hypoglycemic symptoms. METHODS: A volunteer sample of twenty staff physicians from a large urban teaching hospital were recruited from the doctors' lounge. During both the baseline and the intervention day, we measured subjects' cognitive function, capillary blood glucose, "hypoglycemic" nutrition-related symptoms, fluid and nutrient intake, level of physical activity, weight, and urinary output. RESULTS: Cognition scores as measured by a composite score of speed and accuracy (T put statistic) were superior on the intervention day on simple (220 vs. 209, p = 0.01) and complex (92 vs. 85, p < 0.001) reaction time tests. Group mean glucose was 0.3 mmol/L lower (p = 0.03) and less variable (coefficient of variation 12.2% vs. 18.0%) on the intervention day. Although not statistically significant, there was also a trend toward the reporting of fewer hypoglycemic type symptoms. There was higher nutrient intake on intervention versus baseline days as measured by mean caloric intake (1345 vs. 935 kilocalories, p = 0.008), and improved hydration as measured by mean change in body mass (+352 vs. -364 grams, p < 0.001). CONCLUSIONS: Our study provides evidence in support of adequate workplace nutrition as a contributor to improved physician cognition, adding to the body of research suggesting that physician wellness may ultimately benefit not only the physicians themselves but also their patients and the health care systems in which they work. FREE FULL-TEXT AVAILABLE IN PUBMED

Hydration Status of Expatriate Manual Workers During Summer in the Middle East.

BACKGROUND: Implicit in all indices used for risk assessment in the prevention of heat stress is the assumption that workers are healthy and well hydrated; studies in Australian mine workers have shown that this is not the case. Where workers are poorly hydrated, the level of protection offered by management strategies based primarily on environmental monitoring is compromised. OBJECTIVES: To investigate the hydration status of expatriate workers during summer in a range of work environments in the Middle East as large numbers of expatriate workers are employed as manual laborers in construction and other industries under extreme heat stress conditions where heat illness is a significant concern. The aim was to ascertain whether the generally inadequate hydration status, previously documented in Australian workers, is also an issue in these workers and make practical recommendations for control. METHODS: Studies were carried out at four sites to document the hydration status of exposed workers in different workplaces using urine specific gravity at three time points over two different work shifts. RESULTS: Although the workers were found in general to be better hydrated than their Australian counterparts, a high proportion were still found to be inadequately hydrated both on presentation for work and throughout the shift. Hydration status did not alter greatly over the course of the day at individual or group level. CONCLUSIONS: Interventions are required to ensure that workers in extreme heat stress conditions maintain adequate levels of hydration. Failure to do so reduces the protection afforded by heat stress indices based on environmental monitoring. FREE FULL-TEXT AVAILABLE IN PUBMED

Effect of bariatric surgery on normal and abnormal renal function.

BACKGROUND: Obesity has been associated with hypertension, diabetes mellitus, and metabolic syndrome, risk factors for chronic kidney disease. In addition, obesity has been found to have an independent, negative effect on renal function and the progression of renal insufficiency. METHODS: The serum creatinine (CR) in 813 patients who had undergone obesity surgery from 2003 to 2009 at a large academic medical center and had been followed up for ≥24 months was retrospectively monitored. Renal function, as measured by the CR level, was assessed at baseline and at 6, 12, and ≥24 months of follow-up. The groups were stratified by the baseline CR as follows: normal (CR 1.6 mg/dL). RESULTS:Of the 813 patients, 757 had a CR <1.3 mg/dL at baseline. Of those 757 patients, 97.6% had maintained a CR of 1.6 mg/dL (n = 757) at 6 months of follow-up. At 1 year of follow-up, 99% had maintained a CR of 1.3% (n = 509). At 2 years of follow-up, 100% had a CR value of 1.6 mg/dL) before weight loss surgery. Examination of the CR values at ≥2 years after weight loss surgery demonstrated that 76.7% had a normal CR level, 12.5% had mild impairment, and 10.7% had moderate impairment. CONCLUSION: Bariatric surgery does not have a negative effect on renal function as measured by the CR, whether CR at baseline is <1.3 or ≥1.3 mg/dL when monitored for ≥24 months. For those with impaired renal function and a CR ≥1.3 mg/dL, improvement in CR was seen in 76.7% at ≥2 years postoperatively, at a point at which the weight loss velocity, hydration, and nutritional status have stabilized. The weight loss associated with bariatric surgery could potentially have a positive effecton renal function at ≥24 months, such as was found in the present study by a stable or reduced CR level. The etiology for this might be a direct effect of weight loss on impaired renal function or an indirect effect by reducing the rates of co-morbidities, such as diabetes mellitus and hypertension, both risk factors for renal disease. Additional prospective studies, including weight-matched controls, are needed.

The effect of racial origin on total body water volume in peritoneal dialysis patients.

ACKGROUND AND OBJECTIVES: Peritoneal dialysis adequacy is typically assessed by urea clearance corrected for total body water (TBW) on the basis of anthropomorphic equations, which do not readily take into account changes in body composition, which may vary between ethnic groups. To determine whether ethnicity could affect estimates of peritoneal dialysis adequacy, we compared TBW estimated by anthropomorphic equations and that measured by multi-frequency bio-impedance spectroscopy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We calculated TBW in 600 healthy adult peritoneal dialysis outpatient attending two tertiary university hospitals serving an inner-city multiethnic population who had TBW measured by multi-frequency bio-impedance spectroscopy performed. RESULTS: 600 adult peritoneal dialysis patients were studied: mean age, 56.7 ± 0.6 years; 54.2% men; 29.7% diabetic; mean body mass index, 26.1 ± 0.2; 47.3% Caucasian; 29.2% South Asian; 12.8% African/Afro-Caribbean. Total body water was calculated using several anthropomorphic equations and was higher than that calculated MEASURED BY MF-BIS for all ethnic groups, apart from African/Afro-Caribbeans, with the greatest difference between Watson calculated TBW and multi-frequency bioelectrical impedance spectroscopy 12.3 ± 0.6% for the South Asians, 9.0 ± 2.6% for Far Eastern Asians, 2.8 ± 0.6% Caucasians, and -0.2 ± 1.5% for African/Afro-Caribbeans. CONCLUSIONS: In this United Kingdom-based multiethnic population, body composition differed particularly for the South Asian patients compared with Caucasians and African/Afro-Caribbeans. Overestimation of TBW by anthropomorphic-based equations would lead to a lower calculation of Kt/V(urea), which may lead to changes in peritoneal dialysis prescription to achieve clinical standard targets and also affect studies examining the relationship between Kt/V and survival.

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Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities

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