Percent Dehydration Research Articles

Menstrual cycle effects on thermoregulation while exercising in the heat.

Women may be challenged to maintain thermoregulation due to hormonal changes associated with the menstrual cycle. The purpose of this study was to assess the effect of the menstrual cycle phase on core temperature, hydration status, and perceived exertion while exercising under uncompensable heat gain. Eleven eumenorrheic women (24.4±1.1yrs, 65.7±2.4kg, 22.7±1.5% body fat) walked for two 180-min trials in a heat chamber (35°C and 30% relative humidity) during early-follicular (EF) and mid-luteal (ML) phases. Subjects completed three intervals of 50min of exercise at 50% VO2max. Physiological strain index (PSI), core temperature (TC), perceived heat (PH), and rating of perceived exertion (RPE) were measured throughout both trials. Nude body weight (NBW) and blood samples were collected pre- and post-trial. Blood samples were analyzed for hematocrit (Hct), hemoglobin (Hb), serum estrogen, progesterone, and aldosterone. NBW showed a main effect of time (p=0.002, ηp2=0.62). Aldosterone showed main effect of time (p=0.004, ηp2=0.59) and phase (p=0.014, ηp2=0.47), peaking post exercise in both EF and ML (527.6.1±89.0pg·mL-1 vs 827.4±129.5pgmL-1 respectively, p=0.014). Estradiol and progesterone showed main effects of phase (p=0.007, ηp2=0.53; p=0.045, ηp2=0.30) but not time (p=0.68, p=0.32). TC showed main effect of time (p<0.001, ηp2=0.89) and phase, peaking at 170min (EF: 37.8±0.1°C vs. ML: 38.0±0.1°C, p=0.032, ηp2=0.38). Main effect of time was seen for PSI (p=0.002, ηp2=0.88), PH (p=0.004, ηp2=0.66), and RPE (p=0.026, ηp2=0.80). Sweat rate, Hct, Hb, and percent dehydration were not different between the phases. In conclusion, subjects demonstrated elevated Tc and basal aldosterone in ML corresponding with elevations in estrogen and progesterone. Aldosterone significantly increased following exercise in the heat but remained elevated in ML. These results indicate that elevated Tc during ML is maintained during exercise in the heat despite similar perceived heat and effort between phases.

Clinical and socio-environmental determinants of multidrug-resistant vibrio cholerae 01 in older children and adults in Bangladesh

ObjectivesFew studies have evaluated determinants of multidrug-resistant (MDR) Vibrio cholerae O1 in older children and adults. This study aimed to characterize the prevalence of MDR V. cholerae O1 and associated risk factors among patients over five years of age in Bangladesh. MethodsStool culture and antimicrobial susceptibility testing were performed as a part of a larger study at Dhaka Hospital in Bangladesh from March 2019–March 2020. Univariate statistics and multiple logistic regression were used to assess the association between a range of variables and MDR V. cholerae O1. ResultsMDR was found in 175 of 623 (28.1%) V. cholerae O1 isolates. High levels of resistance were found to erythromycin (99.2%), trimethoprim-sulfamethoxazole (99.7%), and ampicillin (88.9%), while susceptibility was high to tetracyclines (99.7%), azithromycin (99.2%), ciprofloxacin (99.8%), and cephalosporins (98.6%). MDR was associated with prior antibiotic use, longer transport time to hospital, higher income, non-flush toilet use, greater stool frequency, lower blood pressure, lower mid-upper arm circumference, and lower percent dehydration. ConclusionsMDR V. cholerae O1 was common among patients over five in an urban hospital in Bangladesh. Significant factors associated with MDR may be actionable in identifying patients with a high likelihood of MDR.

Do The National Institute Of Occupational Safety And Health Recommendations Prevent Hyperthermia And Dehydration?

The National Institute of Occupational Safety and Health (NIOSH) recommendations for work in the heat suggest consuming 237 mL of water every 15-20 min and rest intervals are not necessary for work if conditions are not extreme. The efficacy of these recommendations to protect against hyperthermia (rise in core temperature) and dehydration (percent body mass loss) has not been tested. PURPOSE: To test the effectiveness of the NIOSH guidelines to prevent body temperature from exceeding 38.0°C and dehydration greater than 2% of body mass. METHODS: Seven men walked for 2 hours at 6.4 kph in the highest thermal stress NIOSH allows before recommending work-to-rest ratios (34°C, 30% relative humidity). Participants drank 237 mL of water every 20 minutes while rectal temperature (Tre) monitored. Body mass and urine specific gravity (USG) were measured before and after exertion. Tre was extrapolated out to four- and eight-hour workdays based on the rate of Tre rise in the last hour of exertion. Percent dehydration was extrapolated out to four- and eight-hour workdays based on body mass lost and planned hydration during exertion. RESULTS: Tre rose from baseline (36.8±0.3°C) to the completion of exertion (38.1±0.6°C, p<0.001), with two subjects reaching the 38°C threshold. Four- and eight-hour predicted Tre were 38.6±1.1°C and 39.6±2.1°C, respectively, with 5 subjects predicted to exceed Tre threshold at 4hr and 6 subjects at 8hr. Subjects began work euhydrated (USG: 1.013±0.005) and dehydrated 0.03±0.48% during the work protocol, with no subjects reaching 2% dehydration. Four- and eight-hour predicted percent dehydration were 0.05±0.95% and 0.10±1.90%, respectively. CONCLUSIONS: Adherence to the NIOSH recommendations may be insufficient to prevent workers from reaching the hyperthermia threshold but would protect against dehydration during heavy intensity work in the heat. Adjustments to NIOSH work-to-rest ratio recommendations should be explored to maintain worker safety.

Effect of vivisection on haematobiochemical parameters of experimental dogs: Towards improved animal welfare

Introduction: Vivisection could lead to the derailment of vital body functions and hence severe health consequences. The effect of multiple vivisections on haematobiochemical parameters of dogs was investigated with a perspective to improve animal welfare. Methods: Fifteen healthy Nigerian indigenous dogs that were to be used for student wet-labs were recruited for this study. The dogs were acclimatized for four weeks and then exposed to four (4) weeks (bi-weekly) vivisection. Complete physical examination and blood sampling were carried out on days 0, 14, and 28 post-vivisection. Blood samples were analysed for blood and serum biochemical profiles. Results: Post-vivisections results were compared to pre-vivisection results using ANOVA. Physical examination also reveals loss of body weight, body condition score, decreased skin elasticity, sunken eyeballs, dry oral and nasal mucous membrane, as well as percent dehydration on post-vivisection parameters. Findings also revealed a decrease in haematocrit, haemoglobin, and erythrocyte count (p &lt; 0.05), coupled with hyperproteinaemia, hyperalbuminemia, and azotaemia (p &lt; 0.05) which are generally accepted as indices for dehydration. Significance: Conclusively, the reported anaemia and dehydration in this study could potentiate serious adverse medical effects and it was therefore recommended that the use of animals for multiple surgical procedures should be guided by standard surgical protocols with a perspective of improving animal welfare.

A synthetic undergarment increases physiological strain

Our aim was to examine the effect of a synthetic material undergarment on heat stress during exercise in a hot environment. Ten active males completed two trials of intermittent (50min walking, 10min sitting) treadmill walking over 3h in 35°C and 30% relative humidity. Subjects wore wildland firefighter flame-resistant meta-aramid blend pants and shirt with either a 100% cotton (C) or flame-retardant modacrylic undergarment (S), while carrying a 16-kg pack, helmet and leather gloves. Exercise was followed by a 30-min rest period without pack, helmet, gloves, and outerwear shirt. Rectal temperature and physiological strain were greater in S than C (P=0.04). No significant differences were found for heart rate, rating of perceived exertion, energy expenditure or skin temperature between C and S. Skin blood flow increased significantly in S following the second hour of exercise, resulting in a time×trial interaction (P=0.001). No significant differences for skin blood flow were found post exercise. Sweat rate and percent dehydration were not different between C and S. These data indicate that, of the two undergarments investigated, the synthetic undergarment negatively affected physiological factors that have been shown to indicate an increased risk of heat-related injuries.

Sex and Gender Differences in Acute Pediatric Diarrhea: A Secondary Analysis of the DHAKA Study

Pediatric diarrheal disease is a significant source of morbidity and mortality in the developing world. While several studies have demonstrated an increased incidence of diarrheal illness in boys compared with girls in low- and middle-income countries (LMIC), the reasons for this difference are unclear. This secondary analysis of the dehydration: assessing kids accurately (DHAKA) derivation and validation studies included children aged <5 years old with acute diarrhea in Dhaka, Bangladesh. The dehydration status was established by percentage weight change with rehydration. Multivariable regression was used to compare percent dehydration, while controlling for differences in age and nutritional status. In this cohort, a total of 1396 children were analyzed; 785 were male (56.2%) and 611 were female (43.8%). Girls presenting with diarrhea were older than boys (median age 17 months vs. 15 months, p = 0.02) and had significantly more malnutrition than boys, even when controlled for age (mean mid-upper arm circumference 134.2 mm vs. 136.4 mm, p < 0.01). The mean percent dehydration did not differ between boys and girls after controlling for age and nutrition status (p = 0.25). Although girls did have higher rates of malnutrition than boys, measures of diarrhea severity were similar between the two groups, arguing against a cultural bias in care-seeking behavior that favors boys.

Assessing Dehydration Employing End-Tidal Carbon Dioxide in Children With Vomiting and Diarrhea.

Serum bicarbonate reflects dehydration severity in children with gastroenteritis. Previous work in children receiving intravenous rehydration has correlated end-tidal carbon dioxide (EtCO2) with serum bicarbonate. We evaluated whether EtCO2 predicts weight change in children with vomiting and/or diarrhea. A prospective cohort study was conducted. Eligible children were 3 months to 10 years old and presented for emergency department (ED) care because of vomiting and/or diarrhea. End-tidal carbon dioxide measurements were performed after triage. The diagnostic standard was weight change determined from serial measurements after symptom resolution. A receiver operating characteristic curve was constructed to identify a cut-point to predict 5% or more dehydration. In total, 195 children were enrolled. Among the 169 (87%) with EtCO2 measurements, the median (interquartile range [IQR]) was 30.4 (27.8 to 33.1). One hundred fifty-eight had repeat weights performed at home; the median (IQR) weight change from ED presentation to well weight was +0.06 (-0.14 to +0.30) or +0.72% (-1.2% to +2.1%). Sixteen percent (25/158) had 3% or more and 4% (6/158) had 5% or more weight gain (ie, percent dehydration). One hundred sixteen (60%) completed home follow-up and had acceptable EtCO2 recordings. Receiver operating curve analysis revealed an area under the curve of 0.34 (95% confidence interval, 0.06 to 0.62) for EtCO2 as a predictor of 5% or more dehydration. The limited accuracy of EtCO2 measurement to predict 5% or more dehydration precludes its use as a tool to assess dehydration severity in children. End-tidal carbon dioxide monitoring does not have the ability to identify those children with 5% or more dehydration in a cohort of children with vomiting and/or diarrhea presenting for ED care.

Comparison of Sports Drink Versus Oral Rehydration Solution During Exercise in the Heat

This study compared 2 commercially available beverages, an oral rehydration solution (ORS; 60.9 mM Na+; 3.4% carbohydrate) and a sports drink (SDS; 18.4 mM Na+; 5.9% carbohydrate), on hydration and metabolism during submaximal exercise in the heat. Ten male subjects completed two 90-min exercise trials (39ºC, 30%) of walking at 50% VO2max followed by a 30-min rest period in the heat while wearing wildland firefighter personal protective clothing. After 45 min of exercise, fluid delivery by either ORS or SDS replaced 150% of sweat loss. Subjects continued the exercise for 45 additional minutes followed by a 30-min rest period. Blood samples were collected pre-exercise (0 min), post-exercise (90 min), and post-trial (120 min) to measure plasma volume (%) and blood glucose (mg·dL-1). Expired gases were collected twice for 3 min for substrate oxidation. The sweat rate and percent dehydration did not differ between the groups (P=0.86 and P=0.79, respectively). Changes in plasma volume did not differ (P=0.55). Hemoglobin levels significantly increased in both groups post-trial (P=0.009). Blood glucose was significantly greater post-trial in SDS versus ORS (116±19 vs 103±13 mg·dL-1, respectively; P=0.01). Fat oxidation was lower post-exercise in SDS vs ORS (0.38±0.1 vs 0.47±0.2 g·min-1, respectively; P=0.049). These data indicate no difference in fluid retention between ORS or SDS when supplemented during exercise in the heat. This implies that fluid volume, and not drink contents, may be more important when ingested during exercise in a hot environment.

Acute Hypotension after High-Intensity Interval Exercise in Metabolic Syndrome Patients.

The purpose of this study was to compare the magnitude of post-exercise hypotension (PEH) after a bout of cycling exercise using high-intensity interval training (HIIT) in comparison to a bout of traditional moderate-intensity continuous exercise (CE). After supine rest 14 obese (31±1 kg·m-2) middle-age (57±2 y) metabolic syndrome patients (50% hypertensive) underwent a bout of HIIT or a bout of CE in a random order and then returned to supine recovery for another 45 min. Exercise trials were isocaloric and compared to a no-exercise trial (CONT) of supine rest for a total of 160 min. Before and after exercise we assessed blood pressure (BP), heart rate (HR), cardiac output (Q), systemic vascular resistance (SVR), intestinal temperature (TINT), forearm skin blood flow (SKBF) and percent dehydration. HIIT produced a larger post-exercise reduction in systolic blood pressure than CE in the hypertensive group (-20±6 vs. -5±3 mmHg) and in the normotensive group (-8±3 vs. -3±2 mmHg) while HIIT reduced SVR below CE (P<0.05). Percent dehydration was larger after HIIT, and post-exercise TINT and SKBF increased only after HIIT (all P<0.05). Our findings suggest that HIIT is a superior exercise method to CE to acutely reduce blood pressure in MSyn subjects.

Cardiovascular Drift during Training for Fitness in Patients with Metabolic Syndrome.

The health benefits of a training program are largely influenced by the exercise dose and intensity. We sought to determine whether during a training bout of continuous versus interval exercise the workload needs to be reduced to maintain the prescribed target heart rate (HR). Fourteen obese (31 ± 4 kg·m) middle-age (57 ± 8 yr) individuals with metabolic syndrome, underwent two exercise training bouts matched by energy expenditure (i.e., 70 ± 5 min of continuous exercise [CE] or 45 min of interval exercise, high-intensity interval training [HIIT]). All subjects completed both trials in a randomized order. HR, power output (W), percent dehydration, intestinal and skin temperature (TINT and TSK), mean arterial pressure, cardiac output (CO), stroke volume (SV), and blood lactate concentration (La) were measured at the initial and latter stages of each trial to assess time-dependent drift. During the HIIT trial, power output was lowered by 30 ± 16 W to maintain the target HR, whereas a 10 ± 11 W reduction was needed in the CE trial (P < 0.05). Energy expenditure, CO, and SV declined with exercise time only in the HIIT trial (15%, 10%, and 13%, respectively). During HIIT, percent dehydration, TINT, and TSK increased more than during the CE trial (all P = 0.001). Mean arterial pressure and La were higher in HIIT without time drift in any trial. Our findings suggests that while CE results in mild power output reductions to maintain target HR, the increasingly popular HIIT results in marked reductions in power output, energy expenditure, and CO (21%, 15%, and 10%, respectively). HIIT based on target HR may result in lower than expected training adaptations because of workload adjustments to avoid HR drift.

Accuracy of Inferior Vena Cava Ultrasound for Predicting Dehydration in Children with Acute Diarrhea in Resource-Limited Settings.

IntroductionAlthough dehydration from diarrhea is a leading cause of morbidity and mortality in children under five, existing methods of assessing dehydration status in children have limited accuracy.ObjectiveTo assess the accuracy of point-of-care ultrasound measurement of the aorta-to-IVC ratio as a predictor of dehydration in children.MethodsA prospective cohort study of children under five years with acute diarrhea was conducted in the rehydration unit of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). Ultrasound measurements of aorta-to-IVC ratio and dehydrated weight were obtained on patient arrival. Percent weight change was monitored during rehydration to classify children as having “some dehydration” with weight change 3–9% or “severe dehydration” with weight change > 9%. Logistic regression analysis and Receiver-Operator Characteristic (ROC) curves were used to evaluate the accuracy of aorta-to-IVC ratio as a predictor of dehydration severity.Results850 children were enrolled, of which 771 were included in the final analysis. Aorta to IVC ratio was a significant predictor of the percent dehydration in children with acute diarrhea, with each 1-point increase in the aorta to IVC ratio predicting a 1.1% increase in the percent dehydration of the child. However, the area under the ROC curve (0.60), sensitivity (67%), and specificity (49%), for predicting severe dehydration were all poor.ConclusionsPoint-of-care ultrasound of the aorta-to-IVC ratio was statistically associated with volume status, but was not accurate enough to be used as an independent screening tool for dehydration in children under five years presenting with acute diarrhea in a resource-limited setting.

Midupper Arm Circumference Outperforms Weight-Based Measures of Nutritional Status in Children with Diarrhea ,

Background: Undernutrition contributes to 45% of all deaths in children <5 y of age worldwide, with a large proportion of those deaths caused by diarrhea. However, no validated tools exist for assessing undernutrition in children with diarrhea and possible dehydration.Objective: This study assessed the validity of different measures of undernutrition in children with diarrhea.Methods: A prospective cohort study was conducted at an urban hospital in Bangladesh. Children <60 mo of age presenting to the hospital rehydration unit with acute diarrhea were eligible for enrollment. Study staff randomly selected 1196 children for screening, of which 1025 were eligible, 850 were enrolled, and 721 had complete data for analysis. Anthropometric measurements, including weight-for-age z score (WAZ), weight-for-length z score (WLZ), midupper arm circumference (MUAC), and midupper arm circumference z score (MUACZ), were calculated pre- and posthydration in all patients. Measurements were evaluated for their ability to correctly identify undernutrition in children with varying degrees of dehydration.Results: Of the 721 patients with full data for analysis, the median percent dehydration was 4%. Of the 4 measures evaluated, MUAC and MUACZ demonstrated 92–94% agreement pre- and posthydration compared with 69–76% for WAZ and WLZ. Although each 1% change in hydration status was found to change weight-for-age by 0.0895 z scores and weight-for-length by 0.1304 z scores, MUAC and MUACZ were not significantly affected by dehydration status. Weight-based measures misclassified 12% of children with severe underweight and 14% with severe acute malnutrition (SAM) compared with only 1–2% for MUAC and MUACZ.Conclusions: MUAC and MUACZ were the most accurate predictors of undernutrition in children with diarrhea. WAZ and WLZ were significantly affected by dehydration status, leading to the misdiagnosis of many patients on arrival with severe underweight and SAM. This trial was registered at clinicaltrials.gov as NCT02007733.

(1)H nuclear magnetic resonance (NMR) as a tool to measure dehydration in mice.

Dehydration is a prevalent pathology, where loss of bodily water can result in variable symptoms. Symptoms can range from simple thirst to dire scenarios involving loss of consciousness. Clinical methods exist that assess dehydration from qualitative weight changes to more quantitative osmolality measurements. These methods are imprecise, invasive, and/or easily confounded, despite being practiced clinically. We investigate a non-invasive, non-imaging (1)H NMR method of assessing dehydration that attempts to address issues with existing clinical methods. Dehydration was achieved by exposing mice (n = 16) to a thermally elevated environment (37 °C) for up to 7.5 h (0.11-13% weight loss). Whole body NMR measurements were made using a Bruker LF50 BCA-Analyzer before and after dehydration. Physical lean tissue, adipose, and free water compartment approximations had NMR values extracted from relaxation data through a multi-exponential fitting method. Changes in before/after NMR values were compared with clinically practiced metrics of weight loss (percent dehydration) as well as blood and urine osmolality. A linear correlation between tissue relaxometry and both animal percent dehydration and urine osmolality was observed in lean tissue, but not adipose or free fluids. Calculated R(2) values for percent dehydration were 0.8619 (lean, P < 0.0001), 0.5609 (adipose, P = 0.0008), and 0.0644 (free fluids, P = 0.3445). R(2) values for urine osmolality were 0.7760 (lean, P < 0.0001), 0.5005 (adipose, P = 0.0022), and 0.0568 (free fluids, P = 0.3739). These results suggest that non-imaging (1)H NMR methods are capable of non-invasively assessing dehydration in live animals.

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

To assess heart rate (HR), intestinal body temperature (T(intest)), and hydration status changes and relationships in 12 participants in a 3-day trail run. Descriptive field study. : Three Cranes Challenge trail run, in Karkloof, KwaZulu-Natal, South Africa. Twelve (5 men and 7 women) amateur runners. Trail run of 95 km divided into 3 stages: elevation gains on the 3 days, 1020, 1226, and 680 m, respectively. Changes in HR, T(intest), serum osmolality, and body mass. 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 T(intest) ranged between 36.1 and 40.2°C. The correlation between maximum T(intest) and percent age-predicted maximum HR (n = 12) was significant (R = 0.58; P < 0.05), whereas the correlation between maximum T(intest) and serum osmolality or body mass did not reach significance (R = 0.16, 0.13; P > 0.05). This study provides evidence in support of the contention that maximum T(intest) 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.

Comparing the accuracy of the three popular clinical dehydration scales in children with diarrhea

BackgroundDehydration due to acute gastroenteritis is one of the leading causes of mortality in children worldwide. The World Health Organization (WHO) scale, the Gorelick scale, and the Clinical Dehydration Scale (CDS) were created to estimate percentage dehydration in children with gastroenteritis based on clinical signs. Of these, only the CDS has been prospectively validated against a valid gold standard, though never in low- and middle-income countries. The purpose of this study is to determine whether these clinical scales can accurately assess dehydration status in children when performed by nurses or general physicians in a low-income country.MethodsWe prospectively enrolled a non-consecutive sample of children presenting to three Rwandan hospitals with diarrhea and/or vomiting. A health care provider documented clinical signs on arrival and weighed the patient using a standard scale. Once admitted, the patient received rehydration according to standard hospital protocol and was weighed again at hospital discharge. Receiver operating characteristic (ROC) curves were created for each of the three scales compared to the gold standard, percent weight change with rehydration. Sensitivity, specificity, and likelihood ratios were calculated based on the best cutoff points of the ROC curves.ResultsWe enrolled 73 children, and 49 children met eligibility criteria. Based on our gold standard, the children had a mean percent dehydration of 5% on arrival. The WHO scale, Gorelick scale, and CDS did not have an area under the ROC curve statistically different from the reference line. The WHO scale had sensitivities of 79% and 50% and specificities of 43% and 61% for severe and moderate dehydration, respectively; the 4- and 10-point Gorelick scale had sensitivities of 64% and 21% and specificities of 69% and 89%, respectively, for severe dehydration, while the same scales had sensitivities of 68% and 82% and specificities of 41% and 35% for moderate dehydration; the CDS had a sensitivity of 68% and specificity of 45% for moderate dehydration.ConclusionIn this sample of children, the WHO scale, Gorelick scale, and CDS did not provide an accurate assessment of dehydration status when used by general physicians and nurses in a developing world setting.

High-sweat Na+ in cystic fibrosis and healthy individuals does not diminish thirst during exercise in the heat.

Sweat Na(+) concentration ([Na(+)]) varies greatly among individuals and is particularly high in cystic fibrosis (CF). The purpose of this study was to determine whether excess sweat [Na(+)] differentially impacts thirst drive and other physiological responses during progressive dehydration via exercise in the heat. Healthy subjects with high-sweat [Na(+)] (SS) (91.0 ± 17.3 mmol/l), Controls with average sweat [Na(+)] (43.7 ± 9.9 mmol/l), and physically active CF patients with very high sweat [Na(+)] (132.6 ± 6.4 mmol/l) cycled in the heat without drinking until 3% dehydration. Serum osmolality increased less (P < 0.05) in CF (6.1 ± 4.3 mosmol/kgH(2)O) and SS (8.4 ± 3.0 mosmol/kgH(2)O) compared with Control (14.8 ± 3.5 mosmol/kgH(2)O). Relative change in plasma volume was greater (P < 0.05) in CF (-19.3 ± 4.5%) and SS (-18.8 ± 3.1%) compared with Control (-14.3 ± 2.3%). Thirst during exercise and changes in plasma levels of vasopressin, angiotensin II, and aldosterone relative to percent dehydration were not different among groups. However, ad libitum fluid replacement was 40% less, and serum NaCl concentration was lower for CF compared with SS and Control during recovery. Despite large variability in sweat electrolyte loss, thirst appears to be appropriately maintained during exercise in the heat as a linear function of dehydration, with relative contributions from hyperosmotic and hypovolemic stimuli dependent upon the magnitude of salt lost in sweat. CF exhibit lower ad libitum fluid restoration following dehydration, which may reflect physiological cues directed at preservation of salt balance over volume restoration.

Evaluation of a Gastroenteritis Severity Score for Use in Outpatient Settings

The objective of this study was to evaluate the internal reliability, construct validity, and ease of administration of a gastroenteritis disease severity score, the modified Vesikari score (MVS), which does not require in-person assessment. The MVS was created by replacing 1 variable (percent dehydration) in the original score with the need for future health care visits. We used the MVS to assess the global severity of disease in a cohort of children 3 to 48 months of age with acute gastroenteritis who were evaluated in 1 of 11 participating pediatric emergency departments. In this prospective study, caregivers recorded symptoms at home in a diary and reported the results via telephone at follow-up evaluation 14 days later. To evaluate internal reliability, we examined correlations between the items included in the score. Construct validity was evaluated by assessing the correlation between the total score and other proxy outcomes of disease severity, MVS distribution, and consistency between sites. A total of 455 children were enrolled, and 415 were successfully contacted for follow-up evaluation. Internal reliability was acceptable, with Cronbach's alpha of 0.59. Disease severity was correlated with day care (P = .01) and work (P = .002) absenteeism. The MVS was normally distributed, and mean scores did not differ between the 11 sites. The MVS seems to measure effectively the global severity of disease in a cohort of children with acute gastroenteritis. These data support the use of the MVS as an outcome measure in future clinical trials.

Carbohydrate exerts a mild influence on fluid retention following exercise-induced dehydration

Rapid and complete rehydration, or restoration of fluid spaces, is important when acute illness or excessive sweating has compromised hydration status. Many studies have investigated the effects of graded concentrations of sodium and other electrolytes in rehydration solutions; however, no study to date has determined the effect of carbohydrate on fluid retention when electrolyte concentrations are held constant. The purpose of this study was to determine the effect of graded levels of carbohydrate on fluid retention following exercise-induced dehydration. Fifteen heat-acclimatized men exercised in the heat for 90 min with no fluid to induce 2-3% dehydration. After a 30-min equilibration period, they received, over the course of 60 min, one of five test beverages equal to 100% of the acute change in body mass. The experimental beverages consisted of a flavored placebo with no electrolytes (P), placebo with electrolytes (P + E), 3%, 6%, and 12% carbohydrate solutions with electrolytes. All beverages contained the same type and concentration of electrolytes (18 meq/l Na(+), 3 meq/l K(+), 11 meq/l Cl(-)). Subjects voided their bladders at 60, 90, 120, 180, and 240 min, and urine specific gravity and urine volume were measured. Blood samples were taken before exercise and 30, 90, 180, and 240 min following exercise and were analyzed for glucose, sodium, hemoglobin, hematocrit, renin, aldosterone, and osmolality. Body mass was measured before and after exercise and a final body mass was taken at 240 min. There were no differences in percent dehydration, sweat loss, or fluid intake between trials. Fluid retention was significantly greater for all carbohydrate beverages compared with P (66.3 +/- 14.4%). P + E (71.8 +/- 9.9%) was not different from water, 3% (75.4 +/- 7.8%) or 6% (75.4 +/- 16.4%) but was significantly less than 12% (82.4 +/- 9.2%) retention of the ingested fluid. No difference was found between the carbohydrate beverages. Carbohydrate at the levels measured exerts a mild influence on fluid retention in postexercise recovery.

Initial Fluid Resuscitation for Patients With Diabetic Ketoacidosis: How Dry Are They?

A prospective consecutive case series of patients aged 5 to 20 years who presented to a pediatric emergency department with diabetic ketoacidosis (DKA) was studied to determine the actual percent loss of body weight during an episode of DKA to determine the degree of dehydration and thereby provide a guide for hydration therapy during such an episode. Patients' weights at the time of presentation, inpatient discharge, and at the first follow-up clinic visit were used to calculate the percent loss of body weight. Data from 33 episodes of DKA showed that the majority of patients with DKA had moderate (4% to 8%) dehydration. Clinical assessment was a poor predictor of severity of dehydration and overestimated the percent dehydration in 67% of patients. Based on these data it is recommend that initial fluid therapy for DKA should assume moderate dehydration with adjustment made according to clinical response.

Blood Electrolytes in NFL Players while Experiencing EAMC compared to when they are not Cramping after Similar Practice Conditions

Exercise associated muscle cramps (EAMC) are common in NFL players during preseason but they are difficult to study experimentally therefore the etiology is not well understood. Electrolyte disturbances and dehydration have been implicated in EAMC. PURPOSE: To analyze blood samples taken from NFL players at the time of EAMC with those taken from the same players after similar practices when they are not cramping and make comparisons in blood electrolytes and percent dehydration (%Dehy). METHODS: During the first two weeks of preseason training camp blood samples were drawn from 12 NFL players (age = 26.4 ± 2.9 y, height = 187 ± 7 cm, mass = 109 ± 19 kg, BSA = 2.34 ± 0.2 m2 and BSA/mass = 216 ± 17 cm2 kg-1) when they were experiencing EAMC prior to receiving intravenous fluids. Blood was also obtained from these players after a similar practice in similar environmental conditions when they did not have EMAC. Blood samples were immediately analyzed for sodium (Na+), potassium (K+) and chloride (C1-) by ion-selective electrode. Body mass was recorded before and after the same practices when blood was drawn to determine %Dehy. Additional data obtained at the time of EAMC but not used for comparisons were hematocrit (Hct), hemoglobin (Hb), lactate and serum osmolality (freezing point depression). RESULTS: There were no differences in blood Na+ (139.6 ± 2.0 mmol/l) or K+ (4.65 ± 0.8 mmol/l) when players had EAMC compared to when they did not (139 ±1.0 mmol/l and 4.88 ± 0.4 mmol/l) respectively. Blood Cl- was significantly lower when players had EAMC (98.2 ± 2.1, range = 94 to101 mmol/l) compared to no EAMC (104 ± 2.1 mmol/l), p<0.0001. There were no differences in %Dehy (EAMC = 2.1 ± 1.1% versus no EAMC = 2.3 ± 0.8%). At the time of EAMC hematocrit = 48 ±1.8%, hemoglobin = 16 ±1.0 mg/dL, lactate = 3.5 ±1.2 mmol/l and serum osmolality = 288 ± 5.6 mOsm/l. CONCLUSIONS: We did not find differences in blood Na+ or K+ when players had EAMC and it did not appear that dehydration or the accumulation of lactate were causative factors. %Dehy (2.1%), Hct (48%) and serum osmolality (288mosm/L) indicated that players with EAMC were only mildly dehydrated (and not different from no EAMC), and lactate (3.5 mmol/l) was not elevated. Low blood Cl-, in many cases clinically low, may play a role in reducing hyperpolarization of the alpha motor neuron thus allowing easier excitation.