Effect of fluid replacement with green tea on body fluid balance and renal responses under mild thermal hypohydration: a randomized crossover study.

PURPOSE: Maintaining an appropriate hydration level by ingesting fluid in a hot environment is a measure to prevent heat-related illness. Caffeine-containing beverages, including green tea (GT), have been avoided as inappropriate rehydration beverages to prevent heat-related illness because caffeine has been assumed to exert diuretic/natriuretic action. However, the influence of caffeine intake on urine output in dehydrated individuals is not well documented. The aim of the present study was to examine the effect of fluid replacement with GT on body fluid balance and renal water and electrolyte handling in mildly dehydrated individuals. METHODS: Subjects were dehydrated by performing three bouts of stepping exercise for 20 min separated by 10 min of rest. They were asked to ingest an amount of water (H2O), GT, or caffeinated H2O (20 mg/100 ml; Caf-H2O) that was equal to the volume of fluid loss during the dehydration protocol; fluid balance was measured for 2 h after fluid ingestion. RESULTS: The dehydration protocol induced hypohydration by ~ 10 g/kg body weight (~ 1% of body weight). Fluid balance 2 h after fluid ingestion was significantly less negative in all trials, and the fluid retention ratio was 52.2 ± 4.2% with H2O, 51.0 ± 5.0% with GT, and 47.9 ± 6.2% with Caf-H2O; those values did not differ among the trials. After rehydration, urine output, urine osmolality, and urinary excretions of osmotically active substances, sodium, potassium and chloride were not different among the trials. CONCLUSION: The data indicate that ingestion of GT or an equivalent caffeine amount does not worsen the hydration level 2 h after ingestion and can be effective in reducing the negative fluid balance for acute recovery from mild hypohydration. TRIAL REGISTRATION: ISRCTN53057185; retrospectively registered.

The effects of betaine supplementation on fluid balance and heat tolerance during passive heat stress in men.

INTRODUCTION: Consuming intracellular osmolytes, like betaine (BET), may attenuate symptoms of heat stress. The purpose of this study was to examine the effects of BET supplementation on fluid balance and heat tolerance after a 7-day loading period and during passive heat exposure. METHODS: A double-blind, placebo controlled, crossover study compared BET or placebo consumption (50 mg·kg-1 , twice daily) for 7 days in young, recreationally active men (N = 11). RESULTS: During the loading period, no significant interactions were found for any marker of fluid balance between or within conditions. During heat exposure, significant time effects but no condition x time interactions, were found for plasma characteristics (i.e., volume, osmolality, sodium, albumin, and total protein). Plasma volume was significantly increased by min 30 in both conditions (PLA: +6.9. ± 5.0%, BET: +10.2 ± 7.4%) and remained elevated for the remainder of the experimental trial, but was not significantly different between conditions. After 60 min of passive heat exposure, both conditions experienced a similar increase in core temperature (PLA: +0.32 ± 0.22°C, BET: +0.31 ± 0.21°C; p = 0.912). CONCLUSIONS: Supplemental BET did not improve markers of fluid balance or heat tolerance during 7 days of loading or during passive heat exposure.

Midwives' perspectives of intravenous fluid management and fluid balance documentation in labour: A qualitative reflexive thematic analysis study.

AIM: To describe current practice, examine the influences and explore barriers and facilitators to accurate documentation, for the administration of intravenous fluids during labour. DESIGN: A descriptive qualitative study was performed. METHODS: Qualitative semi-structured interviews were conducted with Registered Midwives working across Australia. Midwives were recruited via email and social media advertisements. A maximum variation sampling strategy was used to identify potential participants. Interview questions explored four main areas: (i) understanding of indications for IV fluids in labour; (ii) identification of current practice; (iii) barriers to documentation and (iv) benefits and complications of IV fluid administration. Reflexive thematic analysis of recorded-transcribed interviews was conducted. RESULTS: Eleven midwives were interviewed. Clinical practice variation across Australia was recognized. Midwives reported a potential risk of harm for women and babies and a current lack of evidence, education and clinical guidance contributing to uncertainty around the use of IV fluids in labour. Overall, eight major themes were identified: (i) A variable clinical practice; (ii) Triggers and habits; (iii) Workplace and professional culture; (iv) Foundational knowledge; (v) Perception of risk; (vi) Professional standards and regulations; (vii) The importance of monitoring maternal fluid balance and (viii) barriers and facilitators to fluid balance documentation. CONCLUSION: There was widespread clinical variation identified and midwives reported a potential risk of harm. The major themes identified will inform future quantitative research examining the impact of IV fluids in labour. IMPACT: The implications of this research are important and potentially far-reaching. The administration of IV fluids to women in labour is a common clinical intervention. However, there is limited evidence available to guide practice. This study highlights the need for greater education and evidence examining maternal and neonatal outcomes to provide improved clinical guidance.

Oral Electrolyte and Water Supplementation in Horses.

Horses that sweat for prolonged periods lose considerable amounts of water and electrolytes. Maintenance of hydration and prevention of dehydration requires that water and electrolytes are replaced. Dehydration is common in equine disciplines and can be avoided, thus promoting equine wellness, improved performance and enhanced horse and rider safety. Significant dehydration occurs through exercise or transport lasting one hour or more. Oral electrolyte supplementation is an effective strategy to replace water and electrolytes lost through sweating. The stomach and small intestine serve as a reservoir for uptake of water and electrolytes consumed 1 to 2 h prior to exercise and transport. The small intestine is the primary site of very rapid absorption of ions and water. Water and ions absorbed in the small intestine are taken up by muscles, and also transported via the blood to the skin where they serve to replace or augment the losses of water and ions in the body. Effective electrolyte supplements are designed to replace the proportions of ions lost through sweating; failure to do so can result in electrolyte imbalance. Adequate water must be consumed with electrolytes so as to maintain solution osmolality less than that of body fluids in order to promote gastric emptying and intestinal absorption. The electrolyte supplement should taste good, and horses should be trained to drink the solution voluntarily prior to and during transport, and prior to and after exercise.

Effect of rapid weight loss incorporating hot salt water immersion on changes in body mass, blood markers, and indices of performance in male mixed martial arts athletes.

PURPOSE: To investigate the effects of rapid weight loss (RWL), incorporating comparison of hot water immersion (HWI) in fresh or salt water, on changes in body mass, blood markers, and indices of performance in mixed martial arts athletes. METHODS: In a crossover design comparing fresh water (FWB) to salt water (SWB; 5.0%wt/vol Epsom salt) bathing, 13 males performed 20 min of HWI (~ 40.3 °C) followed by 40 min wrapped in a heated blanket, twice in sequence (2 h total). Before bathing, ~ 26 to ~ 28 h of fluid and dietary restriction was undertaken, and ~ 24 to ~ 26 h of a high carbohydrate diet and rehydration was undertaken as recovery. RESULTS: During the entire RWL process, participants lost ~ 5.3% body mass. Body mass lost during the 2 h hot bath protocol was 2.17 ± 0.81 kg (~ 2.7% body mass) and 2.24 ± 0.64 kg (~ 2.8% body mass) for FWB and SWB, respectively (P = 0.647 between trials). Blood urea nitrogen, creatinine, sodium, chloride, hemoglobin, and hematocrit were increased (all P < 0.05), and plasma volume was decreased (~ 14%; P < 0.01), but did not differ between FWB and SWB, and were similar to baseline values after recovery. No indices of performance (e.g., countermovement jump, isometric strength, and functional threshold power) were impacted when RWL was followed by the recovery process. CONCLUSION: Under the conditions of this hot bath protocol, fluid loss was not augmented by the addition of ~ 5.0%wt/vol of Epsom salt during HWI, and RWL of ~ 5.3% body mass followed by > 24 h of recovery did not impact indices of performance.

Keeping time in the lamina terminalis: Novel oscillator properties of forebrain sensory circumventricular organs.

Drinking behavior and osmotic regulatory mechanisms exhibit clear daily variation which is necessary for achieving the homeostatic osmolality. In mammals, the master clock in the brain's suprachiasmatic nuclei has long been held as the main driver of circadian (24 h) rhythms in physiology and behavior. However, rhythmic clock gene expression in other brain sites raises the possibility of local circadian control of neural activity and function. The subfornical organ (SFO) and the organum vasculosum laminae terminalis (OVLT) are two sensory circumventricular organs (sCVOs) that play key roles in the central control of thirst and water homeostasis, but the extent to which they are subject to intrinsic circadian control remains undefined. Using a combination of ex vivo bioluminescence and in vivo gene expression, we report for the first time that the SFO contains an unexpectedly robust autonomous clock with unusual spatiotemporal characteristics in core and noncore clock gene expression. Furthermore, putative single-cell oscillators in the SFO and OVLT are strongly rhythmic and require action potential-dependent communication to maintain synchrony. Our results reveal that these thirst-controlling sCVOs possess intrinsic circadian timekeeping properties and raise the possibility that these contribute to daily regulation of drinking behavior.

Comparison of hot water immersion at 37.8°C with or without salt for rapid weight loss in mixed martial arts athletes.

Hot water immersion, known as a hot bath, is used by MMA athletes to produce rapid weight loss (RWL) by means of passive fluid loss. This study investigated the magnitude of body mass losses using a standardized hot bath protocol with or without the addition of salt. In a crossover design, eleven male MMA athletes (28.5 ± 4.6 y; 1.83 ± 0.07 m; 82.5 ± 9.1 kg) performed a 20-min immersion at 37.8°C followed by a 40-min wrap in a warm room. This bath and wrap was performed twice per visit. During one visit, only fresh water was used (FWB), and in the other visit, magnesium sulphate (1.6% wt/vol) was added to the bath (SWB). Prior to each visit, 24 h of carbohydrate, fibre, and fluid restriction was undertaken as part of the RWL protocol. Body mass losses induced by the hot bath protocols were 1.63 ± 0.75 kg and 1.60 ± 0.80 kg for FWB and SWB, respectively, and equivalent to ~2.1% body mass. Under the conditions employed, the magnitude of body mass loss in SWB was similar to FWB. However, further research should explore bathing in a temperature that is consistent with that habitually used by fighters, and/or higher concentrations of salt.

Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat.

PURPOSE: This study examined the effects of sodium chloride and potassium chloride supplementation during 48-h severe energy restriction on exercise capacity in the heat. METHODS: Nine males completed three 48-h trials: adequate energy intake (100 % requirement), adequate electrolyte intake (CON); restricted energy intake (33 % requirement), adequate electrolyte intake (ER-E); and restricted energy intake (33 % requirement), restricted electrolyte intake (ER-P). At 48 h, cycling exercise capacity at 60 % VO2 peak was determined in the heat (35.2 °C; 61.5 % relative humidity). RESULTS: Body mass loss during the 48 h was greater during ER-P [2.16 (0.36) kg] than ER-E [1.43 (0.47) kg; P < 0.01] and CON [0.39 (0.68) kg; P < 0.001], as well as greater during ER-E than CON (P < 0.01). Plasma volume decreased during ER-P (P < 0.001), but not ER-E or CON. Exercise capacity was greater during CON [73.6 (13.5) min] and ER-E [67.0 (17.2) min] than ER-P [56.5 (13.1) min; P < 0.01], but was not different between CON and ER-E (P = 0.237). Heart rate during exercise was lower during CON and ER-E than ER-P (P < 0.05). CONCLUSIONS: These results demonstrate that supplementation of sodium chloride and potassium chloride during energy restriction attenuated the reduction in exercise capacity that occurred with energy restriction alone. Supplementation maintained plasma volume at pre-trial levels and consequently prevented the increased heart rate observed with energy restriction alone. These results suggest that water and electrolyte imbalances associated with dietary energy and electrolyte restriction might contribute to reduced exercise capacity in the heat.

Higher calorie diets increase rate of weight gain and shorten hospital stay in hospitalized adolescents with anorexia nervosa.

PURPOSE: Current recommendations for refeeding in anorexia nervosa (AN) are conservative, beginning around 1,200 calories to avoid refeeding syndrome. We previously showed poor weight gain and long hospital stay using this approach and hypothesized that a higher calorie approach would improve outcomes. METHODS: Adolescents hospitalized for malnutrition due to AN were included in this quasi-experimental study comparing lower and higher calories during refeeding. Participants enrolled between 2002 and 2012; higher calories were prescribed starting around 2008. Daily prospective measures included weight, heart rate, temperature, hydration markers and serum phosphorus. Participants received formula only to replace refused food. Percent Median Body Mass Index (%MBMI) was calculated using 50th percentile body mass index for age and sex. Unpaired t-tests compared two groups split at 1,200 calories. RESULTS: Fifty-six adolescents with mean (±SEM) age 16.2 (±.3) years and admit %MBMI 79.2% (±1.5%) were hospitalized for 14.9 (±.9) days. The only significant difference between groups (N = 28 each) at baseline was starting calories (1,764 [±60] vs. 1,093 [±28], p < .001). Participants on higher calories had faster weight gain (.46 [±.04] vs. .26 [±.03] %MBMI/day, p < .001), greater daily calorie advances (122 [±8] vs. 98 [±6], p = .024), shorter hospital stay (11.9 [±1.0] vs. 17.6 [±1.2] days, p < .001), and a greater tendency to receive phosphate supplementation (12 vs. 8 participants, p = .273). CONCLUSIONS: Higher calorie diets produced faster weight gain in hospitalized adolescents with AN as compared with the currently recommended lower calorie diets. No cases of the refeeding syndrome were seen using phosphate supplementation. These findings lend further support to the move toward more aggressive refeeding in AN.

Hypertensive diseases of pregnancy.

PIP: A meeting in Singapore of principal investigators from 7 countries in a WHO collaborative study on hypertensive disease of pregnancy, also called pre-eclampsia or eclampsia, pointed out women at risk, suggested management guidelines, and summarized operations research projects involving administration of aspirin or calcium supplements. Hypertensive disease of pregnancy may ultimately end in fatal seizures. It is often marked by warning signs of severe headaches and facial and peripheral edema. A survey in Jamaica found that 0.72% of a group of 10,000 pregnant women had eclamptic seizures. These were the cause of almost one-third of all obstetric deaths in the period 1981-1983. 10.4% of the pregnant women had hypertension, and half of these had proteinuria. Associated risk factors were primigravida, age 30, abnormal weight gain, edema, 1+ proteinuria. A phased program of management guidelines for identifying and treating affected women is being instituted in half of Jamaica's parishes. An operations research project involves administration of low-dose aspirin vs. placebo. Another controlled trial, in Peru, is testing calcium supplements. A third trial in Argentina will compare 2 drug regimens.^ieng

Does oral rehydration therapy alter food consumption and absorption of nutrients in children with cholera?

In order to estimate consumption of food and absorption of nutrients, a metabolic balance study was conducted in 47 children between 1 and 5 years old, suffering from acute cholera. Twenty-two of the children were treated by intravenous solution (IV) only and 25 others by oral rehydration along with intravenous solution (ORS/IV) when necessary. After initial rehydration a nonabsorbable charcoal marker was fed to the patients followed by a typical Bangladeshi home food of known composition offered ad libitum. Appearance of the first marker in the faeces was taken as zero hour (0 h); at 72 h a second marker was fed. Faeces, urine and vomitus were collected up to the appearance of the second marker. Intake of IV fluid, ORS and any other fluid or food were recorded accurately. Samples of faeces, urine and vomitus were analysed for energy, fat and nitrogen. Consumption of nutrients and absorption in both groups were calculated. There was no significant difference in the intake or absorption of energy or carbohydrate between the two groups. The consumption of fat and protein was slightly, but significantly, lower in the ORS/IV group during the acute stage of diarrhoea than in the IV group. Absorption of nitrogen was significantly lower in the ORS/IV group, but absorption of fat was not significantly impaired. Vomiting was significantly higher in the ORS/IV group. The differences in the consumption and absorption of nutrients between the two groups were transient and came to the same level within 2 weeks after recovery.

PIP: Between May 1983-March 1984, the International Centre for Diarrhoeal Disease Research, Bangladesh conducted a metabolic balance study involving 47 children with acute cholera between 1-5 years old. Researchers randomly assigned 22 children to the intravenous (IV) solution treatment group. The children received it continuously until the diarrhea stopped. The remaining 25 were treated with oral rehydration solution (ORS) and IV fluid as needed. Health staff attempted to maintain hydration in the ORS/IV group with ORS alone, but IV therapy was reinstated if a child vomited excessively or the child exhibited signs of severe dehydration. Within 6-8 hours after admission and initial rehydration, the children took a nonabsorbable charcoal marker before taking in any food. The appearance of the 1st marker in the stool was called 0 hour and all stools, urine and vomitus between the 0-72 hours were collected. At 72 hours, the children ingested a 2nd marker. The ORS/IV group consumed 40% of the fluid orally. Vomiting within this group was significantly higher than the IV group (p.001). Intake of protein on day 2 and intake of both fat and protein on day 3 were significantly higher in the IV group (p.05, p.01). Daily intake and absorption of energy or carbohydrates in both of the groups, however, were similar. No significant differences in the total consumption of nutrients after recovery existed. Nitrogen absorption was significantly higher in the IV group than the ORS/IV group (p.05). This study demonstrates that an adequate amount of food is consumed and utilized by patients with acute diarrhea while receiving ORS and therefore there is no justification for withholding food during the acute stage of diarrhea.

Eclampsia.

PIP: The perceptive physician can anticipate and prevent eclampsia. If possible, he should try to prolong preeclamptic pregnancies to the 37th week to avoid neonatal deaths from complications and prematurity. In some cases, preeclampsia strikes and progresses rapidly before the 30th week, however, and, in order to save the mother, the pregnancy must be terminated. If the preeclamptic woman deteriorates to the point where severe headache, epigastric pain, vomiting, and hyperreflexia exist, eclampsia is imminent. If she becomes eclamptic, clinicians must immediately begin to manage the convulsions with a sedative. Diazepam has proved successful which accounts for its widespread use in Great Britain and developing countries. Large doses given over a long period of time, however, adversely affect the newborn, e.g. respiratory depression. Another popular sedative is magnesium sulphate (in use for 50 years). Dangers of overdose can be avoided by testing the patella reflex every hour when magnesium sulphate is being administered intravenously: the reflex becomes null before serious toxic effects occur. If the systolic blood pressure exceeds 170mmHg, antihypertensives should also be given selectively to prevent cerebral hemorrhage. The preferred antihypertensive must act rapidly and predictably, with a wide margin of safety between the therapeutic and toxic dose. Hydralazine hydrochloride meets these requirements. Fluid and acid-base balances must be controlled to treat hypovolemia, oliguria, and acidosis. The longer delivery is delayed, the worse the outlook for mother and infant. Regardless of the type of delivery, clinicians must avoid hemorrhage and operative shock because eclamptics cannot tolerate blood loss. It is imperative that clinicians do not become so involved in saving the patient that they overtreat her, e.g., mixing antihypertensives.^ieng

The current status of oral therapy in the treatment of acute diarrheal illness.

PIP: Diarrheal diseases are a primary cause of morbidity and mortality in the developing countries. This is a literature review and evaluation of the new form of oral therapy, surveying field and clinical studies which have been performed. The etiology and effects of diarrheal diseases are discussed. Oral fluid therapy aims at preventing and treating dehydration and facilitating continued dietary intake, not in terminating the diarrhea. The composition of the widely used fluid therapy solution is explained; there are presently some differences of opinion regarding the optimal composition of the solution. Clinical experience with the therapy in hospitals, clinics, and relatively unsupervised home use is cited. This simple, inexpensive therapy seems to be effective for a wide variety of diarrheal diseases and for people in all age groups. The greatest current controversy regarding oral therapy is whether it should be widely used as a home remedy. Further study will be necessary to measure its effectiveness on a home-use basis.^ieng

Treatment of diarrheal dehydration.

A regimen for the treatment of diarrheal dehydration is presented. It was devised for use in conditions found in developing countries. Application to large number of patients has been successful. One of its characteristics is the infusion at the start of treatment of a larger amount of fluid than generally recommended. The advantages of magnesium supplementation and phosphate supplementation have been studied. Fecal electrolyte composition has been studied during recovery from diarrheal dehydration. Components of acid balance and generation have been measured with the "net acid" balance technique.

PIP: A regimen for treating diarrheal dehydration is presented which was devised specifically for use in developing countries. Also reported is the author's experience when using this regimen for rehydration on a large population of people with diarrheal diseases. The fluid therapy recommended has 3 phases: reparation, maintenance, and replacement. The fluid therapy is designed to reduce the volume of the extracellular fluid compartment by reestablishing normal tissue perfusion and normal renal regulatory function. The main difference between this regimen and previously published procedures is an emphasis on correction of sodium and chloride deficit within the first 2-3 hours of therapy. To this end, the authors recommend infusion at the start of treatment of a larger amount of fluid than heretofore recommended. Also discussed are the advantages of magnesium supplementation and phosphate supplementation is some cases. Also studied was fecal electrolye composition during recovery from diarrheal dehydration as a gauge for measuring rehydration effectiveness. The net balance technique was used to measure components of acid balance and generation. Tables and graphs present data on urine and fecal component losses during diarrheal dehydration and rehydration.

A positive effect on the nutrition of Philippine children of an oral glucose-electrolyte solution given at home for the treatment of diarrhoea. Report of a field trial by an international study group.

PIP: All children with diarrhea aged up to 5 years and residing in 2 communities (community B was the study, community M the control) in a province in the Philippines were studied to test the hypothesis that an oral glucose-electrolyte solution (Oresol) used freely for outpatient children with diarrhea would improve their nutritional status. Both communities were given nutrition education and emphasis was placed on feeding and the provision of fluids during diarrheal attacks. Only in community B was a glucose-electrolyte mixture used. There were 519 children had had 710 separate bouts of diarrhea during 7 months of observation. Oresol was associated with a relative weight gain in relation to the Philippine median. The increase averaged a statistically significant 3% in the 1-5 year age group but not in those under 1 year of age. The effect on relative weight gain was apparent 1 to 2 months after an attack of diarrhea. In contrast, the children in the control community lost relative weight. Oresol-administered children gained nearly twice as much weight during a diarrheal attack compared to those not given Oresol. The Oresol-induced weight gain may reflect better hydration, lower catabolism, or both. However, the relationship between weight gain during an attack and long-term relative weight gain is not clear. There were no side effects observed. Oresol administration did not significantly reduce hospitalization, mainly due to the design of the study. The introduction of packaged powders like Oresol in areas where the ingredients for an oral glucose electrolyte solution are not available or prescribed may help reduce the incidence of serious dehydration.^ieng