Sensory Perception of an Oral Rehydration Solution during Exercise in the Heat

Prolonged exercise in the heat elicits a number of physiological changes as glycogen stores are low and water and electrolytes are lost through sweat. However, it is unclear whether these changes provoke an increase in liking of saltiness and, therefore, palatability of an oral rehydration solution (ORS). Twenty-seven recreationally active participants (n = 13 males; n = 14 females) completed sensory analysis of an ORS, a traditional sports drink (TS), and a flavored water placebo (PL) at rest and during 60 min (3 × 20-min bouts) of cycling exercise at 70% age-predicted maximum heart rate (HR_max) at 35.3 ± 1.4 °C and 41 ± 6% relative humidity. Before and after every 20 min of exercise, drinks were rated (using 20-mL beverage samples) based on liking of sweetness, liking of saltiness, thirst-quenching ability, and overall liking on a nine-point hedonic scale. Hydration status was assessed by changes in semi-nude body mass, saliva osmolality (S_Osm), and saliva total protein concentration (S_PC). After 60 min of exercise, participants lost 1.36 ± 0.39% (mean ± SD) of body mass and there were increases in S_Osm and S_PC. At all time points, liking of sweetness, saltiness, thirst-quenching ability, and overall liking was higher for the TS and PL compared to the ORS (p < 0.05). However, the saltiness liking and thirst-quenching ability of the ORS increased after 60 min of exercise compared to before exercise (p < 0.05). There was also a change in predictors of overall liking with pre-exercise ratings mostly determined by liking of sweetness, saltiness, and thirst-quenching ability (p < 0.001), whereas only liking of saltiness predicted overall liking post-exercise (R² = 0.751; p < 0.001). There appears to be a hedonic shift during exercise in which the perception of saltiness becomes the most important predictor of overall liking. This finding supports the potential use of an ORS as a valuable means of hydration during the latter stages of prolonged and/or intense exercise in the heat.

An Amino Acid-Based Oral Rehydration Solution Regulates Radiation-Induced Intestinal Barrier Disruption in Mice

BACKGROUND

Radiotherapy inadvertently affects gastrointestinal (GI) epithelial cells, causing intestinal barrier disruption and increased permeability.

OBJECTIVE

We examined the effect of amino acid-based oral rehydration solution (AA-ORS) on radiation-induced changes of intestinal barrier function and epithelial tight junctions (TJs) in a randomized experimental study using a total-body irradiation (TBI) mouse model.

METHODS

Eight-week-old male Swiss mice received a single-dose TBI (0, 1, 3, or 5 Gy), and subsequent gastric gavage with AA-ORS (threonine, valine, serine, tyrosine, and aspartic acid) or saline for 2 or 6 d. Intestinal barrier function of mouse ileum was characterized by electrophysiological analysis of conductance, anion selectivity, and paracellular permeability [fluorescein isothiocyanate (FITC)-dextran]. Ultrastructural changes of TJs were evaluated by transmission electron microscopy. Membrane protein and mRNA expression of claudin-1, -2, -3, -5, and -7, occludin, and E-cadherin were analyzed with western blot, qPCR, and immunohistochemistry. Nonparametric tests were used to compare treatment-dose differences for each time point.

RESULTS

Saline-treated mice had a higher conductance at doses as low as 3 Gy, and as early as 2 d post-TBI compared with 0 Gy (P < 0.001). Paracellular permeability and dilution potential were increased 6 d after 5 Gy TBI (P < 0.001). Conductance decreased with AA-ORS after 2 d in 3-Gy and 5-Gy mice (P < 0.05 and P < 0.001), and on day 6 after 5 Gy TBI (P < 0.001). Anion selectivity and FITC permeability decreased from 0.73 ± 0.02 to 0.61 ± 0.03 pCl/pNa (P < 0.01) and from 2.7 ± 0.1 × 105 to 2.1 ± 0.1 × 105 RFU (P < 0.001) in 5-Gy mice treated with AA-ORS for 6 d compared with saline. Irradiation-induced ultrastructural changes of TJs characterized by decreased electron density and gap formation improved with AA-ORS. Reduced claudin-1, -3, and -7 membrane expression after TBI recovered with AA-ORS within 6 d, whereas claudin-2 decreased indicating restitution of TJ proteins.

CONCLUSIONS

Radiation-induced functional and structural disruption of the intestinal barrier in mice is reversed by AA-ORS rendering AA-ORS a potential treatment option in prospective clinical trials in patients with gastrointestinal barrier dysfunction.

Enteral resuscitation with oral rehydration solution to reduce acute kidney injury in burn victims: Evidence from a porcine model

Intravenous (IV) resuscitation of burn patients has greatly improved outcomes and become a cornerstone of modern burn care. However, the heavy fluids and vascular access required may not be feasible in austere environments, mass casualty, or delayed transport scenarios. Enteral resuscitation has been proposed for these situations; we sought to examine the effectiveness of this strategy on improving burn-induced kidney injury. Anesthetized Yorkshire swine sustaining 40% TBSA full-thickness contact burns were randomized to three groups (n = 6/group): fluid deprivation, ad libitum water access, or 70 mL/kg/d Oral Rehydration Salt solution (ORS). Urine and blood were collected at baseline (BL), 6, 12, 24, 32, and 48h post-burn, at which point tissue was harvested and CT angiography performed. Although fluid consumption by ad libitum and ORS groups were matched (132±54mL/kg versus 120±24mL/kg, respectively), ORS intake increased urine output compared with water and no water (47.3±9.0 mL/kg versus 16.1±2.5 mL/kg, and 24.5±1.7 mL/kg respectively). Plasma creatinine peaked 6h following burn (1.67±0.07mg/dL) in all animals, but at 48h was comparable to BL in animals receiving water (1.23±0.06mg/dL) and ORS (1.30±0.09mg/dL), but not fluid deprived animals (1.56±0.05mg/dL) (P<0.05). Circulating levels of blood urea nitrogen steadily increased, but also decreased by 48h in animals receiving enteral fluids (P<0.05). Water deprivation reduced renal artery diameter (-1.4±0.17mm), whereas resuscitation with water (-0.44±0.14 mm) or ORS maintained it (-0.63±0.20 mm;P< 0.02). Circulating cytokines IL-1β, IL-6, IFNγ, and GM-CSF were moderately elevated in the fluid-deprived group. Taken together, the data suggest that enteral resuscitation with ORS rescues kidney function following burn injury. Incorporating enteral fluids may improve outcomes in resource-poor environments and possibly reduce IV fluid requirements to prevent co-morbidities associated with over-resuscitation. Studies into different volumes/types of enteral fluids are warranted. While ORS has saved many lives in cholera-associated dehydration, it should be investigated further for use in burn patients.

Fluid intake restores retinal blood flow early after exhaustive exercise in healthy subjects

PURPOSE

It remains unclear whether rehydration restores retinal blood flow reduced by exhaustive exercise. We investigated the effect of fluid intake on retinal blood flow after exhaustive exercise.

METHODS

Blood flow in the inferior (ITRA) and superior temporal retinal arterioles (STRA) was measured before and after incremental cycling exercise until exhaustion in 13 healthy males. After the exercise, the subjects rested without drinking (control condition: CON) or with drinking an electrolyte containing water (rehydrate condition: REH) and were followed up for a period of 120 min. To assess the hydration state, the body mass was measured, and venous blood samples were collected and plasma volume (PV) was calculated.

RESULTS

Body mass decreased in CON after the trial [- 1.1 ± 0.1% (mean ± SE), p < 0.05]. PV was lower in CON than in REH during recovery. The ITRA and STRA blood flows decreased immediately after exercise from the resting baseline (ITRA; - 23 ± 4% in REH and - 30 ± 4% in CON, p < 0.05). The ITRA blood flow recovered baseline level at 15 min of recovery in REH (- 9 ± 3%, p = 0.5), but it remained reduced in CON (-14 ± 3%, p < 0.05). The STRA blood flow was higher in REH than in CON at 15 min (2 ± 3 vs. - 5 ± 3%, p < 0.05).

CONCLUSIONS

The results of this study suggest that the reduction in retinal blood flow induced by exhaustive exercise can be recovered early by rehydration.

Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat

The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT1R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% V̇o2peak) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receiving FR to offset sweat losses (FR condition). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with: 1) lactated Ringer (Control); 2) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, NOS inhibition); 3) 10 mM ascorbate (nonselective antioxidant); or 4) 4.34 nM losartan (AT1R inhibition). Relative to Control (71% CVCmax at both time points), CVC with ascorbate (80% and 83% CVCmax) was elevated at 60 and 90 min of exercise during FR (both P < 0.02) but not at any time during No FR (all P > 0.31). In both conditions, CVC was reduced at end exercise with l-NAME (60% CVCmax; both P < 0.02) but was not different relative to Control at the losartan site (76% CVCmax; both P > 0.19). LSR did not differ between sites in either condition (all P > 0.10). We conclude that NOS regulates cutaneous vasodilation, but not sweating, irrespective of FR, and that ROS influence cutaneous vasodilation during prolonged exercise with FR.

Diapers in war zones: ethnomedical factors in acute childhood gastroenteritis in Peshawar, Pakistan

This article considers ethnomedical knowledge and practices among parents related to contraction of acute gastroenteritis among children in Peshawar, Pakistan. Research methods included analysis of the Emergency Pediatric Services' admission register, a structured interview administered to 47 parents of patients seen in the Khyber Medical College Teaching Hospital, semi-structured interviews of 12 staff, and four home visits among families with children treated at the hospital. The use of native research assistants and participant observation contributed to the reliability of the findings, though the ethnographic, home-visit sample is small. Our research indicated that infection rates are exacerbated in homes through two culturally salient practices and one socioeconomic condition. Various misconceptions propagate the recurrence or perserverance of acute gastroenteritis including assumptions about teething leading to poor knowledge of disease etiology, rehydration solutions leading to increased severity of disease, and diaper usage leading to the spread of disease. In our Discussion, we suggest how hospital structures of authority and gender hierarchy may impact hospital interactions, the flow of information, and its respective importance to the patient's parents leading to possible propagation of disease. These ethnographic data offer a relatively brief but targeted course of action to improve the effectiveness of prevention and treatment efforts.

[Ways of improving the efficacy of preoperative preparation in patients with acute intestinal obstruction]

The comparative assessment of preoperative fluid therapy was made in 56 patients with acute intestinal obstruction. Parameters of central hemodynamics, the intra-abdominal pressure and water sectors of organism were investigated. The fluid therapy was conducted during 3 hours and included Tetraspan and Sterofundin on average 615 ml and 1585 ml, respectively. It was shown, that the fluid therapy facilitated to the elimination of water-electrolytic and hemodynamic shifts and to some extent it improved the outcomes of surgical treatment.

[Effect of different preoperative rehydration on sugar metabolism; comparison between Arginaid Water and OS-1]

BACKGROUND

Enhanced Recovery After Surgery (ERAS) program recommends carbohydrate load before surgery. However, the dose and dosing method of carbohydrate load are not clear. In this paper, effect of different preoperative rehydration on sugar metabolism in healthy volunteers is reported.

METHODS

Arginaid Water (ArgW) and OS-1 (OS) used as preoperative rehydration in Japan were employed for measuring sequential changes in sugar metabolism in blood. Both ArgW intake group and OS intake group started fasting at 9 PM. At 8 AM in the morning, respective preoperative rehydration 250 ml was taken as a bolus. Blood test was performed before intake, 30 minutes, 2 hours and 4 hours after intake.

RESULTS

Subject included 10 healthy volunteers for ArgW and OS respectively. Subjects drank each preoperative rehydration two hours before entering operating room. In ArgW intake group, free fatty acid (FFA) and beta-hydroxybutyric acid concentration (beta-OHB) were reduced and sugar metabolism was favorably maintained. Meanwhile, OS intake group, FFA and beta-OHB were elevated and catabolism of adipose began. However, even if ArgW were taken, rebound increases of FFA and beta-OHB were observed after entering operating room.

CONCLUSIONS

Optimum dosage and dosing method of preoperative carbohydrate should be scientifically verified in the future.

A retrospective analysis of the haemodynamic and metabolic effects of fluid resuscitation in Vietnamese adults with severe falciparum malaria

Background

Optimising the fluid resuscitation of patients with severe malaria is a simple and potentially cost-effective intervention. Current WHO guidelines recommend central venous pressure (CVP) guided, crystalloid based, resuscitation in adults.

Methods

Prospectively collected haemodynamic data from intervention trials in Vietnamese adults with severe malaria were analysed retrospectively to assess the responses to fluid resuscitation.

Results

43 patients were studied of whom 24 received a fluid load. The fluid load resulted in an increase in cardiac index (mean increase: 0.75 L/min/m² (95% Confidence interval (CI): 0.41 to 1.1)), but no significant change in acid-base status post resuscitation (mean increase base deficit 0.6 mmol/L (95% CI: −0.1 to 1.3). The CVP and PAoP (pulmonary artery occlusion pressure) were highly inter-correlated (r_s = 0.7, p<0.0001), but neither were correlated with acid-base status (arterial pH, serum bicarbonate, base deficit) or respiratory status (PaO₂/FiO₂ ratio). There was no correlation between the oxygen delivery (DO₂) and base deficit at the 63 time-points where they were assessed simultaneously (r_s = −0.09, p = 0.46).

Conclusions

In adults with severe falciparum malaria there was no observed improvement in patient outcomes or acid-base status with fluid loading. Neither CVP nor PAoP correlated with markers of end-organ perfusion or respiratory status, suggesting these measures are poor predictors of their fluid resuscitation needs.

Estimation of acute fluid shifts using bioelectrical impedance analysis in horses

BACKGROUND

Multi-frequency bioelectrical impedance analysis (MF-BIA) has been used to evaluate extracellular fluid volume (ECFV), but not fluid fluxes associated with fluid or furosemide administration in horses. If able to detect acute changes in ECFV, MF-BIA would be useful in monitoring fluid therapy in horses.

HYPOTHESIS

The purpose of this study was to evaluate the ability of MF-BIA to detect acute fluid compartment changes in horses. We hypothesized that MF-BIA would detect clinically relevant (10-20%) changes in ECFV.

ANIMALS

Six healthy mares were used in the study.

METHODS

This is an original experimental study. Mares were studied in 3 experiments: (1) crystalloid expansion of normally hydrated subjects, (2) furosemide-induced dehydration followed by crystalloid administration, and (3) acute blood loss followed by readministration of lost blood. MF-BIA measurements were made before, during, and after each fluid shift and compared to known changes in volume calculated based on the intravenous fluids that were administered in addition to urinary fluid losses. Mean errors between MF-BIA estimated change and known volume change were compared using nonparametric analysis of variance. Estimated ECFV pre- and post-fluid administration similarly were compared. The level of statistical significance was set at P < .05.

RESULTS

Results of the study revealed a statistically significant change in ECFV and total body water during crystalloid expansion and dehydration. Statistically significant changes were not observed during blood loss and administration. Mean errors between MF-BIA results and measured net changes were small.

CONCLUSIONS AND CLINICAL IMPORTANCE

MF-BIA represents a practical and accurate means of assessing acute fluid changes during dehydration and expansion of ECFV using isotonic crystalloids with potential clinical applications in equine critical care.

Hydration during Exercise in Warm, Humid Conditions: Effect of a Caffeinated Sports Drink

Caffeine is regarded as a diuretic despite evidence that hydration is not impaired with habitual ingestion. The purpose of this study was to determine whether a caffeinated sports drink impairs fluid delivery and hydration during exercise in warm, humid conditions (28.5 °C, 60% relative humidity). Sixteen cyclists completed 3 trials: placebo (P), carbohydrate-electrolyte (CE), and caffeinated (195 mg/L) sports drink (CAF+CE). Subjects cycled for 120 min at 60–75%VO2max followed by 15 min of maximal-effort cycling. Heart rate and rectal temperature were similar until the final 15 min, when these responses and exercise intensity were higher with CAF+CE than with CE and P. Sweat rate, urine output, plasma-volume losses, serum electrolytes, and blood deuterium-oxide accumulation were not different. Serum osmolality was higher with CAF+CE vs. P but not CE. The authors conclude that CAF+CE appears as rapidly in blood as CE and maintains hydration and sustains cardiovascular and thermoregulatory function as well as CE during exercise in a warm, humid environment.

Evaluation of oral rehydration solution by whole-gut perfusion in rats: effect of osmolarity, sodium concentration and resistant starch

BACKGROUND

Reduced osmolarity oral rehydration solution (ORS) improved small bowel absorption of fluid and electrolytes in segmental perfusion in experimental animals; this was borne out in clinical practice. Adding amylase-resistant starch (RS) to ORS is expected to increase colonic fluid absorption. This study used combined small and large bowel perfusion to evaluate combinations of reduced osmolarity and starch in ORS.

METHODS

Single-pass steady-state perfusions of the whole gut at 30 mL/h, using the nonabsorbable marker C-polyethylene glycol 4000, were performed in Wistar rats after exposure to cholera toxin or Escherichia coli heat-stable enterotoxin (STa).

RESULTS

Steady state was established within 90 minutes after commencing perfusion. Net secretion of water, sodium and chloride induced by cholera toxin was partially reversed by standard glucose-ORS (G-ORS). Substituting glucose in G-ORS with RS (RS-ORS) substantially increased net water absorption (P < 0.001) as did reduced osmolarity ORS (RO-ORS) (P < 0.001); addition of RS to RO-ORS further increased water absorption (P < 0.001). In STa-treated intestine, RO-ORS and RS-ORS significantly improved water absorption compared to G-ORS (P < 0.005). RO- and RS-RO-ORS did not significantly augment net electrolyte absorption compared with G-ORS. RS-ORS was associated with highest net absorption of sodium and chloride compared with all other groups.

CONCLUSIONS

RS increased net water (and sodium) absorption from isosmolar and reduced osmolar ORS consistent with increased absorption by the colon. RS in reduced osmolar ORS may have advantages to reduce severity of diarrhea and prevent hyponatremia in severe diarrhea and may be applicable to diarrhea of different etiologies.

The effects of commonly used resuscitation fluids on whole blood coagulation

OBJECTIVES

Evidence on the effect of crystalloid and colloid resuscitation fluids on coagulation is confusing, with contradictory results from previous studies. This study was performed to test the effect on whole blood coagulation of a range of resuscitation fluids in vitro using a single method at a single dilution.

METHODS

Seven resuscitation fluids were tested in vitro at a dilution of 40%. Whole blood coagulation was measured using a Sonoclot analyser.

RESULTS

A crystalloid/colloid split of effect on coagulation in vitro was not seen. The time to clot formation with Gelofusine, dextran and hydroxyethyl starch was a greatly increased, whereas saline and Haemaccel had little effect, or were slightly procoagulant.

CONCLUSIONS

Some resuscitation fluids have a profound effect on coagulation. The confusion in the literature may result from the effect on coagulation being both fluid and dilution dependent, with no simple crystalloid/colloid split.

Comparison of two oral electrolyte solutions and route of administration on the abomasal emptying rate of Holstein-Friesian calves

Dehydrated calves with diarrhea are routinely given an oral electrolyte solution (OES) by suckling or esophageal intubation. An important issue related to rehydration therapy is the rate of OES delivery to the small intestine. It is widely assumed that the glucose content of the OES does not impact the speed of resuscitation and that fluid administered by esophageal intubation provides a similar resuscitative response to that obtained by suckling. The aims of this study were to compare the abomasal emptying rate in calves suckling an OES containing a high or low glucose concentration and in calves administered a high-glucose OES by suckling or esophageal intubation. Seven male Holstein-Friesian calves were given the following treatments in random order: 2 L of a commercially available high-glucose OES ([glucose] = 405 mM) by suckling or esophageal intubation or 2 L of a commercially available low-glucose OES ([glucose] = 56 mM) by suckling. Abomasal emptying rate was determined by acetaminophen absorption, ultrasonography, and glucose absorption. High-glucose OES rapidly increased plasma glucose concentration after suckling but produced a slower rate of abomasal emptying than did low-glucose OES. Esophageal intubation of high-glucose OES produced the same initial change in abomasal volume as did suckling, but delayed the rate of OES delivery to the small intestine. Our results suggest that suckling a low-glucose OES provides the fastest rate of abomasal emptying and plasma volume expansion, whereas a high-glucose OES provides the most appropriate oral solution for treating hypoglycemic calves.

Effect of reducing sodium or glucose concentration in a hypo-osmolar ORS (oral rehydration salts) on absorption efficiency: marker perfusion study in rat jejunum

We evaluated the relative absorption efficiency of reducing the sodium or glucose concentration to make an ORS hypo-osmolar in a perfusion model. In nine adult albino rats 30 cm of jejunum was perfused at 0.4 ml/min with three glucose salt solutions for 45 min each, one with 60 mM sodium, 111 mM glucose, and osmolarity 247, one with 90 mM sodium, 60 mM glucose, and osmolarity 250, and one with 90 mM sodium, (111 mM) glucose, and osmolarity 301 (control solution). Each contained 2 g/L polyethylene glycol 4000 as a marker. The net water and sodium absorption were 2.8 (P < 0.001) and 2.6 (P < 0.001) times higher from low-sodium and 1.7 (P < 0.001)- and 1.5 (P < 0.001)-fold higher from low-glucose solutions compared to the control. Net glucose absorption was 2.2 (P < 0.001)-fold higher from low-sodium solutions compared to the control. The net water, sodium, potassium, and glucose absorptions were 1.6 (P < 0.001)-, 1.7 (P < 0.001)-, 1.36 (P < 0.05)-, and 4.15 (P < 0.001)-fold higher from low-sodium compared to low-glucose solutions. The hypo-osmolar ORS with reduced sodium was substantially more absorption efficient compared to the one with reduced glucose.

Duration of the increase in amniotic fluid index (AFI) after acute maternal hydration

The long-term effect of acute maternal hydration on amniotic fluid index (AFI) has not been previously studied. We evaluated the AFI of 25 pregnant women (ten women with normal AFI and 15 with decreased AFI) at 3, 24 and 48 h after maternal oral hydration with 2 l of water over 1 h. Post-hydration AFI at 3 h was significantly greater than pre-hydration AFI. However, AFI at 24 and 48 h were not significantly different from pre-hydration AFI. Maternal hydration increases AFI in women with normal and decreased amniotic fluid, but the increase in AFI lasts for less than 24 h.

cDNA profiling in leukocytes exposed to hypertonic resuscitation fluids

BACKGROUND

Resuscitative fluids induce distinctive changes in leukocyte functions: incubation with colloid Dextran increases production of reactive oxygen species and adhesion, whereas exposure to hypertonic saline (HTS) inhibits "oxidative burst" and phagocytosis. In hypertonic saline Dextran (HTD), the hypertonic component determines the leukocyte functional behavior and subsequently activation response. We investigated whether leukocyte gene expression is analogously affected.

METHODS

Whole blood from eight volunteers was diluted and incubated for 30 min at 37(o)C in 6.0% Dextran-70, 7.5% HTS, and 7.5% HTD. Total leukocyte RNA was extracted and used to synthesize biotinylated cDNA probes. Each probe was individually hybridized to a cDNA array to simultaneously measure the expression of 23 genes involved in inflammation, cell migration, and apoptosis.

RESULTS

Leukocytes incubated with Dextran-70 demonstrated greater than a 6-fold (p < 0.05) increase in the expression of interleukin-8, growth-regulated oncogenes alpha and beta, L-selectin, superoxide dismutase, tumor necrosis factor-alpha (TNF-alpha), and mitogen-activated protein kinase 3. The expression profile induced by HTS was not significantly different from that of unstimulated blood, except for prominent induction of only three genes. HTD attenuated the expression of Dextran-70 upregulated genes, although the level of their expression was higher than in HTS-treated leukocytes.

CONCLUSIONS

Hypertonic resuscitation fluids diminish the expression of immune activation-associated genes. Hypertonic component of HTD determines the leukocyte gene expression profile.

The in vitro effects of crystalloids and colloids on coagulation

Classically haemodilution is regarded as causing coagulopathy. However, haemodilution with saline seems to cause a hypercoagulable state both in vivo and in vitro. The aim of the present study was to measure the effect of mild to severe haemodilution using thrombelastography. Blood samples were taken in 12 healthy volunteers and divided into seven aliquots. One aliquot was undiluted and acted as control. The other six were diluted with normal saline, Ringer Acetate, 4% albumin, Dextran 70, 6% and 10% hydroxyethylstarch to 10%, 20%, 40%, 50% and 60% dilution. The dilution was checked by measuring the haemoglobin concentration. Each aliquot was placed in a temperature-controlled thrombelastography channel. Increased coagulation activity, as measured by thrombelastography changes, was detected at low and medium levels of dilution with all the tested solutions. At more than 40% dilution, coagulation returned to normal while in the case of dextran and hydroxyethylstarch coagulopathy developed. For crystalloids and albumin,dilution had to exceed 50% before coagulation was impaired. If these findings can be reproduced in vivo, they may have implications for transfusion practice and prophylaxis against thrombosis.

Oxygen transport dynamics of acellular hemoglobin solutions in an isovolemic hemodilution model in swine

BACKGROUND

One of the perceived advantages of a hemoglobin-based blood substitute is the provision of oxygen-carrying capacity. Although the hemodynamic response to the infusion of acellular hemoglobin solutions has been extensively studied, less is known about the oxygen transport dynamics of such solutions. We hypothesized that acellular hemoglobin solutions are useful oxygen carriers in anemic states and that higher P50 solutions transport O2 more efficiently than low P50 solutions. We sought to quantify O2 transport dynamics of hemoglobin solutions in an isovolemic hemodilution model in swine.

METHODS

Eighteen swine were anesthetized, ventilated, and instrumented for hemodynamic measurements and for withdrawal of arterial and mixed venous blood. The swine were randomized into three groups and progressively bled from an initial hematocrit (Hct) of 30% to Hcts of 19%, 13%, and 8% using isovolemic exchange with pyridoxalated hemoglobin polyoxyethylene conjugate (PHP, n = 6); an identical hemoglobin solution without the pyridoxalation, resulting in a low P50 solution (POE-Hb, n = 6); or an osmotically similar control solution of pentastarch (PS, n = 6). Hemodynamic measurements, arterial and mixed venous O2 content, and O2 extraction ratio (ER), were determined in whole blood (WB), the red blood cell (RBC) phase, and the plasma phase utilizing a compartmentalized approach.

RESULTS

Mean pulmonary arterial pressure was higher with hemodilution in the PHP and POE-Hb groups than in the PS group (p < 0.05). Cardiac index increased with hemodilution in all groups, but was significantly less than the cardiac index in the PS group at Hcts = 19% and 13%. Oxygen delivery and consumption were maintained at all hematocrits at baseline levels in the PHP and POE-Hb groups, but O2 delivery was significantly decreased in the PS group at Hct = 8% (p < 0.05 for PS vs. baseline and p < 0.05 for PHP and POE-Hb vs. PS). Oxygen extraction ratio increased with progressive hemodilution in both the RBC hemoglobin and plasma phases to a maximum of 39% for PHP and 36% for POE-Hb at Hct = 8%. The percent contribution from the plasma phase to total oxygen delivery and consumption likewise increased with hemodilution to maximum values of 52.7% (PHP) and 68.2% (POE-Hb) for delivery and 40.9% (PHP) and 39.3% (POE-Hb) for consumption.

CONCLUSION

Acellular hemoglobin solutions provide a significant contribution to O2 delivery and consumption, particularly in severe anemia, in this model of isovolemic exchange. The differences in the P50 of the two hemoglobin solutions do not appear to significantly influence oxygen dynamics over the range of hematocrits studied.

Effects of fluid ingestion on cognitive function after heat stress or exercise-induced dehydration

This study investigated the effects of heat exposure, exercise-induced dehydration and fluid ingestion on cognitive performance. Seven healthy men, unacclimatized to heat, were kept euhydrated or were dehydrated by controlled passive exposure to heat (H, two sessions) or by treadmill exercise (E, two sessions) up to a weight loss of 2.8%. On completion of a 1-h recovery period, the subjects drank a solution containing 50 g l(-1) glucose and 1.34 g l(-1) NaCl in a volume of water corresponding to 100% of his body weight loss induced by dehydration. (H1 and E1) or levels of fluid deficit were maintained (H0, E0). In the E0, H0 and control conditions, the subject drank a solution containing the same quantity of glucose diluted in 100 ml of water. Psychological tests were administered 30 min after the dehydration phase and 2 h after fluid ingestion. Both dehydration conditions impaired cognitive abilities (i.e. perceptive discrimination, short-term memory), as well as subjective estimates of fatigue, without any relevant differences between the methods. By 3.5 h after fluid deficit, dehydration (H0 and E0) no longer had any adverse effect, although the subjects felt increasingly tired. Thus, there was no beneficial effect of fluid ingestion (H1 and E1) on the cognitive variables. However, long-term memory retrieval was impaired in both control and dehydration situations, whereas there was no decrement in performance in the fluid ingestion condition (H1, E1).

[The influence of resuscitation with solutions containing different concentrations of sodium on the homeostasis of burn patients during the early postburn stage]

OBJECTIVE

To investigate the influence of resuscitation with solutions containing different concentrations of sodium on the homeostasis of burn patients during the early postburn stage.

METHODS

Thirty-five cases of burn patients inflicted with 50% approximately 100% of TBSA including 20% approximately 88% of 3rd degree burn were enrolled in the study. All the patients studied were divided into A[(Na+) = 174 mmol/L] and B [(Na+) = 130 mmol/L] groups according to different concentrations of sodium in the infusion solution. The input of the fluid, plasma crystal osmotic pressure, plasma ratio of albumin to globulin, urine output and pH value and anasarcous degree were observed during 1 to 5 postburn days (PBDs).

RESULTS

The infusion fluid amount per hour in A group was 20 approximately 30 ml less than that in B group within 3 PBDs. The infused sodium amount in A group was more than that in B group within 5 PBDs. The FENa in A group was in normal range within 5 PBDs, while that in B group was lower than normal. This might be related to different infusion amounts of water and sodium.

CONCLUSION

The homeostasis of burn patients could be significantly affected by the water load and the sodium concentration in the resuscitation solution during early postburn stage.

Pre-exercise hypervolemia and cycle ergometer endurance in men

Time to exhaustion at 87-91% of peak VO2 was measured in 5 untrained men (age: 31 +/- 8 years, body mass: 74.20 +/- 16.50 kg, body surface area: 1.90 +/- 0.24 m2, peak VO2: 2.87 +/- 0.40 l min-1, plasma volume: 3.21 +/- 0.88 l; means +/-SD) after consuming nothing (N) or two fluid formulations (10 ml kg-1, 743 +/- 161 ml): Performance 1 (P1), a multi-ionic carbohydrate drink, containing 55 mEq l-1 Na+, 4.16 g l-1 citrate, 20.49 g l-1 glucose, and 365 mOsm kg-1 H2O, and AstroAde (AA), a sodium chloride-sodium citrate hyperhydration drink, containing 164 mEq l-1 Na+, 8.54 g l-1 citrate, <5 mg l-1 glucose, and 253 mOsm kg-1 H2O. Mean (+/-SE) endurance for N, P1 and AA was 24.68 +/- 1.50, 24.55 +/- 1.09, and 30.50 +/- 3.44 min respectively. Percent changes in plasma volume (PV) from -105 min of rest to zero min before exercise were -1.5 +/- 3.2% (N), 0.2 +/- 2.2% (P1), and 4.8 +/- 3.0% (AA; P < 0.05). The attenuated endurance for N and P1 could not be attributed to differences in exercise metabolism (VE, RE, VO2) from the carbohydrate or citrate, terminal heart rate, levels of perceived exertion, forehead or thigh skin blood flow velocity, changes or absolute termination levels of rectal temperature. Thus, the higher level of resting PV for AA just before exercise, as well as greater acid buffering and possible increased energy substrate from citrate, may have contributed to the greater endurance.

Body fluid shifts in soldiers after a jogging/walking exercise in the heat: effects of water and electrolyte solution on rehydration

OBJECTIVES

To examine the relationships between dehydration and body fluid shifts and the effects of ingesting water or oral rehydration solution or no fluid during and after exercise in the heat [mean (SE)] temperature, 40.5 (0.66) degrees C and 32 (3.7)% humidity.

DESIGN

PRE and POST three hours exercise comparative study.

SETTING

Zimbabwe National Army Wafa-Wafa Training Camp, Kariba, Zimbabwe.

SUBJECTS

18 male soldiers volunteered to be studied during and after a 20 km (three hour) jogging/walking exercise in full kit.

MAIN OUTCOME MEASURES

Body mass, total body water, extracellular water, intracellular water, plasma osmolality, plasma sodium, and volume changes compared using paired t-test.

RESULTS

Total body water decreased by 4.9 (0.38) 1 (p < 0.02) in soldiers exercising without fluid, 1.5 (0.3) 1 (oral rehydration solution), 2.4 (0.8) 1 (water). Extracellular water decreased by 3.6 (0.3) 1 (p < 0.05), 1.3 (0.2) 1, 1.7 (0.3) 1, and intracellular water decreased by 1.3 (0.1) 1, 0.2 (0.01) 1, 0.7 (0.01) 1 respectively in these groups. Plasma volume decreased by [mean (SE)] 16 (1.4)% on no fluid, three (0.3)% on oral rehydration solution, five (0.3)% on water. Plasma osmolality increased significantly from 285 (1.0) to 301 (2.3) mosmol.kg-1 (p < 0.001) in subjects exercising without fluid and from 283 (2.0) to 291 (0.7) mosmol.kg-1 (p < 0.02) in subjects taking oral rehydration solution. No significant increases were observed when taking water only.

CONCLUSIONS

During dehydration, total body water loss was derived from both fluid compartments but extracellular water contributed the most. Effective rehydration depends on adequate replacement of electrolytes lost from each fluid compartment. Water alone may not provide adequate rehydration.

Sapid solutions and food intake in repeated dehydration and rehydration periods in rats

In a previous report, it has been shown that water deprivation significantly affects the two-bottle taste preferences and one-bottle taste acceptance in rats when no food was available during tests. Since no food was available, the course of drinking was never interrupted by eating. Theoretically, if a rat faces a simultaneous choice between food and fluid, and if the course of drinking is interrupted by eating, these conditions might interfere with taste preferences, total fluid intake and eating in thirsty rats. The aims of the present experiments were: to ascertain whether food intake during both two-bottle preference and one-bottle acceptance tests in thirsty rats might be influenced by the palatability of the solutions; to verify whether the availability of food during tests influences taste preference and acceptance, and total fluid intake; to detect variations induced by dehydration on body weight and some plasma and urinary parameters that might interfere with food and fluid intake, taste preference and acceptance. Using naive rats, five groups of rats showing the same taste preferences for one of four prototypical tastes and water were selected. Then, both two-bottle preference (Expt 1) and one-bottle acceptance tests (Expt 2) were performed in rats deprived of water for either 12, 24, 36 or 48 h. The results showed that in both Expt 1 and Expt 2, inhibition of feeding and decrease of body weight during dehydration was very similar in all rats. The presence of food during the tests did not affect taste preference and acceptance. During Expt 1, after severe water deprivation (36 and 48 h), food intake was related to the palatability of the solution paired with water. When rats drank either NaCl or sucrose, they ate less food than rats drinking HCl, quinine, or water. In Expt 2, rats drinking NaCl solution as the only source of fluid ate significantly less food than all other groups. The intake of sucrose and/or NaCl solutions be may explained by two different post-ingestion effects (energetic and osmotic). Since rats drinking either sucrose or NaCl ate less food but drank more fluid, they had a significantly higher fluid/food intake ratio than that of rats who drank water, quinine, or HCl, who ate more food but drank less fluid. The increase of the fluid/food intake ratio in rats drinking sucrose or NaCl was directly correlated with the length of dehydration. Self-denial of food during dehydration may be responsible for overeating and overdrinking during the recovery period after tests. After dehydration lasting for 24 and 48 h, plasma [Na(+)], [protein], osmolality and haematocrit values increased but [K(+)] decreased. Urinary volume decreased but urinary [Na(+)] increased. These results are related to food and fluid intake, taste preference and acceptance after dehydration periods. Experimental Physiology (2001) 86.4, 489-498.

Towards a better oral rehydration fluid

Improvements in characteristics of solutions used for oral rehydration therapy, to provide significant reductions in amount and duration of diarrhea, are expected to contribute to wider use of these fluids. Recent studies suggest that these may come about from reducing the osmolality of the solution, and by providing short chain fatty acids for better fluid absorption from the colon. This article briefly reviews the physiology of intestinal and colonic absorption in diarrhea, and indicates the further studies that are needed to translate the above advances into universal practice for the treatment of diarrhea.

Starch-deferoxamine conjugate inhibits hepatocyte Ca2+ uptake during hemorrhagic shock and resuscitation

BACKGROUND

This study investigated whether hepatocyte Ca2+ dysregulation after hemorrhagic shock and resuscitation could be modulated by the iron chelator hydroxyethyl starch-conjugated deferoxamine (HES-DFO).

METHODS

In a randomized experimental study, anesthetized rats (n = 7) were bled for 60 minutes to maintain mean arterial blood pressure at 40 mm Hg. They were then resuscitated with 60% of shed blood and threefold the shed-blood volume as lactated Ringer's solution, 1 mL of pentastarch solution (hydroxyethyl starch 10%) per mL of shed blood, or 1 mL of HES-DFO solution (10%) per mL of shed blood. In isolated hepatocytes, the rate of Ca2+ influx (Ca2+ in), total Ca2+ uptake (Ca2+ up), and membrane Ca2+ flux (Ca2+ flux) were determined by 45Ca incubation. Reduced or oxidized glutathione and malondialdehyde concentrations were assessed fluorometrically.

RESULTS

Significant increases of hepatocellular Ca2+ in, Ca2+ up, and Ca2+ flux were observed in rats resuscitated with lactated Ringer's solution compared with control groups (p < 0.05). Although hydroxyethyl starch decreased Ca2+ in but not Ca2+ up, HES-DFO not only prevented the increase of Ca2+ in and Ca2+ up but also inhibited hepatocyte oxidative injury.

CONCLUSION

Iron-catalyzed oxyradical production and membrane peroxidation seem to alter hepatocyte Ca2+ homeostasis after hemorrhagic shock and resuscitation.

Tolerance of a rice-based oral rehydration solution given to normal calves

The objective of the study was to test the tolerance of a rice-based oral rehydration formula when fed to calves. Six healthy Holstein calves, 1 week of age, were fed the formula instead of milk replacer for 3 days. Pre- and posttreatment results of clinical examination and laboratory parameters were compared. Vital signs, attitude, appetite, clinical hydration status, urine specific gravity, and most routine serum biochemistry test results did not vary and remained within the normal range. Five of the 6 calves developed diarrhea when fed the rice-based formula, which was accompanied by a reduction in fecal pH and presence of reducing sugars in the feces. This effect was reversed when calves were returned to the milk replacer diet at the end of the study. Diarrhea was accompanied by increased water consumption, which allowed the calves to maintain normal hydration status. These results suggest that calves are unable to properly digest the rice-derived carbohydrate, and this type of formula is not recommended for oral rehydration of calves.

Effects of anion substitution on hydration behavior and water uptake of the red-spotted toad, Bufo punctatus: is there an anion paradox in amphibian skin?

Amphibians absorb water osmotically across their skins and rely on chemosensory information from the skin to assess the suitability of hydration sources. The time spent with skin in contact with a moist surface provides a quantitative measure of their ability to perceive the ionic and osmotic properties of aqueous solutions. Dehydrated toads given hyperosmotic (250 mM) solutions of NaCl or Na-gluconate showed significantly longer periods of hydration behavior on the gluconate solution, but they lost water osmotically when immersed in either solution. Similarly, dehydrated toads given 250 mM solutions of NaCl, Na-acetate, Na-phosphate or Na-gluconate showed a progressively greater length of hydration time on solutions with the larger mol. wt anions. These results are consistent with the chemosensory phenomenon previously described in mammalian tongue as 'anion paradox'. On dilute (50 mM) solutions of NaCl or Na-gluconate, the hydration time was not different between anions, despite toads gaining water more rapidly when immersed in dilute NaCl than in Na-gluconate solutions. The differing behavioral results with hyperosmotic and hypoosmotic salt solutions suggest that chemosensory transduction through toad skin involves both transcellular and paracellular pathways.

Input rate as a major determinant of furosemide pharmacodynamics: influence of fluid replacement and hypoalbuminemia

To investigate how the response to a bolus and an infusion of furosemide is modulated by the rate of fluid replacement and by hypoalbuminemia, rabbits received 5 mg/kg of furosemide as a bolus or infused over 60 min, whereas diuresis was replaced with 13, 121, or 238 ml/h NaCl 0.9%/glucose 5% (50:50). Natriuretic and diuretic efficiencies were greater with the infusion than with the bolus of furosemide. Fluid replacement increased natriuretic and diuretic efficiency of furosemide bolus but only diuretic efficiency of furosemide infusion. Furosemide net fluid depletion reached a plateau when fluid replacement increased beyond 121 ml/h. Repeated plasmapheresis decreased plasma albumin by 30% (P <.05) and increased furosemide unbound fraction (P <.05). Compared with control rabbits, hypoalbuminemia decreased the natriuresis of the bolus (22.7 +/- 1.5-16.6 +/- 1.3 mmol, P <.05) but not that elicited by furosemide infusion (26.2 +/- 1.8 mmol). Given as a bolus, furosemide natriuretic and diuretic response as a function of its urinary rate of excretion exhibited an hyperbolic relationship, and after its infusion a clockwise hysteresis, denoting tolerance. Plasma renin activity was increased by the bolus and the infusion of furosemide, even in the presence of 121 ml/h of fluid replacement. It is concluded that: 1) the increase in natriuretic/diuretic efficiency of the bolus induced by fluid replacement is greater than when furosemide is infused, 2) furosemide net effect does not increase proportionally to fluid replacement, and 3) the infusion of furosemide prevents the hypoalbuminemia-induced decrease in response of furosemide given as a bolus.

Hypertonic saline dextran produces early (8-12 hrs) fluid sparing in burn resuscitation: a 24-hr prospective, double-blind study in sheep

OBJECTIVE

Resuscitation of large burn injuries must quickly restore and maintain cardiovascular function and fluid balance while minimizing secondary edema-related damage. We tested the hypothesis that two 4-mL x kg(-1) doses of hypertonic saline dextran (HSD; 7.5% NaCl/6% dextran-70) can produce prolonged reduction in fluid requirements after burn injury.

DESIGN

Prospective, pseudo randomized, double-blind study.

SETTING

Animal research laboratory.

SUBJECTS

Female adult Merino sheep (n = 12).

INTERVENTIONS

Sheep were given a 40% total body surface area full-thickness flame burn under halothane anesthesia. One hour after the burn, the conscious animals received an initial dose of 4 mL x kg(-1) HSD (n = 6) or normal saline (NS; NaCl 0.9%) (n = 6) intravenously during 30 mins. This was followed by lactated Ringer's solution, infused to a target urine output of 1 mL x kg(-1) x hr(-1) throughout the 24-hr study. A second 4-mL x kg(-1) dose of HSD or NS was started at 12 hrs, and infused during 5 hrs.

MEASUREMENTS AND MAIN RESULTS

Hourly urine output measurements were used to guide the infusion rate of the lactated Ringer's. The initial infusion of HSD 1 hr after the burn injury promptly restored cardiac index, promoted diuresis, and reduced fluid requirements compared with the NS controls (73% reduction for HSD relative to NS at 8 hrs). Subsequent rebound fluid accumulation resulted in similar net fluid balances in both groups within 12 hrs after the burn. The second dose of HSD, given at 12 hrs, was without effect on hemodynamics and fluid balance.

CONCLUSIONS

We conclude a considerable initial, but not sustained fluid-sparing effect of early HSD, and no effect of a late, slowly infused HSD dose in this two-dose regimen.

I.V. fluid therapy. Part 2. I.V. fluid selection

I.v. fluid selection depends on the estimated fluid loss, the primary fluid compartment involved, the patient's underlying problem and the physiological and haemodynamic impact of the i.v. solution. Clinically, the most important problem is intravascular fluid volume deficit, which is associated with hypotension, inadequate tissue oxygenation and hypoperfusion of essential organs. Intravascular volume resuscitation is therefore of primary importance. Crystalloid solutions have the disadvantage of only small amounts remaining in the IVS whereas colloids are known as plasma volume expanders due to predominantly remaining in the IVS in the presence of an intact capillary endothelium. Managing i.v. fluid administration requires close observation of the patient's subtle responses that may indicate states of fluid depletion or overload. Understanding the physiological principles of the body's fluid distribution in relation to the clinical assessment of the patient's hydration status, together with knowledge of the selected i.v. solution's properties, will enable the nurse to provide quality nursing care and improve patient outcomes.

Treatment of neonatal calf diarrhea with an oral electrolyte solution supplemented with psyllium mucilloid

Dairy calves under 14 days of age with naturally occurring, uncomplicated diarrhea were treated for 3 days with a hypertonic oral electrolyte solution with (n = 15) or without (n = 12) psyllium. Clinical response and clinical pathology data were compared between the 2 groups. Glucose absorption was evaluated on days 1 and 3 by measurement of plasma glucose and lactate and serum insulin concentrations for 4 hours after formula administration. On day 1, glucose, lactate, and insulin concentrations were lower in psyllium-fed calves than in control calves, with significant differences noted in glucose and lactate concentrations at several time points (P < 0.05). Plasma lactate concentrations were higher at several times in both treatment groups on day 3 than on day 1 (P < 0.05). Fecal consistency was markedly different in psyllium-fed calves as compared with control calves within 24 hours of psyllium supplementation. Fecal percent dry matter content was lower in psyllium-fed calves than in control calves at least once a day during supplementation and on day 3 compared with day 0 in the psyllium-fed calves (P < 0.05). There were no significant differences in clinical performance scores, hydration status, arterial blood gas, serum anion gap, electrolyte, or total CO2 concentrations. Addition of psyllium to an oral electrolyte solution resulted in immediate alterations in glucose absorption without impairing rehydration in diarrheic calves, but differences were transient and did not affect clinical outcome.

Efficacy of oral hyposmolar glucose-based and rice-based oral rehydration salt solutions in the treatment of cholera in adults

BACKGROUND

Recent animal experiments and clinical trials have shown that both osmolarity and rice as the organic components are important factors for net intestinal absorption of an oral rehydration salt solution.

METHODS

In a controlled clinical trial 123 male adult patients with severe cholera, after initial rehydration with intravenous Ringer's lactate solution, were randomly assigned to receive one of the four oral rehydration salt solutions: WHO ORS, ORS containing 70 mmol/l Na+ and 16.2 g/l glucose, rice ORS containing 50 g/l rice and 90 mmol/l Na+, and rice ORS containing 50 g/l rice and 70 mmol/l Na+. All patients received 300 mg of doxycycline as a single dose.

RESULTS

Patients who received rice-low-sodium ORS subsequently had lower (P < 0.05) stool output, ORS consumption, and diarrhoea duration than the other three ORS groups.

CONCLUSIONS

We conclude that rice-based low-sodium ORS is superior for treating adult cholera.

Acute affect of mitral calve replacement on extravascular lung water in patients receiving colloid or crystalloid priming of cardiopulmonary bypass

Despite numerous studies on extravascular lung water (EVLW) in patients undergoing coronary artery bypass surgery, few data are available on the perioperative time course of EVLW in patients undergoing mitral valve replacement for mitral valve insufficiency (MVI). We have investigated 26 patients undergoing elective mitral valve replacement in order to determine the influence of the preoperative degree of mitral valve insufficiency (degree III or IV) and the effect of different priming solutions for cardiopulmonary bypass. Crystalloid priming with Ringer's lactate was compared with human albumin priming solution. Measurement of EVLW was performed using the thermo-dye dilution technique, before and 1, 6 and 24 h after surgery. Before operation, EVLW is increased significantly in patients with MVI degree IV (MVI-degree IV) compared with patients with degree III (MVI-degree III) and patients undergoing coronary artery bypass surgery. During the postoperative time course a significant decrease in EVLW was observed in patients with MVI-degree IV whereas in patients with MVI-degree III the amount of EVLW did not change. However, compared with patients undergoing coronary artery bypass surgery, EVLW remained above normal in both groups. There was no interaction between the type of priming solution and the postoperative time course of EVLW, and no differences in respiratory variables or duration of mechanical ventilation were observed between groups.

Effects of an isotonic oral rehydration solution, enriched with glutamine, on fluid and sodium absorption in patients with a short-bowel

AIM

To compare the effects of a standard oral rehydration solution with a polymeric glucose isotonic solution enriched with glutamine on water and sodium absorption in the short bowel.

METHODS

Six patients with high jejunostomy were tested in a random order on 2 consecutive days with the standard solution (20 g/L glucose, 94 mmol/L sodium, 292 mOsm/kg osmolality) and a solution containing maltodextrins (18 g/L Glucidex 12; hydrolysis of 18 g of Glucidex 12 yields 20 g glucose) enriched with 14.6 g/L of glutamine (94 mmol/L sodium, 282 mOsm/kg osmolality). Solutions were administered via a naso-gastric tube at a rate of 2 mL/min. Jejunal effluent for each solution was collected during an 8-h period, after a 14-h equilibrium period.

RESULTS

The net 8-h fluid absorption was not significantly different between the standard solution and the solution with glutamine (333 +/- 195 and 213 +/- 251 mL, respectively (mean +/- S.E.M.)). Net sodium absorption was higher for the standard solution than for the solution with glutamine (15 +/- 15 vs. 2 +/- 20 mmol, P < 0.05). The rate of glucose absorption was not different between the solutions.

CONCLUSION

The replacement of glucose by maltodextrins and the addition of glutamine to the standard oral rehydration solution, without changing its sodium content or osmolality, results in a reduction of sodium absorption in the short-bowel syndrome.

Acute effects of intravenously administered hypertonic saline solution on transruminal rehydration in dairy cows

OBJECTIVE

To determine the effect of IV administered hypertonic saline solution (HSS) on transruminal rehydration in clinically normal dairy cows.

ANIMALS

10 Holstein cows.

PROCEDURE

Cows in a 2-way randomized cross-over design study were given nothing per os for 36 hours, then were randomly assigned to receive either an oral water load (OWL; 40 ml/kg of body weight) by ruminal gavage or HSS IV (5 ml/kg of body weight) plus OWL; 10 days later, each cow received the other treatment. Outcome measures included serum and urine osmolality, electrolyte (Ca, P, Na, K, and Cl), creatinine, blood glucose, hemoglobin (Hgb), and plasma total protein (PTP) concentrations; serum colloid osmotic pressure (SCOP); urine volume; PCV; and blood gas analytes (pH, P(CO2), P(O2), HCO3-, base excess [BE], and O2 saturation).

RESULTS

IV administered HSS plus OWL caused Hgb, PCV, PTP, SCOP, blood pH, BE, HCO3-, and urine osmolality values to decrease and fractional excretion (FE) of electrolytes, serum osmolality, and urine volume to increase. Blood glucose concentration was different between treatments at 0 and 150 minutes, and FEK, FECl, and FECa were similar by 180 minutes after OWL alone, but absolute excretion of Na and P and FENa and FE(P) remained high after HSS administration. Oral water load caused Hgb, PCV, PTP, serum electrolyte and creatinine, SCOP, and urine osmolality values to remain unchanged or decrease slowly and pH, BE, HCO3-, FECa values to increase slightly by 180 minutes.

CONCLUSIONS AND CLINICAL RELEVANCE

IV administration of HSS plus OWL, unlike OWL alone, increases circulatory volume rapidly, induces slight metabolic acidosis, increases renal perfusion and glomerular filtration rate, and effects changes in serum Ca and P homeostasis that may be useful in treating sick dairy cows.

Prospective crossover study of the effect of phlebotomy and intravenous crystalloid on hematocrit

OBJECTIVE

To compare the changes in hematocrit (Hct) between phlebotomized and nonphlebotomized individuals given IV crystalloid.

METHODS

A prospective, crossover volunteer study was performed comparing Hct changes immediately and 30 minutes after IV crystalloid bolus in 20 healthy adults with and without prebolus phlebotomy. In the control portion, volunteers were given a 15-mL/kg bolus of normal saline over 30 minutes with Hct determination before (H1), immediately after (H2), and 30 minutes after (H3) crystalloid infusion. At least 7 days later, the same subjects were phlebotomized 1 unit of blood and then administered a 15-mL/kg IV bolus of normal saline 30 minutes later. Hcts were obtained before (H4) and 30 minutes after (H5) phlebotomy (immediately prior to crystalloid infusion). Hcts were also obtained immediately after (H6) and 30 minutes after (H7) crystalloid infusion. A post-hoc test performance analysis was then performed to determine the Hct drop thresholds that would yield the maximal sensitivity and specificity for 500 mL of blood loss (via phlebotomy) in this population.

RESULTS

The Hct (%) drops in the nonphlebotomized individuals receiving IV fluids averaged 4.5 +/- 1.3 immediately and 3.2 +/- 1.3 30 minutes after infusion. These drops were different (p < 0.05) from the Hct drop in individuals receiving IV fluids after phlebotomy, which averaged 6.6 +/- 1.5 and 5.7 +/- 1.1, respectively. Post-hoc analysis revealed that Hct drops of 5.4 immediately, or 4.3 at 30 minutes after infusion, had a sensitivity of > 90% and a specificity of 75% for identification of patients in the phlebotomy group.

CONCLUSIONS

The practice of measuring serial Hcts may be helpful to identify trauma patients with occult blood loss. A prospective clinical trial is needed to validate these Hct drop thresholds (immediate and 30 minutes postinfusion) in crystalloid-resuscitated trauma patients.

Influence of different volume therapy regimens on regulators of the circulation in the critically ill

Various vasoactive substances are involved in the regulation of the macro- and microcirculation. We have investigated if these regulators change during long-term volume therapy with human albumin (HA) or hydroxyethylstarch solution (HES) in trauma and sepsis patients. To maintain pulmonary capillary wedge pressure (PCWP) at 10-15 mm Hg, either 20% HA (HA-trauma, n = 14; HA-sepsis, n = 14) or 10% low-molecular weight HES solution (HES-trauma, n = 14; HES-sepsis, n = 14) were infused for 5 days, otherwise patient management did not differ between the two groups (trauma/sepsis). Mean arterial pressure (MAP), heart rate (HR), PCWP and cardiac index (CI) were monitored in all patients. Liver function was assessed using the monoethylglycinexylidide (MEGX) test, and gastric intramucosal pH (pHi) was monitored by tonometry to assess splanchnic perfusion. Plasma concentrations of vasopressin, endothelin-1, adrenaline, noradrenaline, atrial natriuretic peptide and 6-keto-prostaglandin F1 alpha were measured from arterial blood samples. All measurements were carried out on the day of admission to the intensive care unit (trauma patients) or on diagnosis of sepsis, and daily over the next 5 days at 12:00. MAP, HR and PCWP did not differ between the corresponding subgroups (trauma/sepsis). Cl increased significantly more in the HES than in the HA groups. pHi and MEGX plasma concentrations did not differ in the trauma patients throughout the study. Both were lower than normal in the sepsis groups and increased more markedly in the HES than in the albumin-treated patients (P < 0.05). In the trauma patients, concentrations of all vasoactive regulators were very similar in both groups. In both sepsis groups, vasopressors (vasopressin, endothelin-1, noradrenaline and adrenaline) were significantly increased above normal at baseline and decreased more markedly in HES than in HA patients. Concentrations of atrial natriuretic peptide increased only in the HA patients (from 159 (SD 31) to 215 (38) pg ml-1 on day 2). Plasma concentrations of 6-keto-prostaglandin F1 alpha decreased significantly only in the HES sepsis patients (from 112 (25) to 47 (15) pg ml-1).

[The effect of rehydration on the elasticity modulus and strength of lyophilised and irradiated femur bone in the human]

The influence of rehydration on elasticity modulus and strength of lyophilized and irradiated cortical bone of human femur was studied by means of balance rheometer. The measurements were taken in 20(C and at sample deformation frequency of 12.5 Hz. The bone samples were taken from 40 individuals aged 35-45 who died suddenly. It was found, that after 24 hours rehydration the elasticity modulus of lyophilized and irradiated cortical bone decreased about 11% and strength increased about 18%. The greatest changes of elasticity modulus were observed during first 10 hours of rehydration. Strong negative correlation (r = -0.8, p < 0.001) between changes of elasticity modulus and degree of the bone rehydration was confirmed.

Influence of ingesting a carbohydrate-electrolyte solution on endurance capacity during intermittent, high-intensity shuttle running

The aim of this study was to examine the effects of ingesting a carbohydrate-electrolyte solution on endurance capacity during a prolonged intermittent, high-intensity shuttle running test (PIHSRT). Nine trained male games players performed two exercise trials, 7 days apart. On each occasion, they completed 75 min exercise, comprising of five 15-min periods of intermittent running, consisting of sprinting, interspersed with periods of jogging and walking (Part A), followed by intermittent running to fatigue (Part B). The subjects were randomly allocated either a 6.9% carbohydrate-electrolyte solution (CHO) or a non-carbohydrate placebo (CON) immediately prior to exercise (5 ml kg-1 body mass) and every 15 min thereafter (2 ml kg-1 body mass). Venous blood samples were obtained at rest, during and after each PIHSRT for the determination of glucose, lactate, plasma free fatty acid, glycerol, ammonia, and serum insulin and electrolyte concentrations. During Part B, the subjects were able to continue running longer when fed CHO (CHO = 8.9 +/- 1.5 min vs CON = 6.7 +/- 1.0 min; P < 0.05) (mean +/- S.E.M.). These results show that drinking a carbohydrate-electrolyte solution improves endurance running capacity during prolonged intermittent exercise.

Fluid management in patients with traumatic brain injury

Movement of water between the brain and the intravascular space is dependent on osmotic gradients, which may be established by the acute administration of either hyper- or hypo-osmolar solutions. Mannitol, a hypertonic crystalloid solution, is commonly used to decrease brain water content and reduce intracranial pressure (ICP). Hypertonic saline solutions also decrease brain water and ICP while temporarily increasing systolic blood pressure and cardiac output. Hypo-osmolar solutions, such as 5% dextrose in water, reduce serum sodium and increase brain water and ICP. Colloid solutions exert little influence on either variable. Fluid restriction minimally affects cerebral edema and, if pursued to excess, may result in episodes of hypotension, which may increase ICP and are associated with worse neurologic outcome. Although there is no single best fluid for patients with traumatic brain injury, isotonic crystalloids are widely used and can be justified on a scientific basis.

Inhibition of intestinal secretion by rice

Rates of stool output are reduced when cooked rice is incorporated into oral rehydration solutions. We found that a fraction extracted from rice inhibited the response of intestinal epithelial crypt cells to adenosine 3'5'-cyclic monophosphate, a major intracellular mediator of secretion. This response to rice was seen as an inhibition of cell shrinkage and of chloride efflux in fresh suspended guinea pig crypt cells. The active fraction was of low molecular weight (< 1.5 kDa), hydrophobic, and not a peptide or glycoprotein. It may be chloride-channel blocker.

Redistribution of organ blood flow after hemorrhage and resuscitation in full-term piglets

Newborn piglets (aged 1 to 2 days and 7 to 14 days) were used to study (1) the redistribution of organ blood flow after a 25% acute blood loss and (2) the response to resuscitation with shed blood (20 mL/kg), crystalloid (normal saline [NS] or lactated Ringer's [LR]; 60 mL/kg), and colloid (Dextran-40, 20 mL/kg). Hemodynamic parameters showed little differences in the response to hemorrhage and resuscitation. The two age groups had no significant differences in parameters or blood flow (results combined). The animals maintained flow to the heart and central nervous system (CNS) and had significantly decreased flow to the kidneys and splanchnic organs. In the gastrointestinal tract, the small intestine was affected most severely, with a significant decrease in blood flow, especially to the mucosa. In all organ systems, Dextran 40 restored blood flow to levels significantly above the baseline. Shed blood and crystalloid restored flow to organs sustaining decreased flow, but crystalloid did not restore flow to the baseline level in the kidney and all segments of the gastrointestinal tract.

Carbohydrate drinks and cycling performance

We compared the effects of similarly tasting orange flavored drinks containing 0% (P), 6.4% (E1), and 10% (E2) carbohydrate (CHO) using 12 well-trained cyclists (VO2max = 5.0 l/min-1) on metabolic responses to exercise (EX) and a sprint type performance ride (PR). Each subject completed 3 separate 2 h EX bouts at 65% VO2max followed by a PR identified as the time in sec to complete 500 revolutions at a constant belt resistance of 29.4 N (ANOVA*). The CHO feedings or placebo of 3 ml/kg body weight were given double blind and counter-balanced at 0 min and every 20 min thereafter during EX. Blood samples were drawn and core temperature (Tr) was recorded at 0, 30, 60, 90, and 120 min of EX and 1 min post PR. Blood samples were analyzed for glucose (G) and lactate [LA-]. Blood G at 0 min were similar; however, at 120 min, G was 3.96 mM for P*, 4.57 mM for E1, and 4.77 mM for E2. Blood [LA-] remained similar throughout EX averaging (P, 2.6 mM; E1, 2.9 mM; E2, 2.5 mM). Tr at 120 min was also similar (P, 38.5 degrees C; E1, 38.6 degrees C; E2, 38.3 degrees C). Mean PR times for P(264.4 s)**, E1 (255.3 s)*, E2 (252.4 s)* indicate consumption of a CHO drink during EX improves PR. Furthermore, a 10% CHO drink improves PR more than a 6.4% CHO drink.

Neurohumoral mechanism involved in augmentation of canine jejunal absorption following oral rehydration solutions

Throughout the world diarrheal diseases kill over 5 million children annually. Oral rehydration therapy, initially using glucose-based solutions and more recently cereal-based solutions, prevents complications and death from dehydration. These experiments compared the effect of these two rehydration solutions and a mixed meal on jejunal water and ionic transport. Five dogs had 25-cm proximal jejunal Thiry-Vella fistulae constructed. Following recovery, jejunal absorption studies (N = 40) were performed using an isotonic electrolyte solution containing [14C]PEG to calculate net fluxes of water, sodium, and chloride. Each study consisted of a 1-hr basal period, followed by a 3-hr experimental period. Each animal was randomly studied in each of four study groups: control, mixed meal, glucose-based and cereal-based rehydration solution. In the mixed meal, glucose-based, and cereal-based solution groups there were significant increases (P < 0.0001) in jejunal Thiry-Vella fistula water and ion absorption following the stimuli, in the absence of direct luminal nutrient contact with the Thiry-Vella fistula. There were no differences between the observed responses to the glucose-based or cereal-based rehydration solutions. Glucose-based and cereal-based rehydration solutions were equally effective in stimulating jejunal absorption of water and electrolytes, but less effective than a mixed meal. Both food and oral rehydration solutions appear to increase jejunal absorption partially via a neurohumoral mechanism that is independent of luminal nutrient contact with the Thiry-Vella fistula.

Glucose polymer ingestion--effect on fluid balance and glycemic state during a 4-d march

The effect of glucose-polymer solution on physical performance has been extensively studied under controlled laboratory conditions. The present study was conducted to investigate the influence of such beverages on fluid balance and on glycemic state during a moderate, prolonged field exercise. Forty-eight endurance trained, male subjects participated in the study. The maneuver consisted of a 4-d march; 29, 39, 36, 30 km.d-1, at a speed of 5-6 km.h-1. The subjects covered a total distance of 134 km at an estimated exercise intensity of approximately 40% VO2max, under hot climate conditions (ambient temperature, 32-41 degrees C; relative humidity, 60-14%). Subjects were randomly assigned to one of two groups: glucose polymer-electrolyte beverage (GP; N = 24) and tap water (TW; N = 24). Each group was then divided into two subgroups consuming fluid ad libitum (TWa, GPa) or instructed to consume 900 ml.h-1 (TWb, GPb). The mean daily fluid consumption of all subgroups was similar (5252 +/- 229 and 4640 +/- 67 ml in TWa and TWb; 5257 +/- 317 and 5253 +/- 216 ml in GPa and GPb, respectively). Weight loss, reflecting the degree of dehydration, was 1.2 +/- 0.1% and 1.9 +/- 0.3% of initial body weight in TW and GP, respectively. On day 1, plasma volume changed by +0.4% and -1.8% in the TW and GP groups, respectively. On the days 2-4 changes in both groups were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of rehydrating fluid 'Electral' on Vibrio cholerae cells

V. cholerae OGAWA 154 cells underwent rapid loss of colony forming capacity during the first few minutes' incubation in the Electral medium at 37 degrees C, the turbidity of the suspension however increasing with time of incubation and leading to a plateau from 5 min onward. The vibrio suspension in the Electral medium released small amounts of 280 nm and much higher amounts of 260 nm absorbing materials. On withdrawal of the Electral medium, the cells underwent significant liquid holding recovery in the phosphate buffered saline, pH 7. Majority of the cells underwent no significant ultrastructural change but grew into long filamentous forms. The mode of action of the Electral medium on the vibrios is discussed.