Reduced osmolarity oral rehydration salt in Cholera

Post-exercise rehydration: Comparing the efficacy of three commercial oral rehydration solutions

Introduction

This study compared the efficacy of three commercial oral rehydration solutions (ORS) for restoring fluid and electrolyte balance, after exercise-induced dehydration.

Method

Healthy, active participants (N = 20; ♀ = 3; age ∼27 y, V˙O₂peak ∼52 ml/kg/min) completed three randomised, counterbalanced trials whereby intermittent exercise in the heat (∼36°C, ∼50% humidity) induced ∼2.5% dehydration. Subsequently, participants rehydrated (125% fluid loss in four equal aliquots at 0, 1, 2, 3 h) with a glucose-based (G-ORS), sugar-free (Z-ORS) or amino acid-based sugar-free (AA-ORS) ORS of varying electrolyte composition. Urine output was measured hourly and capillary blood samples collected pre-exercise, 0, 2 and 5 h post-exercise. Sodium, potassium, and chloride concentrations in urine, sweat, and blood were determined.

Results

Net fluid balance peaked at 4 h and was greater in AA-ORS (141 ± 155 ml) and G-ORS (101 ± 195 ml) than Z-ORS (-47 ± 208 ml; P ≤ 0.010). Only AA-ORS achieved positive sodium and chloride balance post-exercise, which were greater for AA-ORS than G-ORS and Z-ORS (P ≤ 0.006), as well as for G-ORS than Z-ORS (P ≤ 0.007) from 1 to 5 h.

Conclusion

when provided in a volume equivalent to 125% of exercise-induced fluid loss, AA-ORS produced comparable/superior fluid balance and superior sodium/chloride balance responses to popular glucose-based and sugar-free ORS.

Issues and Controversies in the Evolution of Oral Rehydration Therapy (ORT)

The original studies demonstrating the efficacy of oral glucose-electrolytes solutions in reducing or eliminating the need for intravenous therapy to correct dehydration caused by acute watery diarrheas (AWD) were focused chiefly on cholera patients. Later research adapted the oral therapy (ORT) methodology for treatment of non-cholera AWDs including for pediatric patients. These adaptations included the 2:1 regimen using 2 parts of the original WHO oral rehydration solution (ORS) formulation followed by 1 part additional plain water, and a “low sodium” packet formulation with similar average electrolyte and glucose concentrations when dissolved in the recommended volume of water. The programmatic desire for a single ORS packet formulation has led to controversy over use of the “low sodium” formulations to treat cholera patients. This is the subject of the current review, with the conclusion that use of the low-sodium ORS to treat cholera patients leads to negative sodium balance, leading to hyponatremia and, in severe cases, particularly in pediatric cholera, to seizures and other complications of sodium depletion. Therefore it is recommended that two separate ORS packet formulations be used, one for cholera therapy and the other for non-cholera pediatric AWD.

Treatment of severe cholera: a review of strategies to reduce stool output and volumes of rehydration fluid

Background

Severe cholera is a life-threatening illness of hypovolemic shock and metabolic acidosis due to rapid and profuse diarrheal fluid loss. Emergency life-saving therapy is i.v. saline, optionally supplemented with potassium and alkali to correct the fluid deficit, potassium losses and acidosis. After this initial rehydration, for the next 2 days ongoing stool losses are replaced with oral rehydration solution (ORS), which contains sodium chloride, potassium and alkali together with glucose or rice powder as a source of glucose to serve as a carrier for sodium.

Results

In actual field trials, antibiotics are given to reduce fluid requirements, but large volumes averaging about 7 liters of i.v. fluid followed by about 14 liters of ORS have been given to adult patients. Disturbing trends during therapy have included overhydration, hyponatremia and polyuria.

Conclusions

It is suggested that stool output and fluid requirements could be reduced, if borne out in future research, by avoiding overhydration by restricting ORS intake to match stool output and promoting intestinal reabsorption of luminal fluid by early introduction of glucose without salts into the intestine, more gradual correction of dehydration, giving mineralocorticoid and vasopressin, and infusing glucose or short-chain fatty acids into the proximal colon.

Oral rehydration salt solution for treating cholera: ≤ 270 mOsm/L solutions vs ≥ 310 mOsm/L solutions

BACKGROUND

Oral rehydration solution (ORS) is used to treat the dehydration caused by diarrhoeal diseases, including cholera. ORS formulations with an osmolarity (a measure of solute concentration) of ≤ 270 mOsm/L (ORS ≤ 270) are safe and more effective than ORS formulations with an osmolarity of ≥ 310 mOsm/L (ORS ≥ 310) for treating non-cholera diarrhoea. As cholera causes rapid electrolyte loss, it is important to know if these benefits are similar for people suffering from cholera.

OBJECTIVES

To compare the safety and efficacy of ORS ≤270 with ORS ≥ 310 for treating dehydration due to cholera.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register (April 2011), CENTRAL (The Cochrane Library Issue 4, 2011), MEDLINE (1966 to April 2011), EMBASE (1974 to April 2011), and LILACS (1982 to April 2011). We also contacted organizations and searched reference lists.

SELECTION CRITERIA

Randomized controlled trials comparing ORS ≤ 270 with ORS ≥ 310 for treating adults and children with acute diarrhoea due to cholera.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied eligibility criteria, assessed trial quality, and extracted data. We pooled dichotomous data using risk ratio (RR), pooled continuous data using mean difference (MD) or the standardized mean difference (SMD), and presented the results with 95% confidence intervals (CI).

MAIN RESULTS

For glucose-based ORS, seven trials (718 participants) met the inclusion criteria. Biochemical hyponatraemia (blood sodium levels < 130 mmol/L) was more common with ORS ≤ 270 (RR 1.67, CI 1.09 to 2.57; 465 participants, four trials), while a higher level of severe biochemical hyponatraemia (blood sodium levels < 125 mmol/L) in the same group was not significant (RR 1.58, CI 0.62 to 4.04; 465 participants, four trials). No instances of symptomatic hyponatraemia or death were noted in the trials that intended to record them. We found no statistically significant difference in the need for unscheduled intravenous infusion. Analyses separating children and adults showed no obvious trends.Two trials also examined rice-based ORS. In the ORS ≤ 270 group, duration of diarrhoea was shorter (MD -11.42 hours, CI -13.80 to -9.04; 102 participants, two trials).

AUTHORS' CONCLUSIONS

In people with cholera, ORS ≤ 270 is associated with biochemical hyponatraemia when compared with ORS ≥ 310, but there are no differences in terms of other outcomes. Although this risk does not appear to be associated with any serious consequences, the total patient experience in existing trials is small. Under wider practice conditions, especially where patient monitoring is difficult, caution is warranted.

Treatment of cholera-like diarrhoea with oral rehydration

Cholera diarrhoea remains a major global health problem that has caused seven pandemics. The pathogenesis of cholera is attributable to the production of cholera toxin by the causative pathogen, Vibrio cholerae. The toxin causes increased production of cyclic adenosine monophosphate and this results in massive water and electrolyte secretion into the intestinal lumen. These changes manifest clinically as the painless defecation of voluminous stools that resemble 'rice water', leading to severe dehydration. The cornerstone in the management of cholera diarrhoea is the use of oral rehydration solutions (ORS) to replace the water and electrolytes lost as stools. The World Health Organization recommends the use of ORS of 'reduced osmolarity' for the treatment of acute non-cholera diarrhoea and the use of rice-based ORS for the management of cholera diarrhoea. Although several attempts have been made to improve ORS, studies to evaluate some of the modifications, which include the addition of amylase-resistant starch, the use of amino acids (such as glycine, alanine and glutamine) as sodium cotransporters, and zinc-supplemented ORS, are still needed.

Oral rehydration solutions in non-cholera diarrhea: a review

The use of oral rehydration solution (ORS) has revolutionized the management of acute diarrhea. The implementation of the standard World Health Organization ORS (WHO-ORS) has resulted in decreased mortality associated with acute diarrheal illnesses in children, although in general stool volume and diarrhea durations are not reduced. Decreased morbidity and mortality have occurred because of improved hydration status. Decreased morbidity has also been described in adults who used this therapy. Various modifications to the standard ORS have been derived. These modifications have included hypo-osmolar or hyperosmolar solutions, use of rice-based ORS, zinc supplementation, and the use of amino acids, including glycine, alanine, and glutamine. Some of these variations have been successful, some have not, and others are still under investigation. ORS has been used for travelers' diarrhea and to decrease intravenous (IV) fluid requirements in patients with short bowel syndrome (SBS) who require parenteral nutrition (PN). This paper reviews the standard WHO-ORS and its mechanism of action, followed by more contemporary reduced osmolarity ORS and rice-based ORS in non-cholera diarrhea. Various modifications to improve ORS are also discussed.

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.

Reduced osmolarity oral rehydration solution for treating cholera

BACKGROUND

Oral rehydration solution (ORS) is used to treat dehydration caused by diarrheal diseases including cholera. Reduced osmolarity formulations are safe and more effective than standard ORS for treating non-cholera diarrhea. As cholera causes rapid electrolyte loss, it is important to know if these benefits are similar for people with cholera.

OBJECTIVES

To compare the safety and efficacy of reduced osmolarity oral rehydration solution (ORS) with standard ORS for treating diarrhea due to cholera.

SEARCH STRATEGY

We searched the Cochrane Infectious Disease Group Specialized Register (January 2004), CENTRAL (The Cochrane Library Issue 1, 2004), MEDLINE (1966 to January 2004), EMBASE (1974 to January 2004), and LILACS (1982 to January 2004). We also contacted organizations and searched reference lists.

SELECTION CRITERIA

Randomized controlled trials comparing reduced osmolarity ORS with standard ORS for treating adults and children with acute diarrhea due to cholera.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied eligibility criteria, assessed trial quality, and extracted data. We pooled binary data using relative risks (RR), continuous data using weighted mean difference (WMD) or the standardized mean difference (SMD), and presented the results with 95% confidence intervals (CI).

MAIN RESULTS

For glucose-based reduced osmolarity ORS, seven trials (718 participants) met the inclusion criteria. Biochemical hyponatremia (serum sodium < 130 mmol/L) was more common with reduced osmolarity ORS (RR 1.67, CI 1.09 to 2.57; 465 participants, 4 trials); for severe biochemical hyponatremia (serum sodium < 125 mmol/L) this was not significant (RR 1.58, CI 0.62 to 4.04; 465 participants, 4 trials). No trials reported symptomatic hyponatremia or death. We found no statistically significant difference in the need for unscheduled intravenous infusion. Analyses separating children and adults showed no obvious trends. Two trials also examined rice-based ORS. In the reduced osmolarity group, duration of diarrhea was shorter (WMD -16.85 hours, CI -21.22 to -12.48; 102 participants, 2 trials).

REVIEWERS' CONCLUSIONS

In people with cholera, reduced osmolarity ORS is associated with biochemical hyponatremia when compared with standard ORS, although there are similar benefits in terms of other outcomes. Although this risk does not appear to be accompanied by serious consequences, the total patient experience in existing trials is small. Under wider practice conditions, especially where patient monitoring is difficult, caution is warranted.

Efficacy and safety of a modified oral rehydration solution (ReSoMaL) in the treatment of severely malnourished children with watery diarrhea

OBJECTIVES

Efficacy, development of overhydration, and correction of electrolyte disturbances of severely malnourished children with acute diarrhea using a modified oral rehydration solution for malnourished children (termed ReSoMaL and recommended by the World Health Organization [WHO]) were evaluated and compared with standard WHO-oral rehydration solution (ORS).

STUDY DESIGN

Children age 6 to 36 months with severe malnutrition and acute watery diarrhea were randomized to ReSoMaL (n=65) or standard WHO-ORS (n=65). Major outcome measures included the number of children who developed overhydration and the number who corrected hypokalemia.

RESULTS

The numbers of children who developed overhydration were not significantly different (ReSoMaL vs WHO-ORS, 5% vs 12%, P=.2). ReSoMaL corrected basal hypokalemia in a greater proportion of children by 24 hours (36% vs 5%, P=.0006) and 48 hours (46% vs 16%, P=.004) compared with WHO-ORS. More children on ReSoMaL than WHO-ORS remained hyponatremic at 48 hours (29% vs 10%, P=.017). Three children in the ReSoMaL group developed severe hyponatremia by 24 hours, with one experiencing hyponatremic convulsions (serum sodium, 108 mmol/L).

CONCLUSIONS

ReSoMaL has a large beneficial effect on potassium status compared with standard ORS. However, ReSoMaL therapy may result in symptomatic hyponatremia and seizures in patients with severe diarrhea.

Reduced osmolarity oral rehydration solution for treating dehydration due to diarrhoea in children: systematic review

OBJECTIVES

To compare reduced osmolarity oral rehydration solution with standard World Health Organization oral rehydration solution in children with acute diarrhoea.

DESIGN

Systematic review of randomised controlled trials.

STUDIES

15 randomised controlled trials including 2397 randomised patients.

OUTCOMES

The primary outcome was unscheduled intravenous infusion; secondary outcomes were stool output, vomiting, and hyponatraemia.

RESULTS

In a meta-analysis of nine trials for the primary outcome, reduced osmolarity rehydration solution was associated with fewer unscheduled intravenous infusions compared with standard WHO rehydration solution (odds ratio 0.61, 95% confidence interval 0.47 to 0.81). Three trials reported that no patients required unscheduled intravenous infusion. Trials reporting secondary outcomes suggested that in the reduced osmolarity rehydration solution group, stool output was lower (standardised mean difference in the log scale -0.214 (95% confidence interval -0.305 to -0.123; 13 trials) and vomiting was less frequent (odds ratio 0.71, 0.55 to 0.92; six trials). Six trials sought presence of hyponatraemia, with events in three studies, but no significant difference between the two arms.

CONCLUSION

In children admitted to hospital with dehydration associated with diarrhoea, reduced osmolarity rehydration solution is associated with reduced need for unscheduled intravenous infusions, lower stool volume, and less vomiting compared with standard WHO rehydration solution.

Evaluation of oral hypo-osmolar glucose-based and rice-based oral rehydration solutions in the treatment of cholera in children

In a randomized controlled clinical trial, the efficacy of a low-sodium low-glucose oral rehydration solution (ORS) and a low-sodium rice-based ORS was compared with standard WHO glucose ORS in the treatment of severe cholera in children aged 2-10y. In total, 120 children were evaluated for the study, of whom 58 patients were positive for Vibrio cholerae and were included in the study. Of these 58 cases, 19 received rice-based hypo-osmolar ORS, 20 received WHO-ORS and 19 received glucose-based hypo-osmolar ORS. The clinical characteristics (age, preadmission duration of diarrhoea, frequency of stool before admission, incidence of vomiting, body weight and volume of initial fluid requirement) were comparable in the three treatment groups. All patients received tetracycline in a dose of 50 mg/kg/d of body weight in 4 divided doses for 3 d.

CONCLUSIONS

Patients who received rice-based hypo-osmolar ORS had subsequently reduced (p < 0.05) stool output, ORS consumption and diarrhoea duration than the patients who received either WHO-ORS or glucose-based hypo-osmolar ORS.

Reduced osmolarity oral rehydration solution for persistent diarrhea in infants: a randomized controlled clinical trial

OBJECTIVE

We evaluated and compared the efficacy of the World Health Organization (WHO) oral rehydration solution (ORS) and 2 different formulations of reduced osmolarity ORSs in infants with persistent diarrhea.

STUDY DESIGN

Infants with persistent diarrhea (n = 95) were randomized to 1 of the 3 ORSs: WHO-ORS (control, n = 32), a glucose-based reduced osmolarity ORS (RORS-G, n = 30), or a rice-based reduced osmolarity ORS (RORS-R, n = 31) for replacement of ongoing stool losses for up to 7 days. Major outcome measures were stool volume and frequency, ORS intake, and resolution of diarrhea.

RESULTS

Although there were variations from one study day to another, the stool volume was approximately 40% less in the reduced osmolarity ORS groups; consequently, these children required less ORS (22% for RORS-G and 27% for RORS-R groups). A higher proportion of children in the RORS-R groups also had resolution of diarrhea during the study period. No children in any of the treatment groups had hyponatremia.

CONCLUSION

Reduced osmolarity ORS is clinically more effective than WHO-ORS and may thus be advantageous for use in the treatment of children with persistent diarrhea.

Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children

BACKGROUND

Oral rehydration solution (ORS) has reduced childhood deaths from diarrhoea in many countries. Recent studies suggest that the currently recommended formulation of ORS recommended by the World Health Organization (WHO) may not be optimal, and solutions that contain lower concentrations of sodium and glucose may be more effective.

OBJECTIVES

In children with acute diarrhoea, to compare reduced osmolarity glucose-based oral rehydration salt solution with international WHO formulation.

SEARCH STRATEGY

The Cochrane Collaboration Trials Register, MEDLINE, and EMBASE were searched. Additional trials were identified by hand searching. Content experts were contacted.

SELECTION CRITERIA

Randomised controlled trials comparing reduced osmolarity ORS solution with the WHO formulation. Outcomes sought were unscheduled intravenous fluid infusion therapy and measures of clinical illness.

DATA COLLECTION AND ANALYSIS

Data were extracted by two reviewers. We tested for heterogeneity using the chi-square statistic, conducted sensitivity analysis by allocation concealment, and the regression approach to assess funnel plot asymmetry from selective trial publication.

MAIN RESULTS

The primary outcome was reported in 12 trials. In a meta-analysis of nine trials, reduced osmolarity ORS was associated with fewer unscheduled infusions compared with standard WHO ORS (Mantel Haenzel odds ratio 0.61, 95% confidence interval 0.47 to 0.81) with no evidence for heterogeneity between trials. No unscheduled intravenous fluid infusion therapy was required in any participant in three trials. Thirteen trials reported stool output, and data suggested less stool output in the reduced osmolarity ORS group. Vomiting was less frequent in the reduced osmolarity group in the six trials reporting this. Six trials sought hyponatraemia, with events in three studies, but no obvious difference between the two arms.

REVIEWER'S CONCLUSIONS

In children admitted to hospital with diarrhoea, reduced osmolarity ORS when compared to WHO ORS is associated with fewer unscheduled intravenous infusions, smaller stool volume post randomisation, and less vomiting. No additional risk of developing hyponatraemia when compared with WHO ORS was detected.

Efficacy and safety of oral rehydration solution with reduced osmolarity in adults with cholera: a randomised double-blind clinical trial. CHOICE study group

BACKGROUND

The effects of oral rehydration solution (ORS) with reduced osmolarity on children with acute watery diarrhoea are known, but little is known about the effects of such ORS on adults with cholera. We aimed to compare the efficacy and safety of an ORS with reduced osmolarity with that of standard WHO ORS in adults with cholera.

METHODS

We undertook a double-blind, controlled clinical trial in adults with severe cholera at the International Centre for Diarrhoeal Disease Research, Bangladesh. Our primary outcomes were mean stool output in the 24 h after randomisation, proportion of patients who needed unscheduled intravenous therapy, and proportion of patients with biochemical hyponatraemia 24 h after randomisation.

FINDINGS

147 patients received ORS with reduced osmolarity and 153 received standard WHO ORS. There was no significant difference between the two groups in terms of main outcome variables: mean initial 24 h and total stool output (reduced osmolarity vs standard WHO ORS 212 [SE 8] vs 207 [8] and 284 [13] vs 273 [13] g/kg respectively), duration of diarrhoea (46 [1.5] vs 43 [1.5]). The proportion of patients vomiting during the first 24 h and the proportion who received unscheduled intravenous infusion during the first 24 h was similar between groups. More patients on reduced osmolarity ORS than on standard WHO ORS developed hyponatraemia during the first 24 h, defined as serum sodium concentration below 130 mmol/L (29 of 142 vs 16 of 150; odds ratio 2.1 [95% CI 1.1-4.1]). However, all hyponatraemic patients in both groups were symptom-free and the proportion of patients with serum sodium concentration below 125 mmol/L was similar between groups.

INTERPRETATION

There was no difference in clinical outcome between cholera patients treated with reduced osmolarity ORS solution and those treated with standard WHO ORS. The risk of increased incidence of symptom-free hyponatraemia in patients with cholera treated with an ORS with reduced osmolarity should be further assessed by meta-analysis. The risk should be taken into account when choice of ORS is made in areas in which cholera is endemic.

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.