Oral rehydration therapy with glucose-electrolyte solutions has been one of the major therapeutic advances of the century. This alarmingly simple intervention developed from a basic scientific observation in the laboratory, when it was shown that sodium and glucose transport in the small intestine are coupled and thus the presence of glucose in an electrolyte solution promotes absorption of both sodium ions and water. Even more important, sodium/glucose co-transport continues despite the secretory diarrhoea of cholera and enterotoxigenic E. coli and after intestinal damage due to rotavirus. Despite widespread use of the oral rehydration solutions (ORS) recommended by the World Health Organization (WHO), controversy continues about the optimal composition of these solutions. Discussion centres around the sodium and glucose concentrations, the osmolality and whether base (bicarbonate) or base-precursor (citrate) is necessary. Already there is a clear divide between the developing world, where the WHO solution (Na 90, glucose 111 and bicarbonate 30 mmol/L) is widely used, and the industrialised world, where solutions with lower sodium and until recently higher glucose concentrations have been favoured. Recently, attempts have been made to optimise ORS using animal and human model systems before submitting new candidate ORS to clinical trial. Results to date suggest that hypotonic ORS containing 50-60 mmol/L sodium and 90-100 mmol/L glucose produce maximal water absorption. The presence of base or base-precursor appears to offer little with regard to the promotion of sodium and water absorption and its role in combating acidosis remains controversial. Complex substrates such as rice powder and glucose polymers may eventually replace glucose in ORS, since their addition reduces ORS osmolality still further.

In a randomized trial, 62 infants 2 to 35 months of age with dehydration due to acute watery diarrhea were allocated to one of two groups: group A received solution A (World Health Organization-recommended oral rehydration solution), which contained (mmol/L): Na+ 90, K+ 20, Cl- 80, citrate3- 10, and glucose 110; group B received solution B (Pedialyte RS; Abbott Laboratories, North Chicago), which contained (in mmol/L): Na+ 75, K+ 20, Cl- 65, citrate3- 10, and glucose 139. Oral therapy was given until clinical signs of hydration status were normal. During the 48-hour trial, the following laboratory data were collected: blood gases, serum electrolytes, glucose, urea, and creatinine values and sodium and potassium concentrations in stool and urine; serial weights and clinical signs were also reported. Six of the 62 infants, three in each group, required intravenous fluids because of high stool output. Results of clinical outcome and normalization of altered serum electrolyte values were similar in both groups. During the 48-hour trial, eight patients in group A and four in group B had mild, asymptomatic hypernatremia. Pedialyte RS was found to be a safe glucose/electrolyte solution for oral rehydration therapy.

Children generally have a higher body water content (60-75%) compared to adults (55-60%). Dehydration in children is a concern as their higher body water content makes them more prone to water, sodium and potassium loss during acute illnesses. Vomiting, diarrhea, or other causes of excessive fluid loss can lead to varying degrees of dehydration from mild (3-5% weight loss) to moderate (6-10% weight loss) and severe (10-15% weight loss). Symptoms of dehydration in children differ according to the degree of dehydration, but can include hyperirritability, lethargy, intense thirst, mottled or cyanotic skin, a rapid pulse, hypotension and shock in more severe cases. Three types of dehydration can occur: isonatremic, hypernatremic, and hyponatremic. Isonatremic dehydration is the most common presentation (80% of cases) and is characterized by equal loss of water and salt. Hypernatremic dehydration represents a smaller fraction of cases (15%) and is characterized by a greater water loss. Hyponatremic dehydration is the rarest presentation (5% of cases) and is characterized by either excessive water intake, sodium depletion or an artificial lowering of serum sodium concentration secondary to an increase in glucose, electrolytes, lipids and proteins. The treatments of the different types of dehydration vary, but all involve replacing fluid deficits. Oral rehydration therapy is the first line treatment for children with mild to moderate dehydration. Commercially available oral rehydration solutions contain specific concentrations of sodium, potassium and glucose with the aim of optimizing fluid absorption through the gastrointestinal tract via the sodium-glucose cotransporter pump., Oral rehydration solutions can thus be used for all types of dehydration as long as the serum sodium concentrations are not at the extreme ends of the spectrum in hyponatremic or hypernatremic dehydration. However, oral rehydration solutions are considered to be prohibitively expensive for some patients (or their guardians) and often have an unpleasant taste. This may lead to dehydrated children being treated with other beverages which may not contain the optimal carbohydrate and electrolyte concentrations needed for rehydration. Other, often more palatable, oral rehydration options include water, clear broths, ice pops, and juice or sports drinks. This report aims to summarize the evidence regarding the comparative clinical effectiveness of oral rehydration solution versus other fluids of choice for pediatric patients with, or at risk of, dehydration.

Oral rehydration of neonates and young infants with dehydrating diarrhea: comparison of low and standard sodium content in oral rehydration solutions. Oral rehydration among infants aged 0-3 months has not been adequately investigated. A controlled, randomized study was thus conducted in 65 young infants hospitalized with acute noncholera dehydrating diarrhea. The study was designed to compare the efficacy and safety of the standard WHO oral glucose-electrolyte solution containing 90 mmol of sodium per liter (Group A: 22 infants) with that of an oral glucose-electrolyte solution containing 60 mmol of sodium per liter (Group B: 22 infants) and with standard intravenous therapy (Group C: 21 infants). Among the 44 infants in Groups A and B, none required intravenous therapy. Dehydration, acidosis, and initial hyponatremia or hypokalemia were corrected with equal efficacy in all the three groups. In the critical first 8 h, the mean sodium absorption was significantly higher (p less than 0.01) in Group A. This resulted in hypernatremia (50%), periorbital edema (50%), mild pedal edema (27%), excessive irritability, and convulsions (4.5%).