These experimental studies were followed by a number of clinical studies in patients with diarrhea, including a multi-center international trial. (15) Meta-analysis of these studies concluded that, compared to WHO standard ORS, hypo-osmolar ORS was associated with fewer unscheduled intravenous fluid infusions, lower stool volumes, and less vomiting.(16,17) These differences are shown in Table 2. Based on these studies, the UNICEF and WHO organized a meeting of experts in New York in July 2001 which suggested a consensus reduced osmolarity ORS formulation.(18) The WHO officially incorporated this change in the recommended composition of ORS to this low sodium, low glucose, low osmolarity solution in 2002.

The Journal of the American Medical Association in 2004 carried two opinion pieces, one defending the change in ORS to reduced osmolarity solution, and the other pointing out the potential problems that may be encountered with recommending a reduced osmolarity solution for universal use in all forms of diarrhea.(19,20) A meta-analysis of studies of reduced osmolarity ORS in patients with cholera concluded that its use is associated with biochemical hyponatremia when compared with standard ORS, although there were similar benefits in terms of outcomes; and that under wider practice conditions, where monitoring is likely to be difficult, caution is warranted in the use of reduced osmolarity ORS in cholera or other severe diarrhea.(21) Therefore it may be useful to have one solution (with low sodium and low osmolarity) for use in children with diarrhea, while another solution (the old WHO formula) may be more appropriate for adults with cholera.

The use of zinc to reduce diarrhea duration has been widely studied. Zinc supplementation has been found to reduce diarrhea duration and to reduce the frequency of persistent diarrhea and consequent malnutrition which complicates diarrhea in children in developing countries.(22,23) Currently the consensus is to use zinc in the form of 20 mg elemental zinc given once daily for 14 days.

Although reduced osmolarity ORS has major advantages in the treatment of children with non-cholera diarrhea, the reduction of diarrhea volume and duration is a goal that remains to be attained. Short chain fatty acids are produced in the colon by fermentation of unabsorbed carbohydrate and stimulate sodium absorption. Like glucose-linked sodium absorption in the small intestine, this absorptive process in the colon is not altered in diarrheal disease. Amylase resistant starch, found in some foods such as cereals and green banana, is fermented to short chain fatty acids in the colon and reduces diarrhea both in adults with cholera and in children with non-cholera diarrhea. (24,25)

Children presenting with acute diarrhea should be assessed as to whether they have a watery diarrhea syndrome or bloody diarrhea syndrome, and whether there is evidence of clinical dehydration. Dehydration is assessed as 'none', 'some' or 'severe' according to the WHO Management of diarrhoea guidelines (Figure 1). Children who have severe dehydration require intravenous hydration (with Ringer lactate solution preferentially) of which 100 ml/kg is given over four hours, 30% in the first hour and the remaining 70% over three hours. Children with 'some' dehydration are presumed to have dehydration of between 5-10% of body weight and should be treated with reduced osmolarity ORS. ORS can be administered via nasogastric tube in the initial stages of rehydration in sick children who are unable to take adequate amounts of ORS. It is estimated that approximately one in every 25 children that are given ORS will go on to require intravenous hydration. Children are assessed frequently and oral intake, urine output and stool output measured. It is expected that rehydration (replacement of lost fluid) would have completed in the first four hours and the subsequent phase is maintenance of hydration, where ORS intake is matched to stool losses. The usual diet of the child is allowed after the first four hours in children with significant dehydration, and is continued without interruption in normal in children with no dehydration. The use of zinc has become commonplace and 20 mg of elemental zinc is given as suspension or tablet once daily for 14 days. The use of starchy foods is encouraged. Commercially available fruit juices have a high osmolarity and are best avoided in the initial phase of hydration of the child. Antibiotics are generally not necessary in the treatment of diarrhea in children, except in older children with severely dehydrating diarrhea where cholera is suspected or proved by dark field microscopy of the feces, or in children with blood and mucus diarrhea due to an invasive organism such as Shigella. Early return to normal nutritional intake is highly desirable both in terms of recovery from the current episode of diarrheal illness and in prevention of persistent diarrhea and malnutrition.

Figure 1. Flow chart for ORS administration and management of diarrhea in children. The WHO classification of dehydration is shown and equivalent percentage dehydration is shown. Use the reduced osmolarity ORS for children. Zinc is given in 20 mg dose daily for a period not exceeding 14 days.

References

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