ORS - WHICH ONE TO USE?
Professor of Gastroenterology
Department of Gastrointestinal Sciences, Christian Medical College & Hospital, Vellore 632004, India.
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.
Table 2: A summary of the meta-analysis of trials with reduced osmolarity ORS in children with diarrhea. 15 trials involving 2397 patients were analyzed (Hahn et al, 2001).
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)
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