A comparative study of isotonic and hypotonic intravenous maintenance fluids in hospitalised children

Abstract

Background : For almost half a century,most of the Paediatricians around the world were using hypotonic solution(0.2% saline in 5% dextrose) for maintenance fluids according to the guidelines set by Holliday and Segar .The wisdom of this approach has been questioned recently, especially in the hospitalised children who have various osmotic and non-osmotic stimuli for vasopressin release, leading to clinically symptomatic hyponatremia.We hypothesized that use of isotonic maintenance fluid (0.9% saline in 5% dextrose) would be more safer than hypotonic fluid (0.14% saline in 5% dextrose) in sick children at standard maintenance rate. Methods : This open-labelled randomized controlled trial was conducted on 125 admitted children of secondary care hospital,in the age group of 0.6 to 12 years who were anticipated to receive maintenance intravenous fluid for first 24 hours.63 were randomized to receive isotonic fluid(0.9% saline in 5% dextrose) and 62 for hypotonic fluid(0.14% saline in 5% dextrose)at standard maintenance rate by computer generated tables.Baseline investigation,serum sodium,serum potassium,blood sugar,renal function tests and those relevant to the patient illness were done. Serum osmolality was calculated at the time of enrolment and after 24 hours.Serum sodium was repeated after 24 hours of intravenous fluid therapy. All enrolled patients were monitored for signs and symptoms of sodium imbalance,signs of dehydration during first 24 hours. Results : Baseline variables were comparable in two groups. Hyponatremia at 24 hours was seen in 11(17.4%)patients in isotonic and in 29(47%)patients of hypotonic group (P=0.02).The odds ratio for developing hyponatremia in hypotonic group was 4.32(95%CI: 1.89, 9.90)as compared to isotonic group.There were 25 patients (59.5%) of respiratory tract illness who developed hyponatremia in hypotonic group as compared to 6 patients (13.9%)of isotonic group (P=0.001).At 24 hours,both mean serum sodium and mean serum osmolality were significantly lower in hypotonic group as (P=0.002) and (P=0.001) respectively Conclusion : To conclude,the type of fluid is important in deciding the incidence of hyponatremia in hospitalized children.Among the fluids,isotonic fluids are safer choice than the traditional hypotonic fluids in hospitalized children requiring maintenance fluid therapy.