Isotonic versus hypotonic saline as maintenance intravenous fluid therapy in children under 5 years of age admitted to general paediatric wards: a randomised controlled trial.

Background : To prevent the risk of iatrogenic hyponatraemia in hospitalised children, isotonic fluid has been recommended as maintenance intravenous fluid (IVF). There are few studies which compare half normal saline with normal saline as maintenance IVF in general paediatric wards. Aim : To compare the safety and efficacy of half normal saline with normal saline as maintenance IVF in general paediatric wards. Methods : Children aged between 3 months and 5 years with an anticipated requirement for IVF for 24 h were randomised to receive either half normal saline (0.45% saline in 5% dextrose) or normal saline (0.9% saline in 5% dextrose). The primary objective was to compare the incidence of hyponatraemia (serum sodium <135 mmol/L with a decrease from baseline of at least 4 mmol/L) at 24 h in children receiving half normal saline with those receiving normal saline. Secondary objectives were to compare the incidence of moderate (sodium <130 mmol/L), severe (sodium <125 mmol/L) and symptomatic hyponatraemia, change in serum sodium level from baseline and the incidence of hypernatraemia. Results : A total of 168 children were randomised to receive either normal saline ( n = 84) or half normal saline ( n = 84). More than two-thirds of the children were suffering from respiratory diseases (pneumonia and bronchiolitis) and diseases of the nervous system (meningoencephalitis, febrile seizures and epilepsy). The incidence of hyponatraemia at 12 h in children receiving half normal saline was similar to that in those receiving normal saline (6 vs 4.8%; Relative risk (RR) 1.2; 95% CI 0.3.0-4.8; p = 0.73). Although the incidence of hyponatraemia at 24 h in children receiving half normal saline was higher than in those receiving normal saline, the difference was not statistically significant (14.3 vs 6%; RR 2.6; 95% CI 0.9-7.8; p = 0.07). One child in the isotonic group and one in the hypotonic group developed moderate and severe hyponatraemia, respectively. There was no significant difference in the incidence of hypernatraemia between two groups (RR 0.7; 95% CI 0.16-3.3). Conclusion : Half-normal saline as maintenance IVF does not result in a significantly increased risk of hyponatraemia in general paediatric ward patients under 5 years of age.