Comparison of isotonic and hypotonic intravenous maintenance fluids: a randomized clinical trial.

IMPORTANCE Use of hypotonic intravenous fluids for maintenance requirements is associated with increased risk of hyponatremia that results in morbidity and mortality in children. Clinical trial data comparing isotonic and hypotonic maintenance fluids in nonsurgical hospitalized pediatric patients outside intensive care units are lacking. OBJECTIVE To compare isotonic (sodium chloride, 0.9%, and dextrose, 5%) with hypotonic (sodium chloride, 0.45%, and dextrose, 5%) intravenous maintenance fluids in a hospitalized general pediatric population. DESIGN, SETTING, AND PARTICIPANTS In this double-blind randomized clinical trial,we recruited 110 children admitted to a general pediatric unit of a tertiary care children's hospital from March 1, 2008, through August 31, 2012 (age range, 1 month to 18 years), with normal baseline serum sodium levels who were anticipated to require intravenous maintenance fluids for 48 hours or longer (intent-to-treat analyses). Children with diagnoses that required specific fluid tonicity and volumes were excluded. INTERVENTIONS Patients were randomized to receive isotonic or hypotonic intravenous fluid at maintenance rates for 48 hours. MAIN OUTCOMES AND MEASURES The primary outcome was mean serum sodium level at 48 hours. The secondary outcomes were mean sodium level at 24 hours, hyponatremia and hypernatremia, weight gain, hypertension, and edema. Confounding variables were included in multiple regression models. Post hoc analyses included change from baseline sodium level at 24 and 48 hours and subgroup analysis of children with primary respiratory diagnosis. RESULTS Of 110 enrolled patients, 54 received isotonic fluids and 56 received hypotonic fluids. The mean (SD) sodium level at 48 hours was 139.9 (2.7) mEq/L in the isotonic group and 139.6 (2.6) mEq/L in the hypotonic group (95% CI of the difference, -0.94 to 1.74 mEq/L; P = .60). Two patients in the hypotonic group developed hyponatremia, 1 in each group developed hypernatremia, 2 in each group developed hypertension, and 2 in the isotonic group developed edema. Mean (SD) change from baseline to 48-hour sodium level was +1.3 (2.9) vs -0.12 (2.8) mEq/L, respectively (absolute difference, 1.4 mEq/L; 95% CI of the difference, -0.01 to 2.8 mEq/L; P = .05). CONCLUSIONS AND RELEVANCE Our study results support the notion that isotonic maintenance fluid administration is safe in general pediatric patients and may result in fewer cases of hyponatremia. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00632775.