Hyponatremia is not induced by the administration of hypotonic fluids (half saline) during postoperative maintenance of infants with biliary atresia after sufficient diuresis is achieved

Abstract Background: In Japan, the administration of extra-hypotonic fluids (approximately 35 mEq/L of sodium) as maintenance fluid is still the mainstream practice, and there have been relatively few reports concerning maintenance intravenous fluid therapy. At our institution, since 2014, maintenance fluids containing 83 mEq/L of Na (HALF) have been administered after diuresis was achieved post-Kasai portoenterostomy for biliary atresia. We investigated whether hyponatremia is induced by the administration of half saline during postoperative maintenance of infants with biliary atresia. Methods: Patients who underwent surgery for biliary atresia at our institution were included. The serum sodium concentration ([Na]) before and after surgery and the incidence of hyponatremia were compared between the group of patients administered fluid with [Na] of 35 mEq/L (exHYPO group, 59 patients) and the group of patients administered fluid with [Na] of 83 mEq/L (HALF group, 20 patients). Results: The median age of the patients was 59 days. There were no significant differences in the background or preoperative [Na] between the two groups. There was a significant decrease in [Na] on postoperative day 3 (POD3) in the exHYPO group compared with the preoperative [Na] value in the exHYPO group and the [Na] value on POD3 in the HALF group. There were no significant differences in [Na] before and after surgery in the HALF group. The odds ratio was 21.0 and the 95% confidence interval was 3.31–130, indicating that the exHYPO group had an increased risk of hyponatremia. Conclusion: Administration of half saline as maintenance fluid can maintain [Na] during postoperative maintenance of infants with biliary atresia.