# Hyponatremia is not induced by postoperative hypotonic fluids in infants with biliary atresia after sufficient diuresis

## TL;DR

This study shows that using half saline fluids after surgery for biliary atresia in infants helps avoid low sodium levels compared to lower sodium fluids.

## Contribution

The study demonstrates that half saline fluids prevent hyponatremia in infants post-Kasai surgery for biliary atresia.

## Key findings

- The exHYPO group showed a significant decrease in serum sodium on postoperative day 3.
- The HALF group maintained stable serum sodium levels before and after surgery.
- The exHYPO group had a 21-fold higher risk of hyponatremia.

## Abstract

In Japan, the administration of extra‐hypotonic fluids (approximately 35 mmol/L of sodium) as maintenance fluid is still the mainstream practice, and there have been relatively few reports on maintenance intravenous fluid therapy. Since 2014, our institution has administered maintenance fluids containing 83 mmol/L of Na (HALF) after diuresis is achieved post‐Kasai portoenterostomy for biliary atresia (BA). We investigated whether hyponatremia is induced by the administration of half saline during postoperative maintenance of infants with BA.

Patients who underwent surgery for BA at our institution were included. The serum sodium concentration ([Na]) before and after surgery and the incidence of hyponatremia were compared between patients administered fluids with [Na] of 35 mmol/L (exHYPO group, 59 patients) and those with [Na] of 83 mmol/L (HALF group, 20 patients).

The median age of patients was 59 days. There were no significant differences in the background or preoperative [Na] between 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.

Administration of half saline as maintenance fluid can maintain [Na] levels during postoperative care of infants with BA.