Postoperative hyponatremia in neonates with esophageal atresia and tracheoesophageal fistula receiving restricted hypotonic fluids.

Background: During the postoperative course following neonatal surgery, several stimuli like respiratory distress, pain, and stress cause the release of the antidiuretic hormone which can induce hyponatremia. This hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH) in neonates can lead to neurologic impairment and in severe cases can cause significant morbidity and mortality. Lung involvement in neonates undergoing TEF makes this subset of patients vulnerable to this entity because most of them are sick and require ventilation in the postoperative period. The incidence of postoperative hyponatremia following neonatal surgery has not been studied vastly. To the best of our knowledge, this is the first prospective study that has analyzed the incidence of postoperative hyponatremia in this vulnerable population. Methods: Prospective observational study to assess the incidence of postoperative hyponatremia in neonates with esophageal atresia and tracheoesophageal fistula (EA and TEF) receiving restricted hypotonic fluids. As per the unit policy N/4 5% D is given in the postoperative period. Most neonatal units follow a protocol in which fluid is hiked daily to reach 150 ml/kg/day in 5-7 days. However, in our neonatal surgical unit a protocol to restrict the maintenance fluid at 100 ml/kg/day irrespective of day of life is followed. Results: Out of a total of 90 neonates (270 sodium measurements), we identified 16 with hyponatremia (11%). Most of the neonates had mild hyponatremia(130-135 meq/l). The incidence of moderate and severe hyponatremia was low. Conclusion: Postoperative restriction of fluids especially in neonates who are at a high risk for developing SIADH can lead to decreased incidence of severe hyponatremia.