The effect of the implementation of therapeutic hypothermia on fluid balance and incidence of hyponatremia in neonates with moderate or severe hypoxic-ischaemic encephalopathy

Aim To investigate the effect of the therapeutic hypothermia (TH), used in infants with moderate or severe hypoxic-ischaemic encephalopathy (HIE), on fluid balance and incidence of hyponatremia. Methods Retrospective cohort study of moderate and severe HIE infants before (pre) and after (post) TH implementation. Daily fluid and electrolytes intake/output were collected from the medical records of each patient from day 1 to day 4 of life. Hyponatremia was defined as sodium <130 mEq/L. Results A total of 67 infants were studied: pre-TH = 29 and post-TH = 38. Infants in the post-TH group had greater weight gain [140 g (62, 227) vs. 10 g (-100, 105) p < 0.001] and lower serum sodium (130.9 ± 4.5 mmol/L vs. 133.4 ± 5.7, p = 0.008). The incidence of hyponatremia increased from 48 to 76% (p = 0.02). Conclusion In our centre, the implementation of TH was followed by an increased fluid retention and higher incidence of hyponatremia. Centres adopting TH should have clear guidelines for fluid and electrolyte management.