Incidence of hyponatraemia and hyponatraemic seizures in severe respiratory syncytial virus bronchiolitis

TLDR

Hyponatraemia is a frequent electrolyte disturbance in infants with RSV bronchiolitis requiring intensive care. The study aimed to document the incidence and early evolution of hyponatraemia in this population. A retrospective review of two winter seasons examined 91 infants after excluding those with pre‑existing risk factors for hyponatraemia. Among these infants, 33 % presented with hyponatraemia (11 % severe), but aggressive fluid restriction and diuretics reduced the 48‑hour incidence to 3.3 %, and 4 % experienced seizures that resolved with hypertonic saline and fluid restriction, underscoring the need for tailored fluid management to prevent neurological complications.

Abstract

Aim : To document the incidence and early evolution of hyponatraemia (serum sodium <136 mmol 1 −1 ) associated with respiratory syncytial virus (RSV) bronchiolitis in infants requiring intensive care. Methods : In a retrospective review over two winter seasons, 130 infants were admitted with confirmed RSV infection, of whom 39 were excluded because of either pre‐existing risk factors for hyponatraemia: diuretic therapy ( n = 14), cardiac disease ( n = 10), renal disease ( n = 2) or lack of admission sodium data ( n = 13). Results : The incidence of admission hyponatraemia in the remaining infants (median age 6 wk) was 33% (30/91), with 11% (10/91) exhibiting a serum sodium less than 130 mmol 1 −1 . Hyponatraemic and normonatraemic infants were of a similar age (median 6 vs 7 wk, p = 0.82). With fluid restriction and diuretic therapy, the incidence of hyponatraemia at 48 h had decreased to 3.3%, odds ratio 0.07 (95% confidence interval 0.02–0.24, p < 0.001). Four infants (4%) suffered hyponatraemic seizures at admission (sodium 114–123 mmol 1 −1 ); three had received hypotonic intravenous fluids at 100–150 ml kg −1 d −1 before referral to intensive care. All four were managed successfully with hypertonic (3%) saline, followed by fluid restriction, resulting in immediate termination of seizure activity and normalization of serum sodium values over 48 h. Conclusion : Hyponatraemia is common among infants with RSV bronchiolitis presenting to intensive care. Neurological complications may occur and fluid therapy in vulnerable infants should be tailored to reduce this risk.