Vasopressin-Induced Hyponatremia in Infants Following Cardiovascular Surgery

Vasopressin is increasingly used in infants following cardiac surgery. Hyponatremia is a noted adverse event, but incidence and risk factors remain undefined.

The primary objective was to identify the incidence of vasopressin-induced hyponatremia. Secondary objectives included comparing baseline and change in serum sodium concentrations between infants receiving vasopressin with and without hyponatremia, and comparing vasopressin dose, duration, and clinical characteristics in those with and without hyponatremia.

This Institutional Review Board-approved, retrospective case-control study included infants <6 months following cardiac surgery receiving vasopressin for ≥6 hours at a tertiary care, academic hospital. Patients who developed hyponatremia, cases, were matched to controls in a 1:2 fashion. Demographics and clinical characteristics were collected. Descriptive and inferential statistics were employed. A conditional logistic regression was used to assess odds of hyponatremia.

Of the included 142 infants, 20 (14.1%) developed hyponatremia and were matched with 40 controls. There was significant difference in median nadir between controls and cases, 142.0 versus 128.5 mEq/L (<0.001). A significantly higher number of cases received corticosteroids, loop diuretics, and chlorothiazide versus controls. The regression analysis demonstrated that each additional hour of vasopressin increased the odds of developing hyponatremia by 5% (adjusted odds ratio 1.05 [confidence interval 1-1.1]).

Vasopressin-induced hyponatremia incidence was <15%. Vasopressin duration was independently associated with hyponatremia development.