Hyponatremia during arginine vasopressin therapy in children following cardiac surgery.

OBJECTIVE: To describe the incidence and severity of hyponatremia after initiation of arginine vasopressin therapy in children recovering from cardiothoracic surgery, and to compare these patients with a control group with similar disease complexity and severity who did not receive arginine vasopressin.
DESIGN: Retrospective chart review.
SETTING: PICU at a tertiary care university hospital. PATIENTS: Twenty-nine patients who received arginine vasopressin for at least 6 hours during the first 48 postoperative hours following cardiothoracic surgery were compared with 47 patients who did not receive arginine vasopressin. After surgery, all patients received intravenous fluids consisting of dextrose and 0.22% saline for daily fluid requirements as well as isotonic colloid and blood products as needed for additional resuscitation.
RESULTS: Mean initial postoperative serum sodium did not differ between groups, 144.6 ± 3.4 in those patients who received arginine vasopressin and 144.5 ± 3.7 in those who did not, p = 0.969. Mean lowest sodium in the first 72 hours, however, was 134.7 ± 3.8 in those who received arginine vasopressin as compared with 137.1 ± 4.3 in the control group, p = 0.019. Hyponatremia occurred in 14 of the patients (48%) who received arginine vasopressin but only in 8 of the patients (17%) in the control group, p = 0.004. Mean age, weight, sex, Aristotle score, and duration of cardiopulmonary bypass were not statistically different between groups. Mean volumes of hypotonic fluids administered and cumulative diuretic dosing during the first 72 hours post-surgery were also not statistically different between groups.
CONCLUSIONS: Hyponatremia occurred in nearly half of the infants and children receiving arginine vasopressin therapy in this study. Clinicians should be aware of this association, monitor serum sodium values closely, and consider providing less free water to these patients before hyponatremia occurs.