Hemodynamic correlates of serum cortisol in neonates after cardiopulmonary bypass

To document preoperative and early postoperative serum cortisol levels among a group of neonates with complex congenital heart disease undergoing cardiopulmonary bypass surgery and to describe the relationship between serum cortisol and hemodynamic variables in the early postoperative period.

Prospective observational substudy conducted within a randomized controlled trial.

Tertiary-care pediatric cardiac intensive care unit.

: We consecutively enrolled neonates undergoing a modified Norwood procedure or repair of interrupted aortic arch with ventricular septal defect in a randomized, placebo-controlled trial of triiodothyronine replacement. Methylprednisolone (30 mg/kg intravenously) was administered at anesthetic induction.

We measured serum cortisol preoperatively and at 24 and 48 hrs postoperatively. Atrial filling pressures were documented 24 and 48 hrs after surgery. Oxygen consumption was measured and cardiac index was calculated 48 hrs after surgery. Spearman's correlation and linear regression were used to examine the relationship between serum cortisol and postoperative variables. Thirty-eight patients met eligibility criteria. Median serum cortisol levels 24 and 48 hrs postoperatively were 5.0 μg/dL (range 0.4-74.0) and 4.0 μg/dL (range 0.3-17.0), respectively (p = not significant). Greater atrial filling pressures were correlated with higher serum cortisol levels 24 hrs (r = .42, p = .019) and 48 hrs (r = .46, p = .022) after surgery. A lower cardiac index was correlated with higher serum cortisol levels 48 hrs postoperatively (r = -.49, p = .039), and this relationship remained significant after controlling for inotrope score, treatment with triiodothyronine, and atrial filling pressure in bivariate models. Systolic and diastolic BP did not correlate with serum cortisol at 24 or 48 hrs.

Serum cortisol levels were low in the majority of subjects, although a wide range was observed. Higher cortisol levels were associated with greater atrial filling pressures and a lower cardiac index. The relationship between serum cortisol and cardiovascular performance after cardiopulmonary bypass in infants warrants further evaluation.