Adrenocortical response in infants undergoing cardiac surgery with cardiopulmonary bypass and circulatory arrest

Objective: To detail changes in adrenocorticotropic hormone (ACTH), cortisol, and aldosterone levels following cardiac surgery and to test the hypothesis that postcardiotomy infants requiring excessively high-dose vasopressor support will demonstrate adrenal insufficiency which will be proportional to cardiopulmonary bypass (CPB)/circulatory arrest times and vasopressor requirements. Design: Prospective observational pilot study. Setting: A tertiary care pediatric cardiac intensive care unit. Patients: Prospectively enrolled infants were divided into three subgroups: CPB, CPB with deep hypothermic circulatory arrest (DHCA), and control subjects. Interventions. None. Measurements and Main Results: A representative patient sample from each surgical group underwent preoperative synthetic ACTH testing. Postoperative serum samples for cortisol, ACTH, and inotrope score (IS) were collected at discrete intervals over 48 hrs along with patient demographics, surgical procedure, and CPB/DHCA times. Fifty-eight patients were classified by subgroup: 31 CPB, 22 DHCA, and 5 controls. Ten patients with DHCA, analyzed separately, received intraoperative steroids. Tested patients demonstrated preoperative adrenal competence. Cortisol peaked within 2 hrs of surgery without differences among groups. ACTH inversely correlated with bypass time in patients with DHCA (p = .03) but not with circulatory arrest time. Peak cortisol level did not correlate with simultaneous IS. Although not noted in any DHCA-steroid patients, nine patients had increased ACTH/cortisol ratios in association with elevated ISs suggesting inadequate adrenal responsiveness to endogenous ACTH. Conclusions: The majority of infants with congenital heart disease and intact hypothalamic-pituitary-adrenal axes demonstrated an appropriate adrenocortical stress response to cardiac surgery. Peak serum cortisol was unrelated to CPB/DHCA time and did not predict the level of inotrope support. However, a subset of patients with elevated ACTH/cortisol ratios seemed to have a clinical status consistent with adrenal insufficiency and may be a target group for early postoperative steroid therapy. (Pediatr Crit Care Med 2010; 11:44-51)