Relative Adrenal Insufficiency Is Associated With Prolonged Postoperative Hemodynamic Instability

Abstract

Background: We assessed the hypothesis that a significant proportion of patients undergoing cardiac surgery have postoperative relative adrenal insufficiency (RAI), and that this puts them at higher risk of persistent hemodynamic instability.

Methods: A prospective study included 135 patients who underwent cardiac surgery using cardiopulmonary bypass between July 2006 and December 2007. Adrenal function was assessed 36 hours after surgery using a 1-μg cosyntropin (adrenocorticotropic hormone [ACTH]) stimulation test. Relative adrenal insufficiency was defined as a peak cortisol level inferior to 500 nmol/L or an increase in cortisol of less than 250 nmol/L, or both, compared with baseline. The primary endpoint was hemodynamic instability at 48 hours after surgery, defined as persistent requirement for any vasoactive drug. The secondary endpoint was long-term survival.

Results: Postoperative RAI was diagnosed in 75 patients (56%). Compared with patients who showed a normal response to the ACTH stimulation test, patients with RAI had significantly higher rates of hemodynamic instability at 48 hours (40% versus 22%, p = 0.03). On multivariable analysis, adrenal response to the ACTH test was a significant independent predictor of hemodynamic instability at 48 hours after surgery (odds ratio 1.06 [95% confidence interval: 1.02 to 1.11] per 10 nmol/L cortisol decrease; p = 0.002). At a mean follow-up of 8.3 ± 2.8 years, patients without perioperative RAI had survival equivalent to that of the general population, whereas patients with RAI had lower than expected survival.

Conclusions: Postoperative RAI is common among patients undergoing cardiac surgery and is associated with an increased risk of persistent hemodynamic instability.