Relative adrenal insufficiency in cardiopulmonary bypass surgery patients: impact on the postoperative hemodynamic status

Introduction

The objective of this study was to determine the incidence and risk factors for relative adrenal insufficiency (RAI) in cardiopulmonary bypass (CPB) patients and the impact on postoperative hemodynamic status.

Methods

A prospective cohort study was performed on elective CPB patients on a 24-bed ICU of a tertiary university hospital. RAI was defined as a rise in serum cortisol ≤ 9 μg/dl after the administration of 250 μg cosyntropin. Plasma cortisol levels were measured preoperatively, immediately before and 30 minutes, 60 minutes and 90 minutes after the administration of cosyntropin (250 μg).

Results

We included 120 from 137 consecutive patients, of whom 17 met criteria for exclusion (eight off-pump, two surgical emergencies, two with endocarditis, five corticoid dependency). We studied 84 (70%) males and 36 (30%) females. Mean age 67 ± 12 years. Plasma cortisol levels were measured pre-operatively, immediately before, 30, 60, and 90 minutes after the administration of cosyntropin and at 24 postoperative hours. The RAI (Δcortisol ≤ 9 μg/dl) incidence was 77.5%. Etomidate was the only independent risk factor associated with RAI (OR = 8.51, 95% CI = 3.09 to 23.42). RAI patients needed more vasopressor requirements just after surgery (P = 0.04), and at 4 postoperative hours (P = 0.01). Pretest and post-test plasma cortisol levels were inversely associated with maximum norepinephrine dose in the same time periods (ρ = -0.22, P = 0.02; ρ = -0.18, P = 0.05; ρ = -0.21, P = 0.02; and ρ = -0.22, P = 0.02, respectively).

Conclusion

RAI and lower cortisol levels in CPB patients induce postoperative vasopressor dependency. Use of etomidate in these patients is a modifiable risk factor for the development of RAI that should be avoided.