Relative Adrenal Insufficiency Is Not Associated With Prognosis In Patients Undergoing Cardiac Surgery

Low cortisol levels (<276 nmol/L) are regarded as relative adrenal insufficiency (RAI) and associated with adverse events in critical illness. Whether RAI affects cardiac surgery patients is unknown. In this study, serum cortisol and adrenocorticotropic hormone (ACTH) levels were prospectively examined in 90 adult patients who underwent elective cardiac surgery from April to August, 2015. RAI was defined as basal cortisol <276 nmol/L at postoperative day 1. Perioperative outcomes were recorded. It was found that the incidence of RAI was 55.56% (50/90). Patients with RAI did not show worse outcomes as compared with patients with non-RAI (P>0.05). A longer duration of surgery and higher preoperative ACTH levels were shown to significantly delay weaning (B = 0.349, P<0.001; B = 1.367, P = 0.001, respectively) and prolong time spent in the ICU (B = 0.385, P<0.001; B = 1.255, P = 0.003, respectively). Age (B = 0.245, P = 0.012) and operation duration (B = 0.058, P = 0.002) prolonged the hospitalization. Cox proportional hazards regression showed that preoperative ACTH levels and New York Heart Association class were associated with a higher rate of 48-hour ICU hospitalization (hazard rate [HR] 0.977, P = 0.034; HR 0.568, P = 0.005, respectively). These results presented here indicated that RAI after heart surgery does not lead to worse outcomes, and the cut-off value of 276 nmol/L for cortisol is not appropriate for identifying RAI in patients who underwent cardiac surgery.