Etomidate, but not thiopental, decreases serum cortisol concentration in morbidly obese patients. A randomized controlled trial.

BACKGROUND The effect of etomidate administration on the adrenal cortex in obese patients is still unclear. The objective of the study was to determine the influence of a single dose of etomidate on cortisol secretion in the morbidly obese. METHODS 127 healthy patients were enrolled into the study. Data from 82 patients scheduled for elective laparoscopic surgery were analyzed. 62 of them were morbidly obese, while 20 had normal body mass. The participants were divided equally into etomidate and thiopental groups, depending on the kind of intravenous anaesthetic used for the induction of anaesthesia. Each patient's serum cortisol concentration was measured five times: on the day before surgery (sample A), two hours after the induction of anaesthesia (sample B), after a short tetracosactide test (sample C), 24 hours after the induction of anaesthesia (sample D), and after a second short stimulation test (sample E). RESULTS The mean cortisol concentration in obese patients in the etomidate group was lower two hours after the induction of anaesthesia (sample B, P < 0.001), and 30 minutes after the first tetracosactide test (sample C, P < 0.001) compared to obese patients in the thiopental group. There were no differences between the groups in sample A (P = 0.833), D (P = 0.614) and E (P = 0.769). We found no changes in haemodynamic parameters between both groups. CONCLUSIONS Etomidate decreased serum cortisol concentration and decreased reactivity to tetracosactide both in morbidly obese and in normal weight patients. This effect was reversible within 24 hours.