OBJECTIVETo investigate the relationship between the circadian rhythm of perioperative cortisol secretion and neuropsychological states in patients undergoing coronary artery bypass grafting surgery.

METHODSForty male patients scheduled for elective coronary artery bypass grafting (CABG) under hypothermic cardio-pulmonary bypass (CPB) or off-pump were enrolled in this study. They were allocated into CPB group or off-pump group with 20 patients in each group. Blood samples were withdrawn during surgery at specific time-points and every 3 h for 24 h in the immediate postoperative period. Plasma cortisol was measured by radioimmunoassay. All subjects were investigated preoperatively as well as 7 to 10 d and 3 months postoperatively with a comprehensive neuropsychologic assessment, while depression and anxiety were assessed by Self-Rating Depression Scale and the State-Trait Anxiety Inventory respectively.

RESULTSDuring postoperative 24 h, three patients in the CPB group and 7 patients in the off-pump group were demonstrating a circadian secretion pattern, while they were disturbed in the remaining patients in both groups. Postoperative depression scores of patients in both groups were significantly higher than preoperative values. Postoperative anxiety scores of patients in the CPB group were significantly higher than those in the off-pump group. The CABG with CPB patients showed a significant deficit in the Digit Span subtest of the WAIS-R and the Stroop colour word interference test. The disturbed cortisol circadian secretion in the CPB group correlated with depression and the Stroop colour word interference test, whereas in the off-pump group it correlated with depression, Digit Span subtest (forward), symbol digit modalities test and the Stroop colour word interference test. Degree of depression correlated with some items of cognitive dysfunctions.

CONCLUSIONPerioperative secretion rhythm of cortisol in patients undergoing CABG surgery with CPB or off-pump was disturbed. The disordered cortisol may correlate directly or indirectly through mood with neuropsychological deficits.