The immune-endocrine interaction varies with the duration of the inflammatory process in cardiac surgery patients

The present study investigated the perioperative course of cytokine release and hypothalamic-pituitary-adrenal (HPA) axis activation in relation to th e duration of the inflammatory response in cardiac surgery patients. Twelve male patients scheduled for elective coronary artery bypass grafting surge ry with cardiopulmonary bypass and general anaesthesia were divided into tw o study groups: group 1 (n = 6) underwent surgery at 13.00 h +/- 30 min, gr oup 2 (n = 6) at 08.30 h +/- 50 min. Blood samples were collected preoperat ively and up to the first postoperative day. Postoperatively, on the day of surgery, serum concentrations of the proinflammatory cytokines interleukin (IL)-6, IL-1 beta and tumour necrosis factor (TNF)-alpha were not signific antly different between the two groups, while blood concentrations of corti sol, adrenocorticotrophic hormone (ACTH) and beta-endorphin in group 2 pati ents were significantly higher than in group 1 patients. Postoperatively, o n the day of surgery, ACTH and cortisol concentrations in group 1 patients were positively correlated to the blood concentrations of IL-1 beta, IL-6 a nd TNF-alpha. By contrast, group 2 patients showed no significant relations hip between cytokine release and activation of HPA axis at this time. Our r esults suggest that in patients undergoing cardiac surgery, the cytokine re sponse is initiated before the HPA axis is fully activated. In the early po stoperative period, cytokines appear to be involved in the activation of th e HPA axis, while in the later postoperative period, high cortisol concentr ations may inhibit the release of IL-6.