EFFECTS OF EXTRADURAL ANESTHESIA ON INTERLEUKIN-6 AND ACUTE-PHASE RESPONSE TO SURGERY

Serum concentrations of the cytokine, interleukin-6 (IL-6), increase after surgical trauma. lL-6 mediates She synthesis of acute phase proteins and stimulates secretion of pituitary hormones. We have examined the time course of circulating lL-6, and cortisol and growth hormone responses in patients undergoing hysterectomy to determine if lL-6 contributes to the early pituitary hormone changes found during surgery. One group (n = 8) received a standardized general anaesthetic while the remaining patients (n = 8) received extradural analgesia to T4-S5 in addition to a similar general anaesthetic. in the general anaesthesia group, there was a significant increase in serum cortisol and growth hormone concentrations before any changes in lL-6 were detected. Furthermore, in the extradural group, in whom these hormonal responses were attenuated circulating lL-6 concentrations did not differ significantly from the general anaesthesia group. There were no significant differences between the groups in the acute phase response, as measured by circulating concentrations of C-reactive protein and zinc, but the expected effects of extradural block on circulating metabolites and white cell count were demonstrated. We conclude that IL-6 is unlikely to contribute to the initial increases in secretion of pituitary hormones found during surgery, but a later effect of the cytokine on endocrine responses cannot be excluded.