DETERMINANTS OF CATECHOLAMINE AND CORTISOL RESPONSES TO LOWER-EXTREMITY REVASCULARIZATION

Background. Surgical trauma elicits diffuse changes in hormonal secret ion and autonomic nervous system activity. Despite studies demonstrati ng modulation of the stress response by different anesthetic/analgesic regimens, little is known regarding the determinants of catecholamine and cortisol responses to surgery. Methods: Plasma catecholamines and cortisol secretion data were obtained from 60 patients undergoing low er extremity revascularization. Patients were randomized to receive ei ther general anesthesia combined with patient-controlled intravenous m orphine (GA) or epidural anesthesia combined with epidural fentanyl an algesia (RA). All aspects of intra- and postoperative clinical care we re defined by written protocol. Plasma catecholamines were measured be fore induction, intraoperatively, and for the first 18 h postoperative ly (by HPLC). Urine cortisol was measured intra- and postoperatively u sing RIA. Data were evaluated using univariate and multivariate analys es to evaluate demographic and perioperative variables as determinants of stress hormone secretion. Results. Plasma catecholamines increased during skin closure in the GA group, and remained higher relative to the RA group in the postoperative period. Multivariate analysis indica ted that age and anesthetic regimen predicted increases in catecholami nes during skin closure (P < 0.005), although duration of surgery, blo od loss, and body temperature were not correlated. Early postoperative norepinephrine concentrations were correlated with pain score and dur ation of surgery (P < 0.004), but not with anesthetic management, bloo d loss, or body temperature. All postoperative norepinephrine levels w ere highly correlated (r = 0.7) with norepinephrine levels during skin closure. Cortisol excretion was higher postoperatively than intraoper atively. No patient or perioperative variable predicted cortisol excre tion, and cortisol excretion was not correlated with catecholamine lev els at any time. Conclusions. These data indicate that patient factors , such as age and inherent sympathetic responsivity, are important det erminants of the catecholamine response to surgery. Modulation of the norepinephrine response by regional anesthesia/analgesia appears to be related, in part, to superior analgesia. The lack of correlation betw een catecholamine and cortisol secretion indicates that the stress res ponse may consist of discrete systems responding to different stimuli.