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Nociception, hemodynamics and endocrine responses during surgery are attenuated or modified by anesthesia. We studied the effects of adding a single bolus of sodium thiopental to continuous infusion of low-dose fentanyl, on plasma beta-endorphin (iBE) immunoresponses to cardiopulmonary bypass (CPB) in patients undergoing elective coronary artery bypass grafting(CABG) or valve procedures. All patients received a uniform anesthetic induction regimen with feneanyl, vecuronium and isoflurane, and had a similar anesthetic regimens for maintenance including continuous infusion of low dose fentanyl(2 microgram/kg/hr), intraoperatively. The compositions of the CPB prime, oxygenator, cardioplegia, perfusion flow rates, and cooling procedure for hypothermia, were also standardized in all patients. Sodium thiopental(500 mg) was injected just prior to declamping of venous cannula to initiate CPB in the thiopental group. The iBE levels and the hemodynamic indices were measured prebypass, and again at 30 minutes(min) and 60 min after initiation of CPB. After initiation of CPB, iBE levels increased at 30 min(P=0.006), and 60 min(P=0.004) in the control group(n=14), but not in the thiopental group(n=14). The changes of iBE levels were significantly different in both groups(F=8.7, P=0.001). The hemodynamic indices were similar in both groups. The results of this study, no changes of iBE levels in thiopental group during CPB, suggest that the prophylactic use of sodium thiopental prior to initiation of bypass could prevent CPB-induced beta-endorphin responses. 1. Carr DB, et al: Quantitative relationships between plasma beta-endorphin immunoactivity and hemodynamic performance in preoperative cardiac surgical patients, Anesth Analg 1989;68:77-82.
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