EFFECT OF ORAL CLONIDINE PREMEDICATION ON ANESTHETIC REQUIREMENT, HORMONAL RESPONSE, HEMODYNAMICS, AND RECOVERY IN CORONARY-ARTERY BYPASS GRAFT-SURGERY PATIENTS

Study Objective: To examine how premedication with clonidine affects o pioid use, hemodynamic effects, hormonal responses, and recovery effec ts. Design: Double-blind, placebo-controlled study. Setting: Operating room and surgical intensive care unit of a university medical center. Patients: 54 patients undergoing elective coronary artery bypass graf t (CABG) surgery. Interventions: Patients received approximately 5 mu g/kg of oral clonidine or a placebo together with 40 mu g/kg lorazepam 90 minutes pries to titrated sufentanil induction of anesthesia. Thir ty minutes prior to cardiopulmonary bypass, a second dose of either ap proximately 5 mu g/kg clonidine or placebo runs given as a slurry via a nasogastric tube. Measurements and Main Results: Opioid use, hemodyn amic effects, hormonal responses, and recovery effects were recorded. Values for ten hemodynamic variables were compiled on the evening prio r to surgery, prior to Induction, and during seven additional events a nd compared. Catecholamines and beta-endorphins were measured prior to induction, after intubation, and after sternotomy. The amount of sufe ntanil used for induction, maintenance, and total opioid were compared . The times to awakening and response to verbal commands were compared . The two groups exhibited similar patient demographics, cardiopulmona ry bypass time, and duration of surgery. Patients receiving clonidine required significantly (p < 0.04) less sufentanil for indiction (cloni dine: 2.19 +/- 0.95 mu g/kg vs. placebo: 2.93 +/- 1.07 mu g/kg) and to tal amount of sufentanil (clonidine: 9.1 +/- 3.9 mu g/kg vs. placebo. 11.7 +/- 4.6 mu g/kg). Patients receiving clonidine required significa ntly (p < 0.01) less isoflurane (9.7 +/- 6.8 MAC min vs. 19.7 +/- 9 MA C min) to maintain heart rate (HR) and mean arterial pressure (MAP) to within 15% of baseline without significant differences in other vasoa ctive drugs. Catecholamine concentrations were significantly (p < 0.02 ) lower in patients receiving clonidine without any difference in beta -endorphin concentrations. Patients receiving clonidine had significan tly (p < 0.02) lower HR, systolic arterial pressure, MAP, and systemic vascular resistance prior to induction than patients receiving placeb o without differences in other hemodynamic variables. Conclusion: Clon idine decreases opioid use and lowers hormonal response while maintain ing stable hemodynamics in patients undergoing CABG with sufentanil an esthesia.