DOSE-RESPONSE EFFECTS OF INTRAVENOUS CLONIDINE ON STRESS-RESPONSE DURING INDUCTION OF ANESTHESIA IN CORONARY-ARTERY BYPASS GRAFT PATIENTS

This study was designed to evaluate the dose-response effects of different doses of clonidine on the stress response to laryngoscopy and endotracheal intubation. In a randomized, double-blind study, 48 coronary artery bypass grafting (CABG) patients received 0, 2, 4, or 6 mu g/kg clonidine as an intravenous (IV) infusion during a 15-min period 30 min prior to induction of anesthesia with etomidate (0.3 mg/kg), fentanyl (5-7 mu g/kg), and pancuronium (0.1 mg/kg). Sedation was assessed prior to induction of anesthesia. Cardiovascular variables and catecholamine plasma levels were measured at predefined intervals. Additional bolus doses of etomidate and fentanyl for suppression of stress-induced reactions were administered if predefined limits of heart rate and blood pressure were exceeded. Clonidine 4 and 6 mu g/kg significantly attenuated hemodynamic and adrenergic reactions to stress, reduced pharmacologic interventions, and increased sedation. However, clonidine 6 mu g/kg was not more effective than 1 mu g/kg, and clonidine 2 mu g/kg was equally effective as placebo. We conclude that clonidine 4 mu g/kg IV is the appropriate dose to attenuate the stress response to laryngoscopy in CABG patients. Side effects limiting the use of IV clonidine were not observed.