EFFECTS OF PERIOPERATIVE DEXMEDETOMIDINE INFUSION IN PATIENTS UNDERGOING VASCULAR-SURGERY

Background: Dexmedetomidine, a highly selective alpha(2)-adrenergic ag onist, increases perioperative hemodynamic stability in healthy patien ts but decreases blood pressure and heart rate. The goal of this study was to evaluate, in a preliminary manner, the hemodynamic effects of perioperatively administered dexmedetomidine in surgical patients at h igh risk for coronary artery disease. Methods: Twenty-four vascular su rgery patients received a continuous infusion of placebo or one of thr ee doses of dexmedetomidine, targeting plasma concentrations of 0.15 n g/ml (low dose), 0.30 ng/ml (medium dose), or 0.45 ng/ml (high dose) f rom 1 h before induction of anesthesia until 48 h postoperatively. All patients received standardized anesthesia and hemodynamic management. Blood pressure, heart rate, and Holter ECG were monitored; additional monitoring included continuous 12-lead ECG preoperatively, anesthetic concentrations and myocardial wall motion (echocardiography) intraope ratively, and cardiac enzymes postoperatively. Results: Preoperatively , there was a decrease in heart rate (low dose 11%, medium dose 5%, hi gh dose 20%) and systolic blood pressure (low dose 3%, medium dose 12% , high dose 20%) in patients receiving dexmedetomidine. Intraoperative ly, dexmedetomidine groups required more vasoactive medications to mai ntain hemodynamics within predetermined limits. Postoperatively, dexme detomidine groups had less tachycardia (minutes/monitored hours) than the placebo group (placebo 23 min/h; low dose 9 min/h, P = 0.006; medi um dose 0.5 min/h, P = 0.004; high dose 2.3 min/h, P = 0.004). Bradyca rdia was rare in all groups, There were no myocardial infarctions or d iscernible trends in the laboratory results. Conclusions: Infusion of dexmedetomidine up to a targeted plasma concentration of 0.45 ng/ml ap pears to benefit perioperative hemodynamic management of surgical pati ents undergoing vascular surgery but required greater intraoperative p harmacologic intervention to support blood pressure and heart rate.