Effects of perioperative dexmedetomidine infusion in patients undergoing vascular surgery. The Study of Perioperative Ischemia Research Group.

BACKGROUND

Dexmedetomidine, a highly selective alpha 2-adrenergic agonist, increases perioperative hemodynamic stability in healthy patients 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 high risk for coronary artery disease.

METHODS

Twenty-four vascular surgery patients received a continuous infusion of placebo or one of three doses of dexmedetomidine, targeting plasma concentrations of 0.15 ng/ml (low dose), 0.30 ng/ml (medium dose), or 0.45 ng/ml (high dose) from 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) intraoperatively, and cardiac enzymes postoperatively.

RESULTS

Preoperatively, there was a decrease in heart rate (low dose 11%, medium dose 5%, high dose 20%) and systolic blood pressure (low dose 3%, medium dose 12%, high dose 20%) in patients receiving dexmedetomidine. Intraoperatively, dexmedetomidine groups required more vasoactive medications to maintain hemodynamics within predetermined limits. Postoperatively, demedetomidine groups had less tachycardia (minutes/monitored hours) than the placebo group (placebo 23 min/h; low dose 9 min/h, P = 0.006; medium dose 0.5 min/h, P = 0.004; high dose 2.3 min/h, P = 0.004). Bradycardia was rare in all groups. There were no myocardial infarctions or discernible trends in the laboratory results.

CONCLUSIONS

Infusion of dexmedetomidine up to a targeted plasma concentration of 0.45 ng/ml appears to benefit perioperative hemodynamic management of surgical patients undergoing vascular surgery but required greater intraoperative pharmacologic intervention to support blood pressure and heart rate.