BACKGROUND: Alpha-2 adrenergic agonists decrease the sympathetic tones of hemodynamic and endocrine responses to surgical stimuli. The goal of this study was to evaluate the hemodynamic and endocrinologic effects of intraoperatively administered dexmedetomidine, a highly selective alpha-2 adrenergic agonist, in patients undergoing coronary artery bypass graft surgery.

METHODS: Fifty coronary artery bypass graft patients, in a double-blind, randomized manner, received a continuous infusion of normal saline placebo or dexmedetomidine, 10 ng/kg/min for 1 hr from 5 minutes after sternotomy. All patients received standardized anesthesia. Plasma catecholamine was measured at 5 minutes after sternotomy (T1), 30 minutes after drug infusion (T2), and 30 minutes after drug cessation (T3). Heart rate, blood pressure, pulmonary artery pressure and cardiac output were monitored.

RESULTS: Compared with the placebo group, plasma norepinephrine concentrations decreased in the dexmedetomidine group Dexmedetomidine attenuated increased blood pressure on surgical stimuli and induced more hypotension.

CONCLUSIONS: The intraoperative infusion of dexmedetomidine to patients undergoing coronary artery bypass graft surgery reduced sympathetic tone and attenuated hemodynamic responses to surgical stimuli.