The hemodynamic and adrenergic effects of perioperative dexmedetomidine infusion after vascular surgery

We tested dexmedetomidine, an alpha(2) agonist that decreases heart rate, b rood pressure, and plasma norepinephrine concentration, for its ability to attenuate stress responses during emergence from anesthesia after major vas cular operations. Patients scheduled for vascular surgery received either d exmedetomidine (n = 22) or placebo (n = 19) IV beginning 20 min before the induction of anesthesia and continuing until 48 h after the end of surgery. All patients received standardized anesthesia. Heart rate and arterial blo od pressure were kept within predetermined limits by varying anesthetic lev el and using vasoactive medications. Heart rate, arterial blood pressure, a nd inhaled anesthetic concentration were monitored continuously; additional measurements included plasma and urine catecholamines. During emergence fr om anesthesia, heart rate was slower with dexmedetomidine (73 +/- 11 bpm) t han placebo (83 +/- 20 bpm) (P = 0.006), and the percentage of time the hea rt rate was within the predetermined hemodynamic limits was more frequent w ith dexmedetomidine (P < 0.05). Plasma norepinephrine levels increased only in the placebo group and were significantly lower for the dexmedetomidine group during the immediate postoperative period (P = 0.0002). We conclude t hat dexmedetomidine attenuates increases in heart rate and plasma norepinep hrine concentrations during emergence hum anesthesia. Implications: The alp ha(2) agonist, dexmedetomidine, attenuates increases in heart rate and plas ma norepinephrine concentrations during emergence from anesthesia in vascul ar surgery patients.