Dexmedetomidine as an anesthetic adjunct in coronary artery bypass grafting.
BACKGROUND
Alpha 2-adrenergic agonists decrease sympathetic tone with ensuing attenuation of neuroendocrine and hemodynamic responses to anesthesia and surgery. The effects of dexmedetomidine, a highly specific alpha 2-adrenergic agonist, on these responses have not been reported in patients undergoing coronary artery bypass grafting.


METHODS
Eighty patients scheduled for elective coronary artery bypass grafting received, in a double-blind manner, either a saline placebo or a dexmedetomidine infusion, initially 50 ng.kg-1.min-1 for 30 min before induction of anesthesia with fentanyl, and then 7 ng.kg-1.min-1 unit the end of surgery. Filling pressures, blood pressure, and heart rate were controlled by intravenous fluid and by supplemental anesthetics and vasoactive drugs.


RESULTS
Compared with placebo, dexmedetomidine decreased plasma norepinephrine concentrations by 90%, attenuated the increase of blood pressure during anesthesia (3 vs. 24 mmHg) and surgery (2 vs. 14 mmHg), but increased slightly the need for intravenous fluid challenge (29 vs. 20 patients) and induced more hypotension during cardiopulmonary bypass (9 vs. 0 patients). Dexmedetomidine decreased the incidence of intraoperative (2 vs. 13 patients) and postoperative (5 vs. 16 patients) tachycardia. Dexmedetomidine also decreased the need for additional doses of fentanyl (3.1 vs. 5.4), the increments of enflurane (4.4 vs. 5.6), the need for beta blockers (3 vs. 11 patients), and the incidence of fentanyl-induced muscle rigidity (15 vs. 33 patients) and postoperative shivering (13 vs. 23 patients).


CONCLUSIONS
Intraoperative intravenous infusion of dexmedetomidine to patients undergoing coronary artery revascularization decreased intraoperative sympathetic tone and attenuated hyperdynamic responses to anesthesia and surgery but increased the propensity toward hypotension.
Jalonen
J
J
Department of Anesthesiology, Turku University Hospital, Finland.
Hynynen
M
M
Kuitunen
A
A
Heikkilä
H
H
Perttilä
J
J
Salmenperä
M
M
Valtonen
M
M
Aantaa
R
R
Kallio
A
A
D000759:Adjuvants, Anesthesia / Q000494:pharmacology*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000097:blood; D001026:Coronary Artery Bypass; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D020926:Medetomidine; D008875:Middle Aged; D009127:Muscle Rigidity / Q000517:prevention & control; D017202:Myocardial Ischemia / Q000517:prevention & control; D012768:Shivering / Q000187:drug effects
D000759:Adjuvants, Anesthesia; D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D007093:Imidazoles; D020926:Medetomidine