Effect of dexmedetomidine on the minimum alveolar concentration (MAC) of sevoflurane in adults age 55 to 70 years.
OBJECTIVE
To determine the effect of two target dexmedetomidine infusions (0.3 ng/ml and 0.6 ng/ml) on the minimal alveolar concentration (MAC) of sevoflurane in adults age 55 to 70 years.


METHODS
Prospective, randomized, placebo-controlled study.


METHODS
University-affiliated hospital.


METHODS
45 ASA physical status I and II adults, age 55 to 70 years, undergoing elective surgery with at least a 3 inch skin incision.


METHODS
Patients were given a dexmedetomidine or placebo infusion for at least 15 minutes before anesthetic induction with sevoflurane in oxygen by face mask. After tracheal intubation, a target sevoflurane concentration was maintained for 15 minutes while the dexmedetomidine or placebo infusion continued to run.


RESULTS
At the time of skin incision, two observers independently determined movement or nonmovement to the incision. Blood samples for dexmedetomidine were taken before the infusion and at the time of skin incision. The dexmedetomidine plasma concentrations were 0 before infusion with all treatment groups. At the time of incision, they were 0 in the placebo group, 0.39 +/- 0.13 ng/ml in the 0.3 ng/ml target group, and 0.7 +/- 0.13 ng/ml in the 0.6 ng/ml target group. The MAC of sevoflurane was 1.83% in the placebo group, 1.78% in the 0.3 ng/ml target dexmedetomidine group, and 1.51% in the 0.6 ng/ml target dexmedetomidine group.


CONCLUSIONS
Dexmedetomidine 0.7 ng/ml decreased the MAC of sevoflurane by 17%, whereas there was no difference between the placebo and the dexmedetomidine 0.39 ng/ml group.
Fragen
R J
RJ
Department of Anesthesiology, Northwestern University Medical School, Chicago, IL 60611, USA. rfragen@nmff.nwu.edu
Fitzgerald
P C
PC
D000316:Adrenergic alpha-Agonists / Q000097:blood / Q000494:pharmacology*; D000368:Aged; D018685:Anesthetics, Inhalation / Q000378:metabolism / Q000493:pharmacokinetics*; D020927:Dexmedetomidine / Q000097:blood / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000378:metabolism / Q000493:pharmacokinetics*; D008875:Middle Aged; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000378:metabolism*; D000077149:Sevoflurane
D000316:Adrenergic alpha-Agonists; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D020927:Dexmedetomidine