Effect of alfentanil on hypnotic and antinociceptive components of thiopental sodium anesthesia.
OBJECTIVE
To determine the effects of alfentanil on the hypnotic and antinociceptive components of thiopental sodium anesthesia.


METHODS
Randomized double-blind study.


METHODS
Inpatients at a university-affiliated county hospital.


METHODS
Eighty unpremedicated ASA physical status I or II female patients aged 18 to 60 years, with a weight range of 50 to 90 kg.


METHODS
Intravenous injection of thiopental sodium in doses ranging from 1.0 mg/kg to 6.0 mg/kg with or without the addition of alfentanil, 0.01 mg/kg.


RESULTS
Dose-response curves were determined for the following three endpoints of anesthesia: eye opening in the response to voice command; eye opening in the response to noxious stimulation induced by pressure on the trapezius muscle; and purposeful movement in the response to the same type of noxious stimulation. The addition of alfentanil, 0.01 mg/kg, markedly decreased thiopental ED50 values for all three endpoints: from 2.6 mg/kg to 1.9 mg/kg (p less than 0.02) for eye opening to voice command, from 3.2 mg/kg to 1.9 mg/kg (p less than 0.0005) for eye opening to noxious pressure, and from 4.2 mg/kg to 2.4 mg/kg (p less than 0.0001) for purposeful movement to noxious pressure. The alfentanil-induced increase in thiopental potency for the antinociceptive effect was greater than that for the hypnotic effect (75% vs 36%, p = 0.02).


CONCLUSIONS
Alfentanil strengthened both the hypnotic and antinociceptive components of thiopental anesthesia, although to a different degree: the antinociceptive component more so than the hypnotic, possibly because each component of anesthesia has different underlying mechanisms.
Mehta
D
D
Department of Anesthesiology, School of Medicine, University of Alabama, Birmingham 35294.
Bradley
E L
EL
Kissin
I
I
D000328:Adult; D015760:Alfentanil; D000771:Anesthesia, Intravenous; D004311:Double-Blind Method; D004357:Drug Synergism; D005260:Female; D006801:Humans; D008875:Middle Aged; D013874:Thiopental
D015760:Alfentanil; D013874:Thiopental