• D Mehta, E L Bradley, and I Kissin.
• Department of Anesthesiology, School of Medicine, University of Alabama, Birmingham 35294.
• J Clin Anesth. 1991 Jul 1; 3 (4): 280-4.

Study ObjectiveTo determine the effects of alfentanil on the hypnotic and antinociceptive components of thiopental sodium anesthesia.DesignRandomized double-blind study.SettingInpatients at a university-affiliated county hospital.PatientsEighty unpremedicated ASA physical status I or II female patients aged 18 to 60 years, with a weight range of 50 to 90 kg.InterventionsIntravenous 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.Measurements And Main ResultsDose-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).ConclusionsAlfentanil 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.

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