Estimation of the effect-site equilibration rate constant using the time-to-peak effect of muscle relaxants measured by train-of-four stimulation during general anesthesia induction.

Abstract

BackgroundThe concept of the effect-site concentration of anesthetic agents is important. The effect compartment model can be explained using the concepts of effect-site concentration and effect-site equilibration rate constant (ke0). This study confirms that the time-to-peak effect (tpe) can be measured easily in clinical practice by applying a priming dose and train-of-four (TOF) during general anesthesia induction, and ke0 can be calculated from the tpe of the four muscle relaxants that are commonly used in general anesthesia.MethodsEighty patients who received general anesthesia were divided into the succinylcholine, rocuronium, atracurium, or vecuronium groups. Priming doses of muscle relaxants were administered. The effects of muscle relaxants were quantified by recording the twitch response of the adductor pollicis muscle after stimulating the ulnar nerve. The tpe was measured at the lowest TOF value. ke0 was calculated from the measured tpe.ResultsThe ke0 values of the succinylcholine, rocuronium, atracurium, and vecuronium groups were 0.076 (0.030)/min, 0.228 (0.122)/min, 0.062 (0.011)/min, and 0.077 (0.019)/min, respectively.ConclusionsIt is possible to estimate ke0 from the tpe of muscle relaxants using a priming dose and TOF during general anesthesia induction.