CALCULATION OF AN EFFECT COMPARTMENT RATE-CONSTANT USING RECOVERY INDEXES OBTAINED WITH AN ISOLATED ARM TECHNIQUE

We have examined the implications of the theoretical single pharmacoki netic compartment associated with blocker-induced paralysis, in relati on to the isolated arm technique. It is assumed that the blocker conce ntration-effect relationship can be characterized by a sigmoid curve, which incorporates an exponent, s. After tourniquet release, the conce ntration gradient between the effect compartment and plasma should be large, and elimination related to the rate constant, k(eo). The major measurement of spontaneous recovery with the isolated arm is the time interval between 75% and 25% twitch depression, T25-T75. The general e quation relating these three variables is developed: k(eo) = 2.2/(s x (T25-T75)). Insertion of published values for T25-T75 with isolated ar m studies into this equation gave estimates for an intrinsic k(eo) for atracurium, vecuronium, rocuronium and pancuronium.