British Journal of Anaesthesia, Vol 75, Issue 1 109-112, Copyright © 1995 by The Board of Management and Trustees of the British Journal of Anaesthesia
C. A. Shanks, M. J. Avram, T. C. Krejcie and T. K. Henthorn
We have examined the implications of the theoretical single pharmacokinetic
compartment associated with blocker-induced paralysis, in relation to the
isolated arm technique. It is assumed that the blocker concentration-effect
relationship can be characterized by a sigmoid curve, which incorporates an
exponent, s. After tourniquet release, the concentration gradient between
the effect compartment and plasma should be large, and elimination related
to the rate constant, keo. The major measurement of spontaneous recovery
with the isolated arm is the time interval between 75% and 25% twitch
depression, T25- T75. The general equation relating these three variables
is developed: keo = 2.2/(s x (T25-T75)). Insertion of published values for
T25-T75 with isolated arm studies into this equation gave estimates for an
intrinsic keo for atracurium, vecuronium, rocuronium and pancuronium.
COMMENTARY
Calculation of an effect compartment rate constant using recovery indices obtained with an isolated arm technique
Northwestern University Medical School, Department of Anesthesia, Ward Building, 12-189, 303E Chicago Avenue, Chicago, IL 60611, USA
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