Time constant of single-twitch decay during the induction phase of neuromuscular block: a clinical study with atracurium besylate

Visual inspection of several records of the onset of neuromuscular block due to atracurium suggested that the temporal decay in the response to the first stimulus (T1) of train-of-four could be regarded as an exponential process, analogous to the distribution (alpha) phase of the drug. Retrospective analysis of 69 train-of-four tracings recorded in patients of both sexes scheduled for minor elective surgery confirmed that T1% decay is best described by an exponential function, theoretical values correlating well with the recorded values (r greater than 0.9, P less than 0.01).