Background: To identify individual factors and combination of factors predictive of reversal time (defined as time from neostigmine administration to train-of-four (TOF) ratio 0.70) from atracurium-induced neuromuscular block, the present study tested the following variables as possible predictors of reversal time: 1) degree of block at the time of antagonism as quantified by first response to TOF or double-burst stimulation (DBS); 2) time from last supplemental dose of atracurium to administration of neostigmine (pre-reversal time); and 3) time from administration of initial atracurium dose to T1 (the magnitude of the first twitch in TOF) recovered to 10% (duration of action of the initial dose of atracurium).
Methods:The study population comprised 83 female patients, ASA physical status 1 or 2, anaesthetized with fentanyl, thiopental, halothane and nitrous oxide. Initial and supplemental doses of atracurium were 0.5 mg ¡ kg ª1 and 0.15 mg ¡ kg ª1 , respectively. Evoked responses to TOF or DBS were recorded mechanomyographically. Neuromuscular block was antagonized with neostigmine, 0.07 mg ¡ kg ª1 , at varying time intervals (6-50 min) after the final atracurium dose. Results: Multiple linear regression analyses testing T1, D1 (the magnitude of the first twitch in DBS), pre-reversal time and dur-