EDROPHONIUM ANTAGONISM OF INTENSE MIVACURIUM-INDUCED NEUROMUSCULAR BLOCK IN CHILDREN

We have studied the time course of recovery after administration of ed rophonium during intense mivacurium block in children aged 2-10 yr, us ing thumb acceleration in response to train-of-four (TOF) stimulation. Forty-three children receiving alfentanil, propofol, nitrous oxide, i soflurane anaesthesia and mivacurium 0.2 mg kg(-1) were allocated rand omly to one of three groups. Patients in group 1 (n = 15) received edr ophonium 1 mg kg(-1), 2 min after maximum block (intense block group). At the time of administration of edrophonium in this group, there was no response to TOF stimulation (100% block) and the post-tetanic coun t was 10.7 (range 0-20). Patients in group 2 received the same dose of edrophonium after 10% recovery of the first twitch (T1) in the TOF (c onventional reversal). Patients in group 3 (n = 13) recovered spontane ously. All patients developed complete suppression of twitch height in response to the bolus dose of mivacurium. All recovery times were mea sured from the point of maximum block after mivacurium. Mean time for 25% recovery of T1 (clinical duration) was 3.8 (SD 1.1) min in the int ense block group. This was significantly shorter than the conventional reversal (8.3 (2.4) min) and spontaneous recovery (9.2 (3.5) min) gro ups (P < 0.001). The times for 75% and 90% recovery of T1 were shorter in the intense block group (9.4 (2.8), 12.3 (4.2) min) compared with the conventional (13.1 (3.8), 17.3 (4.8) min) and spontaneous recovery (14.9 (4.5), 17.9 (5.2) min) groups (P < 0.01). Total recovery time r equired for 70% recovery of the TOF ratio (T4/T1) was 8.8 (2.4) min in the intense block group. This was significantly shorter than the conv entional reversal (11.9 (3.2) min) and spontaneous recovery (17.1 grou ps (P < 0.001). Conventional reversal was associated with a shorter to tal recovery time compared with spontaneous recovery (P < 0.01). The r ecovery index (time interval between T1 25% and 75%) was comparable in groups 1-3 (5.5 (2.0), 4.8 (2.1) and 5.7 (1.4) min respectively). Ten minutes after development of maximum block, the numbers of patients w ho recovered adequately (TOF ratio 70% or more) were, respectively, 12 (80%), 8 (53%) and 1 (8%) in groups 1-3. We conclude that edrophonium antagonized intense (no response to TOF stimulation) mivacurium-induc ed block in children, with significant reduction in the recovery times of T1 and TOF ratio compared with conventional reversal and spontaneo us recovery.