Comparison of neostigmine-induced recovery with spontaneous recovery from mivacurium-induced neuromuscular block

Abstract

In 24 ASA I-II adults anaesthetized with thiopentone, fentanyl and nitrous oxide in oxygen, we studied neuromuscular transmission with isometric adductor pollicis monitoring. Patients received mivacurium 0.2 mg kg-1 followed by an infusion lasting at least 60 min and adjusted to maintain twitch height at 1-5%. After termination of the mivacurium infusion, when twitch height spontaneously regained 25% of its control value, the patients were allocated to two groups of 12 patients each. In group NEO patients received neostigmine 40 μg kg-1 and atropine 15 μg kg-1 and in group SPO neuromuscular transmission was allowed to recover spontaneously. Twitch height was measured every 10 s and train-of-four (TOF) (2Hz) every 3 min. After 15 min, residual force after tetanic stimulation (50 and 100 Hz, 5-s duration (RF50HZ, RF100Hz), 1 min apart) were recorded sequentially. At 15 min, mean TOF ratio was greater in group NEO (0.94 (SEM 0.01)) than in group SPO (0.87 (0.02)) (P < 0.01). All patients in group NEO recovered to a TOF ratio greater than 0.7 after 6 min compared with 15 min in group SPO (P < 0.005). A TOF ratio greater than 0.9 was observed in all patients in group NEO compared with only six in group SPO (P < 0.025). Nevertheless, RF50HZ and RF100HZ did not differ significantly (0.92 (0.01) (group NEO), 0.91 (0.01) (group SPO) and 0.83 (0.02) (group NEO), 0.78 (0.03) (group SPO), respectively). We conclude that although there was a high degree of spontaneous recovery, administration of neostigmine-atropine accelerated the rate of recovery of neuromuscular transmission after mivacurium and greatly increased the number of patients satisfying the criteria for complete recovery of neuromuscular transmission (TOF ratio < 0.9) within 15 min. © 1994 British Journal of Anaesthesia.