COMPARISON OF NEOSTIGMINE-INDUCED RECOVERY WITH SPONTANEOUS-RECOVERY FROM MIVACURIUM-INDUCED NEUROMUSCULAR BLOCK

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-l 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 mu g kg(-1) and atropine 15 mu g 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) (2 Hz) every 3 min. After 15 min, residual force after tetanic stimulation (50 and 100 Hz, 5-s duration (RF50(HZ), RF100(HZ)), 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, RF50(HZ) and RF100(HZ) 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.