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

In 24 ASA I-II adults anaesthetized with thiopentone, fentanyl and nit rous oxide in oxygen, we studied neuromuscular transmission with isome tric 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 in fusion, when twitch height spontaneously regained 25% of its control v alue, the patients were allocated to two groups of 12 patients each. I n 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 t rain-of-four (TOF) (2 Hz) every 3 min. After 15 min, residual force af ter tetanic stimulation (50 and 100 Hz, 5-s duration (RF50(HZ), RF100( HZ)), 1 min apart) were recorded sequentially. At 15 min, mean TOF rat io 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 g reater 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) (g roup SPO), respectively). We conclude that although there was a high d egree of spontaneous recovery, administration of neostigmine-atropine accelerated the rate of recovery of neuromuscular transmission after m ivacurium and greatly increased the number of patients satisfying the criteria for complete recovery of neuromuscular transmission (TOF rati o > 0.9) within 15 min.