A Comparison of Recovery from Mivacurium during Enflurane or Propofol Anesthesia in Children

Ahn, Mi Jung; Lee, Mi Jeong; Son, Soo Chang; Choi, Sae Jin

Abstract

BACKGROUND: Mivacurium is a new, short acting, nondepolarizing muscle relaxant of the benzylisoquinolinium type. Enflurane produces relaxation and augments the neuromuscular blockade from muscle relaxation, but propofol does not produce muscle relaxation. We compared maintenance infusion rates, recovery index and correlations of recovery index to maintenance infusion rates and infusion duration after mivacurium during enflurane or propofol anesthesia in children.
METHODS
Maintenance infusion rates, and the recovery index after mivacurium were studied in 30 pediatric patients in enflurane anesthesia (n = 15) and propofol anesthesia (n = 15). The ulnar nerve was stimulated at the wrist by repeated single twitch (1Hz) stimulus using the peripheral nerve stimulator (Model ST5 MaxiStimTM, Life-Tech , Inc, Texas, USA). We recorded the contraction of adductor pollicis longus via mechanomyography (MYOTRACE, Life-Tech, Inc, Texas, USA).
RESULTS
The infusion rates of mivacurium for the maintenance of muscle relaxation (below 10% of control) were 9.6 0.80 microgram/kg/min in the enflurane anesthesia, and 11.04 1.22 microgram/kg/min in the propofol anesthesia. There was a significant difference between the groups. The recovery index was shorter in the propofol anesthesia, but regarding this index, there was no significant difference between both groups. The correlation between the recovery index and the infusion duration was significantly different in the enflurane anesthesia.
CONCLUSIONS
We conclude that maintenance infusion rates are significantly lower in the enflurane anesthesia, the recovery index is insignificantly shorter in the propofol anesthesia, that there is a significant correlation between the maintenance infusion rates and recovery index in the enflurane anesthesia.