This investigation was carried out in healthy twenty-four pregnant women undergoing elective Caesarean section and twelve nonpregnant women of the same age group.
The premedication was performed with glycopyrrolated 0.2mg and hvdroxyzine 1mg/kg IM respectively in the nonpregnant women, and glycopyrrolate 0.2mg IM only in the pregnant women. Anesthesia was induced with Ⅳ pentothal sodium(4~5mg/kg),
vecuronium(0.08mg/kg) and ketamine(0.2mg/kg) in the nonpregnant(Group I, N=12) or pregnant women(Group Ⅱ,n=12), and pentothal sodium(4~5mg/kg), vecuronium(reducing dose of 20% from 0.08mg/kg) and ketamine(0.2mg/kg) in the pregnant women(Group
Ⅲ,
n=12)
anesthesia was maintained with 1~2% enflurane, 50% N2O, and O2. The ulnar nerve was stimulated sypramaximally at the wrist with train-of-four stimuli every 20 sec. With ABM(Datex Co.) and the electromyograbhic response of the adductor pollicis
muscle
was measured.
The onset of 50% block of first twitch height(T1) was faster in the group Ⅱ(1.33(0.36min) than in the group I(1.9(0.6 min) and group Ⅲ(1.6(0.3 min) (p<0.05).
Also, the onset of 95% block of T1 was faster in the group Ⅱ(2.5(0.5 min) and Ⅲ(1.6(0.3 min) than in the group I(3.8(0.9 min)(p<0.05).
The time of recovery of T1 to 10%, 25% and 50% of control were longer in the group Ⅱ(34.9(5.3, 43.1(7.2 and 53.3(9.1 min respectively) and Ⅲ(22.3(3.2, 29.5(4.5, 38.8(8.3 min respectively) than in the group I(21.1(4.8, 25.6(4.8 and 32.6(6.3 min
respectively)(p<0.05).
The conditions of intubation at 50% block of T1 were adequate in the group I and Ⅱbut poor in the group Ⅲ(p<0.05).
Apgar score at 1 and 5 minutes after delivery were not significantly different between group Ⅱand Ⅲ.
Conclusively, administration of vecuronium dose on body weight basis in the pregnant women resulted in a more rapid onset and prolonged recovery of neuromuscular block than in the nonpregnant women without any adverse effects. Moreover, the
conditions
of intubation was poor when the dose of vecuronium was reduced by 20% in the pregnant women.
Therefore, it is inadequate to reduce the dose of vecuronium concerning about relative overdose in the pregnant women undergoing Caesarean section.
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