The Effect of Using Sevoflurane for Cesarean Section on the Bispectral Index (BIS) and on Neonates

Abstract

Background: In case of inhalational anesthesia for cesarean section, there is a high risk of recall, and the bispectral index (BIS) is useful for measuring the depth of anesthesia. Sevoflurane has advantages in terms of rapid induction and emergence from anesthesia. This study was designed to determine optimal end-tidal concentrations of sevoflurane and BIS values during cesarean section. Methods: We randomized 30 patients scheduled for elective cesarean section to receive end-tidal sevoflurane 0.8 vol% (Group 1, n = 10), end-tidal sevoflurane 1.0 vol% (Group 2, n = 10), or end-tidal sevoflurane 1.2 vol% (Group 3, n = 10) in a 50% nitrous oxide oxygen mixture until delivery. Each group was assessed for BIS, blood pressure, and heart rate at preinduction, intubation, and at 2 and 4 minutes after intubation and delivery. Neonatal effect was assessed by Apgar score at 1and 5 minutes and blood gas analysis of the umbilical artery and vein. Results: The BIS of group 3 was lower than 70 on each occasion and most of BISs of the other groups wear also more than 70. The BIS of group 3 was lower than that of group 2 at 4 min after intubation and the BIS of group 3 was lower than that of group 1 at delivery (P ＜ 0.05), while blood pressure, heart rate, Apgar scores and blood gas analysis of the umbilical artery and vein were not significantly different among the groups. No awareness was observed in the subjects. Conclusions: We found that the use of sevoflurane at on end-tidal concentration of 1.2 vol% was desirable to prevent recall by parturients, in the absence of fetal depression and a decline in uterine contractility.