Evaluation of the anesthetic depth by Bispectral Index during Cesarean Section under general anesthesia

Abstract

Background: The incidence of accidental awareness in cesarean section under general anesthesia is higher than in other surgeries because we had to use a minimal dose of drugs and inhalation to avoid the side effects to the neonate. Today, we do not have data about the depth of anesthesia and the incidence of awareness during cesarean section under general anesthesia in Surat Thani Hospital.

Objective: To evaluate the depth of anesthesia by using the Bispectral index and detect the awareness during cesarean section under general anesthesia

Method: This study was conducted on 70 parturient patients undergoing elective cesarean section. A standardized anesthetic technique was applied: induction with routine anesthetic agents. Electrocardiogram, heart rate, blood pressure, SpO2, Bispectral index, and minimal alveolar concentration (MAC) of Sevoflurane in 50% Nitrogen oxide were continuously monitored and recorded during anesthesia.

Result: BIS index value was 97.09± 2.02 ,61.8±16.48 ,42.23±8.33 ,39.27± 8.53 ,36.44±7.09, 34.50±7.72, 34.50±7.72, 34.50±7.72,37.01±14.29,61.47± 9.16,68.21±6.89,79.57±5.31, and 86.90±5.85 at Baseline, Induction, Intubation, Skin incision, Uterine incision, Delivery, Suture uterus, Suture sheath, Skin closure, Open eyes, and Extubation. MAC of sevoflurane in 50% nitrous oxide was between 0.4 and 0.7.  Hemodynamic profiles and Apgar scores were satisfactory. There was no case of uterine atony but one case of incidental awareness during the surgery.

Conclusion: The currently used general anesthetic technique in Surat Thani Hospital appears inadequate for depth of anesthesia because using only midazolam after delivery is not appropriate. The level of sevoflurane may be adjusted by applying BIS during surgery to prevent incidental awareness.