title: Bispectral index values during sevoflurane-nitrous oxide general anesthesia in women undergoing cesarean delivery: a comparison between women with and without prior labor.
abstract: BACKGROUND
  An end-tidal concentration of 1% sevoflurane (1% ET(SEVO)) in 50% nitrous oxide (N(2)O) during elective cesarean delivery has been associated with bispectral index (BIS) values >60, which are associated with an increased risk of awareness. We hypothesized that BIS values during sevoflurane-N(2)O general anesthesia for cesarean delivery would be lower in women with prior labor compared with women without prior labor.
  
  
  METHODS
  Forty patients undergoing cesarean delivery were enrolled in this observational study. One group had urgent surgery after labor (labor group, n = 20) and the other had elective surgery without labor (control group, n = 20). General anesthesia was induced with thiopental 4 mg/kg, followed by succinylcholine 1.5 mg/kg, and maintained with 1% ET(SEVO) and 50% N(2)O in oxygen. BIS values, systolic arterial blood pressure, heart rate, plasma stress hormone concentrations, Apgar scores, and postoperative analgesia variables were assessed and compared between groups.
  
  
  RESULTS
  BIS values during the period between intubation and delivery were lower in the labor group than in the control group (P < 0.001). Plasma norepinephrine concentrations increased at delivery compared with baseline in both groups. They were higher in the labor group than in the control group both at baseline and at delivery. Systolic arterial blood pressure, heart rate, Apgar scores, surgical characteristics, and plasma concentrations of vasopressin and cortisol were not different between groups. Postoperative visual analog scale pain scores were similar between groups, while the labor group consumed less analgesics (P < 0.01) during the first 24 h after the operation.
  
  
  CONCLUSIONS
  Prior labor was associated with lower intraoperative BIS values during sevoflurane/N(2)O general anesthesia and reduced postoperative analgesic consumption in women undergoing cesarean delivery compared with women without prior labor.
authors.affiliation: Department of Anesthesiology, Chonnam National University Medical School, Gwangju, Korea. kyyoo@jnu.ac.kr
authors.forename: Kyung Y
authors.initials: KY
authors.lastname: Yoo
authors.forename: Cheol W
authors.initials: CW
authors.lastname: Jeong
authors.forename: Myung W
authors.initials: MW
authors.lastname: Kang
authors.forename: Seok J
authors.initials: SJ
authors.lastname: Kim
authors.forename: Sung T
authors.initials: ST
authors.lastname: Chung
authors.forename: Min H
authors.initials: MH
authors.lastname: Shin
authors.forename: JongUn
authors.initials: J
authors.lastname: Lee
mesh_terms: D000328:Adult; D000700:Analgesics / Q000627:therapeutic use; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D001034:Apgar Score; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002585:Cesarean Section; D017558:Elective Surgical Procedures; D004569:Electroencephalography; D004638:Emergency Treatment; D004837:Epinephrine / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007743:Labor, Obstetric / Q000097:blood / Q000502:physiology; D008738:Methyl Ethers / Q000008:administration & dosage*; D016343:Monitoring, Intraoperative / Q000379:methods*; D009481:Neurophysins / Q000097:blood; D009609:Nitrous Oxide / Q000008:administration & dosage*; D009638:Norepinephrine / Q000097:blood; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control; D011247:Pregnancy; D011498:Protein Precursors / Q000097:blood; D000077149:Sevoflurane; D013997:Time Factors; D014667:Vasopressins / Q000097:blood
chemical_list: C438657:AVP protein, human; D000700:Analgesics; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D009481:Neurophysins; D011498:Protein Precursors; D014667:Vasopressins; D000077149:Sevoflurane; D009609:Nitrous Oxide; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine