title: Nitrous oxide anxiolysis for elective cesarean section.
abstract: OBJECTIVE
  To determine if inhaled 40% nitrous oxide (N(2)O) via facemask is an effective anxiolytic in women undergoing elective cesarean section under spinal anesthesia.
  
  
  METHODS
  Prospective, randomized, double-blinded study.
  
  
  METHODS
  Tertiary-care women's hospital.
  
  
  METHODS
  Sixty American Society of Anesthesiologists physical status I and II patients scheduled for elective cesarean section under spinal anesthesia.
  
  
  METHODS
  Patients were randomized to 2 groups to receive either 100% O2 via facemask or 40% N2O in O2 via facemask.
  
  
  METHODS
  Vital signs (blood pressure, heart rate, and oxygen saturation) and measured variables (visual analog scale [VAS] anxiety, VAS pain, and sedation scores) were obtained at specific periods during the procedure (preoperatively, entering the operating room, spinal injection, skin incision, uterine incision, delivery, and at the conclusion of the surgical procedure). In addition, surgical time and delivery time, mean dose and percentage of patients requiring ephedrine or phenylephrine boluses, the emesis rate, and Apgar scores were measured.
  
  
  RESULTS
  No differences were noted with respect to maternal mean blood pressure, heart rate, pulse-oximeter oxygen saturation, and sedation or VAS pain scores during the measured periods. No differences were noted in surgical and delivery times, mean dose, or percentage of patients who required ephedrine or phenylephrine to maintain maternal blood pressure, the emesis rate, or 1- and 5-minute Apgar scores. Mean anxiety scores for the N2O group were significantly lower at the time of spinal injection, skin incision, and uterine incision. Multivariate analysis of variance for high-anxiety patients (> or =50 VAS) revealed significantly lower VAS scores in the N2O group, compared with the O2 group again at spinal injection, skin incision, and uterine incision.
  
  
  CONCLUSIONS
  Inhaled 40% N2O via facemask provides effective anxiolysis in women undergoing elective cesarean section under spinal anesthesia in patients with high anxiety (> or =50 VAS) at the time of spinal injection, skin incision, and uterine incision.
authors.affiliation: Department of Anesthesia, Magee-Womens Hospital, University of Pittsburgh School of Medicine and Dental Medicine, Pittsburgh, PA 15213, USA. vallejomc@anes.upmc.edu
authors.forename: Manuel C
authors.initials: MC
authors.lastname: Vallejo
authors.forename: Amy L
authors.initials: AL
authors.lastname: Phelps
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Shepherd
authors.forename: Bupesh
authors.initials: B
authors.lastname: Kaul
authors.forename: Gordon L
authors.initials: GL
authors.lastname: Mandell
authors.forename: Sivam
authors.initials: S
authors.lastname: Ramanathan
mesh_terms: D000328:Adult; D018685:Anesthetics, Inhalation / Q000627:therapeutic use*; D014151:Anti-Anxiety Agents; D001794:Blood Pressure / Q000502:physiology; D002585:Cesarean Section / Q000523:psychology*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D009609:Nitrous Oxide / Q000627:therapeutic use*; D010100:Oxygen / Q000097:blood; D010147:Pain Measurement; D011247:Pregnancy; D011446:Prospective Studies
chemical_list: D018685:Anesthetics, Inhalation; D014151:Anti-Anxiety Agents; D009609:Nitrous Oxide; D010100:Oxygen