Study objective: To assess the efficacy of intraoperative different inspired oxygen fractions (FIO2) of 0.8 and 0.5 when compared with standard FIO2 0.3 in prevention of postoperative nausea and vomiting (PONV).Design: A prospective, controlled, randomized, double-blind study.Setting: General hospital, postanesthesia care unit (PACU) and gynecologic floor room. Patients: 120 ASA physical status I and II women, aged 21 to 76 y, undergoing elective gynecologic laparoscopic surgery.Interventions: Patients were randomized to receive gas mixture of 30% oxygen in air (FI O2=0.3, group G30), 50% oxygen in air (FIO2=0.5, group G50) or 80% oxygen in air (FIO2=0.8, group G80), n=36 in each group. A standardized sevoflurane general anesthesia, postoperative pain management and antiemetic regimen were used.Measurements: The incidence of nausea, vomiting or both was assessed for early (0-2h) and late PONV (2-24h) along with the use of rescue antiemetic, degree of nausea and severity of pain.Main results: There was no overall difference in the incidence of PONV at early and late assessment periods among the three groups. Patients in G80 had significantly less vomiting than G30 at 2 hours, 3% (1/36) vs. 22% (8/36), respectively, P=0.028. Nausea scores, rescue antiemetic use, pain scores and opioid consumption were not different among the groups.Conclusion: High intraoperative FIO2 of 0.8 and FIO2 of 0.5 does not prevent PONV in patients without antiemetic prophylaxis. Intraoperative FIO2 of 0.8 has beneficial effect on early vomiting only.
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