The Effect of Oxygenation Technique in General Anesthesia on Postoperative Nausea and Vomiting

Objective(s): To evaluate the effect of routine positive pressure mask ventilation (PPV) for preoxygenation on the occurrence of postoperative nausea and vomiting (PONV) Design: Double-blind randomized clinical trial Setting: Teaching Hospital of Birjand University of Medical Sciences, Iran Subjects: One hundred sixty elective surgical patients undergoing general, urologic, and orthopedic surgeries between 2007 and 2008. Intervention(s): Patients were divided into two groups (A & B). All patients underwent the same method of general anesthesia using sodium thiopental, fentanyl and suxamethonium. Both groups received 100% oxygen for three minutes before induction of anesthesia. Patients in group A received positive pressure oxygenation for 30 seconds after induction of anesthesia whereas group B patients did not. Main Outcome Measure(s): The incidence of PONV and decrease in SPO2 (saturation < 89%) was compared in the two groups. Results: Out of 160 patients, 20 patients were excluded (abdominal and laparoscopic surgeries or operation time > 1 h). Group A had 73 and group B had 67 patients. There was no decrease in SPO2 saturation observed in the two groups. The prevalence of PONV was significantly higher in group A (45.2 Vs 28.4% for group A and B, respectively, p < 0.05). Conclusion(s): Thirty seconds of additional oxygenation with PPV after induction of anesthesia resulted in a higher incidence of PONV. There was no de-saturation in group B patients. Therefore, in non-emergency cases when a short-acting muscle relaxant drug (e.g., suxamethonium) is used, PPV before intubation can be avoided.