The effect of supplemental 70% oxygen on postoperative nausea and vomiting in patients undergoing inguinal hernia surgery

Background Postoperative nausea and vomiting ( PONV) are among the leading side-effects after surgery performed under general anaesthesia. The role of oxygen as an important method for treatment of PONV was studied. The aim of this study was to compare intraoperative 30% oxygen with 70% oxygen for improvement of PONV in patients undergoing inguinal hernia surgery. Methods In a clinical double-blind study, patients (n = 100) undergoing inguinal hernia surgery were given a standardized halothane anesthetic. After induction, they were randomly assigned to the following two groups: routine oxygen administration with 30% oxygen, balance nitrogen ("30% oxygen group," n = 50) and supplemental oxygen administration with 70% oxygen, balance nitrogen (" 70% oxygen group," n = 50). The overall incidence of nausea and vomiting during the initial postoperative 24 h and correlation between arterial oxygen saturation and incidence of PONV was evaluated. Results There was significant difference in PONV incidence between the two studied groups (14.3% in group treated with 70% oxygen versus 40.0% in group treated with 30% oxygen, P < 0.0001). There was a positive correlation between increase in arterial oxygen saturation and decrease in PONV incidence (P < 0.0001). Conclusion Supplemental oxygen effectively prevents postoperative nausea and vomiting after inguinal hernia surgery: the higher the arterial oxygen saturation, the less frequent PONV.