The effect of different concentrations of oxygen on postoperative nausea and vomiting after spinal anesthesia

Postoperative nausea and vomiting (PONV) are common complications after both general and regional anesthesia. A number of different drugs are used for prevention and treatment of PONV. However, the complications are still common. Some of the recent investigations showed that using high concentration of oxygen decreased nausea and vomiting after general anesthesia but there is no study about effects of oxygen on PONV after regional anesthesia. Therefore, in this study the effect of different doses of oxygen is studies on the neusea and vomiting of after spinal anesthesia. In this double-blinded clinical trial, 132 patients with ASA I and II (American Society of Anesthesiologyists) criteria and 15-70 years old who were scheduled to undergo elective surgery for reduction and fixation of tibia open fracture were randomly divided into three equal groups. Spinal anesthesia was performed with 0.5% bupivacaine solution and oxygen with concentrations of 30% (group 1), 50% (group 2) and 70% (group 3) has been administered during operation. The frequency of vomiting and the severity of nausea with regard to VAS (visual analogue scale) were determined. Data was analyzed by ANOVA and c2 tests with SPSS software and a P value< 0.05 is considered significant. The mean of vomiting frequency, nausea intensity and dose of metoclopramid consumption in the patients of the 3 groups were not significantly different. The result of this study revealed that the higher concentrations of oxygen didn’t reduce PONV or metochlopramide consumption during and after the operation.