Supplemental oxygen reduces the incidence of postoperative nausea and vomiting.

BACKGROUND Despite new anesthetic drugs and antiemetics, particularly 5-hydroxytryptamines, the incidence of postoperative nausea or vomiting remains between 20% and 70%. The authors tested the hypothesis that supplemental perioperative oxygen administration reduces the incidence of postoperative nausea or vomiting. METHODS Patients undergoing colon resection were anesthetized with fentanyl and isoflurane. During and for 2 h after surgery they were randomly assigned to (1) 30% oxygen, balance nitrogen (n = 119); or (2) 80% oxygen, balance nitrogen (n = 112). The incidence of nausea or vomiting during the first 24 postoperative hours was evaluated by nurses blinded to group assignment and oxygen concentration. Data were analyzed with unpaired t or Mann-Whitney U tests. Results are presented as means +/- SD; P < 0.05 was considered significant. RESULTS Factors known to influence nausea and vomiting were comparable in the two groups. Perioperative oxygen saturation was well within normal limits in each treatment group; saturations the first postoperative morning were comparable in each group. Supplemental oxygen reduced the incidence of postoperative nausea or vomiting from 30% in the patients given 30% oxygen to 17% in those given 80% oxygen (P = 0.027). CONCLUSIONS Supplemental oxygen reduced the incidence of postoperative nausea or vomiting nearly twofold after colorectal surgery. The mechanism by which oxygen administration reduces the incidence of these postoperative sequelae remains unknown but may be related to subtle intestinal ischemia. Because oxygen is inexpensive and essentially risk-free, supplemental oxygen appears to be an effective method of reducing postoperative nausea and vomiting.