Association between intraoperative end-tidal carbon dioxide and postoperative nausea and vomiting in gynecologic laparoscopic surgery.

Gynecologic laparoscopic surgery has a high incidence of postoperative nausea and vomiting (PONV). Studies suggest that low intraoperative end-tidal carbon dioxide (EtCO) is associated with an increased incidence of PONV, but the results have not been consistent among studies. This study investigated the association between intraoperative EtCO and PONV in patients undergoing gynecologic laparoscopic surgeries under general anesthesia. This retrospective cohort study involved patients who underwent gynecologic laparoscopic surgeries under general anesthesia at Kyoto University Hospital. We defined low EtCO as a mean EtCO of < 35 mmHg. Multivariable modified Poisson regression analysis examined the association between low EtCO and PONV during postoperative two days and the postoperative length of hospital stay (PLOS). Of the 739 patients, 120 (16%) had low EtCO, and 430 (58%) developed PONV during postoperative two days. There was no substantial association between low EtCO and increased incidence of PONV (adjusted risk ratio: 0.96; 95% confidence interval [CI] 0.80-1.14; p = 0.658). Furthermore, there was no substantial association between low EtCO and prolonged PLOS (adjusted difference in PLOS: 0.13; 95% CI - 1.00 to 1.28; p = 0.816). Intraoperative low EtCO, specifically a mean intraoperative EtCO below 35 mmHg, was not substantially associated with either increased incidence of PONV or prolonged PLOS.