Impact of intraoperative hypocapnia on postoperative complications in laparoscopic surgery for colorectal cancer

In laparoscopic surgery (LS) for colorectal cancer (CRC), the relationship between intraoperative end-tidal carbon dioxide concentration (EtCO2) and surgery-related complications remains unexplored. This study assessed the impact of intraoperative EtCO2 on postoperative complications in LS for CRC. In total, 909 patients who underwent LS for CRC were enrolled. Hypocapnia and hypercapnia were defined as EtCO2 40 mmHg, respectively, and the relationships between hypocapnia or hypercapnia duration and postoperative complications were analyzed. The median (range) durations of hypocapnia and hypercapnia were 2.0 (0–8.3) h and 0.3 (0–5.8) h, respectively. Complications were observed in 208 cases (23.0%), which included 37 (4.1%) instances of anastomotic leakage and 86 (9.5%) of superficial surgical site infection (SSI). While the hypercapnia duration was not associated with the short-term outcomes, prolonged hypocapnia was significantly correlated with complications (p = 0.02), specifically superficial SSI (p = 0.005). Multivariate analyses adjusted for confounding factors confirmed that hypocapnia prolongation was an independent risk factor for postoperative superficial SSI [OR 1.19; 95% confidence interval (Cl) 1.03–1.36, p = 0.01]. Intraoperative hypocapnia may be a risk factor for postoperative complications, in particular superficial SSI, in LS for CRC.