Intraoperative end-tidal carbon dioxide levels are not associated with recurrence-free survival after elective pancreatic cancer surgery: a retrospective cohort study.

Background: Intraoperative end-tidal carbon dioxide concentrations (EtCO) values are associated with recurrence-free survival after colorectal cancer surgery. However, it is unknown if similar effects can be observed after other surgical procedures. There is now evidence available for target EtCO and its relation to surgical outcomes following pancreatic cancer surgery.

Methods: In this single-center, retrospective cohort study, we analyzed 652 patients undergoing elective resection of pancreatic cancer at Heidelberg University Hospital between 2009 and 2016. The entire patient cohort was sorted in ascending order based on mean intraoperative EtCO values and then divided into two groups: the high-EtCO group and the low-EtCO2 group. The pre-specified primary endpoint was the assessment of recurrence-free survival up to the last known follow-up. Cardiovascular events, surgical site infections, sepsis, and reoperations during the hospital stay, as well as overall survival were pre-specified secondary outcomes.

Results: Mean EtCO was 33.8 mmHg ±1.1 in the low-EtCO group vs. 36.8 mmHg ±1.9 in the high-EtCO group. Median follow-up was 2.6 (Q1:1.4; Q3:4.4) years. Recurrence-free survival did not differ among the high and low-EtCO groups [HR = 1.043 (95% CI: 0.875-1.243), log rank test: = 0.909]. Factors affecting the primary endpoint were studied via Cox analysis, which indicated no correlation between mean EtCO levels and recurrence-free survival [Coefficient -0.004, HR = 0.996 (95% CI:0.95-1.04); = 0.871]. We did not identify any differences in the secondary endpoints, either.

Conclusions: During elective pancreatic cancer surgery, anesthesiologists should set EtCO targets for reasons other than oncological outcome until conclusive evidence from prospective, multicenter randomized controlled trials is available.