An observational study of end-tidal carbon dioxide trends in general anesthesia

Abstract

PurposeDespite growing evidence supporting the potential benefits of higher end-tidal carbon dioxide (ETCO2) levels in surgical patients, there is still insufficient data to formulate guidelines for ideal intraoperative ETCO2 targets. As it is unclear which intraoperative ETCO2 levels are currently used and whether these levels have changed over time, we investigated the practice pattern using the Multicenter Perioperative Outcomes Group database.MethodsThis retrospective, observational, multicentre study included 317,445 adult patients who received general anesthesia for non-cardiothoracic procedures between January 2008 and September 2016. The primary outcome was a time-weighted average area-under-the-curve (TWA-AUC) for four ETCO2 thresholds (< 28, < 35, < 45, and > 45 mmHg). Additionally, a median ETCO2 was studied. A Kruskal-Wallis test was used to analyse differences between years. Random-effect multivariable logistic regression models were constructed to study variability.ResultsBoth TWA-AUC and median ETCO2 showed a minimal increase in ETCO2 over time, with a median [interquartile range] ETCO2 of 33 [31.0–35.0] mmHg in 2008 and 35 [33.0–38.0] mmHg in 2016 (P <0.001). A large inter-hospital and inter-provider variability in ETCO2 were observed after adjustment for patient characteristics, ventilation parameters, and intraoperative blood pressure (intraclass correlation coefficient 0.36; 95% confidence interval, 0.18 to 0.58).ConclusionsBetween 2008 and 2016, intraoperative ETCO2 values did not change in a clinically important manner. Interestingly, we found a large inter-hospital and inter-provider variability in ETCO2 throughout the study period, possibly indicating a broad range of tolerance for ETCO2, or a lack of evidence to support a specific targeted range. Clinical outcomes were not assessed in this study and they should be the focus of future research.Electronic supplementary materialThe online version of this article (10.1007/s12630-018-1249-1) contains supplementary material, which is available to authorized users.

Strawman redux: management of end-tidal gases in patients at risk of perioperative neurocognitive disorder

“…Control of end-tidal gases may be important, but a multicentre retrospective analysis of over 300,000 non-cardiac surgical patients suggests clinicians have not reached consensus on appropriate goals. 6 After controlling for patient and procedural factors, the median ETCO 2 was consistently less than 40 mmHg with large inter-hospital and inter-provider variability.…”

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

“…To determine the study power, we estimated that approximately 120 laparoscopic gynecologic surgeries were performed annually at Kyoto University Hospital, with 720 surgeries performed over six years. The risk ratio was 1.53, the incidence of PONV was 40% 4 , and the proportion of low EtCO 2 was 50% 24 , giving an estimated power of 80%. The rate of missing data was 0.04%, so we conducted a complete case analysis.…”

Association between Intraoperative End-Tidal Carbon Dioxide and Postoperative Organ Dysfunction in Major Abdominal Surgery: A Retrospective Cohort Study

“…To maximize statistical power, all eligible patients in the Kyoto-IMPACT database were included in the analyses. To determine the statistical power, we predicted 4,500 eligible surgeries in our database in the 9 years, a risk ratio of 1.5 with postoperative organ dysfunction of 30%[17] and low EtCO 2 proportion of 50%[24], resulting in an estimated power of 100%. We conducted complete case analysis because the percentage of missing data was 0.12%.…”