Utilization and Estimation of Environmental Impact of End-Tidal Control in a Multisite Academic Health System: A Retrospective Observational Cross-Sectional Study.

backgroundEnd-tidal control (ETC) is a technology new to the United States that enables automated titration of anesthetic gases while using low-flow anesthesia. Although previous, smaller clinical trials have demonstrated that ETC use leads to reductions in fresh gas flow (FGF), anesthetic agent consumptions, and carbon dioxide equivalents (CO2 equivalents) per hour of maintenance, there is limited information about large-scale deployment of ETC including detailed case information and real-world impact in a large academic health system. We sought to describe the utilization of ETC and quantify the impact of ETC utilization on FGF, sevoflurane consumption, and CO2 equivalents per hour of maintenance of anesthesia.

methodsData were obtained from an electronic health record-derived registry for adult patients receiving general anesthesia between April 1, 2023, and September 30, 2024, on an anesthesia machine with ETC available at University of Michigan Health-Ann Arbor locations. Utilization rates of ETC were calculated. Using multilevel mixed-effects models, we assessed case, in-room clinician, and attending anesthesiologist contributions to utilization of ETC and quantified the impact of ETC on FGF, sevoflurane consumption, and CO2 equivalents.

resultsIn 12,818 included general anesthetics, ETC was used in 6755 (52.7%). ETC use was associated with greater anesthesia duration (odds ratio [OR], 1.27 per hour; 95% confidence interval [CI], 1.23-1.31), involvement of a resident anesthesiologist (OR, 2.11; 95% CI, 1.56-2.86), and cases performed at an ambulatory surgical center (ASC; OR, 1.65; 95% CI, 1.3-2.09). Factors associated with decreased use of ETC included American Society of Anesthesiologists (ASA) physical status III to V (OR, 0.89; 95% CI, 0.80-0.99). In-room clinician explained 38.5% of the variation in ETC use compared to 3.9% due to attending anesthesiologist. ETC was associated with an adjusted difference in median FGF of -1.14 L/min (95% CI, -1.16 to -1.12), difference in mean FGF of -1.00 L/min (95% CI, -1.02 to -0.98), difference in sevoflurane consumption of -5.23 mL/h (95% CI, -5.34 to -5.10), and a difference in CO2 equivalents of -1.06 kg CO2 equivalents/hour (95% CI, -1.12 to -0.99) during maintenance.

conclusionsETC was used in approximately half of available cases. Variation in the decision to use was significantly driven by in-room anesthesia clinician, with wide variation within this group. Use of ETC was associated with a 62.3% reduction in median FGF and sevoflurane consumption of 39.3%.