Accuracy of Transcutaneous Carbon Dioxide Measurement During Transcatheter Aortic Valve Replacement Under Monitored Anesthesia Care: A Prospective Observational Study

Background Transcutaneous carbon dioxide tension (PtcCO ) measurement is a promising alternative to arterial carbon dioxide tension (PaCO ) measurement. PaCO measurement is invasive and intermittent, whereas PtcCO measurement is non-invasive and continuous. However, previous studies evaluating PtcCO measurements did not include patients undergoing transcatheter aortic valve replacement (TAVR), who experience anticipated hemodynamic changes, particularly before and after valve placement. Therefore, we investigated whether PtcCO measurement could provide an alternative to PaCO measurement during transfemoral TAVR under monitored anesthesia care (MAC) with local anesthesia. Methodology We conducted a prospective observational study. We included all consecutive patients with severe aortic stenosis who were scheduled to undergo a transfemoral TAVR under MAC at our institution from November 1, 2020, to April 30, 2021. During the procedures, PaCO and PtcCO were concurrently monitored six times as a reference standard and index test, respectively. PtcCO was monitored continuously using a non-invasive earlobe sensor. The agreement between PtcCO and PaCO measurements was assessed using the Bland-Altman method, and the 95% limits of agreement were calculated. Based on previous studies, we determined that 95% limits of agreement of ±6.0 mmHg would be clinically acceptable to define PtcCO as an alternative to PaCO . Results We obtained 88 measurement pairs from 15 patients. The lower and upper 95% limits of agreement between the PtcCO and PaCO measurements were -4.22 mmHg and 6.56 mmHg, respectively. Conclusions During TAVR under MAC with local anesthesia, PtcCO measurement could not provide a viable alternative to PaCO measurement to reduce high PaCO2 events. This study focused on comparing intraoperative periods before and after valve implantation. Therefore, further investigation is warranted to assess the impact of various factors, including the prosthetic valve type and the hemodynamic effects of balloon aortic valvuloplasty, on PtcCO measurement in TAVR.