Limitations of transcutaneous carbon dioxide monitoring in apneic oxygenation

Thilo Schweizer; Volker Hartwich; Thomas Riva; Heiko Kaiser; Lorenz Theiler; Robert Greif; Sabine Nabecker

doi:10.1371/journal.pone.0286038

Limitations of transcutaneous carbon dioxide monitoring in apneic oxygenation

PLoS One. 2023 Jun 1;18(6):e0286038. doi: 10.1371/journal.pone.0286038. eCollection 2023.

Authors

Thilo Schweizer¹, Volker Hartwich², Thomas Riva^{1

3}, Heiko Kaiser^{1

4}, Lorenz Theiler⁵, Robert Greif^{1

6}, Sabine Nabecker^{1

7}

Affiliations

¹ Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
² Independent Researcher, Bern, Switzerland.
³ Unit for Research and Innovation, Department of Paediatric Anaesthesia, Istituto Giannina Gaslini, Genova, Italy.
⁴ Centre for Anaesthesiology and Intensive Care Medicine, Hirslanden Klinik Aarau, Hirslanden Group, Aarau, Switzerland.
⁵ Department of Anesthesiology, Cantonal Hospital Aarau, Aarau, Switzerland.
⁶ School of Medicine, Sigmund Freud University Vienna, Vienna, Austria.
⁷ Department of Anesthesiology and Pain Management, Sinai Health System, University of Toronto, Toronto, Canada.

Abstract

Background: High-flow nasal oxygenation is increasingly used during sedation procedures and general anesthesia in apneic patients. Transcutaneous CO2 (ptcCO2)-monitoring is used to monitor hypercapnia. This study investigated ptcCO2-monitoring during apneic oxygenation.

Methods: We included 100 patients scheduled for elective surgery under general anesthesia in this secondary analysis of a randomized controlled trial. Before surgery, we collected ptcCO2 measured by TCM4 and TCM5 monitors and arterial blood gas (ABG) measurements every two minutes during 15 minutes of apnea. Bland-Altman plots analyzed agreement between measurement slopes; linear mixed models estimated the different measuring method effect, and outlined differences in slope and offset between transcutaneous and arterial CO2 partial pressures.

Results: Bland-Altman plots showed a bias in slope (95% confidence intervals) between ABG and TCM4-measurements of 0.05mmHg/min (-0.05 to 0.15), and limits of agreement were -0.88mmHg/min (-1.06 to -0.70) and 0.98mmHg/min (0.81 to 1.16). Bias between ABG and TCM5 was -0.14mmHg/min (-0.23 to -0.04), and limits of agreement were -0.98mmHg/min (-1.14 to -0.83) and 0.71mmHg/min (0.55 to 0.87). A linear mixed model (predicting the CO2-values) showed an offset between arterial and transcutaneous measurements of TCM4 (-15.2mmHg, 95%CI: -16.3 to -14.2) and TCM5 (-19.1mmHg, -20.1 to -18.0). Differences between the two transcutaneous measurements were statistically significant.

Conclusions: Substantial differences were found between the two transcutaneous measurement systems, and between them and ABG. Transcutaneous CO2 monitoring cannot replace arterial CO2-monitoring during apneic oxygenation. In clinical settings with rapidly changing CO2-values, arterial blood gas measurements are needed to reliably assess the CO2-partial pressure in blood.

Trial registration: ClinicalTrials.gov (NCT03478774).

Copyright: © 2023 Schweizer et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Anesthesia, General
Blood Gas Monitoring, Transcutaneous* / methods
Carbon Dioxide*
Humans
Hypercapnia
Respiration, Artificial

Substances

Carbon Dioxide

Associated data

ClinicalTrials.gov/NCT03478774

Grants and funding

This study was supported only by an institutional research grant assigned to Dr. Lorenz Theiler (KAS THLD 1-18) of the Department of Anaesthesiology and Pain Medicine, Bern University Hospital, Bern, Switzerland. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. There was no additional external funding received for this study.