Background
Transcutaneous carbon dioxide monitoring (TCM) offers a non-invasive and real-time assessment of patient's ventilation and oxygenation, making it a potential alternative to arterial blood gas analysis (ABG) for continuous monitoring of carbon dioxide. This pioneering clinical study represents the first investigation of its kind conducted in Hong Kong, contributing unique insights to the local context.
Objective
To compare TCM with ABG in the measurement of partial pressure of arterial carbon dioxide (PaCO2) in adult patients with respiratory problems.
Method
A non-interventional observational prospective cross-sectional clinical study was conducted in two medical wards of Ruttonjee Hospital from 8 May 2023 to 31 December 2023. TOSCA device was used to measure transcutaneous carbon dioxide (TcCO2) level, while arterial puncture for ABG was performed on the same occasion. Based on the literature review, the sensor temperature of the TOSCA device was set to 43°C to induce local vasodilation, enhance skin permeability to carbon dioxide, and improve gas diffusion at the pre-selected measurement site (i.e. second intercostal space in the mid-clavicular line). Bland-Altman analysis was used to evaluate the agreement between the measurement of TcCO2 from TCM and PaCO2 from ABG.
Results
A total of 59 paired measurements were analyzed, showing no significant difference between both pooled transcutaneous and arterial measurements (paired sample t-test). The mean bias ±SD between TcCO2 and PaCO2 was -0.75 ±4.01mmHg, with 95% limits of agreement ranging from -8.62 to 7.11 mmHg. In total, 5.08% of the measured values fell outside the acceptable clinical range of agreement (±7.5mmHg). A strong correlation (r=0.9, p< 0.001) between TcCO2 and PaCO2 was observed. During the study, there were no complications, like pain-related discomfort, formation of hematoma and nerve damage to blood vessels, observed on patients.
Conclusion
For adult patients with respiratory problems, TCM provides an accurate estimate of PaCO2. It offers a clinically acceptable, safe and reliable non-invasive alternative to ABG for painless, real-time, continuous monitoring of carbon dioxide levels without the need for invasive procedures or repeated ABG sampling.
