Background Transcutaneous carbon dioxide (Ptcco2) measurement is a non-invasive surrogate marker for arterial carbon dioxide (Paco2), which requires invasive arterial blood sampling. Use of Ptcco2 has been examined in different clinical settings, however, most existing evidence in the adult emergency department (ED) setting shows insufficient agreement between the measurements. This study assessed the level of agreement between Ptcco2 and Paco2 in undifferentiated adult ED patients across multiple timepoints.
Methods This prospective observational study (study period 2020–2021) assessed paired Ptcco2 and Paco2 measurements at four consecutive timepoints (0, 30, 60 and 90 min) in adult (aged 18 years or over) Australian ED patients requiring hospital admission and arterial catheter insertion. Agreement between the pairs was assessed using Bland-Altman analysis. It was prospectively determined by expert consensus that limits of ±4 mm Hg would be a clinically acceptable level of agreement between Ptcco2 and Paco2.
Results During the study period 168 paired Ptcco2 and Paco2 readings were taken from 42 adult ED patients. Bland-Altman analysis showed a mean Ptcco2 reading 3.85 mm Hg higher than Paco2, although at each timepoint the 95% CIs breached the limit of 4 mm Hg difference. In addition, only 66% (111/168) of results fell within the clinically acceptable range.
Conclusion The level of agreement between Ptcco2 and Paco2 measurements may not be sufficiently precise for the adoption of Ptcco2 monitoring in patients presenting to the ED.
- critical care
- emergency department
Data availability statement
No data are available.
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Handling editor Mary Dawood
Contributors This study was conceived and designed by all four authors. Data was collected in the emergency department by IF, SF and AC. Data analysis was performed by SF. The paper was written by all four authors—IF, YC, SF and AC. The guarantor for this study is SF.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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