Objective: The objective was to assess agreement between end-tidal carbon dioxide values measured by a handheld capnometer (Petco(2)) and values measured by a blood gas analyzer (Paco(2)) in nonintubated patients with respiratory distress in an out-of-hospital setting.
Methods: This prospective study compared Petco(2) values obtained by an end-tidal capnometer (Microcap Plus; Oridion Capnography Inc, Needham, Mass) to Paco(2) values by the Bland and Altman statistical method.
Results: A total of 50 patients were included. Continuous Petco(2) monitoring was easily performed in all 50 patients during ambulance transport, but blood gas analysis failed in 1 patient. Agreement between the 2 methods was poor with a bias (mean difference) between Petco(2) and Paco(2) measurements of 12 mm Hg and a precision (SD of the difference) of 8 mm Hg. The gradient between Petco(2) and Paco(2) was greater than 5 and 10 mm Hg in 41 and 25 patients, respectively.
Conclusions: Petco(2) measurements poorly reflected Paco(2) values in our population of nonintubated patients with respiratory distress of various origins.