Concordance between capnography and capnia in adults admitted for acute dyspnea in an ED
Received 9 April 2009; accepted 16 April 2009. published online 26 March 2010.
Abstract
Background
End-tidal carbon dioxide pressure (etCO2) is widely used in anaesthesia and critical care in intubated patients. The aim of our preliminary study was to evaluate the feasibility of a simple device to predict capnia in spontaneously breathing patients in an emergency department (ED).
Patients and methods
This study was a prospective, nonblind study performed in our teaching hospital ED. We included nonintubated patients with dyspnea (≥18 years) requiring measurement of arterial blood gases, as ordered by the emergency physician in charge. There were no exclusion criteria. End-tidal CO2 was measured by an easy-to-use device connected to a microstream capnometer, which gave a continuous measurement and graphical display of the etCO2 level of a patient's exhaled breath.
Results
A total of 43 patients (48 measurements) were included, and the majority had pneumonia (n = 12), acute cardiac failure (n = 8), asthma (n = 7), or chronic obstructive pulmonary disease exacerbation (n = 6). Using simple linear regression, the correlation between etCO2 and Paco2 was good (R = 0.82). However, 18 measurements (38%) had a difference between etCO2 and Paco2 of 10 mm Hg or more. The mean difference between the Paco2 and etCO2 levels was 8 mm Hg. Using the Bland and Altman matrix, the limits of agreement were −10 to +26 mm Hg.
Conclusion
In our preliminary study, etCO2 using a microstream method does not seem to accurately predict Paco2 in patients presenting to an ED for acute dyspnea.
aDepartment of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance-Publique Hôpitaux de Paris (AP-HP), 75013 Paris, UPMC- Univ Paris 6, France
bLaboratory of Emergency Biology, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance-Publique Hôpitaux de Paris (AP-HP), 75013 Paris, UPMC- Univ Paris 6, France
Corresponding author. Service d'Accueil des Urgences, Groupe Hospitalier Pitié-Salpêtrière, 47-83 boulevard de l'hôpital, 75013 Paris, France. Tel.: +33 1 42 17 72 49; fax: +33 1 42 17 72 64.
ABSTRACT