title: Concordance between capnography and capnia in adults admitted for acute dyspnea in an ED.
abstract: BACKGROUND
  End-tidal carbon dioxide pressure (etCO(2)) 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).
  
  
  METHODS
  This study was a prospective, nonblind study performed in our teaching hospital ED. We included nonintubated patients with dyspnea (> or =18 years) requiring measurement of arterial blood gases, as ordered by the emergency physician in charge. There were no exclusion criteria. End-tidal CO(2) was measured by an easy-to-use device connected to a microstream capnometer, which gave a continuous measurement and graphical display of the etCO(2) 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 etCO(2) and Paco(2) was good (R = 0.82). However, 18 measurements (38%) had a difference between etCO(2) and Paco(2) of 10 mm Hg or more. The mean difference between the Paco(2) and etCO(2) levels was 8 mm Hg. Using the Bland and Altman matrix, the limits of agreement were -10 to +26 mm Hg.
  
  
  CONCLUSIONS
  In our preliminary study, etCO(2) using a microstream method does not seem to accurately predict Paco(2) in patients presenting to an ED for acute dyspnea.
authors.affiliation: Department of Emergency Medicine and Surgery, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance-Publique Hôpitaux de Paris, 75013 Paris, UPMC- Univ Paris 6, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Delerme
authors.forename: Yonathan
authors.initials: Y
authors.lastname: Freund
authors.forename: Robin
authors.initials: R
authors.lastname: Renault
authors.forename: Catherine
authors.initials: C
authors.lastname: Devilliers
authors.forename: Samuel
authors.initials: S
authors.lastname: Castro
authors.forename: Sebastien
authors.initials: S
authors.lastname: Chopin
authors.forename: Gaelle
authors.initials: G
authors.lastname: Juillien
authors.forename: Bruno
authors.initials: B
authors.lastname: Riou
authors.forename: Patrick
authors.initials: P
authors.lastname: Ray
mesh_terms: D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D019296:Capnography / Q000295:instrumentation*; D004417:Dyspnea / Q000097:blood* / Q000209:etiology; D004636:Emergency Service, Hospital; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D008173:Lung Diseases, Obstructive / Q000097:blood* / Q000150:complications* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013990:Tidal Volume