The additional use of end-tidal alveolar dead space fraction following D-dimer test to improve diagnostic accuracy for pulmonary embolism in the emergency department.
OBJECTIVE
To determine the diagnostic performance of bedside assessment of end-tidal alveolar dead space fraction (ADSF) for pulmonary embolism (PE) and whether the use of additional ADSF assessment following D-dimer assay can improve the diagnostic accuracy in suspected PE patients in the emergency department.


METHODS
A prospective observational study of 112 consecutive adult patients suspected of PE of whom 102 were eligible for analysis. ADSF was calculated using arterial carbon dioxide and end-tidal carbon dioxide. An ADSF less than 0.2 was considered normal.


RESULTS
PE was confirmed in 11 (10.8%) of 102 patients. D-dimer assay alone as a reference standard test for PE had a sensitivity of 100%, specificity of 38.5% and false negativity of 0%. Area under the receiver-operator characteristic curve for the diagnosis of PE using ADSF values alone was 0.894, Sensitivity, specificity and false negativity for the combined results of a positive D-dimer test and abnormal ADSF were 100%, 78.0% and 0% for the presence of PE, respectively. Of 65 patients with a low or intermediate clinical probability and a positive D-dimer assay, 36 (55.4%) patients displayed normal ADSF and had no PE.


CONCLUSIONS
By itself ADSF assessment performed well in diagnosis of PE. The combined result of a positive D-dimer and abnormal ADSF increased the specificity for diagnosing PE compared with the D-dimer test alone. The use of additional bedside ADSF assessment following a positive D-dimer test may reduce the need for further imaging studies to detect PE in patients with a low or intermediate clinical probability.
Yoon
Young Hoon
YH
Department of Emergency Medicine, College of Medicine, Korea University, Seoul, Korea.
Lee
Sung Woo
SW
Jung
Dong Min
DM
Moon
Sung Woo
SW
Horn
Jan Kurt
JK
Hong
Yun-Sik
YS
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D019296:Capnography; D002245:Carbon Dioxide / Q000032:analysis; D004636:Emergency Service, Hospital; D005188:False Negative Reactions; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D019370:Observation; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000503:physiopathology; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000401:mortality; D015203:Reproducibility of Results; D012126:Respiratory Dead Space / Q000502:physiology; D012129:Respiratory Function Tests; D056152:Respiratory Rate / Q000502:physiology; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D002245:Carbon Dioxide