Diagnostic accuracy of a bedside D-dimer assay and alveolar dead-space measurement for rapid exclusion of pulmonary embolism: a multicenter study

JAMA. 2001 Feb 14;285(6):761-8. doi: 10.1001/jama.285.6.761.


Context: A previous study suggested that the combination of a normal D-dimer assay and normal alveolar dead-space fraction is a highly sensitive screening test for pulmonary embolism (PE).

Objective: To determine if the combination of a normal alveolar dead-space fraction (volume of alveolar dead space/tidal volume </=20%) and a normal whole-blood agglutination D-dimer assay can exclude PE in emergency department (ED) patients.

Design: Prospective, noninterventional study conducted in 1998-1999. Study data were obtained prior to standard testing for PE, consisting of radionuclide lung scanning or contrast-enhanced computed tomography and 6-month follow-up plus selective use of venous ultrasonography and pulmonary angiography. Imaging studies were interpreted by blinded observers.

Setting: Six urban teaching hospitals in the United States.

Patients: A total of 380 hemodynamically stable ED patients aged 18 years or older with suspected acute PE.

Main outcome measures: Sensitivity and specificity for PE with a positive test defined as having either alveolar dead-space fraction or D-dimer assay results abnormal. Alveolar dead-space fraction was determined by subtracting airway dead space from physiological dead space (determined using the modified Bohr equation) and D-dimer assay, assayed at bedside using 20 microL of arterial blood.

Results: Pulmonary embolism was diagnosed in 64 patients (16.8%), of those 20 had an abnormal D-dimer assay result, 3 had an abnormal alveolar dead-space fraction, 40 had abnormal results in both, and 1 had normal results for both tests. The sensitivity for diagnosis of PE was 98.4% (95% confidence interval [CI], 91.6%-100.0%). Among the 316 patients without PE, both D-dimer and dead-space results were normal in 163, for a specificity of 51.6% (95% CI, 46.1%-57.1%). Posterior probability of PE with normal results on both tests was 0.75% (95% CI, 0%-3.4%).

Conclusion: In this multicenter study of ED patients, a normal D-dimer assay result plus a normal alveolar dead-space fraction was associated with a low prevalence of PE.

Publication types

  • Evaluation Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Emergency Service, Hospital
  • Female
  • Fibrin Fibrinogen Degradation Products / analysis*
  • Humans
  • Likelihood Functions
  • Male
  • Middle Aged
  • Point-of-Care Systems*
  • Predictive Value of Tests
  • Prospective Studies
  • Pulmonary Alveoli
  • Pulmonary Embolism / diagnosis*
  • Respiratory Function Tests*
  • Sensitivity and Specificity
  • Tidal Volume*


  • Fibrin Fibrinogen Degradation Products
  • fibrin fragment D