• Marc A Rodger, Christopher N Bredeson, Gwynne Jones, Pasteur Rasuli, François Raymond, Anne Marie Clement, Alan Karovitch, Helene Brunette, Dimitri Makropoulos, Mark Reardon, Ian Stiell, Rama Nair, and Philip S Wells.
• University of Ottawa, Ottawa Health Research Institute, and Department of Medicine, Ottawa Hospital, Ottawa, Ontario, Canada.
• Arch Intern Med. 2006 Jan 23;166(2):181-7.

BackgroundWe sought to determine whether using combinations of 3 bedside tests (7-variable clinical model, non-enzyme-linked immunosorbent assay D-dimer test, and alveolar dead-space fraction) to exclude pulmonary embolism (PE) before diagnostic imaging was as safe as a standard strategy of starting with ventilation-perfusion (V/Q) scan.MethodsIn this double-blind, randomized, controlled equivalency trial, patients were randomized to initial bedside tests or to initial V/Q scan without bedside tests. Patients assigned to the bedside test group had a sham V/Q scan performed if at least 2 of 3 bedside test results were negative; otherwise, they underwent an actual V/Q scan. Further diagnostic management was determined by a blinded physician after V/Q scan. The primary outcome measure was recurrent venous thromboembolic events during 3 months among patients who were not taking anticoagulant agents after the initial investigations were completed.ResultsFour hundred fifty-eight consecutive adults with suspected PE were eligible for the study; 398 of 399 consenting and randomized patients completed the study. The follow-up venous thromboembolic event rate was 2.4% in the bedside test group vs 3.0% in the V/Q scan group (P = .76). Pulmonary embolism was excluded in 34% (67/199) of the bedside test group patients with at least 2 negative results on 3 bedside tests vs 18% (35/199) excluded using only the 7-variable clinical model and the D-dimer test.ConclusionExcluding PE with at least 2 negative results on 3 bedside tests safely eliminates the need for diagnostic imaging in 34% of patients with suspected PE.

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