Non-invasive diagnostic work-up of patients with clinically suspected pulmonary embolism; results of a management study.

BACKGROUND: Clinicians often deviate from the recommended algorithm for the diagnosis of pulmonary embolism consisting of ventilation-perfusion scintigraphy and pulmonary angiography. OBJECTIVES: To assess the safety and feasibility of a diagnostic algorithm which reduces the need for lung scintigraphy and avoids the use of angiography. PATIENTS AND METHODS: Consecutive patients with a clinical suspicion of pulmonary embolism were prospectively investigated according to an algorithm in which the diagnosis of pulmonary embolism was excluded after a low clinical probability estimate and a normal d-dimer test result, a normal perfusion scintigraphy result, or a non-high probability scintigraphy result in combination with normal serial ultrasonography of the legs. In these patients anticoagulant treatment was withheld and they were followed up for 3 months to record possible thromboembolic events. During the study period, 923 consecutive patients were seen, of whom 292 were excluded because of predefined criteria. RESULTS: Of the 631 included patients, the diagnosis was refuted on the basis of a low clinical probability estimate and a normal d-dimer test result (95 patients), normal perfusion scintigraphy (161 patients) and non-high probability lung scintigraphy followed by normal serial ultrasonography (210 patients). Of these 466 patients, venous thromboembolic complications during follow-up occurred in six (complication rate 1.3%, 95% confidence interval 0.5, 2.8). The diagnostic protocol was completed in 92% of all included patients. CONCLUSION: The diagnosis of pulmonary embolism can be safely ruled out by a non-invasive algorithm consisting of d-dimer testing combined with a clinical probability estimate, lung scintigraphy, or serial ultrasonography of the legs (in case of non-diagnostic lung scintigraphy).

The application of a Dutch consensus diagnostic strategy for pulmonary embolism in clinical practice.

In The Netherlands, the 'Dutch consensus strategy' was formulated in 1993 as a diagnostic strategy for patients with suspected pulmonary embolism. Four years after its introduction, the application of this strategy was investigated. A questionnaire was sent to the hospital management and the departments of internal medicine and pulmonology of all Dutch hospitals. In total, 384 questionnaires were sent out. The response rates of the internists and pulmonologists were 63 and 65%, respectively. The specialists reported to have followed the consensus strategy in 75% of the patients seen the month prior to the questionnaire. However, analysis of only the last patient with the suspicion of pulmonary embolism revealed that the consensus strategy was followed in 55 of the 162 patients. As well, an overuse and an underuse of the different diagnostic facilities was documented. Furthermore almost a quarter of the patients were treated without an ascertained diagnosis, whereas 11% were not treated despite an improper exclusion of venous thrombo-embolism. Compared to a survey in 1994, the use of the 'Dutch consensus strategy' has not improved dramatically. In 34% of the patients, the consensus strategy was strictly followed (i.e. without any additional investigation); however in 67% of the patients a proper diagnosis was achieved. In any diagnostic strategy, two aspects should be considered. First the availability of the different facilities. Second the acceptance of the strategy by the physicians, involved in the diagnosis of patients with clinically suspected pulmonary embolism.

Technegas versus (81m)Kr ventilation-perfusion scintigraphy: a comparative study in patients with suspected acute pulmonary embolism.

UNLABELLED: 81mKr is widely used as a ventilation agent to diagnose pulmonary embolism (PE). However, (81m)Kr is expensive, which limits its continuous availability. Technegas can be an alternative ventilation agent with the advantage of being less expensive and available daily. The aim of this study was to compare the value of technegas with that of (81m)Kr in the detection of PE. METHODS: Ninety-two consecutive patients (29 men; mean +/- SD, 53 +/- 17 y old) with at least one segmental perfusion defect (Hull criteria) were studied prospectively. Perfusion and ventilation (V/Q) lung scintigraphy with both technegas and (81m)Kr were performed within 24 h on all patients. V/Q lung scan results were classified as high probability for PE (normal ventilation study) or nondiagnostic (abnormal ventilation study). All V/Q lung scans were read by two experienced nuclear physicians in consensus. For the intra- and interobserver variabilities, two experienced observers independently read the V/Q lung scans. RESULTS: (81m)Kr and technegas showed a good agreement (kappa, 0.68; 95% confidence interval [CI], 0.53-0.82). However, technegas significantly increased the number of nondiagnostic V/Q lung scans (P: = 0.035). In 15 patients, a discrepancy was found between (81m)Kr and technegas. False-positive V/Q lung scan results occurred in 4 of 12 patients (33%) with (81m)Kr and in 2 of 3 patients (66%) with technegas. The intra- and interobserver variabilities were 0.71-0.88 (95% CI, 0.56-1.0) for perfusion/(81m)Kr and 0.74-0.96 (95% CI, 0.58-1.0) for perfusion/technegas. CONCLUSION: In comparison with (81m)Kr, technegas does not result in more false-positive V/Q lung scan results. The use of technegas, however, increases the number of nondiagnostic V/Q lung scan results, which would increase the demand for further additional testing to confirm or refute PE.

Diagnosing acute pulmonary embolism: effect of chronic obstructive pulmonary disease on the performance of D-dimer testing, ventilation/perfusion scintigraphy, spiral computed tomographic angiography, and conventional angiography. ANTELOPE Study Group. Advances in New Technologies Evaluating the Localization of Pulmonary Embolism.

In patients with chronic obstructive pulmonary disease (COPD), differentiating a pulmonary embolism (PE) from an exacerbation of COPD can be difficult, since clinical signs and symptoms of the two conditions overlap. Development of reliable noninvasive or minimally invasive techniques for the diagnosis of PE is, especially in these patients, necessary. In this study we assessed the effect of COPD on the accuracy of the clinical probability estimate (CPE), spiral computed tomographic angiography (SCTA), D-dimer analysis, ventilation perfusion (V/Q) scintigraphy, and pulmonary angiography for the diagnosis of PE. From May 1997 through March 1998, 627 consecutive patients with suspected PE were investigated in six teaching hospitals. In these patients, D-dimer testing, CPE, V/Q scintigraphy, and SCTA and/or pulmonary angiography were performed according to a strict diagnostic protocol. The patients were also independently categorized as having COPD or not. A diagnosis of COPD was established in 91 patients (15%). The prevalence of PE was similar in patients with and without COPD (29% and 31%, respectively), notwithstanding the larger proportion of nondiagnostic V/Q scan results in patients with COPD (46% versus 21%, p < 0.001). The distribution of CPEs, diagnostic value of the D-dimer assay and SCTA, and reproducibility of pulmonary angiography were comparable among patients with and without COPD. The presence of COPD does not affect the diagnostic performance of CPE, D-dimer testing, SCTA, or pulmonary angiography. Furthermore, although more nondiagnostic V/Q scan results can be expected in the presence of COPD, V/Q scintigraphy remains a valuable screening test in patients with COPD.

Availability of diagnostic facilities in the Netherlands for patients with suspected pulmonary embolism. ANTELOPE Study Group. Advances in New Technologies Evaluating the Localisation of Pulmonary Embolism.

Pulmonary embolism remains a complex diagnostic problem. Although accurate and cost-effective, the 'Dutch consensus' strategy is not widely applied. We assessed the availability and investment plans of the different facilities used in this strategy. Furthermore, the current and future availability of new diagnostic modalities was investigated. A questionnaire was sent to all Dutch hospitals. The questionnaire contained separate sections with questions for the hospital management and the medical practitioners at the departments of radiology, nuclear medicine, internal medicine and pulmonology. Five hundred and eighty-four questionnaires were sent out (response rate 68%). Forty-three percent of the hospitals had no nuclear medicine facility, 11% had no pulmonary angiography facility, and 59% had no spiral CT scan (SCTA). Forty-six percent of the responding hospitals had a nuclear medicine facility; and 5% used Technegas for ventilation studies. Strategies with SCTA were available in about 27% of the hospitals. Due to future investments this number will increase to approximately 55%. Strategies with Technegas were available in 2.4% of the hospitals, this number might increase to 25% if Technegas is proven accurate. The 'Dutch consensus' strategy is available in two-thirds of the hospitals. All other strategies were less feasible. Several equivalent strategies for diagnosing pulmonary embolism should be developed. These strategies should be accurate, widely available and accepted.