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07-09-2011 | Cardiology | Article

PE diagnostic algorithms not followed properly among clinicians


Free abstract

MedWire News:Study findings show that the complex set of diagnostic flow charts for pulmonary embolism (PE) are often not followed properly, putting patients at risk for adverse consequences.

"This improper use of an algorithm could lead to a potential delay of establishing or excluding PE, a delay of therapy and/or unnecessary treatment," say Kirsten Kortekaas (Leiden University Medical Center, The Netherlands) and colleagues.

The findings confirm the drawbacks of such widely implemented tests, suggesting that more simple algorithms may resolve this diagnostic management dilemma.

The researchers evaluated whetheran algorithm was correctly used in daily clinical practice for diagnosing acute PE among 130 patients aged a median of 52 years.

For the algorithm to function correctly, patients with suspected acute PE and a raised D-dimer test undergo a chest X-ray. If the chest X-ray isnormal, ventilation/perfusion (V/Q) scanning is required, while patients with an abnormal X-ray are directly referred for computed tomographic pulmonary angiography(CTPA).

Results of the V/Q scan were categorized as normal, nonhighprobability, or high probability for PE. PE was excluded if the V/Q or Q scan was normal. A nonhigh probability V/Q scan was followed by a CTPA scan to establish or exclude acute PE. High probability V/Q scans are indicative of PE and are characterized by the presence of at least a segmental perfusion defect and a concomitant normal ventilation scan.

Patients with confirmed PE on the CTPA scan or with a high probability V/Q scan are given therapeutic dose low molecular weight heparin, followed by vitamin K antagonists according to local practice.

When the researchers assessed V/Q scans of patients with suspected acute PE, they found that a chest X-ray was performed on101 (78%)of patients. Of these, 89 had a normal chest X-ray, while 12 had an abnormal X-ray. In line with the protocol, these 12 patients should have had a CTPA scan, although none of these patients underwent a CTPA scan directly.

Of the 130 V/Q or Q scans, 59% were normal. A V/Q scan showing a nonhigh probability for PE was observed in 23% of patients and a V/Q scan showing a high probability for PE was seen in 18% of patients. Of the 30 patients with a nonhigh probability V/Q scan, only three (10%) underwent an indicated CTPA scan.

In total, 74% of patients were treated according to protocol, starting with the V/Q scan as the baseline diagnostic tool with a prior normal chest X-ray. Evaluation of the 89 patients with a normal chest X-ray showed that two of the 16 patients with a nonhigh probability V/Q scan underwent a CTPA scan directly as indicated.

Of the 77 patients with a normal V/Q scan, five underwent a CTPA scan that was not indicated by the algorithm and four patients received a combination of vitamin K antagonists and low molecular weight heparin in spite of their normal V/Q or Q-scan.

Writing in the journal Thrombosis Research, the team calls for a prospective study investigating non-adherence to the protocol and its impact on morbidity and mortality.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Ingrid Grasmo

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