Is a V/Q scan based algorithm correctly used to diagnose acute pulmonary embolism? A daily practice survey

Diagnostic flow-charts for pulmonary embolism (PE) are widely implemented in the management of PE. A major drawback of a diagnostic PE algorithm is the use of several consecutive tests, which may be challenging in daily clinical practice.

Evaluation whether the use of an algorithm, starting with a ventilation/perfusion (V/Q) scan after a normal chest X-ray, is correctly used in daily clinical practice for diagnosing acute PE. Consecutive V/Q scans of patients with suspected acute PE were assessed to evaluate the use of the predefined diagnostic algorithm.

A chest X-ray had been performed in 101 of the 130 patients who underwent V/Q scanning; 89 patients had a normal chest X-ray. The V/Q scan was normal in 77/130 patients (59%), 30/130 patients (23%) had a non-high probability and 23/130 patients (18%) a high probability for PE. Only 3 of the 30 patients with a non-high V/Q scan (10%) underwent a computed tomographic pulmonary angiography (CTPA) scan, in contrast to the algorithm that required a CTPA scan in every patient with a non-high V/Q scan. Overall, the diagnostic strategy, starting with a V/Q scan as the baseline diagnostic tool with a prior chest X-ray, was appropriately followed in only 75/101 patients (74%).

A complex diagnostic algorithm for diagnosing PE is often not followed properly. 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. More simple algorithms could resolve this diagnostic management dilemma.