Overview of Prospective Investigation of Pulmonary Embolism Diagnosis II

The Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) is a prospective multicenter study funded by the National Heart, Lung, and Blood Institute which began recruiting patients in the fall of 2001. It was designed to assess the efficacy of the spiral computed tomographic pulmonary angiogram in patients suspected of having acute pulmonary embolism (PE). In contrast to the original PIOPED study, which used contrast pulmonary angiography as the primary reference test for PE, PIOPED II will use a composite reference test for venous thromboembolism that is based on the ventilation/perfusion lung scan, venous compression ultrasound of the lower extremities, digital subtraction pulmonary angiography, and contrast venography in various combinations to establish the PE status of the patient. New criteria for ventilation/perfusion lung scan diagnosis have been developed for PIOPED II. This article describes the various techniques that will be used, the combination of the composite reference tests that will be used to determine the PE status of the patient, and the PIOPED II diagnostic criteria that will be used for the ventilation/perfusion scan diagnosis of PE in the study.