Spiral computed tomography for the diagnosis of pulmonary embolism in critically ill surgical patients - A comparison with pulmonary angiography

Hypothesis: Spiral computed tomographic pulmonary angiography (CTPA) is sen sitive and specific in diagnosing pulmonary embolism (PE) in critically ill surgical patients. Design: Prospective study comparing CTPA with the criterion standard, pulmo nary angiography (PA). Setting: Surgical intensive care unit of an academic hospital. Patients: Twenty-two critically ill surgical patients with clinical suspici on of PE. The CTPAs and PAs were independently read by if radiologists (2 f or each rest) blinded to each other's interpretation. Clinical suspicion wa s classified as high, intermediate, or low according to predetermined crite ria. All but 2 patients had marked pulmonary parenchymal disease at the tim e of the event that triggered evaluation for PE. Interventions: Computed tomographic pulmonary angiography and PA in 22 pati ents, venous duplex scan in 19. Results: Eleven patients (50%) had evidence of PE on PA, 5 in central and 6 in peripheral pulmonary arteries. The sensitivity and specificity of CTPA was, respectively, 45% and 82% for all PEs, 60% and 100% for central PEs, a nd 33% and 82% for peripheral PEs. Duplex scanning was 40% sensitive and 10 0% specific in diagnosing PE. The independent reviewers disagreed only in 1 4% of CTPA and 14% of PA interpretations. There were no differences in risk factors or clinical characteristics between patients with and without PE. The level of clinical suspicion was identical in the 2 groups. Conclusions: Pulmonary angiography remains the gold standard for the diagno sis of PE in critically ill surgical patients. Computed tomographic pulmona ry angiography needs further evaluation in this population.