Clinical and instrumental diagnosis of pulmonary embolism

Pulmonary embolism shows a high mortality especially for the difficulty in establishing an early correct diagnosis. The pathophysiology and thus the clinical manifestations of pulmonary embolism (PE) are essentially conditioned by three factors: the size of the embolus, the pre-existing cardiorespiratory condition, the release caused by the embolus, of some substances or the activation of reflexes which tend to worsen the purely mechanical consequences of PE. The clinical manifestations resulting from the combination of these factors result in three clinical patterns: acute cor pulmonare, pulmonary infarction, acute dyspnea. PE symptoms may be absent in a moderate percentage of cases and if present, they are nonspecific. Some laboratory tests were shown to be of no diagnostic accuracy, as enzyme determination, a sign of necrosis, blood gas analysis, and determination of alveolar arterial oxygen gradient. Among blood coagulation tests, D-dimer determination was shown to be of some relevance. However, at present, it cannot be used to confirm the diagnostic suspicion of PE. Among the instrumental cardiologic procedures, while ECG has a poor diagnostic reliability, transesophageal echocardiography in central embolism may be able to visualize the embolus and to accurately assess the hemodynamic effects, supplying sufficient information for PE therapy. Even if imaging procedures as pulmonary angiography and more recently CT or MRI are the most reliable diagnostic tools, the diagnostic suspicion of PE in subjects at risk, the use of the examined methods and the search in these patients for the presence of lower limb deep vein thrombosis, often asymptomatic, may increase the number of treated patients thus decreasing the mortality of this disease.