Early and late follow-up of pulmonary embolism.

This study includes 61 patients referred with pulmonary embolism (PE) during 1 year. At admission, blood gas analysis, chest radiography and pulmonary lung scan were obtained in each patient; in a subset of patients pulmonary angiography was also performed to make the definitive diagnosis. Patients were treated with heparin and, later, with oral anticoagulants. Blood gas analysis, chest radiograph and perfusion lung scan were repeated 7, 30, 180 and 365 days after the diagnosis to evaluate the usefulness of these techniques in the follow-up of PE. Arterial hypoxemia and perfusion impairment recovered in parallel, both in the acute phase after embolism (7 days) and later up to 1 year. The great majority of recovery occurred within the first month after embolization. Radiographic signs compatible with PE tended to decrease early and disappeared almost completely after 30 days. Arterial blood gas analysis and perfusion scintigraphy detected 8 recurrences of PE that would be missed by chest radiograph. Arterial hypoxemia and the enlargement of descending pulmonary artery were positively correlated with the number of unperfused lung segments and, thus, may help predicting the severity of perfusion impairment in the acute stage. In conclusion, blood gas analysis and chest radiograph may be employed with or without perfusion lung scan to follow patients with PE up to 1 month after embolization; after that, only blood gas analysis and perfusion lung scan may give useful information about recovery from or recurrence of PE.