Major pulmonary embolism, part 1: The basic diagnostic studies

The outcome for patients who have pulmonary embolism (PE) is largely determined by embolism size and underlying cardiopulmonary status. Major PE, defined by hemodynamic instability, is associated with a mortality rate of at least 30%. The patient's condition must be assessed accurately and without haste because the first "golden hour" following the onset of PE may be the only opportunity to save the patient's life. This assessment requires a rapid integration of the history and physical findings with basic tests, including electrocardiography, chest radiography, and arterial blood gas analysis, as well as the standard tests used to confirm PE. Newer modes of assessment, such as measurement of alveolar dead space volume expressed as a percentage of the tidal volume, the D-dimer assay, and cardiac troponin assays, have shown excellent sensitivity in the differential diagnosis of PE.