Major pulmonary embolism, part 1: Presentation and basic diagnostic studies: Rapidly recognizing the lethal signs and symptoms

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 the ECG, chest radiograph, and arterial blood gas analysis, as well as the standard tests used to confirm PE. Newer modes of assessment, such as the alveolar dead space volume expressed as a percentage of the tidal volume and the D-dimer assay, have shown excellent sensitivity in the differential diagnosis of PE.