This chapter discusses the diagnosis, evaluation and management of pulmonary embolism (PE). The evaluation for suspected PE is tailored to the level of the clinician's suspicion for this diagnosis based on the patient's history, physical examination, and risk factors. A chest radiograph is rarely diagnostic for PE, but can identify alternative diagnoses. Hampton's hump, a pleural-based, wedge-shaped area of infiltrate, can be seen in pulmonary infarction and is suggestive of PE. Patients diagnosed with PE should be started on anticoagulation unless otherwise contraindicated to prevent clot propagation. Patients with a high clinical probability of PE should be started on anticoagulation therapy while awaiting diagnostic confirmation. The most common causes for sudden decompensation are respiratory and hemodynamic as the result of sudden shift or increase in clot burden. Intubation may be necessary to improve oxygenation/ventilation and establish control of the airway of the patient with PE.