This review is available as free full text in Emergency Medicine.
Here are some key points:
The definitions for massive hemoptysis (MH) in terms of volume vary widely and are not useful because of difficulty in estimating volume. A more practical definition of MH is any degree of hemoptysis sufficient to threaten respiratory function.
The most common causes of MH parallel the causes of all hemoptysis.
Surprisingly (to me anyway) pulmonary embolism can be a cause of MH.
80% of MH originates from the bronchial artery circulation and 20% from the pulmonary artery circulation and that generally under conditions of acute or chronic pulmonary hypertension.
Assemble the appropriate specialty help early. This will depend on the resources available at your institution and might include anesthesiology, pulmonary/critical care, thoracic surgery and interventional radiology.
Plan for early intubation and consider specialized techniques such as selective intubation (of the nonbleeding lung) or double lumen intubation if the appropriate expertise is available.
Plain chest xrays will identify the bleeding lung in most but not all cases. CT (contrast if the patient's kidneys can tolerate it) is the next imaging step if the patient is stable enough to make the trip to the department and lie flat. The specific technique chosen (CTA vs HRCT, etc.) depends on the suspected etiology.
Bronchoscopy would follow CT but may have to precede it in very unstable patients.
Whether rigid bronch is preferred over flexible bronch depends on the rate of bleeding, with the former preferred in some patients with more massive bleeding.
The article presents an algorithm for diagnosis and management.