Hemoptysis is the expectoration of blood from the respiratory tract. The first step in evaluation is to ascertain whether the bleeding is coming from the respiratory tree or instead originating from the nasal cavities (i.e., epistaxis) or the gastrointestinal tract (i.e., hematemesis) as the therapies for these etiologies will be significantly different. Once established as hemoptysis, the exact nature of the expectoration is important as the term can be applied to blood-tinged phlegm, the pink frothy sputum of pulmonary edema, or frank blood. Next steps include identifying the source and etiology of bleeding.
ANATOMY AND PHYSIOLOGY OF HEMOPTYSIS
Hemoptysis can arise from anywhere in the respiratory tract; from the glottis to the alveolus. Most commonly, bleeding arises from the bronchi or medium sized airways, but a thorough evaluation of the entire respiratory tree is often necessary.
A unique feature of the lung that predisposes to hemoptysis of varied severity is its dual blood supply—the pulmonary and bronchial circulations. The former is a low-pressure system that is essential to gas exchange at the alveolar level; in contrast, the bronchial arteries originate from the aorta and are under systemic pressure. The bronchial arteries supply the airways and have the ability to neovascularize tumors, dilate airways of bronchiectasis, and cavitary lesions. Most hemoptysis is due to vessels in the bronchial circulation and is, therefore, under systemic pressure, making it more challenging to arrest the bleeding.
Hemoptysis commonly results from infection, malignancy, or vascular disease; however, the differential for bleeding from the respiratory tree is varied and broad.
Most blood-tinged sputum and small-volume hemoptysis is due to viral bronchitis. Patients with chronic bronchitis are at risk for bacterial superinfection with organisms such as Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis, increasing airway inflammation and potential for bleeding. Similarly, patients with bronchiectasis are prone to hemoptysis with exacerbations of disease. Due to recurrent bacterial infection, bronchiectatic airways are dilated, inflamed, and highly vascular, supplied by the bronchial circulation. In several case series, bronchiectasis is the leading cause of massive hemoptysis and subsequent death.
Tuberculosis had long been the most common cause of hemoptysis worldwide, but it is now surpassed in industrialized countries by bronchitis and bronchiectasis. In patients with tuberculosis, development of cavitary disease is frequently the source of bleeding but rarer complications such as the erosion of a pulmonary artery aneurysm into a preexisting cavity (i.e., Rasmussen’s aneurysm) can also be the source.
Other infectious agents such as endemic fungi, Nocardia, and non-tuberculous mycobacteria can present as cavitary lung disease complicated by hemoptysis. In addition, Aspergillus species can develop into mycetomas within preexisting cavities, with neovascularization to these inflamed spaces leading to bleeding. Pulmonary abscesses and necrotizing pneumonia can cause bleeding by devitalizing lung parenchyma. Common responsible organisms include Staphylococcus aureus, ...