Key Clinical Questions
What is the initial approach in a evaluating a patient with suspected hemoptysis?
What are the causes of hemoptysis, and what clinical features can suggest the mechanism of hemoptysis?
What are the diagnostic tests that should be performed for a patient with hemoptysis?
What are treatment modalities for hemoptysis, and when is each appropriate?
Hemoptysis is coughing or spitting up blood or blood mixed with phlegm as a result of bleeding in the lower respiratory tract. The lower respiratory tract is defined as any part of the respiratory system that is below the vocal cords or glottis. This includes the trachea, bronchi, and pulmonary parenchyma. This definition is important in that blood that is generated from other sources has a very different evaluation, triage and treatment.
Hemoptysis may range from large amounts of frank blood to light streaks of blood in the sputum, which suggests that hemoptysis has diverse etiologies and pathology. Bleeding from the lower respiratory tract occurs from one of two sources: either the high-pressure systemic arterial blood supply or the lower pressure pulmonary arteries and their branches.
The lower respiratory tract blood supply starts proximally with the inferior thyroid arteries supplying the upper trachea. Next, the bronchial arteries, originating from the aorta at the level of T3 to T8, travel along the tracheobronchial tree with small penetrating arteries feeding the lower trachea and bronchi. The bronchial arteries end by anastomosing with branches of the pulmonary arteries, together forming the capillary bed around the alveoli. The pulmonary arteries travel alongside the bronchial arteries on the tracheobronchial tree, but only perform oxygen exchange once at the alveoli.
The significance of these anatomical considerations is that massive hemoptysis (defined below) is more likely coming from the systemic arteries, and the volume of blood may help elucidate the origin of the bleeding. Ninety percent of cases of massive hemoptysis are from bronchial arteries. The remaining 5% of cases are from the pulmonary arteries and 5% from other arteries.
It is also important to realize that bronchial, but not pulmonary arteries proliferate in the setting of inflammation. They can enlarge, become tortuous, and create pathologic high-pressure anastomosis with nearby pulmonary arteries. These abnormal vessels are highly prone to bleeding, and explain (in part) the hemoptysis encountered with chronic inflammatory disease (eg, cystic fibrosis, bronchiectasis), and facilitate our understanding of recurrent bleeding in these disorders.
ETIOLOGY OF SUSPECTED HEMOPTYSIS
There are many causes of hemoptysis, with some of the more common listed in Table 90-1. The differential diagnosis of hemoptysis depends primarily on the patient population. In the so-called developed world, the most common causes encountered are bronchitis, bronchogenic carcinoma, bronchiectasis, pneumonia, and tuberculosis. A recent review found that pulmonary embolism is also a common cause of hemoptysis. In ...