Hemoptysis pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]

Pathophysiology

Physiology

• Lung has two main vascular systems that include pulmonary circulation and bronchial circulation.
• There are multiple anastomoses between pulmonary and bronchial arteries which create physiologic right to left shunts.
  • Pulmonary circulation
    • It provides gas exchange where deoxygenated blood enters the lungs through pulmonary arteries and oxygenated blood returns to circulation through pulmonary veins.
    • Pulmonary arteries
    • Pulmonary veins

Illustration from Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0,

This slide shows the arterial and venous blood circulation of the pulmonary system. By Artwork by Holly Fischer - http://open.umich.edu/education/med/resources/second-look-series/materials - Respiratory Tract Slide 20, CC BY 3.0,

• Bronchial vessels

• Bronchial vessels provide blood and nutrients to the bronchi and connective tissue of the lungs. They supply blood to the respiratory bronchioles and the visceral pleura of the lung.
• Bronchial arteries carry oxygenated blood to the lung tissues. They are arised from the thoracic aorta. There are usually two branches to the left lung and one to the right lung.
• Bronchial veins return the deoxygenated blood from the lung tissues to the systemic circulation. The right side drains into the azygos vein and the left side drains into the left superior intercostal vein or the accessory hemiazygos vein.

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Pathogenesis

• Hemoptysis is an important symptom that has different etiologies and pathogenesis mechanisms.
• Blood in the hemoptysis is mostly originated from the Lung. However, it could be from the gastrointestinal system as well.
• Primary origin of the blood comes from bronchial arteries.
• Hemoptysis could be happened following infarction and ischemia of pulmonary parenchyma. It is seen in following conditions:
  • Pulmonary emboli
  • Vasculitis including:
    • Wegener's granulomatosis
  • Infections including:
    • Staphylococcus aureus
    • Pseudomonas aeruginosa
    • Aspergillus fumigatus
    • The phycomycetes
• Another mechanism of hemoptysis is vascular engorgement with erosion. It is seen in following conditions:
  • Acute infection such as
    • Viral bronchitis
    • Bacterial bronchitis
  • Chronic infection such as bronchiectasis
  • Toxic exposure such as cigarette smoke