Monday, May 16, 2011

Unilateral Decreased Lung Perfusion

Unilaterally decreased lung perfusion can be seen in about 3% of patients referred for ventilation/perfusion scans.

Differential considerations for matched (absent or decreased ventilation) unilateral decreased perfusion to the lung:
  • Pneumothorax:
  • Pnuemonectomy:
  • Massive pleural effusion:
  • Endobronchial obstruction: For example mucous plug, foreign body, and broncholithiasis. Hypoperfusion is due to hypoxic vasoconstriction.
  • Sweyer-James syndrome: Delayed wash-in with air trapping.
Differential considerations for mismatched (preserved ventilation) unilateral decreased perfusion to the lung:
  • Centrally obstructing mass: Compressing the main pulmonary artery. Most common cause
  • Radiation: Due to vascular and parenchymal damage. The case shown above is from a patient with prior radiation therapy. Ventilation is relatively preserved compared to perfusion.
  • Pulmonary agenesis or stenosis:
  • Pulmonary atresia (hypoplastic lung): Preserved ventilation to a small lung.
  • Aortic dissection: Rare cause. Due to direct compression of the right pulmonary artery by intramural ascending aortic hemorrhage.
  • Mediastinal fibrosis: Most commonly due to histoplasmosis. Can encase and obstruct the central pulmonary vessels
  • Pulmonary embolism: About 2% of cases of unilateral decreased perfusion.


No comments:

Post a Comment

Note: Only a member of this blog may post a comment.