Acute aspiration pneumonitis

Acute aspiration pneumonitis occurs when solid or liquid ingested particles get into the airways and lungs leading to inflammation.

This article will focus on the acute form of aspiration (c.f. chronic aspiration pneumonia), mainly in regards to its radiographic features, for a broader discussion, please, refer to the parental article on aspiration pneumonia.

Radiographic features

Features can be variable and can range from a pulmonary edema pattern to areas of consolidation. CT is superior to plain films in demonstrating mild aspiration and the distal airways involvement. Findings on imaging typically include :

  • centrilobular nodules, often in a tree-in-bud pattern 
    • reflect distal airways impaction of the aspirated particles 
  • ground-glass opacities
    • reflect the associated parenchymal inflammation 
  • central airways plugging may be seen  
  • segmental or lobar atelectasis 
    • enhancing lung parenchyma and volume loss 
  • consolidation 
    • may be mixed with areas of atelectasis, but instead shows no enhancement
    • "aspiration pneumonia" 

These changes may have a gravity-dependent distribution:

  • posterior segment of the upper lobes and the superior segment of the lower lobes - commonly seen when aspiration occurs in a recumbent patient
  • bilateral basal segments, middle lobe, and lingula - commonly seen in erect patients

In contrast to a chronic etiology, there is no or little evidence of prominent septal lines, regions of bronchiectasis/bronchioloectasis, and/or presence of a reticular interstitial pattern.

See also