Lobar collapse (summary)

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This is a basic article for medical students and other non-radiologists

Lobar collapse is relatively common and occurs following obstruction of a bronchus. Gas is resorbed from the lung parenchyma distal to the obstruction resulting in the collapse of the lung, with volume reduction and negative mass effect.

Reference article

This is a summary article; read more in our article on lobar collapse.

Summary

  • epidemiology
    • broad and dependent on the underlying cause
      • young children: foreign body
      • adolescent: asthma
      • elderly patient: cancer
  • presentation
    • dependent on the underlying cause
      • acute presentations will likely result in breathlessness
      • more chronic collapse may remain asymptomatic
        • symptoms may relate to the underlying cause, e.g. weight loss and cough
  • pathophysiology
    • collapse occurs when the bronchus is obstructed
      • distal gas is absorbed
      • the volume of the lung decreases
      • if all gas is absorbed and obstruction is complete, a tiny wedge of pulmonary parenchyma remains
    • causes
  • investigation
    • chest X-ray
      • confirms collapse
    • blood work for infection or possible cancer
    • CT chest with contrast
      • assess an obstructing or compressing cancer
    • rigid bronchoscopy to locate and remove a foreign body
    • flexible bronchoscopy for suspected cancer to allow biopsy
  • treatment
    • dependent on the cause of the collapse
      • foreign body should be removed
      • mucus may respond to chest physiotherapy

Radiographic features

Chest radiograph

Chest x-rays are the primary method of the initial investigation because they are quick, cheap and relatively easy to perform. They give a good general assessment of the chest and will readily help identify collapse and consolidation.

In a lobar collapse, there is a complete collapse of one of the lobes in either lung. When this happens, we see structures on the chest x-ray in places that they shouldn't be because of volume loss. For example, in left lower lobe collapse, the left lower lobe reduces in volume as air is resorbed from the alveoli. As the volume decreases, the mediastinum is pulled towards the left side of the chest.

With no air left within the collapsed lobe, the density of the lung increases in that region and as described above, the volume decreases.

CT Chest

As with all chest imaging, CT will be more accurate. It will allow an accurate description of which part of which lung is involved.

Critically, CT is also very helpful to determine the likely cause. Is it an obstructing tumor? Or a foreign body, or just some mucous.

Medical student radiology curriculum