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.
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Reference article
This is a summary article; read more in our article on lobar collapse.
Summary
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epidemiology
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broad and dependent on the underlying cause
young children: foreign body
adolescent: asthma
elderly patient: cancer
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presentation
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dependent on the underlying cause
acute presentations will likely result in breathlessness
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more chronic collapse may remain asymptomatic
symptoms may relate to the underlying cause, e.g. weight loss and cough
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pathophysiology
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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
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causes
inflammation: mucus plug in asthma
infection
neoplasia: lung cancer (an endobronchial tumor or external compression)
iatrogenic: malpositioned endotracheal tube
mechanical: inhaled foreign body
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investigation
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chest X-ray
confirms collapse
blood work for infection or possible cancer
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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
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treatment
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dependent on the cause of the collapse
foreign body should be removed
mucus may respond to chest physiotherapy
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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 should not 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 mucus.
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