Aspiration pneumonia

Aspiration pneumonia

Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials that enter the bronchial tree, usually oral or gastric contents (including food, saliva, or nasal secretions). Depending on the acidity of the aspirate, a chemical pneumonitis can develop, and bacterial pathogens (particularly anaerobic bacteria) may add to the inflammation.

Causes

Aspiration pneumonia is often caused by an incompetent swallowing mechanism, such as occurs in some forms of neurological disease (a common cause being strokes) or while a person is intoxicated. An iatrogenic cause is during general anaesthesia for an operation and patients are therefore instructed to be nil per os (NPO) for at least four hours before surgery.

Whether aspiration pneumonia represents a true bacterial infection or a chemical inflammatory process remains the subject of significant controversy. Both causes may present with similar symptoms.

Location

The location is often gravity dependent, and depends on the patient position. Generally the right middle and lower lung lobes are the most common sites of infiltrate formation due to the larger caliber and more vertical orientation of the right mainstem bronchus. Patients who aspirate while standing can have bilateral lower lung lobe infiltrates. The right upper lobe is a common area of consolidation in alcoholics who aspirate in the prone position. Depending on the acidity of the aspirate, a chemical pneumonitis can develop, and bacterial pathogens (particularly anaerobic bacteria) may add to the inflammation.

See also

References

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