Canis ISSN: 2398-2942

Lung: aspiration pneumonia

Introduction

  • Term often used synonomously with inhalation pneumonia however inhalation applies only to breathing in of irritant by smoke while aspiration implies accidental entry into respiratory tract of material from GI tract.
  • Cause: aspiration of solid or liquid into airways.
  • Signs: coughing, sudden onset dyspnea.
  • Diagnosis: history, radiography.
  • Treatment: antibiotics, symptomatic care.
  • Prognosis: guarded - to some extent depends on material aspirated.

Pathogenesis

Etiology

  • Laryngeal dysfunction:
    • Iatrogenic post-surgery.
  • Cricopharyngeal achalasia.
  • Megaesophagus.
  • Iatrogenic (administration of medication into airways instead of gastrointestinal tract).
  • Protracted vomiting.
  • Prolonged recumbency.

Pathophysiology

  • Aspiration of foreign substance into lungs → alveolar wall damage → inflammatory cell infiltration.
  • The severity of the damage depends to some extent on the nature of the material aspirated:
    • Acid material (pH <2), ie stomach contents causes very severe damage.
    • Inert material, eg barium or liquid paraffin may not cause severe damage initally but is not readily cleared from respiratory tree and may persist for years resulting in granulomatous changes.
    • Large volumes of aspirate not only damage a larger area of respiratory epithelium but volumes of liquid may have a near drowning effect.
  • Secondary bacterial infection due to aspiration of bacteria or as a result of damage to the alveoli reducing immunocompetence.

Timecourse

  • Often acute onset signs.
  • In animals with laryngeal dysfunction may be chronic course with repeated aspiration of foreign material.
  • These animals may show acute episodes of exacerbation as a result of secondary bacterial infections.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Broe P J, Toung T J, Permutt S & Cameron J L (1983) Aspiration pneumonia - treatment with pulmonary vasodilators. Surgery 94 (1), 95-99 PubMed.


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