Equis ISSN 2398-2977

Respiratory: smoke inhalation

Contributor(s): Tim Brazil, Graham Munroe

Introduction

  • Cause: decreased inspired oxygen levels, superheated air and inspiration of various noxious gases and particulate material   →   damage to upper and lower respiratory tract. Animal most commonly trapped in burning building.
  • Signs: varying degrees of injury with: evidence of hair scorching, skin burns, dyspnea, coughing, secondary shock, mucous membrane changes, pulmonary edema, collapse and sudden death.
  • Diagnosis: history, chest auscultation, respiratory tract endoscopy, thoracic radiography and blood samples are helpful in assessing degree of damage.
  • Treatment: involves maintenance of arterial oxygen levels, cough suppression, alleviation of bronchoconstriction, pain control, cardiovascular support, secondary antibiotic cover and supportive care.
  • Prognosis: depends on severity of damage - guarded to poor.

Pathogenesis

Etiology

  • Animal trapped within an enclosed burning structure with minimal access to fresh air, eg barn/stable fires, road traffic accident.

Pathophysiology

  • Usually caused by animal becoming trapped in burning building.
  • Damage is caused by decreased inspired oxygen levels, superheated air, inspiration of various noxious gases and particulate matter.
  • Pulmonary edema, upper respiratory tract (URT) obstruction and pseudomembranous casts may all complicate the ensuing clinical picture.
  • Injury to pulmonary tissues is a result of decreased inspired oxygen levels, superheated air and inspiration of various noxious gases, eg carbon monoxide or cyanide, and particulate matter.
  • The type of noxious gases present depends on the type of material that is burning - carbon monoxide poisoning can occur   →   carboxyhemoglobin formation, tissue hypoxia and death.
  • Pulmonary edema results from:
    • Direct pulmonary epithelium damage.
    • Increased capillary permeability due to inflammatory mediators.
    • Progressive worsening over the first 18-24 h.
  • Superheated air may   →   severe URT edema and inflammation   →   upper airway obstruction and asphyxia.
  • Inhalation of particles coated with a variety of chemicals   →   long-term attachment to the respiratory mucosa and chemical injury.
  • Diffuse tracheobronchial mucosal sloughing can   →   pseudomembranous casts which may   →   partial or complete airway obstruction.

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.
  • Kemper Tet al(1993)Treatment of smoke inhalation in five horses.JAVMA202(1), 91-94 PubMed.


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