Canis ISSN: 2398-2942

Pneumomediastinum

Contributor(s): Andrew Gardiner

Introduction

  • Air within the mediastinal space, rendering normally invisible structures visible on radiography.
  • Normally, only the heart, aorta, caudal vena cava and tracheal lumen (not extraluminal borders) should be seen. Other structures are not discerned due to smaller size or because they are surrounded by structures of similar radiographic density.
    The mediastinum contains the heart, trachea, major blood vessels, esophagus, lymph nodes, vagus nerve, phrenic nerve, thoracic duct and thymus.
  • Cause: idiopathic, post-traumatic eg traumatic jugular venipuncture, iatrogenic, neoplastic or infective.
  • Signs: subcutaneous emphysema around head/neck, dyspnea/cyanosis seen only in severe cases.
  • Diagnosis: radiography.
  • Treatment: most cases resolve spontaneously however pneumomediastinum may coexist with other abnormalities, eg pneumothorax.
  • Prognosis: good.

Pathogenesis

Etiology

  • Trauma, eg penetrating injury, esophageal perforation, rupture of the trachea or bronchi, alveolar rupture, diaphragmatic hernia.
  • Idiopathic (spontaneous).
  • Iatrogenic, eg following thoracic surgery.
  • Neoplastic, eg erosions through the mediastinum by a developing neoplasm.
  • Infective, eg gas-forming organisms in the mediastinum.

Pathophysiology

  • Air enters the mediastinal space from adjacent structures or by tracking along tissue planes.
  • Air enters the mediastinal space.

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.
  • Järvinen A K et al (1995) Lung injury leading to respiratory distress syndrome in young Dalmatian dogs. J Vet Intern Med (3), 162-168 PubMed.
  • Wilson D V, Jevens D J (1994) What is your diagnosis? Pneumomediastinum and severe bilateral pneumothorax. JAVMA 204 (3), 347-348 PubMed.
  • Mitten R W (1982) Radiology of mediastinal diseases. Vet Clin North Am Small Anim Pract 12 (2), 193-211 PubMed.
  • Jones B R et al (1975) Spontaneous pneumomediastinum in the racing Greyhound. JSAP 16 (1), 27-32 PubMed.


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