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Pneumothorax
Introduction
- Pneumothorax is air in the pleural cavity via lung, mediastinal or thoracic wall disease or injury.
- Can be divided into open, closed or tension pneumothorax.
- Signs: unilateral condition is quite well tolerated; respiratory distress, change in breathing patterns and arterial oxygen concentrations accompany severe or bilateral disease.
- Diagnosis: chest auscultation and percussion, thoracic radiography, ultrasonography and thoracocentesis are helpful.
- Treatment: includes aspiration of air and oxygen insufflation as well as treatment of any underlying cause.
- Prognosis: guarded, varying with initiating cause.
Presenting signs
- Signs of respiratory distress, tachypnea, nostril flaring with hypoxemia and cyanosis in severe cases.
- Trauma or injury to chest wall.
- Severe lung disease.
- Thoracocentesis or other intervention.
- Minimal clinical signs in mild unilateral cases.
- Prolonged choke or tracheal foreign body.
- Post partum in neonate due to rib fractures lacerating lungs.
Age predisposition
- Adults.
- Neonates.
Cost considerations
- Treatment.
- Loss of animal.
Pathogenesis
Etiology
- Trauma:
- Penetrating wounds to thorax .
- Puncture or rupture of trachea (intrathoracic) Trachea: foreign body .
- Rupture of esophagus Esophagus: trauma , eg following choke, FB.
- Parturitional trauma in neonates - fractured ribs.
- Secondary to:
- Pleuropneumonia Lung: pleuropneumonia - bacterial (pleuritis) or gangrenous pneumonia.
- Bronchopleural fistula.
- Rupture of emphysematous bullae.
- Iatrogenic:
- Thoracotomy - especially standing Thorax: thoracotomy .
- Subsequent to repair of diaphragmatic hernia Diaphragm: hernia .
- Thoracocentesis or thoracic drainage Thorax: thoracentesis .
- Excessive positive pressure ventilation, especially in the neonate → ruptured alveoli, bullae and pleural blebs.
Pathophysiology
- Uncommon.
- Air escapes into the pleural cavity via the lung, mediastinal space or thoracic wall.
- May be uni- or bi-lateral.
- Open, closed or tension pneumothorax.
- Leads to pulmonary collapse and prevents inspiratory lung expansion.
- A potentially life-threatening condition.
- Air can gain access to the pleural space by traversing the lung, mediastinal space and thoracic wall.
- Open pneumothoraxoccurs when a wound allows air to enter and leave the pleural cavity.
- Closed pneumothoraxinvolves trapping air within the chest.
- Tension pneumothoraxoccurs when a flap of tissue acts as a one way valve allowing air to enter but not leave the thorax.
- Unilateral pneumothorax may be tolerated quite well in the horse but if the thin, fenestrated caudal mediastinum breaks down, bilateral pneumothorax will ensue → severe impairment of lung function → death.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Joswig A & Hardy J (2013) Axillary wounds in horses and the development of subcutaneous emphysema, pneumomediastinum and pneumothorax. Equine Vet Educ 25 (3), 139-143 VetMedResource.
- Epstein K L (2009) Pneumothorax and pneumomediastinum: Causes, diagnosis and treatment. Equine Vet Educ 21 (12), 642-647 Wiley Online Library.
- Cornelisse C J et al (1999) What is your diagnosis? Bilateral pneumothorax. JAVMA 214 (9), 1323-1324 PubMed.
- Jorgensen J S (1997) What is your diagnosis? Unilateral pneumothorax with collapse of the left caudal lung lobe. JAVMA 210 (8), 1109-1110 PubMed.
- Hance S R et al (1992) Subcutaneous emphysema from an axillary wound that resulted in pneumomediastinum and bilateral pneumothorax in a horse. JAVMA 200 (8), 1107-1110 PubMed.
- Spurlock S L et al (1988) Consolidating pneumonia and pneumothorax in a horse. JAVMA 192 (8), 1081-1082 PubMed.
- Rantanen N W (1986) Disease of the thorax. Vet Clin North Am Equine Pract 2 (1), 49-66 PubMed.
- Thomson J U (1977) Emergency field treatment of pneumothorax in the horse. Vet Med Small Anim Clin 72 (2), 250 PubMed.
- Lowe J E (1967) Pneumothorax in a horse from a puncture wound - A case report. Cornell Vet 57 (2), 200-204 PubMed.