Experimentally Induced Open Pneumothorax in Horses.

Area of Science:

• Veterinary Medicine
• Cardiovascular Physiology
• Respiratory Physiology

Background:

• Open pneumothorax is a critical condition in horses, necessitating evaluation of its physiological effects.
• Understanding the correlation between pleural and esophageal pressures is crucial for diagnosis.

Purpose of the Study:

• To assess clinical, cardiovascular, pleural, and intra-abdominal pressures in horses following experimentally induced unilateral open pneumothorax.
• To evaluate the diagnostic utility of esophageal pressure and thoracic ultrasonography in equine pneumothorax.

Main Methods:

• Seven horses underwent left hemithorax thoracotomy to induce open pneumothorax for 60 minutes.
• Measurements included pleural pressure, esophageal pressure, arterial blood gases, left ventricular function, and ultrasonographic assessment.
• Data were collected at baseline, during pneumothorax, and for seven days postoperatively.

Main Results:

• A moderate correlation was found between esophageal pressure and pleural pressure (rs = 0.404, P < .00001).
• Esophageal pressure increased and arterial oxygen partial pressure decreased post-pneumothorax, returning to baseline by day 5 and day 3, respectively.
• No significant changes were observed in arterial carbon dioxide partial pressure, arterial blood pH, or left ventricular function.

Conclusions:

• Horses exhibit tolerance to open pneumothorax with minimal cardiovascular impairment.
• Esophageal pressure, combined with blood gas analysis and thoracic ultrasonography, can aid in diagnosing pneumothorax in horses.
• The study highlights the potential of non-invasive monitoring techniques for equine respiratory emergencies.