Effects of 2 modes of positive pressure ventilation on respiratory mechanics and gas exchange in foals.
Authors: Raidal Sharanne L, Catanchin Mel, Sacks Muriel, Carstens Ann, Quinn Chris, Mosing Martina
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Positive Pressure Ventilation in Foals When sedated foals are positioned dorsally, their arterial oxygen levels and breathing mechanics deteriorate significantly—a problem that clinicians managing anaesthetised or critically ill young horses must address. Raidal and colleagues conducted a controlled crossover trial in six healthy foals, applying both continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) whilst measuring arterial blood gases, lung volumes via CT imaging, capnography, and spirometry to determine which mode offered superior respiratory support. CPAP proved particularly effective, raising arterial oxygen pressure without causing carbon dioxide retention, whilst volumetric capnography demonstrated improved ventilation:perfusion matching and enhanced CO₂ clearance; both modalities increased tidal volume, reduced respiratory rate, and expanded lung aeration as visualised on computed tomography. Peak inspiratory pressure showed a moderate correlation with oxygenation and lung volumes, suggesting that pressure titration during ventilation deserves careful attention in clinical practice. For equine practitioners involved in anaesthesia, intensive care, or respiratory rehabilitation, these findings support the use of positive pressure modalities to counteract the respiratory depression common in recumbent or critically ill foals, with CPAP appearing a particularly robust choice for maintaining gas exchange during challenging cases.
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Practical Takeaways
- •CPAP and PSV are effective tools for managing respiratory compromise in sedated or critically ill foals, with both modes improving oxygenation and ventilation without causing carbon dioxide retention
- •Dorsal recumbency during sedation significantly impairs respiratory function in foals; positive pressure ventilation can effectively counteract these effects
- •CT imaging and volumetric capnography provide objective measures of ventilation improvement that correlate with clinical benefit, useful for assessing response to respiratory support in practice
Key Findings
- •CPAP improved arterial oxygen pressure without causing hypercapnia in sedated foals with induced respiratory insufficiency
- •Both CPAP and PSV decreased respiratory rate and increased tidal volume, indicating improved lung mechanics
- •Volumetric capnography showed improved ventilation-perfusion matching and increased CO2 elimination during positive pressure ventilation
- •Peak inspiratory pressure was moderately associated with PaO2 and lung volume, with increased pulmonary aeration evident on CT imaging