Use of continuous positive airway pressure (CPAP) to optimise oxygenation in anaesthetised horses--a clinical study.
Authors: Mosing M, Rysnik M, Bardell D, Cripps P J, MacFarlane P
Journal: Equine veterinary journal
Summary
# Editorial Summary: CPAP Optimisation During Equine Anaesthesia Hypoxaemia remains a significant challenge in equine anaesthesia, particularly when horses are positioned dorsally recumbent—a posture that naturally compromises oxygenation. Mosing and colleagues conducted a randomised clinical trial on 24 healthy horses undergoing routine anaesthesia, comparing spontaneous ventilation at physiological airway pressure against continuous positive airway pressure (CPAP) of 8 cmH₂O, with arterial blood gas analysis performed at induction and 30, 60 and 90 minutes thereafter. Horses managed with CPAP demonstrated substantially higher arterial oxygen tension (PaO₂) and improved oxygen indices without alterations to ventilation parameters or cardiovascular stability, though notably, 33% of the CPAP group and 67% of controls ultimately required assisted ventilation when hypercapnia developed. For practitioners, these findings suggest that applying modest positive pressure (8 cmH₂O) during spontaneous ventilation offers a practical, non-invasive means of extending adequate oxygenation during prolonged dorsal recumbency procedures, potentially delaying or reducing the necessity for controlled ventilation—though the authors appropriately highlight that further investigation into potential cardiovascular effects during extended anaesthesia remains warranted.
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Practical Takeaways
- •Using CPAP at 8 cmH2O during equine general anaesthesia can reduce the incidence of hypoxaemia in dorsally recumbent horses without adverse effects on blood pressure or drug requirements
- •CPAP improves oxygenation without affecting CO2 elimination, meaning it can be applied without routinely converting to controlled ventilation
- •Consider CPAP as a simple, non-invasive tool to optimise oxygenation during routine equine anaesthesia, particularly for horses at risk of hypoxaemia
Key Findings
- •CPAP at 8 cmH2O significantly increased PaO2 and oxygen indices compared to physiological airway pressure alone in anaesthetised horses
- •CPAP did not significantly affect ventilation indices (PaCO2) between groups
- •Eight horses (33%) in the PAP group required controlled ventilation versus 5 horses (21%) in the CPAP group
- •No significant differences in dobutamine requirements or mean arterial pressures were observed between groups