Continuous measurement of arterial oxygenation in mechanically ventilated horses.
Authors: Hummer Emma V, Soares Joao H N, Crockett Douglas C, Aguiar Antonio J A, Tran Minh C, Cronin John N, Brosnan Robert J, Braun Christina, Formenti Federico
Journal: Equine veterinary journal
Summary
# Editorial Summary: Continuous Arterial Oxygenation Monitoring in Anaesthetised Horses Managing hypoxaemia during equine general anaesthesia remains challenging, largely because real-time arterial oxygen measurement has not been readily available; this study evaluated a novel fibreoptic sensor capable of continuously monitoring arterial partial pressure of oxygen (PaO2) in horses undergoing mechanical ventilation. Six healthy horses were anaesthetised in dorsal recumbency, with the fibreoptic sensor placed in a facial artery whilst researchers systematically reduced positive end-expiratory pressure (PEEP) in 5 cm H₂O decrements from 20 to 0 cm H₂O, comparing continuous sensor readings against standard blood gas analysis at each stage. The fibreoptic system demonstrated excellent agreement with reference measurements, achieving a mean bias of only 4% and a correlation coefficient of 0.98 (P <0.001), with 95% concordance in detecting directional changes in oxygenation—though technical limitations arose from clot formation during some ventilatory manoeuvres. For equine anaesthesia teams, this technology offers genuine potential to guide real-time ventilatory adjustments and individualise PEEP titration, provided the catheter system uses heparinisation to prevent blood clots that can compromise signal quality. Whilst the small sample size warrants larger studies, the findings suggest this continuous monitoring approach could meaningfully improve hypoxaemia prevention and management during prolonged equine procedures.
Read the full abstract on PubMed
Practical Takeaways
- •Continuous real-time PaO2 monitoring via fibreoptic sensor is feasible in anaesthetised horses and could improve management of hypoxaemia during general anaesthesia
- •Implementation requires heparinisation of the catheter system to prevent blood clots that generate artefactual noise in the PaO2 signal
- •The sensor shows excellent agreement with standard blood gas analysis, suggesting it could reduce need for frequent arterial sampling during long procedures
Key Findings
- •Fibreoptic sensor demonstrated strong correlation (r=0.98, P<0.001) with reference blood gas measurements for arterial oxygen partial pressure
- •Mean relative bias was 4% with limits of agreement between -17% and 29%
- •Concordance rate for detecting changes in PaO2 was 95% between sensor and reference measurements
- •Blood clot formation in catheter caused signal noise and prevented reliable measurements at certain PEEP levels