Authors: Scardia Annalaura, Mariani Pimenta Eutalio L, Ross Russell Robert I, Jones Gareth J, Staffieri Francesco
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Assessing pulmonary gas exchange during equine general anaesthesia typically requires arterial blood sampling and invasive calculations, but researchers at this institution evaluated whether a non-invasive SpO₂/FiO₂ diagram could reliably estimate intrapulmonary shunting in ten anaesthetised horses. By progressively reducing inspired oxygen from 1.0 to 0.21 and plotting the resulting oxygen saturations against a computer algorithm (which incorporated haemoglobin values and a fixed arterio-venous oxygen difference), the investigators compared the algorithm's shunt estimates (Sshunt) against calculated shunt values derived from arterial blood gas analysis at FiO₂ 1.0 and 0.21. Strong correlation existed between Sshunt and shunt calculated at FiO₂ 1.0 (r = 0.839, P = 0.0069), with moderate but statistically significant correlation at FiO₂ 0.21 (r = 0.644, P = 0.0443), indicating the SpO₂/FiO₂ diagram methodology tracked actual gas exchange reasonably well. For practitioners managing anaesthetised horses, this technique offers a practical means of assessing pulmonary function and ventilation adequacy without repeated arterial puncture, potentially enabling more frequent monitoring and real-time optimisation of ventilator settings during prolonged procedures.
Read the full abstract on PubMed
Practical Takeaways
- •The SpO2/FiO2 diagram offers practitioners a non-invasive method to assess gas exchange quality and intrapulmonary shunt in anaesthetized horses without requiring arterial blood sampling
- •This technique could improve intraoperative monitoring and guide ventilation management decisions during equine general anaesthesia
- •The tool shows better correlation at higher FiO2 levels (1.0), which may be relevant for perioperative oxygen titration strategies
Key Findings
- •SpO2/FiO2 diagram showed strong correlation with Fshunt 1.0 (r=0.839, P=0.0069)
- •SpO2/FiO2 diagram showed moderate correlation with Fshunt 0.21 (r=0.644, P=0.0443)
- •SpO2/FiO2 diagram proved to be a non-invasive tool for characterizing gas exchange during equine general anaesthesia