Pulmonary gas exchange and plasma lactate in horses with gastrointestinal disease undergoing emergency exploratory laparotomy: a comparison with an elective surgery horse population.
Authors: McCoy Annette M, Hackett Eileen S, Wagner Ann E, Mama Khursheed R, Hendrickson Dean A
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Emergency colic surgery presents distinct physiological challenges compared to elective procedures, yet the extent to which anaesthetic-induced hypoxaemia contributes to post-operative outcomes remains poorly understood. McCoy and colleagues prospectively monitored arterial blood gas parameters and plasma lactate in 50 horses undergoing emergency exploratory laparotomy for acute intestinal disease alongside 20 control horses undergoing elective dorsal recumbency surgery, using standardised anaesthetic protocols with serial sampling at predetermined time points. Contrary to expectations, arterial oxygen tension and alveolar-arterial oxygen gradients were comparable between groups and showed no correlation with post-operative outcome; notably, oxygenation improved in colic horses following colon exteriorization. Arterial lactate measurements proved far more clinically valuable: recovery lactate ≥5 mmol/L conveyed a 2.25-fold increased risk of post-operative complications, whilst ≥7 mmol/L indicated a 10.5-fold increased mortality risk. These findings suggest that post-operative lactataemia—reflecting tissue hypoperfusion and systemic compromise rather than anaesthetic-induced pulmonary dysfunction—offers a pragmatic prognostic indicator for clinicians managing acute colic cases, shifting focus from oxygenation monitoring towards metabolic assessment as a key predictor of survival and morbidity.
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Practical Takeaways
- •Measure arterial lactate immediately upon recovery from anesthesia in colic cases—lactate levels are a strong predictor of postoperative complications and mortality risk, more useful than oxygen metrics
- •Do not rely on PaO2 or oxygen gradient measurements alone to predict colic horse outcomes; these were not associated with complications or death in this population
- •Elevated lactate (≥5 mmol/L) should trigger heightened postoperative monitoring and aggressive supportive care protocols for colic patients
Key Findings
- •Arterial lactate ≥5 mmol/L in recovery was associated with 2.25× greater relative risk of postoperative complications in colic horses
- •Arterial lactate ≥7 mmol/L was associated with 10.5× higher relative risk of death
- •PaO2 and alveolar-arterial oxygen gradient were not significantly different between emergency colic and elective surgery groups and did not correlate with outcome
- •PaO2 increased significantly in colic horses after colon exteriorization but hypoxemia was not predictive of postoperative complications