Measuring tissue oxygen saturation in the orad intestinal segment during equine colic surgery may aid in predicting the occurrence of postoperative ileus.
Authors: N. Verhaar, Anna Marei Grages, Fay J Sauer, Tobias Geiger, Wencke Reineking, M. Hewicker-Trautwein, F. Geburek, Sabine Kästner
Journal: American journal of veterinary research
Summary
# Editorial Summary During strangulation colic surgery, assessing the viability of intestine remaining after obstruction release presents a significant clinical challenge, particularly in predicting postoperative ileus and reflux. Verhaar and colleagues prospectively measured tissue oxygen saturation (tSO₂) and blood flow in the proximal (orad) intestine of 18 horses using laser Doppler flowmetry and spectrophotometry immediately following strangulation release, whilst also obtaining histological samples from 28 cases to correlate microscopic injury with perfusion measurements. Critically, horses with tSO₂ below 35% developed postoperative reflux in 100% of cases (6/6), compared to only 17% (1/6) of those with tSO₂ above 69%—a striking and clinically meaningful distinction—though survival to discharge did not differ significantly between these groups. Histological mucosal injury was consistently associated with postoperative reflux (100% versus 23% in non-injured segments), yet surprisingly, no significant difference in tSO₂ or tissue blood flow was detected between microscopically injured and non-injured segments, suggesting that intraoperative tissue oxygenation monitoring may provide independent prognostic value beyond histology. For practitioners, intraoperative spectrophotometry measurement of the orad intestine may offer a practical, objective tool to help guide decisions regarding resection margins and postoperative medical management intensity, though further work is needed to establish whether intervention based on low tSO₂ readings improves clinical outcomes.
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Practical Takeaways
- •Intraoperative measurement of tissue oxygen saturation in the intestine above a strangulation site can help predict which horses are at high risk for postoperative reflux and complications
- •Low oxygen saturation (<35%) readings during surgery should raise concern for poor outcomes even if the intestine appears viable and does not require resection
- •While mucosal injury on biopsy predicts postoperative reflux, oxygen saturation measurements offer real-time assessment during surgery before histological results are available
Key Findings
- •Horses with tissue oxygen saturation (tSO2) <35% had significantly higher postoperative reflux (6/6 cases) compared to tSO2 >69% (1/6 cases)
- •All horses with mucosal injury developed postoperative reflux (6/6), significantly more than those without mucosal injury (3/13)
- •Orad intestinal tSO2 and tissue blood flow were lower than previously reported in healthy horses following strangulation release
- •No significant difference in tSO2 or blood flow was detected between histologically injured and non-injured intestinal segments