Flowmetry and spectrophotometry for the assessment of intestinal viability in horses with naturally occurring strangulating small intestinal lesions.
Authors: Verhaar Nicole, Grages Anna Marei, Bienert-Zeit Astrid, Schwieder Alexander, Reineking Wencke, Hewicker-Trautwein Marion, Kästner Sabine, Geburek Florian
Journal: Equine veterinary journal
Summary
# Laser Doppler Flowmetry and Spectrophotometry for Assessment of Intestinal Viability in Equine Colic Surgery Determining which sections of strangulated small intestine are viable enough to preserve during colic surgery remains a significant clinical challenge, and currently available intraoperative assessment tools lack robust validation. Verhaar and colleagues prospectively measured tissue microperfusion using laser Doppler flowmetry and spectrophotometry (LDFS) in 40 horses undergoing surgical correction of naturally occurring small intestinal strangulations, recording tissue oxygen saturation, haemoglobin concentration and blood flow before and after relieving the strangulation, then correlating these measurements with histopathological injury scores from biopsied segments. The type of strangulation substantially influenced blood flow patterns: pedunculated lipomas produced significantly lower tissue blood flow (13.9 AU) compared with epiploic foramen entrapments (65.2 AU), and importantly, segments showing severe mucosal damage (injury score >5) demonstrated measurably reduced blood flow during strangulation than those with minimal damage (61.1 AU difference). Oxygen saturation and haemoglobin measurements proved less discriminatory across lesion types. Whilst blood flow assessment shows promise for identifying mucosal injury before releasing the strangulation—particularly given the positive correlation between inflammatory cell infiltration and intraoperative blood flow measurements—substantial individual variability and unmeasured factors limit its current clinical utility as a standalone viability indicator. Clinicians should view LDFS as a supplementary tool that may enhance decision-making during colic surgery rather than relying upon it exclusively to determine resection boundaries.
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Practical Takeaways
- •Intraoperative blood flow measurement via laser Doppler flowmetry could help surgeons assess intestinal viability and predict mucosal damage severity before making resection decisions
- •Different types of strangulation cause markedly different ischaemic insults (lipoma entrapments are more severe than epiploic foramen), which may guide prognostic discussions and surgical planning
- •Individual variability in blood flow measurements is substantial, so this technique should complement rather than replace clinical assessment of colour, temperature, and motility when determining intestinal viability
Key Findings
- •Pedunculated lipoma strangulations showed significantly lower blood flow (13.9 AU) compared to epiploic foramen entrapments (65.2 AU), indicating varying degrees of ischaemia by strangulation cause
- •Segments with mucosal injury score >5 demonstrated lower tissue blood flow during strangulation than segments with MIS <4 (mean difference 61.1 AU, p=0.03)
- •Positive correlation found between inflammatory cell count and blood flow during strangulation (r 0.34, p=0.04), suggesting blood flow measurements may help identify mucosal injury
- •Tissue oxygen saturation and haemoglobin levels did not differ significantly between strangulation types, limiting their utility as viability indicators