Changes in microcirculation variables in an acute endotoxaemic equine model.
Authors: Sauter, Steblaj, Kästner, Söbbeler, Reiners, Kutter, Bautitsta, Neudeck
Journal: Equine veterinary journal
Summary
# Editorial Summary: Microcirculatory Changes in Equine Endotoxaemia Endotoxaemia remains a critical challenge in equine practice, particularly given the essential role of microcirculation in delivering oxygen and nutrients to tissues during systemic inflammatory crises. Sauter and colleagues induced experimental endotoxaemia in six anaesthetised horses using E. coli lipopolysaccharide and monitored microcirculatory variables across multiple tissue beds (sublingual, jejunal and genital mucosa) using advanced imaging and spectroscopy techniques, both before and after conventional resuscitation with fluid therapy and noradrenaline infusion. The study revealed tissue-specific microvascular dysfunction: microvascular flow index (MFI) declined significantly at sublingual and genital sites (by approximately 50% at 60 minutes), whilst heterogeneity index increased substantially, indicating uneven perfusion distribution despite restoration of systemic blood pressure—notably, these alterations persisted even after pharmacological normalisation of mean arterial pressure and fluid resuscitation. Conventional haemodynamic targets may therefore mask ongoing microcirculatory derangement during endotoxaemia, suggesting that clinicians cannot rely solely on systemic parameters or peripheral perfusion markers to assess treatment efficacy in endotoxic cases. These findings warrant further investigation into alternative vasopressor strategies or adjunctive therapies that specifically address microvascular heterogeneity, particularly given the heterogeneous response across different vascular beds in naturally occurring equine sepsis and endotoxaemia.
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Practical Takeaways
- •Short-term endotoxaemia causes significant microcirculatory dysfunction in horses that persists despite conventional haemodynamic management with fluids and vasopressors
- •Clinical monitoring of blood pressure and heart rate alone is insufficient to assess microcirculatory adequacy during sepsis; regional tissue perfusion may remain compromised
- •Veterinarians managing endotoxaemic horses should recognise that normalising MAP does not guarantee restoration of organ microcirculation, suggesting need for additional interventions
Key Findings
- •Microvascular flow index (MFI) decreased significantly in sublingual and genital mucosa during endotoxaemia (2.9 to 1.4 at sublingual, p<0.001)
- •Heterogeneity index increased substantially in sublingual mucosa from baseline to ET60 (0.1 to 0.9, p=0.02) indicating flow redistribution
- •Perfused vessel proportion (PPV) decreased by 30% at the jejunum over time (p<0.001)
- •Intravenous fluid therapy and noradrenaline infusion failed to restore microcirculation variables to baseline values despite achieving normotension