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Home / Equine Research Bank / Equine Vet J / Changes in microcirculation variables in an acute endotoxaem...
Equine veterinary journal2025; doi: 10.1111/evj.14473

Changes in microcirculation variables in an acute endotoxaemic equine model.

Abstract: Microcirculation is the essential link between macrocirculation and cellular metabolism. Objective: To test our hypotheses that microcirculation variables will show a heterogeneous flow pattern during experimental endotoxaemia, and that fluid therapy and noradrenaline (NA) infusion will normalise altered microcirculation variables. Methods: In vivo experiments. Methods: Six healthy adult horses were anaesthetised with dexmedetomidine, ketamine, and diazepam and were mechanically ventilated under isoflurane anaesthesia. Endotoxaemia was induced with 30 ng kg Escherichia coli lipopolysaccharide intravenously. One hundred and twenty minutes later fluid bolus and noradrenaline (NA) infusion were administered to produce normotension. Pulse rate (PR) and mean arterial blood pressure (MAP) were measured and microcirculation variables were obtained by side-stream darkfield technique (de Backer density (DBD), perfused de Backer density (PDBD), proportion of perfused vessels, microvascular flow index (MFI), heterogeneity index (HI)), laser Doppler flowmetry (blood flow) and white light spectrometry (tissue oxygen saturation (tSO)) in sublingual, jejunal and genital area. Measurements were obtained at baseline, after endotoxin, at 60 and 120 min and during the normotensive phase. Data were analysed by mixed model variance analysis and Tukey-Kramer. Results: The PPV decreased significantly over time by 30% (p < 0.001) at the jejunum. MFI decreased from baseline to ET60 and from baseline to ET120 in sublingual and genital mucosa (2.9 vs. 1.4, p < 0.001 and 2.8 vs. 1.9, p < 0.01), respectively. The sublingual HI increased from baseline to ET60, ET120 and NA (0.1 vs. 0.9, p = 0.02; vs. 0.6, p = 0.01; vs. 0.3, p = 0.01), respectively. The genital HI increased from baseline to ET120 (0.2 vs. 1.1, p ≤ 0.01) and NA (0.16 vs. 0.53, p < 0.05, respectively). Moderate agreement between observers for MFI assessment was present (kappa = 0.4). The PR significantly increased, and MAP significantly decreased from baseline over time. Conclusions: The obtained data could be influenced by secretions, pressure artefacts, the experience of the examiner and the sampling location. Blood flow was not quantified and there was no control group. Conclusions: Overall, short-term experimental endotoxaemia did negatively alter MFI and HI; however, it did not alter tSO, blood flow, DBD, PDBD or proportion of perfused vessels. Intravenous fluid therapy and NA did not restore MFI and HI to baseline values.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-01-22 PubMed ID: 39844573DOI: 10.1111/evj.14473Google Scholar: Lookup
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Summary

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The research studies the microcirculation variables in horses suffering from an acute endotoxin reaction. By exposing healthy horses to E-Coli Bacteria and monitoring their responses, the experiment seeks to determine the effectiveness of fluid therapy and noradrenaline infusion in restoring regular microcirculation variables.

Research Methodology

  • Six healthy adult horses were selected for this in-vivo experiment.
  • They were induced with anesthesia and mechanically ventilated.
  • Endotoxaemia, a condition characterized by the presence of endotoxins in the blood, was triggered by injecting Escherichia coli lipopolysaccharide intravenously.
  • 120 minutes later, the horses were administered a fluid bolus and noradrenaline infusion to normalize their blood pressure.
  • The research team then measured various sublingual, jejunal and genital microcirculation variables such as Pulse Rate (PR), Mean Arterial Blood Pressure (MAP), tissue oxygen saturation (tSO), and others at different intervals post endotoxin exposure and during the normotensive phase. The noradrenaline and fluid therapy were observed in their effectiveness to restore balance in these variables.

Research Findings

  • The proportion of perfused vessels (PPV) decreased over time by 30% at the jejunum in the subjects.
  • The sublingual Heterogeneity Index (HI) and genital HI increased from baseline to the ET120 (endotoxin 120 minutes) phase and NA(noradrenaline) phase, respectively.
  • The Pulse Rate (PR) increased significantly while the Mean Arterial Blood Pressure (MAP) systematically decreased comparing from the baseline over time.
  • Moderate agreement was found between observers for Microvascular Flow Index (MFI) assessment with a kappa of 0.4.

Research Conclusion

  • The data collected could be influenced by several variables, like secretions, pressure-related artifacts, the expertise of the examining individual, and the sampling location.
  • Despite these potential sources of variation, the study found that short-term exposure to endotoxaemia adversely affected the MFI and HI variables.
  • In contrast, the condition did not influence other microcirculation variables, namely tSO, blood flow, DBD, PDBD, or the proportion of perfused vessels.
  • Moreover, the application of intravenous fluid treatment and noradrenaline infusion did not successfully restore MFI and HI to baseline values, raising questions about the effectiveness of this treatment approach in real-world scenarios.

Cite This Article

APA
Sauter PK, Steblaj B, Kästner SBR, Söbbeler FJ, Reiners JK, Kutter APN, Bautitsta AJG, Neudeck S. (2025). Changes in microcirculation variables in an acute endotoxaemic equine model. Equine Vet J. https://doi.org/10.1111/evj.14473

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Sauter, Philipp K
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Steblaj, Barbara
  • Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Kästner, Sabine B R
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
  • Clinic for Small Animals, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Söbbeler, Franz J
  • Clinic for Small Animals, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Reiners, Julia K
  • Tierärztliche Klinik für Kleintiere am Kaiserberg, Duisburg, Germany.
Kutter, Annette P N
  • Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Bautitsta, Alvaro J Gutiérrez
  • Clinic for Small Animals, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Neudeck, Stephan
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
  • Clinic for Small Animals, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.

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