Sauter Philipp K, Steblaj Barbara, Kästner Sabine B R, Söbbeler Franz J, Reiners Julia K, Kutter Annette P N, Bautitsta Alvaro J Gutiérrez, Neudeck Stephan
Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Equine Vet J. 2025 Nov;57(6):1623-1634. doi: 10.1111/evj.14473. Epub 2025 Jan 22.
Microcirculation is the essential link between macrocirculation and cellular metabolism.
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.
In vivo experiments.
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.
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.
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.
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.
微循环是体循环与细胞代谢之间的关键环节。
验证我们的假设，即在内毒素血症实验期间微循环变量将呈现异质性血流模式，以及液体治疗和去甲肾上腺素（NA）输注将使改变的微循环变量恢复正常。
体内实验。
对6匹健康成年马使用右美托咪定、氯胺酮和地西泮进行麻醉，并在异氟烷麻醉下进行机械通气。静脉注射30 ng/kg大肠杆菌脂多糖诱导内毒素血症。120分钟后给予液体推注和去甲肾上腺素（NA）输注以维持正常血压。测量脉搏率（PR）和平均动脉血压（MAP），并通过旁流暗视野技术（德贝克尔密度（DBD）、灌注德贝克尔密度（PDBD）、灌注血管比例、微血管血流指数（MFI）、异质性指数（HI））、激光多普勒血流仪（血流）和白光光谱法（组织氧饱和度（tSO））在舌下、空肠和生殖区域获取微循环变量。在基线、内毒素注射后、60分钟和120分钟以及正常血压阶段进行测量。数据通过混合模型方差分析和Tukey-Kramer法进行分析。
空肠处的脉压变异度（PPV）随时间显著下降30%（p < 0.001）。舌下和生殖黏膜的MFI从基线到内毒素注射后60分钟以及从基线到内毒素注射后120分钟均下降（分别为2.9对1.4，p < 0.001；2.8对1.9，p < 0.01）。舌下HI从基线到内毒素注射后60分钟、120分钟和NA阶段均升高（分别为0.1对0.9，p = 0.02；对0.6，p = 0.01；对0.3，p = 0.01）。生殖HI从基线到内毒素注射后120分钟升高（0.2对1.1，p≤0.01），到NA阶段也升高（分别为0.16对0.53，p < 0.05）。观察者之间对MFI评估的一致性为中等（kappa = 0.4）。PR随时间从基线显著升高，MAP随时间从基线显著下降。
所获得的数据可能受到分泌物、压力伪像、检查者经验和采样位置的影响。血流未进行量化，且没有对照组。
总体而言，短期实验性内毒素血症对MFI和HI有负面改变；然而，它并未改变tSO、血流、DBD、PDBD或灌注血管比例。静脉液体治疗和NA未能将MFI和HI恢复到基线值。
