Sidestream dark field imaging and biomarker evaluation reveal minimal significant changes to the microcirculation and glycocalyx in a canine hemorrhagic shock model.

OBJECTIVE: To investigate the effects of hemorrhagic shock and fresh whole blood resuscitation on the microcirculation and endothelial glycocalyx using sidestream dark field (SDF) imaging and plasma biomarkers. ANIMALS: 8 purpose-bred dogs. METHODS: Pressure-targeted hemorrhagic shock was induced in anesthetized dogs. SDF measurement of perfused boundary region and microcirculatory variables (RBC flow, total vessel density, and relative and absolute capillary blood volume), biomarker measurement (heparan sulfate, hyaluronan, VE-cadherin, and syndecan-1), mean arterial blood pressure, and cardiac output measurement were performed before anesthesia (TP0), after induction (TP1), after hemorrhagic shock (TP2), and after 50% retransfusion (TP3) and 100% retransfusion (TP4). RESULTS: At TP1, TP2, TP3, and TP4, mean arterial blood pressure was 74.25 ± 7.17 mm Hg, 49.50 ± 13.74 mm Hg, 63.50 ± 13.29 mm Hg, and 71.38 ± 8.77 mm Hg, and cardiac output was 2.57 ± 1.01 L/min, 0.8 ± 0.36 L/min, 1.81 ± 0.57 L/min, and 2.93 ± 1.22 L/min, respectively. Heparan sulfate, hyaluronan, syndecan-1, and VE-cadherin ranges were 24.80 to 77.72 ng/mL, 5.77 to 105.06 ng/mL, below detection to 1,545.69 pg/mL, and 0 to 2.52 ng/mL, respectively. Perfused boundary region, RBC flow, total vessel density, and relative and absolute capillary blood volume ranges were 1.75 to 2.68 µm, 89.6 to 584.5 µm/s, 51.7 to 1,914.3 mm/m2, 0.94 to 1.53 103 µm3, and 1.50 to 94.30 103 µm3, respectively. Heparan sulfate decreased significantly over time (P = .016). No significant differences were found for microcirculatory variables, perfused boundary regions, or other biomarkers. CLINICAL RELEVANCE: This was the first study to assess microvascular dysfunction and endothelial shedding in a canine hemorrhagic shock model using SDF microscopy (Glycocheck) and plasma biomarkers. Further studies are needed to determine clinical relevance.

Comparison of placement characteristics using two intraosseous devices in canine and feline cadavers by novice users.

Introduction: Intraosseous (IO) catheterization enables rapid access to systemic circulation in critical patients. A battery-powered IO device (BPIO) utilized in veterinary practice is reliable in facilitating IO catheter placement. A new spring-powered IO device (SPIO) has been developed for people but has not been tested in veterinary patients. The goal of our study was to compare placement characteristics and flow rates achieved with the BPIO compared to the SPIO in animals when operated by novice users. Methods: Six veterinary students performed 72 catheterizations in the humeri and tibias of 12 dog and 6 cat cadavers. The user, cadaver, device, and site of placement were randomized. Flow rates were determined by three-minute infusions. Results: In dogs, overall success rates (50% BPIO, 46% SPIO; p = 0.775) and flow rates based on location were similar between devices. Successful placement was faster on average with the BPIO (34.4 s for BPIO and 55.0 s for SPIO, p = 0.0392). However, time to successful placement between devices was not statistically significant based on location (humerus: 34.7 s for BPIO and 43.1 s for SPIO, p = 0.3329; tibia: 33.3 s for BPIO and 132.6 s for SPIO, p = 0.1153). In cats, success rates were similar between devices (16.7% for BPIO and 16.7% for SPIO, p = 1.000), but limited successful placements prevented further analysis. Discussion: This is the first study to examine the use of the SPIO in animals, providing preliminary data for future IO studies and potential applications for training in the clinical setting.