E08 - Effect of Holding Time and Sampling Protocol on VCM-Vet Parameters Using Fresh Equine Blood.

Abstract: Background- Viscoelastic testing of equine blood has become more common with great potential to improve case management. A point-of-care (POC) testing device, the VCM-Vet, provides practical repeatable results in fresh equine blood.

Hypothesis/Objectives- Sample holding time and reuse will affect VCM-Vet coagulation parameters when using fresh equine blood without anticoagulant.

Animals- Eight adult horses from University Research/Teaching herd.

Methods- Blood collected by direct jugular venipuncture (18ga needle, 3ml syringe) was held at 37°C for 2,4,6 or 8 minutes according to 1 of 2 protocols. Syringes were gently inverted 2X, a small amount of blood expressed, testing cartridges filled and placed within the VCM-Vet device. Protocol 1: samples were processed from a single syringe. Protocol 2: 4 syringes were drawn through a single needle. VCM-Vet measures assessed included Clot Time(CT), Clot Formation Time(CFT), Alpha Angle, Amplitude 10/20min(A10/A20), Maximal Clot Firmness(MCF) and Lysis Index 30/45min(LI30/LI45). Differences examined using R, ANOVA Type Statistic (ATS) with Bonferroni adjustment, P ≤0.05.

Results- Protocol 1: CT decreased over time (P = 0.0003), 2-6min (P = 0.023, 2-8min (P < 0.001). Protocol 2: P > 0.05 for all parameters. Protocol 1 vs. Protocol 2: There was a significant effect of protocol but not time: CT (P = 0.003), CFT (P = 0.003), A10 (P < 0.001), A20 (P < 0.001), MCF (P < 0.001).

Conclusions and clinical importance: Holding time and handling protocol impact VCM-Vet testing result of fresh blood that is neither anticoagulated nor activated. Samples held unagitated for up to 8min, while warm, are useful.