Rossi Tanya M, Smith Stephanie A, McMichael Maureen A, Wilkins Pamela A
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
Am J Vet Res. 2015 Feb;76(2):122-8. doi: 10.2460/ajvr.76.2.122.
To evaluate the degree of activation of the contact pathway in citrated equine whole blood over holding times ≤ 30 minutes and assess effects of contact activation on recalcification-initiated thromboelastometry.
11 healthy adult mixed-breed horses.
Blood was collected by atraumatic jugular venipuncture into prewarmed evacuated siliconized glass tubes containing citrate anticoagulant and held at 37°C for ≤ 30 minutes. Thromboelastometry was performed with an in vitro viscoelasticity (thromboelastometry) monitoring system. Factor XII and factor XI procoagulant activities were determined in contemporaneously collected platelet-poor plasma samples by assessing changes in turbidity for 1 hour at approximately 25°C, with clotting times calculated by fitting a line to the steepest segment of the absorbance curve and determining its intersection with baseline. Effect of holding time on thromboelastometry parameters and plasma enzyme activity was evaluated by repeated-measures ANOVA on ranks. Association of procoagulant activities with coagulation time was determined by Spearman rank-order correlation analysis.
Thromboelastometry parameters (coagulation time, clot formation time, α angle, and maximum clot firmness) reflected significant increases in coagulability during the holding period. Factor XII and factor XI procoagulant activities were significantly increased at 30 minutes, compared with 2 or 10 minutes (indicating contact activation of samples), and had significant negative correlation with coagulation time.
Ex vivo activation of the contact system in equine whole blood was evident, suggesting that recalcification of blood in the absence of a trigger is not an acceptable method of assessing the hemostatic system in horses.
评估在枸橼酸化马全血中保存时间≤30分钟时接触途径的激活程度，并评估接触激活对再钙化启动的血栓弹力图的影响。
11匹健康成年杂种马。
通过无创伤性颈静脉穿刺采集血液，注入预先温热的含有枸橼酸盐抗凝剂的抽空硅化玻璃管中，并在37°C下保存≤30分钟。使用体外粘弹性（血栓弹力图）监测系统进行血栓弹力图检测。通过在约25°C下评估1小时内的浊度变化，在同期采集的乏血小板血浆样本中测定因子XII和因子XI促凝活性，通过将一条线拟合到吸光度曲线的最陡部分并确定其与基线的交点来计算凝血时间。通过秩重复测量方差分析评估保存时间对血栓弹力图参数和血浆酶活性的影响。通过Spearman秩相关分析确定促凝活性与凝血时间的关联。
血栓弹力图参数（凝血时间、血栓形成时间、α角和最大血栓硬度）反映了保存期间凝血能力的显著增加。与2分钟或10分钟相比，因子XII和因子XI促凝活性在30分钟时显著增加（表明样本发生接触激活），并且与凝血时间呈显著负相关。
马全血中接触系统的体外激活明显，这表明在没有触发因素的情况下对血液进行再钙化不是评估马止血系统的可接受方法。
