Pittman Jennifer R, Koenig Amie, Brainard Benjamin M
Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
J Vet Emerg Crit Care (San Antonio). 2010 Apr 1;20(2):216-23. doi: 10.1111/j.1476-4431.2010.00519.x.
To determine the effect of single and multiple doses of SQ heparin (200 U/kg) on the thrombelastogram of healthy dogs.
Prospective study.
University research facility.
Six random-source female dogs.
Baseline parameters, including a CBC with platelet count, prothrombin time, activated partial thromboplastin time (aPTT), and antithrombin were performed. Thrombelastography (TEG) and aPTT were performed hourly for 12 hours after unfractionated heparin dosing (200 U/kg, SQ). Anti-Xa activity was assayed at 0, 3, 6, and 8 hours. Heparin was then administered every 8 hours for 3 days. The sampling protocol on Day 4 was identical to Day 1.
On Day 1, percentage change from baseline for TEG parameter R, as well as absolute values of K, angle, and maximum amplitude (MA) were evaluated. Statistically significant (P<0.01) prolongation of the R time and a decrease in angle and MA was seen in all dogs by hour 3. R and MA were unmeasurable for most dogs between 3 and 5 hours. All TEG tracings returned to baseline by 12 hours. Day 4 TEG tracings mimicked those on Day 1. Only 1 dog achieved aPTT values outside the reference interval on both days. Anti-Xa activity levels increased on Day 4 but not on Day 1. Based on post hoc in vitro analysis, prolongation of R time occurred at plasma heparin levels as low as 0.075 U/mL, well below the lower limit of detection of the anti-Xa activity level assay.
Administration of SQ heparin results in progressive changes in the TEG tracing, with maximal change occurring 3-5 hours after dosing. The extensive prolongation of the R time also indicates that TEG may be too sensitive and limits its utility as a monitoring tool for unfractionated heparin therapy.
确定单次和多次剂量的皮下注射肝素（200 U/kg）对健康犬血栓弹力图的影响。
前瞻性研究。
大学研究机构。
6只随机来源的雌性犬。
进行基线参数检测，包括全血细胞计数及血小板计数、凝血酶原时间、活化部分凝血活酶时间（aPTT）和抗凝血酶检测。在给予普通肝素（200 U/kg，皮下注射）后12小时内，每小时进行一次血栓弹力图（TEG）和aPTT检测。在0、3、6和8小时测定抗Xa活性。然后每8小时给予肝素，持续3天。第4天的采样方案与第1天相同。
在第1天，评估TEG参数R相对于基线的百分比变化以及K值、角度和最大振幅（MA）的绝对值。到第3小时，所有犬的R时间均出现具有统计学意义（P<0.01）的延长，角度和MA降低。在3至5小时期间，大多数犬的R和MA无法测量。所有TEG描记图在12小时时恢复到基线。第4天的TEG描记图与第1天相似。只有1只犬在两天的aPTT值均超出参考区间。第4天抗Xa活性水平升高，但第1天未升高。基于事后体外分析，血浆肝素水平低至0.075 U/mL时R时间即出现延长，远低于抗Xa活性水平检测的下限。
皮下注射肝素会导致TEG描记图逐渐变化，给药后3至5小时变化最大。R时间的广泛延长还表明TEG可能过于敏感，限制了其作为普通肝素治疗监测工具的实用性。
