Effects of rest temperature, contact activation, and sample technique on canine thrombelastography
2012
Ralph, Alan G. | Brainard, Benjamin M. | Pittman, Jennifer R. | Babski, Danielle M. | Koenig, Amie
OBJECTIVE: To determine the effects of rest temperature, contact activation (CA), and sample collection technique on thrombelastography (TEG) using canine whole blood. DESIGN: Prospective, experimental study. SETTING: University‐based research facility. ANIMALS: Twelve healthy, adult, mixed‐breed dogs. INTERVENTIONS: Blood was collected by jugular venipuncture. Tubes containing 3.2% sodium citrate, with and without 75 μg/mL corn trypsin inhibitor (CTI), were filled by vacuum. Samples rested for 30 minutes at 3 temperatures: 37°C, room temperature (RT, 20–22°C), or warmed to 37°C 5 minutes prior to analysis (prewarmed). Samples were analyzed at 37°C. CTI‐treated samples were analyzed with and without 1:50,000 tissue factor (TF) as activator. Six dogs were also tested similarly using a needle/syringe collection technique. MEASUREMENT AND MAIN RESULTS: Prewarmed samples exhibited greater MA compared to RT (55.5 ± 7.2 mm vs. 53.5 ± 6.0, P< 0.05), while 37°C samples exhibited a steeper angle (56.7 ± 10.4°C vs. 52.4 ± 8.6°C) and greater MA (55.9 ± 7.5 mm vs. 53.5 ± 6.0 mm) than RT samples (both P< 0.05). CTI‐treated samples were hypocoagulable (R time 45 min [7.5–56.8 min], angle 8.2°C [5.1–42.5°C], MA 29.2 ± 9.7 mm, P< 0.001), with TF activation returning all but the angle (42.5 ± 7.6°C) to values similar to citrated samples (angle = 56.7 ± 10.4°C, P = 0.017). Collection using a syringe/needle method revealed a shorter R time for prewarmed samples only (R time 4.7 ± 0.7 min, vs. 5.6 ± 0.8 min for vacuum‐collected samples, P = 0.008). CONCLUSIONS: Even in the absence of exogenous activators, CA has an impact on canine TEG results. The effects of rest temperatures and sample collection technique on TEG appear to be minimal.
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