Comparison of the effects of open-tube and evacuated tube–assisted sampling methods on thromboelastography variables for blood samples from healthy dogs

Abstract

Abstract OBJECTIVE To compare the effects of open-tube blood sampling with previously investigated blood sampling methods via evacuated tube on thromboelastography variables for blood samples from dogs. ANIMALS 10 healthy Beagles from the research colony owned by the Clinic of Small Animal Internal Medicine, University Veterinary of Medicine, Vienna, were used. PROCEDURES In this prospective study, blood was sampled from each dog serially into citrate solution–containing tubes via 20-gauge needle. One evacuated tube was filled from a jugular vein via the evacuated tube port, and the second tube was opened and filled by catching blood flowing through the needle from a lateral saphenous vein. Venipuncture quality was scored with a previously described method. Thromboelastography was performed for each sample. RESULTS Inferential statistics used with the Wilcoxon signed rank test showed significant differences in reaction time (R) of 3.43 ± 0.84 minutes versus 4.53 ± 0.62 minutes (mean ± SD) between evacuated tube assisted and open-tube sampling, respectively. No other significant differences were identified. CLINICAL RELEVANCE The sampling methods compared have a small but significant effect on R in thromboelastographic analysis for blood samples from healthy dogs. Shear stress by vacuum sampling seems to accelerate coagulation in jugular blood samples harvested by evacuated tube, resulting in a shortened R. Results suggested that the open-tube method avoids shear stress induced activation of coagulation and is an appropriate sampling method for thromboelastography when used within a standardized protocol.