Blood was collected via cardiac puncture with the blood collected in sterile 250-ml bags containing 35 ml of citrate phosphate dextrose. If needed to achieve a deep plane of anesthesia, IV propofol (2 to 8 mg/kg) was administered. 9, 10 For the purpose of Chandler loop experiments, terminal blood collection was performed on donor rabbits after the induction of general anesthesia with 15 to 30 mg/kg ketamine HCl and 3 mg/kg xylazine subcutaneously. The Chandler loop is a simplified in vitro simulation of CPB. One milliliter of blood was centrifuged at 700 g for 15 min to obtain plasma for determination of dabigatran concentrations as previously reported, 10 using liquid chromatography/mass spectrometry with a Dionex Ultimate 3000 UHPLC coupled to a Q Exactive Plus mass spectrometer (Thermo Scientific, USA). Activated clotting time and hemoglobin concentration were measured using the Hemochron Signature Elite (Accriva Diagnostics, Inc., USA) and HemoCue (HemoCue Company, Ängelholm, Sweden) according to the manufacturer instructions. Reaction was monitored until reaction time was established. The kaolin/tissue-factor-activated thromboelastography was initiated when 340 µl of blood was mixed with 10 µl of kaolin/tissue-factor-activated thromboelastography reagents and 20 µl of 0.2 M CaCl 2. Kaolin/tissue-factor-activated thromboelastography measurements were performed using a Thromboelastograph Analyzer 5000 (Haemoscope Corp., USA). Reaction time (time in seconds to clot initiation), activated clotting time, hemoglobin concentration, and dabigatran concentration were measured in all blood samples.
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