In vitro effects of a kaolin-coated hemostatic dressing on anticoagulated blood

BACKGROUND The use of kaolin-coated dressings has become common and have efficacy in normal patients, but their increased use will inevitably include use on bleeding patients taking anticoagulants. We hypothesize that kaolin coating material (KCM) will improve clotting regardless of anticoagulation medication. METHODS A prospective study was performed on blood from patients who were on a Vitamin K antagonist (VKA), unfractionated heparin (UH), an antiplatelet (AP) agent, a Xa inhibitor (Xa), or a direct thrombin inhibitor (DTI). None were on more than one type of anticoagulation medication. Viscoelastic testing was performed with and without KCM. All p values were adjusted for multiple comparisons. RESULTS The addition of KCM significantly decreased the time for initial clot formation (CT) in all groups. The mean CT for controls was decreased from 692 to 190.8 s (p < 0.0001). KCM decreased the initial clot formation time by about 1.5 times in those on DTI (p = 0.043) and 2.5 times in those taking AP medication (p < 0.001). The most profound effect was seen in those on UH (no KCM 1,602 s vs. KCM 440 s; p < 0.001), VKA (no KCM 1,152 s vs. 232 s; p < 0.01), and Xa (no KCM 1,342 s vs. 287 s; p < 0.001). Analysis of other clot formation parameters revealed that KCM significantly improved the clot formation kinetics (CFT) only in patients taking Xa (p = 0.03). KCM improved maximum clot strength in patients on Xa inhibitors (p = 0.05). Patients on UH had a larger effect size with an increase in clot strength from 24.35 mm to 43.35 mm whereas those on Xa had an increase of 38.7 mm to 49.85 mm. CONCLUSION In this in vitro analysis, the addition of KCM to the blood of patients taking any of these anticoagulation medications significantly improved the time to initial clot formation, indicating that kaolin-based hemostatic dressings will be effective in initiating clot formation in patients on anticoagulants.