A seesaw-type device to measure the coagulation time of blood: application to assessment of anticoagulant effect of direct oral anticoagulants (DOACs) in patients

A simple seesaw-type method using a sphere-shaped capsule as a blood testing container was developed, which is able to determine the time of onset of coagulation (coagulation time) of blood. The method is based on when a capsule containing a blood sample ceases rolling down a slope in a series of periodic, repetitive runs. From the elapsed time that the capsule stops rolling, the coagulation time can be determined. This method enables concurrent measurement of coagulation times for multiple blood samples. Optimal experimental conditions including the angle of slope and amount of blood were determined using cattle blood. The mean value of coagulation time for normal human donors was 19.6 ± 3.5 min, while that for patients taking direct oral anticoagulants (DOACs) was quite large. Addition of a coagulation accelerant (APTT reagent) to blood obtained from a normal donor and a DOAC-treated patient suffering from atrial fibrillation brought about dramatic shortening of the coagulation time. In addition, coagulation of the patient was slightly delayed compared with that of the normal donor. In this paper, it is shown that the present technique may be useful for assessing the anticoagulant effect of DOACs in patients as well as for determining the coagulation time of blood.