Coagulation monitor based on serum migration through absorbent materials

I describe a method to measure blood coagulation properties, based on the hypothesis that the distance the serum component of a clotted plasma sample moves through a suitable absorbent material should be proportional to the blood's ability to clot. A simple apparatus was constructed to test this principle, in which an absorbent strip contacts clotted plasma samples. At various times, the liquid migration distance into the strip was measured and correlated with clotting times determined by well-accepted procedures. Use of this device to test lyophilized normal and barium-absorbed plasmas, factor VII-deficient plasma, frozen normal plasmas, plasmas from patients undergoing oral anticoagulation, and saline-diluted plasmas (as for Quick Percent assays) showed that clotting times correlated with migration distances for all types of samples (r2 = 0.93-0.99). The device distinguishes between samples from normal and coumadin-treated subjects. The concept can be integrated into an inexpensive, point-of-care coagulation monitor.