Thrombokinetic studies in normal and factor VIII-deficient canine plasmas

Thrombokinetograms are graphic depictions of the optical changes occurring in plasma during the clotting process and provide information, not only on the time required for clotting to begin, but also on the way in which the clot forms. We studied thrombokinetic profiles in plasmas from normal dogs, and dogs with varying degrees of factor VIII deficiency. Clotting was induced through intrinsic, extrinsic and common coagulation pathways [activated partial thromboplastin time, prothrombin time and thrombin time, respectively]. The thrombokinetograms for the various clotting tests were qualitatively similar in normal canine plasmas. After activation of the clotting system there was a period in which no change in optical density occurred. This period was represented by the left base line and corresponded to the duration of the clotting time. When fibrin production commenced there was a rapid increase in the rate of optical density change (DeltaOD) to a maximum (V(max)DeltaOD) in time t(1). This was followed by a more gradual reduction in DeltaOD in time t(2). The activated partial thromboplastin time thrombokinetograms for von Willebrand's disease plasmas were characterized by a reduced V(max)DeltaOD and prolonged t(1). In severe hemophilic plasma [factor VIII coagulant (F VIII:C)<1% of normal] there was a very slow increase in DeltaOD following a prolonged left baseline. The V(max)DeltaOD, t(1) and t(2) could not be determined since a peak was not attained in one minute. The prothrombin and thrombin time thrombokinetograms for von Willebrand's disease plasmas were normal. The prothrombin time thrombokinetogram for hemophilic plasma had a 2X normal V(max)DeltaOD possibly related to the relatively high fibrinogen concentration of this plasma compared to the normal. Changes in thrombokinetogram profiles may be of value in studying mild to moderate clotting factor deficiencies particularly where the clotting times are not markedly prolonged.