Skin Bleeding Time Research Articles

The australasian reference thromboplastin: I. A Study in bleeding patients

The prothrombin time, activated partial thromboplastin time, thrombin time, and skin bleeding time, with assays of factors II, VII, IX, and X, platelet count, and liver function tests were performed on a group of patients receiving long term warfarin therapy. There were 17 bleeding patients and 13 non-bleeding patients. A study was made, using the Australasian Reference Thromboplastin and 2 other thromboplastic reagents in common use. The Australasian Reference Thromboplastin was shown to be more sensitive to the coumarin induced coagulation defect than rabbit brain thromboplastin, and hence of more value in preventing haemorrhagic complications. The level of factor II assayed by the one stage method was a useful independent indicator of the intensity of oral anticoagulation, and correlated well with the development of bleeding.

Bleeding in anticoagulated patients: A study using the australasian reference thromboplastin

Thirty-five patients, all receiving long term warfarin therapy, most of them from the Anticoagulant Clinic at the Royal North Shore Hospital, were studied over a 12mth period. There were 21 patients bleeding to various degrees, and 14 patients who were non-bleeders. Severity of bleeding was graded as O—non-bleeders, I—minor bleeders, II—serious bleeding, and III—major bleeding. There were 14 group O, 13 group I, and 8 in groups II and III. Each patient had a prothrombin time test using the Australasian Reference Thromboplastin (ART), Simplastin (S), and Thrombotest (T). In addition, patients had an activated partial thromboplastin time test using kaolin and Thrombofax (TFX), a thrombin time test using Fibrindex, platelet count employing a Technicon automated platelet counter, skin bleeding time (Ivy), and assays for factors II, VII, IX and X (one stage assays). All of the group II and III patients were outside the accepted therapeutic range for T, all but one were outside the range for ART, but all except one patient were <i>within</i> the accepted therapeutic range for S, in most cases well within the range. Most of the minor bleeders displayed no particular pattern when considering the APTT, but 11 of the 13 non-bleeders had an APTT of less than 80 sec, whereas 7 of the 8 serious and major bleeders had an APTT of greater than 80 sec. The results indicate that factor II levels are of major importance in the genesis of bleeding, with factors IX and X being of lesser importance: factor VII levels appeared to be significant only when considered in conjunction with the other 3 factors. A series of factor II deficient plasmas (factor II deficient plasma + fresh pooled normal plasma) demonstrated the greater sensitivity of ART to factor II deficiency compared to S. The APTT was also sensitive to factor II deficiency <i>in vitro</i>. Factor II levels, as assessed by the one stage assay, are probably a useful independent indicator of the intensity of oral anticoagulation. In view of the results obtained with the APTT, this simple laboratory procedure may be a guide to the probable factor II levels in patients, and hence to the prospect of serious bleeding occurring, without the need for an immediate factor II assay.

Von Willebrand's disease.

Von Willebrand's disease is an autosomally transmitted disorder of hemostasis caused by a deficiency of or defect in the von Willebrand factor in the blood, a protein required for adherence of platelets to an injured vessel wall. The disease's principal manifestations are spontaneous bleeding from mucous membranes, excessive bleeding from wounds, and menorrhagia. The major laboratory abnormality in prolongation of the skin bleeding time, with reduced platelet retention by glass bead columns, impaired platelet agglutination by ristocetin, and reduced factor VIII--related antigen and factor VIII coagulant activity as associated defects. Recommended therapy is infusion of plasma cryoprecipitate, which briefly corrects bleeding time and normalizes the disorder's other manifestations.

Von Willebrand's disease type B: a newly defined bleeding diathesis.

Summary: A patient with a lifelong bleeding diathesis is described. Studies of haemostatic function revealed a prolonged bleeding time and reduced glass bead adhesiveness. All other routine studies of haemostatic function yielded normal results, in particular the Factor VIII level, estimated both by antibody and coagulation techniques. Ristocetininduced platelet aggregation was absent and could be corrected by the addition of plasma or serum from normal controls or haemophiliacs, but not from patients with Von Willebrand's disease. It is apparent that the Von Willebrand plasma factor is either reduced in amount or inactive in this patient without an accompanying reduction in the Factor VIII level. It is postulated that Factor VIII may have two separate sites of biological activity, one concerned with the intrinsic pathway of coagulation and the other with platelet glass bead adhesiveness and skin bleeding time. It is proposed that this patient possesses a specific abnormality in the latter site, in contradistinction to the specific defect in the site concerned with intrinsic coagulant function in haemophilia.

Coagulation, protein and cellular studies on armadillo blood

1. 1. Blood was obtained by cardiac puncture from four armadillos ( Dasypus novemcinctus). Cellular elements differed only slightly from their human counterparts; erythrocytes were smaller, platelets more variable in size, and megakaryocytes (bone marrow) contained one multilobed nucleus. 2. 2. Total plasma protein and fibrinogen concentrations were higher than average human levels, but serum electrophoretic patterns were similar. 3. 3. The skin bleeding time was short. The blood clotted effectively but the clot retracted poorly. Blood coagulation factors showed greater activity (or higher concentration) than their human counterparts. 4. 4. Armadillo tissues, especially lung and brain, were far more thromboplastic to armadillo than to human plasma. Spontaneous fibrinolytic activity was absent. Streptokinase in high concentration activated armadillo profibrinolysin, at least in part.

STIMULATION OF FACTOR VIII (ANTIHAEMOPHILIC) ACTIVITY BY TRANSFUSED SERUM.

PATIENTS with factor VIII deficiency and prolonged skin bleeding time (von Willebrand's syndrome) who receive fresh blood or plasma from normal donors or from patients with haemophilia A with very low factor VIII activity show a much higher factor VIII activity in their plasma than could possibly be explained by the amounts given. The maximum factor VIII activity is reached 4–8 h after transfusion and persists longer than in haemophilia A (refs. 1 and 2).