Office of Naval Research Contract N00014-88-c-0118 Contract N00014-94-c-0149 Technical Report 95-01 Bleeding Time, Volume of Shed Blood Collected at the Bleeding Time Site, and the Peripheral Venous Hematocrit

BACKGROUND: The relation between the bleeding time, the peripheral veous hematocirt and the amount of blood shed at the template bleeding time site has not been previously defined. METHODS; We studied this relation in 227 individuals: 26 were performed on patients with ITP, 137 on patients with a variety of other bleeding disorders, and 64 in normal subjects. Bleeding times were performed by a modified Ivy technique with a commonly used commercially disposable bleeding time device. Hemoglobin was eluted with sodium hydroxide from the filter paper to collect the shed blood from the skin incision, and the hemoglobin was quantitated using a standardized spectrophotometric method. Complete blood counts were peformed on all individuals. RESULTS: The bleeding time for the normal group was 7.1 + 1.2 minutes, and the amount of shed blood was 136.4 + 47.2 |il. In patients with ITP the bleeding time was 14.0 ± 4.1 minutes and the shed blood was 508.1 ± 387 |il. There was a significant correlation between the bleeding time and the platelet count (r = 0.43, p<0.05), in patients with ITP. In the group of individuals with other miscellaneous bleeding disorders, the mean bleeding time was 9.0 + 3.5 minutes and the amount of shed blood was 224.7 ± 184 jul. Bleeding times from all of the normal and abnormal individuals showed a correlation of 0.75, p<0.001 with respect to the amount of shed blood on the filter paper and correlation of 0.28, p<.001 with respect to the peripheral venous hematocrit. CONCLUSIONS: This study demonstrates that the volume of blood shed at the bleeding time site correlates with the peripheral venous hematocrit, and emphasizes the contribution of the hematocrit to primary hemostasis in normal subjects and patients with bleeding disorders.