Vagher Jp

Comparison of thrombelastography with common coagulation tests.

Thrombelastography, although proven as a useful research tool has not been evaluated for its clinical utility against common coagulation laboratory tests. In this study we compare the thrombelastographic measurements with six common tests (the hematocrit, platelet count, fibrinogen, prothrombin time, activated thromboplastin time and fibrin split products). For such comparisons, two samples of subjects were selected, 141 normal volunteers and 121 patients with cancer. The data was subjected to various statistical techniques such as correlation, ANOVA, canonical and discriminant analysis to measure the extent of the correlations between the two sets of variables and their relative strength to detect blood clotting abnormalities. The results indicate that, although there is a strong relationship between the thrombelastographic variables and these common laboratory tests, the thrombelastographic variables contain additional information on the hemostatic process.

The identification of accelerated coagulability

Abstract This report describes a new method for comparing overall clotting characteristics between normal individuals and those with proven malignancy. Native whole blood thrombelastography and celite activated thrombelastography were performed on the same blood collection in 90 normals and 90 patients with new malignancies and the results used to derive a discriminate equation. This equation classified correctly all 90 normals and 80/90 cancer patients. The formulation was verified with an additional 82 patients with only one incorrect classification in the 31 cancer subjects. These results demonstrate a new analysis for accelerated coagulability based on comparative clotting data. Identification of accelerated coagulability in asymptomatic populations may identify occult problems, including cancer.

Hematologic changes following burns.

Abstract These studies demonstrate statistically significant changes between the platelet counts, FDP and plasminogen levels, and C3 and 5-min kinin activity of three groups separated according to their prognostic indices. Subsequent analysis of survivors confirms these trends and reveals additional supporting test data. We postulate that intravascular contamination occurs following major burns due to tissue trauma, and continues as burn wound sepsis develops. Standard heparin therapy does not significantly inhibit Hageman factor, plasmin, complement, or kinin activation products. It is not surprising that this anticoagulant does not change FDP levels or modify the course of most burns; however, further studies are needed to clarify this situation.

Neutralization of heparin by cellular blood elements

Abstract These studies were performed to evaluate heparin neutralization with a kinetic assay. Celite-induced clotting was followed using thrombelastography (TEG) on sequential samples of heparinized whole blood and plasma with and without platelets. Platelet-poor plasma and platelet-poor whole blood do not show the capability of neutralizing heparin activity with time in the TEG. When heparinized (1.15 U/ml) platelet plasma systems are incubated at room temperature for one hour, however, appreciable antiheparin activity is noted. The addition of erythrocytes to this same platelet concentration accelerates antiheparin activity, and the equivalent neutralization occurs at 15 minutes. Three different heparin concentrations were tried, and the platelet-plasma antiheparin activity was always slower to reach equilibrium than the matched platelet-erythrocyte-plasma combinations. No added antiheparin activity can be attributed to the presence of erythrocytes since both systems reach the same end points of clottability. Thus, platelets and erythrocytes interact in the neutralization of heparin, and their interaction does not provide more neutralization than a platelet-plasma system, only faster kinetics. This effect may be related to the red cell-platelet mixing in the thrombelastograph that results in the accelerated PF-4 release or other effects. These studies emphasize the importance of cellular blood elements in the neutralization of intravenous heparin in canines. We conclude that evaluation of platelet function, hematocrit, and platelet count in conjunction with a plasma assay (PTT) may provide more effective clinical heparin therapy with less chance of bleeding complications.