Blood coagulability in patients undergoing anticoagulant therapy has been studied using the Thromboelastograph ®~ and activated partial thromboplastin time. Currently used tests, such as activated partial thromboplastin time (APTT) and whole blood dotting time, lack sensitivity and do not correlate well with clinically significant bleeding and clotting events. The Thromboelastograph ® is an instrument that allows continuous measurement of overall coagulation and fibrinolysis. Sixty patients on heparin therapy were monitored with thromboelastography and activated partial thromboplastin time. Continuous heparin infusion or intermittent administration was used. The Thromboelastograph ® was found to be a more sensitive device for detection of response to heparin than APTT. Early response to heparin was reflected in the reaction time, k time, and maximum amplitude of the thromboelastogram. A more precise administration of heparin was made possible, resulting in use of less heparin and a more stable patient response. A more individualized approach to the patient's therapy was achieved by monitoring with the Thromboelastograph, and the best results were obtained with continuous infusion rather than~intermittent administration of heparin.

No abstract

In order to derive a better understanding of the effect of varying degrees of stenosis on arterial pulsatile waveforms, an in vitro model was constructed and in vivo studies were done in dogs to observe and record the changes in the pulsatile and steady arterial blood flow components. Blood flow measurements were made using the electromagnetic blood flowmeter proximal and distal to the stenosis. The data show that as the degree of stenosis increases, the decreases in the pulsatile components of flow and distal pressure occur earlier and to a much greater degree than changes in mean flow.