In-vitro-Blutungstest (IVBT) mit virtueller Kapillare. Ein neues Verfahren zur Messung der primaeren Haemostase.

In 1985, Kratzer and Born introduced a new technique to simulate the process of primary haemostasis. Under a constant pressure, a capillary and a collagen coated nitrocellulose aperture, soaked with ADP, are perfused with anticoagulated blood. Platelets occlude the ap-erture and decrease the blood flow. The resulting flow is measured with a sensitive feedback device. Analogous to the in vivo bleeding time a closure time (CT) and the blood volume (BV) passing the aperture during that time can be measured ex vivo. The principle of this in vitro bleeding test (IVBT) was turned into a practical application with the "Thrombostat 4000" (VDG, von der Goltz, Seeon, Germany) which mainly was used for scientific purposes. A further development of this method has recently become available with the "PFA-100" (Dade Behring, Marburg, Germany). Numerous studies have shown that dis-turbances of non-vascular haemostasis can be detected with high degree of sensitivity and specificity by the IVBT. However, the PFA-100 shows still too high variability under routine conditions and limited applicability. An integral part of the device is a capillary, which mimics the resistance of the arteriole sys-tem during primary haemostasis. The present paper shows that the exchange of the capillary with an "electronic capillary" (clamp technique) clearly improves the method.