Applications of a hollow fiber device to monitor hemostasis

A global assessment of hemostasis can be determined by the perfusion of una nti-coagulated whole blood through a hollow fiber at a nominal shear rate o f 300 sec(-1). Once the pressure across the hollow fiber is stable, uniform holes are punched through the top and bottom of the fiber, resulting in an optically detectable leakage of blood from the hollow fiber and a pressure drop throughout the system. Changes in the shear rate and flow profile at the puncture site are sufficient to activate platelets mechanically, result ing in a platelet plug observable by electron microscopy. Fibrin is the pri ncipal component of the luminal surface adjacent to the puncture site and a prominent fibrin tail extends downstream from this site. The time from the introduction of the punch site to 90% recovery of the baseline pressure de fines the in vitro bleeding time (IVBT). The rate of the pressure recovery appears to be related to the efficiency of the thrombin-mediated recruitmen t of additional platelets to the plug. Pressure recovery can be delayed by either platelet or thrombin inhibitors. (C) 1998 Elsevier Science Ltd.