BACKGROUND: For most topical hemostatic agents the mechanism of hemostatic action is not fully understood. OBJECTIVE: This work aimed to investigate the hemostatic mechanism of action and viscoelastic properties of polyurethane foam (PU) in comparison to the widely used collagen and gelatin.METHODS: The hemostatic mechanism of action of the materials was tested using human whole blood and platelet-poor plasma (PPP). The ability of the hemostatic agent to exert pressure on the wound was quantified in terms of its viscoelastic properties both under dry and wet conditions using a low load compression tester (LLCT).RESULTS: It has been shown that collagen and PU initiate hemostasis through both thrombocyte aggregation and contact activation of ...