Effects of Plastic and Steel Surfaces on Clotting Time of Human Blood.

Abstract

An instrument was constructed for the measurement of the clotting time of whole human blood on various plastic and steel surfaces. A plastic box was suspended in a constant temp. water bath and continually rocked by a slow speed motor. Blood containers, machined and polished from the materials under study into biconcave receptacles, were placed in the instrument 2 at a time and blood introduced into them under standardized conditions. Silicone coated glass was found the most effective surface in inhibiting clot formation but this effect rapidly declined unless the surface application was renewed. Methyl methacrylate prolonged clotting the most of several plastics studied, followed by polyethylene. Stainless steel surfaces prolonged clotting more than glass. This effect was enhanced by electropolishing. Neither a cationic N compound nor silicone, when applied to steel surfaces altered the mean clotting time.