In vivo interactions between novel filler free silicone rubber and blood.

To evaluate the thrombogenicity of the novel filler free silicone rubber (FFSR) prepared in our laboratory, its interactions with blood were studied. The test samples (FFSR) along with control Silastic samples were placed in an extracorporeal shunt and primed with sterilized normal saline. The blood from an anaesthetized and systemically heparinized dog was passed over these samples for predetermined time intervals. After washing, fixing, etc., the platelets adhering to the samples were counted under light microscopy. To study the morphological changes of the platelets adhering to the samples, they were examined under scanning electron microscope. The number of platelets adhering to the FFSR samples was very small compared to the Silastic samples. For example, when the blood was passed over the samples for 10 min the number of platelets sticking per 0.14 mm2 surface area was 10 for FFSR samples compared to 380 for Silastic. Furthermore, there were no leukocytes on FFSR samples compared to 10 on Silastic. From these studies, the novel filler free silicone rubber prepared in our laboratory was judged to be more compatible with formed elements of blood compared to the Silastic material.