Silastic platelet consumption

None of the smooth surfaces prepared by the depositing of plasma polymer on the smooth surface of Silastic tubing showed detectable thrombus formation by gamma camera imaging. Therefore, they were evaluated by measurement of relative rates of platelet consumption. Table 35.7 shows the results obtained using the plasma polymers described previously [5]. 

Measurements of Platelet Consumption. When the extent of grafting of acrylamide on Silastic was varied, cannular platelet consumption increased... 

Table II shows the effect on platelet consumption of increasing lengths of the polyacrylamide-Silastic tubing. The acrylamide surface is much more destructive to platelets than is the Silastic surface. Table II also shows that platelet consumption increases linearly with shunt area for both the polyacrylamide-Silastic shunts.

A series of shunts with radiation and ceric ion-initiated grafts of polyacrylamide on the luminal Silastic surface, and having water contents varying between 51-83% were also studied. Table III shows these data. The platelet consumption increases linearly with the gel water, such that the ratio of platelet consumption to graft water content remains relatively constant. 

Figure 11. Platelet consumption vs. graft level of polyacrylamide-Silastic shunts (9). (Numbers in parentheses refer to the number of shunts tested for each value reported.)...

Exposed Area (cm2) Mean Platelet Survival Time (days) Cannula Platelet Consumption (platelets/day x 10 10) Polyacrylamide-grafted Silastic Cannula Platelet Consumption/ Unit Area (platelets/cm2 day x 10 H)... 

Figure 12. Rates of production of thromboemboli volume ( 3Is) and equivalent platelet consumption by embolization (platelets/day) vs. surface area for two biomaterials Silastic (bottom) and polyacrylamide-Silastic (top). The equivalent steady-state platelet consumption is (3.0 0.2) x 108 (platelets day-cm2) for polyacrylamide-Silastic and (0.8 0.1) X 108 (platelets day-cm2) for Silastic.

---