Blood-compatible materials by fluid perfusion.

The feasibility of preventing platelet adhesion to porous foreign surfaces in contact with blood by passing (perfusing) a physiologic fluid through the pores into the blood was tested. Porous-walled tubes of Teflon (Gore-tex) and aluminosilicate ceramic were perfused with lactated Ringer's solution at rates between 3.13 and 0.3 cc/min per cm2 of perfused surfaced and exposed to heparinized and unheparinized flowing human whole blood for periods of 3-6 min. Under these conditions, with 0.159 cm I.D. tubes and a mean blood flow rate of 8.3 cm/sec, the adhesion of all blood cells was prevented, compared with the adhesion of 1 to 8 X 10(6) platelets/cm2 on the nonperfused controls. The adhesion of plasma proteins was also markedly reduced as determined by bromophenol blue staining. The critical perfusion rate to prevent platelet adhesion to Gore-tex (0.5 micron pore size, 60% pore volume) was found to be between 0.04 and 0.3 cc/(min-cm2). The boundary layer produced by a perfused segment of porous tubing prevented platelet adhesion for several centimeters downstream from the perfusing segment under experimental conditions used.