Preservation of human platelets with prostaglandin E1 during in vitro simulation of cardiopulmonary bypass.

Abstract

Platelet abnormalities that occur during cardiopulmonary bypass may be produced in vitro by recirculating 500 ml of human blood at 37C in a silicone rubber circuit (0.9 m 1 ) containing a spiral coil membrane oxygenator. Platelet counts fall to 20% of initial levels, plasma levels of low affinity platelet factor 4 (LA-PF4) rise from 0 to 66% of that in control platelet rich plasma, and sensitivity to aggregating agents diminishes. Inhibition of platelet function with prostaglandin Ei (PGEi) prevents these alterations. In 14 trials (PGEi _ o.l to 10 pM), the thrombocyte count achieved a stable value of 88% within 1 hour. Plasma LA-PF4 (PGEi 0.3 /M) rose to only 10% after 6 hours. Electron microscopy revealed intact platelet granules in recirculated platelets. Platelets incubated and recirculated with PGEi remained equally sensitive to epinephrine and ADP for 3 hours. At 6 hours, recirculated platelets in plasma (PGEi 0.1 p.u) and gel-filtered platelets (PGEi < 0.3 M M ) became significantly less sensitive to epinephrine. At PGEi 0.3 pM, however, gel-filtered recirculated platelets responded normally to epinephrine even after 6 hours of recirculation. PGEi preserves platelet numbers, prevents contact-initiated release, and preserves platelet sensitivity to aggregating agents during in vitro extracorporeal bypass.