Evaluation of platelet damage in extracorporeal circuits using a visual platelet morphology method

Platelet damage in extracorporeal circuits occurs as the result of contact with foreign surfaces, shear stress, gas interface, and other nonphysiologic conditions. A scoring method developed to determine platelet activation was modified for evaluating platelet damage in extracorporeal circuits. This method assigns a numerical score to platelet damage, as assessed by direct visualization with phase microscopy. Various commercially available blood oxygenators were tested by using a modified AAMI/ASAIO in vitro blood trauma protocol. Direct gas contact oxygenators showed a marked decrease in total platelet count and significant platelet damage. Platelet depletion and platelet damage were lower in membrane oxygenators than in direct gas contact oxygenators. Differences in platelet damage were observed between membrane oxygenators. The observed differences between devices demonstrate the influence of materials and hemodynamic design on platelet depletion and damage. The method developed allows quantitative evaluation of platelet damage caused by extracorporeal devices and is a sensitive indicator of lethal and sublethal trauma.