Typical Changes of Platelet Volume During and After Extracorporeal Circulation

Abstract

In 32 patients undergoing open-heart-surgery with extracorporeal circulation (ECC), platelet volume distribution curves (PVD) during and immediately and 24 and 48 hours after cardiopulmonary bypass were examined by an electronic particle size analyzer based on the Coulter-Counter-System. The PVD changes, i.e., the reduction of the mean platelet volume (MPV) and the platelet fall correlates significantly with the bypass time (r = 0.78). Two hours after the end of ECC, these changes remained completely irreversible or only partially reversible in patients with perfusion times longer than 60 minutes. In most of the patients with shorter perfusion times, we observed a normalisation of PVD curves and return of platelets to counts approaching normal levels.Some plasma coagulation parameters (i.e., concentration of clottable fibrinogen, FDP) were estimated in parallel and were found to be in good correlation with the platelet defects.In patients with marked changes of MPV up to 48 hours after the end of surgery, a pathologic volume distribution curve of thrombocytes was observed, but platelet counts returned in most of them to normal values. This indicates that the determination of PVD, as a simple reliable diagnostic parameter, gives more essential information about platelet damage than does the platelet count alone.