Platelet dysfunction during CPB is felt to result from a combination of decreased platelet concentration due to hemodilution, and platelet injury (activation, receptor loss) due to extensive exposure to the foreign surface of the membrane oxygenator used during extra-corporeal circulation. Since the platelet injury component should depend on the extent of exposure, the degree of platelet dysfunction should increase as the duration of CPB increases. This study tested whether point-of-care devices, that could be used in the operating room, are capable of detecting increasing degrees of platelet dysfunction as a function of CPB time. After signed informed consent, twenty-four patients undergoing CPB surgery were enrolled in an IRB approved protocol. Platelet function was studied at baseline (prior to CPB) and again within two hours of completion of CPB. All patients received aminocaproic acid as prophylactic antifibrinolytic therapy. Whole blood platelet aggregation, platelet contractile force and thromboelastography (MAg-shear elastic modulus) were measured. The post-CPB values were calculated as percent of the baseline and plotted versus CPB time. Impedance aggregometry decreased with increasing CPB time. The decrease in platelet aggregation 2-4 hours post-CPB correlated (r=0.66;p<0.05) with the duration of CPB. Platelet contractile force also decreased with increasing CPB time. The decrease in platelet contractile force from samples collected post CPB significantly correlated (r=0.68;p<0.05) with the duration of CPB. The MAg of the thromboelastogram decreased with increasing CPB time. The decrease in MAg from samples collected post CPB significantly correlated (r=0.54;p<0.05) with the duration of CPB. These findings confirm that the length of CPB is a direct determinant of the degree of platelet dysfunction and that techniques currently available to study platelet function in the operating room can detect the degree of dysfunction.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|
ASJC Scopus subject areas
- Cell Biology