McNulty SE.  Sasso P.  Vesci J.  Schieren H.  Platelet concentrate effects on thromboelastography.  Journal of Cardiothoracic & Vascular Anesthesia.  11(7):828-30, 1997.

Summary

This study evaluated platelet effects on thromboelastography to determine how morphologically abnormal platelets affected native whole blood analysis. Prospective, controlled comparison. Tertiary care university hospital. Volunteer cardiac surgery patients. Fresh platelets were obtained from volunteers and were either treated normally or cryodisrupted with liquid nitrogen. Fresh platelets, liquid nitrogen-treated platelets, or an equivalent quantity of the patient's blood were added to whole blood samples obtained from cardiac surgery patients before heparinization. Thromboelastographic parameters sensitive to platelet effects were measured in each of the three groups. Maximum amplitude and alpha-angle significantly increased in the two groups receiving added platelets. There were no differences between the fresh platelet and the liquid nitrogen-treated platelet groups (Student's paired t-test). The R-time decreased significantly in both platelet-treated groups compared with the group that did not receive additional platelets. Viscoelastic changes in whole blood coagulation after the addition of platelet concentrates are not dependent on morphologically intact or functionally normal platelets. This in vitro study predicts that transfusion of poorly preserved platelet concentrates as well as fresh platelets would increase clot strength on thromboelastography if the recipient's blood were tested immediately after administration.