Point-of-care laboratory testing is attractive since results can be obtained far more quickly than waiting for the results from the hospital laboratory. Dr. Keyvan Karkouti, Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada, and colleagues used the PlateletWorks® point-of-care assay to measure the relationship of platelet function to blood loss at different times before, during, and after cardiopulmonary bypass. Their results are presented in the article “Platelet Dysfunction as Measured by a Point-of-Care Monitor is an Independent Predictor of High Blood Loss in Cardiac Surgery” that appeared in this month’s issue of Anesthesia & Analgesia.
The authors studied 100 patients who underwent cardiac surgery requiring cardiopulmonary bypass. Clinical care was standardized: tranexamic acid, heparin anticoagulation for cardiopulmonary bypass, cardioplegia, deep hypothermic circulatory arrest when necessary, and protamine neutralization of heparin after cardiopulmonary bypass. Patients received allogenic red cells if the hematocrit was below 20% before or 24% after cardiopulmonary bypass. Platelets were administered if there was bleeding and if the platelet count was <80 X 109/L or if platelet dysfunction was suspected. Fresh frozen plasma was administered if there was bleeding and if the international normalized ratio was greater than 1.5. Cryoprecipitate was given if patients were bleeding and if their fibrinogen level was <1.0 g/L.
As would be expected, concurrent Laboratory- and PlateletWorks®-derived Hb and total platelet counts were highly correlated. The agonist specific functional platelet count was significantly and inversely related to high blood loss when measured at rewarming and after protamine administration.
This was not a study of causation, it was based on care at one institution, and the study size was small. Might prospective use of collagen-aggregated platelet function result in lower use of blood products? Might this technology, when used for other high blood loss cases such as liver transplantation, reduce the need for blood products? Is use of this particular device any better than others? Additional investigation is needed to answer these questions.