Extended Cold Stored Apheresis Platelets in Cardiac Surgery Patients

Cardiac surgery featuring cardiopulmonary bypass (CPB) has a detrimental effect on platelet function. Contact with foreign surfaces causes a transient platelet dysfunction. The bleeding time is prolonged for the time on bypass and reverts to normal approximately one hour after cardiac surgery in uncomplicated cases. Hemorrhage following cardiac surgery with CPB can cause surgical re-exploration and increased mortality. The overall risk for surgical re-exploration is between 2.5-5%. Patients who undergo re-exploration due to excessive bleeding have a 2-6 fold increased mortality compared with non-bleeding patients. Storage of platelets at 1-6°C has the advantage of potentially prolonging storage times while reducing bacterial contamination. Room-temperature storage has led to a 5 day storage time limit since bacterial growth and septic reactions increase rapidly after 5-7 days. CSP were the standard of care in the 1960-70s. CSP were abandoned when a reduced platelet survival was observed in platelet radiolabeling studies. Nevertheless, CSP may have several advantages over RSP in the study population including a state of pre-activation and therefore a potentially superior hemostatic function. A small pilot trial investigating CSP in cardiac surgery patients in Norway found a non-significant trend towards improved bleeding control with CSP transfusions. However, data evaluating the in vivo efficacy of CSP is limited in scale and quality with mixed results. The investigators and others have shown that CSP have a superior function compared with RSP in vitro and more data are needed to clarify the relative efficacy of CSP in vivo. The investigators hypothesize that 1) CSP are more effective than RSP at reducing blood loss and improving platelet function in subjects actively bleeding due to cardiac surgery with cardiopulmonary bypass (CPB), and that 2) CSP are safe and do not lead to increased risks relative to RSP.