Platelet Function Testing Help and Intraoperative Bleeding Risk for Patients Who Are on Plavix Prior to Surgery

A large number of patients are currently on Antiplatelet inhibition using aspirin or Plavix therapy (A Thieno pyridine - ADP mediated platelet inhibitor). A group of these patients often require Cardiac and/or Vascular surgical procedures. These patients are at a higher risk for perioperative bleeding complications and higher re-operation/re-exploration for bleeding and subsequent blood product transfusions. The aim of this protocol is to assess platelet function via the "Verify Now" device prior to surgery. The Verify Now device requires a small drop of fresh blood for each sample and is an FDA approved device. The investigators initial goal is to establish if a certain degree of platelet function abnormality can predict a higher bleeding complication or higher transfusions (Phase I, 20 patients). This initial study will allow us to determine a sample size for Phase II. Phase II will maintain the same protocol, however after completion of Phase I, a more accurate sample size determination can be made. Additionally, the investigators want to establish if knowledge of platelet dysfunction will change procedure technique or preparation to lower bleeding and/or lead to cancellation/rescheduling of procedure (Phase III). Participants will be those patients who are taking plavix and are undergoing vascular or cardiac surgery. They will undergo a platelet function evaluation measured as Platelet Response Unit (PRU) via the "verify now" device on admission/pre surgery. This test involves taking 1 drop of blood from the patient, one time, before the procedure. The Verify Now device is FDA approved. Perioperative bleeding will be assessed by absolute drop in hematocrit immediate post-op compared to the immediate preoperative value. An additional discharge hematocrit will be used if no blood products have been used during the initial hospital stay. Hematocrit evaluation via a complete blood count is a part of standard patient care. Additionally, utilization of blood produ