Traditional cardiac surgery requires patient connection to the Cardiopulmonary Bypass (CPB) apparatus which takes over the function of the heart and lungs while the surgeon performs the necessary surgery. The residual blood left in the CPB equipment (1.5-2.0 L) is centrifuged and washed leaving only red blood cells (RBCs) suspended in a saline solution. The RBCs are reinfused into the patient as needed by the anesthesiologist. The main problem with this technique is that many of the important components of the blood such as plasma proteins and clotting factors are discarded through cell washing. This study will explore a novel method (multiple-pass hemofiltration) of processing the residual pump blood which will allow the patient to receive their own whole blood with minimum waste of important components. The newer method of processing the residual pump volume has also been termed off-line modified ultrafiltration (off-line MUF) and is similar to the process that the kidneys use to filter the blood. It is hypothesized that multiple-pass hemofiltration of the residual CPB volume will reduce the occurrence of inflammatory responses, preserve plasma proteins, and decrease allogenic blood exposure and improve clinical outcomes as compared to centrifugation.

This study is being performed because the traditional method of recovery of the residual volume of blood from the cardiopulmonary bypass circuit involves centrifugation and washing of whole blood with a saline solution. This process is sufficient for the recovery of red blood cells however; it results in the discarding of other important components of the blood. The removal of white blood cells, plasma proteins and clotting factors may result in an increased risk of a adverse outcomes during the post-operative period. The new technique our team wants to investigate returns a greater proportion of the patients' whole blood for reinfusion. Our study objectives are to compare the two techniques and determine which technique produces the safest most reliable method of blood processing to help the patient have a smooth, short, transfusion free post-operative period in the intensive care unit (ICU).

Inclusion Criteria:

• all males and females that will be receiving open heart surgery (Coronary Artery Bypass Grafts and / or Valve repair/replacement) during the study period.

Exclusion Criteria:

• history of bleeding disorders
• history inflammatory diseases rheumatoid arthritis