Sequestration of Platelets Prior to Bypass Reduces Bleeding After Cardiac Surgery

• Incidence of coagulation abnormalities as assessed by thromboelastography and platelet function analyser [ Time Frame: At end of surgery (usually <1 day) ] [ Designated as safety issue: No ]
  

• Volume of blood lost into chest drains during first 24 post-operative hours [ Time Frame: 24 hours ] [ Designated as safety issue: Yes ]
  
• Volume of blood product administered during first 24 post-operative hours [ Time Frame: 24 hours ] [ Designated as safety issue: Yes ]
  
• Length of stay in the intensive care unit (ICU) [ Time Frame: Usually < 30 days ] [ Designated as safety issue: Yes ]
  
• ICU mortality [ Time Frame: Usually < 30 days ] [ Designated as safety issue: Yes ]
  
• Incidence of surgical re-exploration [ Time Frame: Hospital admission (usually < 30 days) ] [ Designated as safety issue: Yes ]
  

Hypothesis:

Patients undergoing repeat median sternotomy or requiring prolonged cardiopulmonary bypass (CPB) often develop a coagulopathy at the end of surgery. We propose sequestering plasma and platelets from these patients prior to CPB and thus prior to the dilution and platelet damage that occurs with CPB. We hypothesise that if these plasma and platelets are stored properly during CPB, and administered at the end of the operation, they will reduce any coagulopathy and the associated bleeding.

Study population:

Patients undergoing repeat median sternotomy, mitral valve repair, double valve operations, aortic surgery, or combined valve and coronary artery surgery.

Exclusion criteria will include those with anaemia, thrombocytopenia, unstable angina, anti-platelet therapy within the previous seven days, known or symptomatic cerebrovascular disease, known disorders of haemostasis, aprotinin sensitivity and pregnancy.

Intervention:

Patients will be randomised by a closed envelope technique to receive platelet/plasma sequestration or not. Patients randomised to undergo sequestration will have 14 mL/Kg blood taken. The blood will be separated into red cells and platelets/plasma. Anaemia would be prevented by returning the processed red blood cells to the patient. We will store platelets at 20-24°C/room temperature on a platelet rocker according to guidelines from the National Blood Service.

Assessment of coagulation:

Patients' coagulation status will be evaluated before and after surgery. Four methods will be employed to comprehensively assess the coagulation system: platelet counts and conventional clotting studies; heparin levels; thromboelastography; and platelet function analyser.