Current methods to reduce the adverse haematological consequences of cardiopulmonary bypass

Bleeding remains a significant cause of morbidity after cardiac surgery and results in a major demand on blood transfusion capacity. The aetiology is multifactorial, but platelet dysfunction is the most important cause. Because of the potential risks of heterologous blood transfusion, a number of techniques have been developed to reduce its need. These can broadly be divided into three categories. First, modification of bypass methods and the use of agents such as aprotinin can reduce blood loss. Second, more use can be made of the patient's own blood through predonation of autologous blood or blood conservation techniques. Finally, transfusion policy can be modified so that a lower postoperative haemoglobin level is accepted. However, a method with which to preoperatively predict those patients who will bleed significantly remains elusive.