Blood Flow During Cardiopulmonary Bypass
Clinical cardiopulmonary bypass (CPB) has been with us now for over 50 years, and in that time it has evolved technologically and practically, embracing all of the major scientific and clinical innovations of the later half of the last century in the fields of material development, electronics, and computer technology. However, despite the adsorption of all of these emerging technologies, materials, and techniques, the CPB system used today would be largely recognizable to the early CPB pioneers. Without a doubt, the materials and devices have improved over the evolution of CPB, but the basic techniques and fundamental principles remain largely unchanged. Despite the continued improvement in devices and better understanding of the mechanisms underlying CPB pathophysiology, which have led to generally improved patient outcome, several aspects of CPB remain controversial. Amongst these controversial issues are the mechanism and nature of blood flow delivery to the patient. That the patient requires artificial provision of blood flow during the procedure is essential and is, in itself, not at all controversial. However, there are issues relating to blood flow which remain controversial, e.g. whether to use pulsatile or nonpulsatile blood flow, which is the most appropriate blood flow index for a particular environment, and which pumping mechanism is most suitable.