"There is a dual purpose in developing a mechanical heart and lung apparatus. The first is to maintain a part of the cardiorespiratory functions temporarily in patients with a failing heart or lung, or both, in the hope that, with such direct aid for a short time, these organs may be able to resume their entire function. The second purpose is of surgical interest."Bernard J. Miller, John H. Gibbon Jr and Mary H. Gibbon, 19511.While the early pioneers of cardiopulmonary bypass (CPB) hoped the technology could be used as a form of temporary life support for patients with acute cardiac or respiratory failure, initial attempts at prolonged "partial perfusion", using rotating disc oxygenators (in which blood was directly exposed to oxygen) proved disappointing2-4. These "direct contact" oxygenators caused considerable trauma to the blood, resulting in haemolysis and protein denaturation, and could rarely be used for more than a few hours before serious complications occurred5.