The Use of an Animal Lung as Oxygenator in a Heart-Lung Machine

Much of the progress in modern cardiac surgery has been made possible by lfl' ventions which mechanically oxygenate blood outside the body and pump this bloo back into the circulation?"the heart and lung bypass." In 1955, when our work was first planned, the only successful heart and lun?j bypass reported in man was that of Gibbon (1953). A variety of other mechani^ oxygenators were being developed, notably those of Melrose (1953), Bjork (I9^ Denis (1951), Helmsworth (1952), Dodrill (1952), Jongbloed (1949), using eithe^ filming or bubbling as the method of oxygenation but success with these was, at tn time, elusive and it seemed possible that there was some inherent defect in the dn*e exposure of blood to gas. There were also the obvious dangers of gas or fibrin emb? ̂ the difficulty of cleaning large oxygenating surfaces and the bogey of the denatur1 of proteins. Mustard (1952) suggested that the lung might also perform some essefl ^ function other than gaseous exchange. It seemed therefore that this method ^ ^ worthy of further trial, and this paper records our experiences in using the lungs one animal to oxygenate blood from another animal undergoing bypass operation^ Choice of species for animal experiments.?In most other laboratories the mental animal for this type of work has been the dog. It seemed to us, however, ruminants?calf, goat and sheep might have advantages over the dog. Among 0{ advantages were larger vessels for cannulation, and a blood flow approaching tn man. With calf and sheep unlimited amounts of blood could be obtained frolTl abbatoir for priming the machine and for transfusion. 0$l With animals of differing species to work with, it would be possible to teS heterologous lungs. Finally, if the method could be applied to man a lung abou same size as man's would obviously be an advantage.