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Laboratory work preceding the first clinical application of cardiopulmonary bypass

As a young surgeon tending to a patient who had suffered a massive pulmonary embolism, Dr. John H Gibbon Jr. envisioned the usefulness of an extracorporeal circuit in the surgical management of both pulmonary embolism and in the correction of congenital intracardiac defects during cardiopulmonary bypass (CPB) and under direct vision. Gibbon first demonstrated the feasibility of such an operation in 1937, when he was able to clamp the pulmonary artery of a cat while an extracorporeal circuit maintained the cardiorespiratory function of the animal. The extracorporeal circuit that he used in the original animal experiments contained a rotating cylinder-type oxygenator in which a film of blood coated the internal surface of a rotating cylinder. The blood pumps were of the Dale-Schuster type in which the blood contained within a finger cot was propelled by exerting alternate positive and negative pressure on the outer surface of the finger cot (Figure 1). In the spring of 1953, Dr John Gibbon Jr. performed for the first time closure of an interatrial septal defect in an 18-year-old female patient while her cardiorespiratory functions were maintained by an extracorporeal circuit containing a mechanical heart and a mechanical lung. Following the second world war, Mr Thomas J Watson, Chairman of the Board of the International Business Machine (IBM) Corporation, became interested in helping to develop a heart-lung machine, and he assigned the experimental laboratory to the construction of a heart-lung machine. Don Rex was the engineer for the project. The new machine was basically the same as Gibbon’s original device, differing only in the enlarged size of the oxygenator with the expectation that it would be able to maintain the cardiorespiratory function of larger experimental animals. The pumps were now rotating pumps, and the collecting bowl at the bottom of the oxygenator cylinder was gold plated with the purpose of minimizing the effect of the interaction of blood with stainless steel. The control of the arterial pump was photoelectric. The entire machine was contained in two precisely made cabinets of stainless steel and glass (Figure 2). Experience with this device was disappointing. Very few dogs were survivors of even partial perfusion. It was clearly obvious, as a result of these experiments, that the oxygenation was insufficient for small dogs. To have further enlarged a smooth film oxygenator of this type, using centrifugal force to provide sufficient film for oxygenation for a human patient, would have resulted in an unrealistic geometric design and a huge hold up of blood. There was also an excessive amount of hemolysis in the blood within the circuit, and the photoelectric control, which safeguarded against air embolization, malfunctioned repeatedly, resulting in air embolization to the systemic arteries. Using this device, a small number of experiments were successful in which the vena cavae were occluded and the cardiorespiratory functions of the dog were maintained with the heart-lung machine. It was decided at this point to use the existing machine only as a structure for further testing of new and advanced components. Animal experiments were suspended. Richards and Drinker introduced turbulence into a film oxygenator of early design and demonstrated that the degree of oxygenation could be vastly enhanced. Accordingly, Stokes and Flick lined the cylinder of the existing oxygenator with a stainless steel screen and were able to show a significant improvement in the degree of oxygenation when turbulence was introduced in this manner. The inadequacy of the photoelectric control was a matter of great importance since a fail-safe system during CPB is required to prevent air embolization. Subsequently, as the ex-