In , John Gibbon had been moved by the death of a patient during cardiac surgery. Convinced the patient would have survived if their blood circulation had been artificially maintained, he began to investigate the possibility of building an external device that could do the job of the heart and lungs for short intervals. These early animal experiments allowed Gibbon to test different types of pumps and oxygenators to improve performance, however, the machine damaged blood cells, and most cats lived no longer than 23 days after surgery.
From , Gibbon and other researchers began to refine the method using experiments in dogs. Although initial survival rates were low, these experiments revealed the need to add filters to the heart-lung device to prevent blood clots, and to apply suction to the heart to prevent air from entering it during surgery. In fact, on May 6, John Gibbon crowned with success the work of his entire life closing for the first time an atrial septal defect in a young woman using a heart-lung machine of his own invention.
Before that, surgeons had explored other roads like hypothermia, cooling the patient in a cold water tub and then rapidly performing the surgical correction of a heart malformation. John Gibbon developed a heart-lung machine that he used in to successfully complete the first open-heart operation. Because of the development of the heart-lung machine, surgeons were able to perform surgeries previously considered too risky.
Improved versions of the heart-lung machine allow surgeons today to repair heart defects and damaged heart valves, and to perform bypass surgery and heart transplants. These were developed in with the intent of providing complete circulation to both the systemic vascular and pulmonary system. The early oxygenator was nothing other than a rotating steel cylinder, where blood was introduced from the top and after coating an inner surface was exposed to oxygen.
His research was briefly interrupted by the Second World War but upon returning to Philadelphia he continued his critical work. There would have to be a reservoir to collect the blood, compatible tubing to connect to the patient, controllers, pressure gauges and so on. A fortuitous connection with a medical student in his lab, E. Watson assigned his chief engineer, Gustav Malmros, and provided resources to help Gibbon with the mechanical and electrical engineering aspects.
The second major problem was the oxygenation of blood. Through a series of experiments in dogs, Gibbon and his team were able to develop an oxygenator with multiple series of stainless-steel screens. Under tight control, the blood was spread as a film across the screen, and oxygen was flooded into the chamber. Using multiple DeBakey roller pumps, one was able to control the flow into the venous reservoir, flow into the oxygenator and eventual flow back through an arterial conduit.
The pH was adjusted pharmacologically or with the aid of carbon dioxide infusion. Hemolysis was aided by controlling the flow so as to not create shear damage. The converse problem of thrombosis was obviated using heparin, which although discovered in , had just entered clinical trial in the s.
The entire contraption was contained in a large stainless-steel cabinet that was 5 feet by 2 feet, 4 feet in height, and weighed almost pounds. Gibbon and his team first attempted using the heart-lung machine on a child with a presumed atrial septal defect.
But the diagnosis was wrong, and the patient succumbed to a patent ductus arteriosus.
0コメント