Disposable Membrane Oxygenator (Heart-Lung Machine) and Its Use in Experimental Surgery

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PROLONGED OPERATIONS in the open heart at normal body temperature require heart-lung machines as a substitute for cardiopulmonary function. The principle of all these is the same: they withdraw blood from the venae cavae, oxygenate it, and return it into the aorta. Thus the patient's heart is completely bypassed (Fig. 1). It was believed for a long time that the machine would have to pump and oxygenate blood in amounts equal to the normal resting cardiac output —at least 100 ml. per kg. of body weight per minute. Accordingly, several elaborate machines have been devised to pump and oxygenate 5 liters of blood per minute, for example by Dennis,1 Jongbloed,2 and Kolff and Dubbelman.3,4 The most successful design was that of Miller, Gibbon, and Gibbon.5 A similar machine is in use at the Mayo Clinic6,7 with outstanding success; its complexity and cost have prevented its wider use.

Andreason and Watson 8,9 in England have shown that dogs survived at least 35 minutes of occlusion of both venae cavae when only the azygos vein was left open and cardiac output was reduced to 10 to 18 milliliters per kilogram of body weight per minute. Lillehei, Varco, and co-workers 10–14 have greatly-advanced cardiac surgery in this country by using this principle. In dogs, they found that flow rates of 30 to 45 milliliters, as provided by cross circulation or some type of artificial heart-lung apparatus, were more suitable than the ‘azygos flow’ rates of 10 to 18 milliliters per kilogram per. . .



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