A practical method of differential hypothermia to permit use of a low pump oxygenator flow

By cooling the blood just before returning it to the body, marked reduction in the temperature of the heart, brain, liver, and kidney can be produced easily and with great economy in heat transfer, since the great bulk of the animal or patient, consisting of skin, muscle, and bone, is cooled much more slowly. This results in a marked oxygen saving, due to the direct antimetabolic effect of the cooling. Metabolic acidosis can be avoided and so far no irreversible effects of the cooling have been discoverable. Warming is so greatly facilitated by the heat stored in the nonvital areas that it is not necessary to warm the blood returning from the extracorporeal circuit. The use of safe, low, extracorporeal flows offers a number of possible advantages including great simplicity of cannulation and of the pump oxygenator design and operation.