ABSTRACT
PROCEDURES Cardiopulmonary bypass Gibbons first introduced the cardiopulmonary bypass (CPB) machine in 1953 (341). The central function of the CPB machine is oxygenation and circulation of blood independent of the heart and lungs. A secondary function is cooling and warming of the blood to regulate the patient’s body temperature. In the standard technique, a circuit is created between the venous and arterial systems by cannulating the right atrium (or the vena cava) and the ascending aorta. Deoxygenated blood is removed from the venous system and passed through a chamber within which the red blood cells, exposed to oxygen, undergo gas exchange. The blood is propelled through the circuit and into the arterial system by a pumping device and passed through a heat exchanger to be cooled. Blood that is removed by suction catheters from within the operating field can also be filtered and introduced into this circuit to be returned to the patient’s circulation. Heparin is used to prevent thrombus formation within the CPB tubing. Once the patient is cooled, the proximal aorta can then be cross-clamped to stop blood flow through the heart. Myocardial preservation is accomplished through general hypothermia, the administration of cardioplegia solution which contains a high potassium con centration to stop the electrical activity of the heart, and often through direct application of ice slush to the heart’s surface.
