Pathophysiology of Cardiopulmonary Bypass

Abstract

Iohn Gibbon with his pioneering work in the late 1930s made a major contribution to the development of CPB, and its later successful clinical application. In 1955 li hei et al., and Kirklin et al. Independently started the use of pump oxygenators with CPB for the repair of intracardiac defects, starting the modem era of cardiac surgery, in which CPB has become indispensable for most cardiac operations. The primary function of CPB is to direct blood away from the heart (both the right and left side and, hence, usually the lungs as well) and return it to the systemic arterial system. The blood is drained by gravity via cannulae placed in the superior and inferior vena cava (and/or right atrium) to the heart lung machine where it passes through the artificial lung (bubble or- membrane "oxygenators") and then is pumped (usually with a roller or centrifugal pump) back into the systemic arterial system via an arterial cannula that is usually placed in the ascending aorta. In cardiac surgery, systemic hypothennia m conjunction with CPB allows lower pump flows, better myocardial protectionless blood trauma, and better organ protection. At the biochemical level, hypothermia changes the reaction rate of all biochemical processes, especially enzymatic reactions.