<P> CPB can be used for the induction of total body hypothermia, a state in which the body can be maintained for up to 45 minutes without perfusion (blood flow). If blood flow is stopped at normal body temperature, permanent brain damage normally occurs in three to four minutes--death may follow shortly afterward . Similarly, CPB can be used to rewarm individuals suffering from hypothermia . </P> <P> Extracorporeal membrane oxygenation (ECMO) is a form of CPB sometimes used as life - support for newborns with serious birth defects, or to oxygenate and maintain recipients for organ transplantation until new organs can be found . </P> <P> CPB mechanically circulates and oxygenates blood for the body while bypassing the heart and lungs . It uses a heart--lung machine to maintain perfusion to other body organs and tissues while the surgeon works in a bloodless surgical field . The surgeon places a cannula in right atrium, vena cava, or femoral vein to withdraw blood from the body . The cannula is connected to tubing filled with isotonic crystalloid solution . Venous blood that is removed from the body by the cannula is filtered, cooled or warmed, oxygenated, and then returned to the body . The cannula used to return oxygenated blood is usually inserted in the ascending aorta, but it may be inserted in the femoral artery . The patient is administered heparin to prevent clotting, and protamine sulfate is given after to reverse effects of heparin . During the procedure, hypothermia may be maintained; body temperature is usually kept at 28 ° C to 32 ° C (82.4--89.6 ° F). The blood is cooled during CPB and returned to the body . The cooled blood slows the body's basal metabolic rate, decreasing its demand for oxygen . Cooled blood usually has a higher viscosity, but the crystalloid solution used to prime the bypass tubing dilutes the blood . </P> <Ul> <Li> Coronary artery bypass surgery </Li> <Li> Cardiac valve repair and / or replacement (aortic valve, mitral valve, tricuspid valve, pulmonic valve) </Li> <Li> Repair of large septal defects (atrial septal defect, ventricular septal defect, atrioventricular septal defect) </Li> <Li> Repair and / or palliation of congenital heart defects (Tetralogy of Fallot, transposition of the great vessels) </Li> <Li> Transplantation (heart transplantation, lung transplantation, heart--lung transplantation) </Li> <Li> Repair of some large aneurysms (aortic aneurysms, cerebral aneurysms) </Li> <Li> Pulmonary thromboendarterectomy </Li> <Li> Pulmonary thrombectomy </Li> </Ul>

Where are the cannula most commonly placed for cardiopulmonary bypass procedures