High Quality Content by WIKIPEDIA articles! Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a heart–lung machine or "the pump". Cardiopulmonary bypass pumps are operated by perfusionists, medically directed by anesthesiologists, and surgically directed by cardiac surgeons who connect the pump to the patient`s body. CPB is a form of extracorporeal circulation.