CARDIOPULMONARY BYPASS
Use of the heart-lung machine in cardiac surgery is called cardiopulmonary bypass. Cardiopulmonary bypass provides patients with cardiac and pulmonary support, while bypassing the heart and lungs. Cardiopulmonary bypass artificially provides patients three physiologic processes or functions:
It adds oxygen to the blood
It pumps or circulates the blood through both the cardiopulmonary bypass circuit and the patient
It removes excess carbon dioxide from the blood
To accomplish this, the surgeon inserts cannulas, which are small tubes, into the patient’s major veins (typically the superior vena cava and inferior vena cava) and arteries (typically the aorta). Once the cannulas from the patient have been connected to the cardiopulmonary bypass circuit, the blood is drained from the veins into the heart-lung machine while the blood is pumped into an artificial lung (oxygenator), which adds oxygen and removes carbon dioxide.
The oxygenated blood is pumped back to the aorta to provide oxygen to the tissues and organs of the patient.