What is Cardiopulmonary Bypass?
- It removes heart and lungs from circulation.
- It is used during open heart surgery.
- For example it is used for coronary artery bypass graft and valve repair.
- Machine does the normal function of heart.
What is Heart Lung Machine?
- It replaces the heart and lungs function.
- It helps for blood pumping, to oxygenate blood, to set body temperature.
- Functioning of lung is replaced with Oxygenator.
- Blood pump does the Heart operation.
Surgical Procedure in which Heart Lung Machine is Used
- Coronary artery bypass surgery.
- Cardiac valve replacement.
- During repair of large septum defect.
- Heart Transplantation and lung transplantation.
Main components of a Heart Lung Machine
- Temperature control
- Roller/ centripetal pumps
Working of a Heart Lung Machine
To withdraw blood from the body, a cannula (tube) is inserted in the right atrium, vena cave or femoral vein. The collected blood is sent to cardiopulmonary bypass machine. Oxygenator performs the function of lungs. After the blood is purified, filtered and cooled, with the help of second of cannula in aorta or femoral artery the blood is pumped back. A third cannula is placed near heart is used to flush potassium solution that can stop the heart functioning. A suction device is used to receive blood from heart and give it to the reservoir. Blood from the vein is collected separately and the receiving reservoir stores it. During the surgery procedure, receiving reservoir collects the accumulated blood with help of coronary sinus pump. From the receiving reservoir, blood is sent to settling reservoir or also named as debubbling reservoir. The collected blood goes to the oxygenator, where the blood is purified. From the oxygenator, blood is given to the heat exchanger via arterial blood pump. This process happens at a lower temperature condition, when our body consumes less amount of oxygen. Brain damages are also avoided when the process is done at low temperature. The time limit for the entire process has to be maintained else, it will result in breakdown of red blood cells.