Cardiopulmonary bypass (CPB) refers to a type of life support that involves using a machine outside the body to act as the heart and lungs. The cardiopulmonary bypass machine (heart-lung machine) is controlled throughout a heart surgery by a perfusionist. A perfusionist is a healthcare professional who works closely with your child’s anaesthetist and cardiac surgeon during the surgery to keep blood circulating through the body.
Every year in Australia, approximately 1,000 cardiopulmonary bypass procedures are performed on children.
What does a CPB machine involve?
The cardiopulmonary bypass machine involves a network of tubing, a pump which acts as the heart, and an oxygenator that acts as the lungs.
Blood is gently drained from the body through a flexible hollow tube (cannula) which is placed in the right (venous) side of the heart. The blood is dark because it contains very little oxygen. The pump pushes the blood through an artificial lung (oxygenator) which adds oxygen and removes carbon dioxide from the blood. This blood is now bright red as it contains oxygen. The oxygenator also controls the temperature of the blood. The blood is returned to the body through another flexible hollow tube (cannula) into the main blood vessel that leaves the heart (aorta). This blood then continues around the body, flowing into the organs and tissues.
The tubing network of the cardiopulmonary bypass machine needs to be filled with fluid and be oxygen-free. This means your child’s blood volume will be diluted. Too much dilution can be unsafe, so to avoid this, your child may require a transfusion of blood products while on cardiopulmonary bypass.
Why is a CPB machine needed?
The machine pumps oxygenated blood around the body, so the heart can rest and can be safely stopped during surgery. When the heart is stopped, there is no heartbeat and the heart does not move. This makes it easier for the surgeon to perform complex repairs.
When the heart is stopped, it can also be emptied of blood. This allows the cardiac surgeon to open the heart to close holes and repair valves in the heart.
More about the perfusion team
There are four full time perfusionists at the Queensland Children’s Hospital. They are specially trained to perform cardiopulmonary bypass on babies and children. They are also trained to use the Extracorporeal Life Support (ECLS) machine to provide a therapy known as ‘ECMO’ (Extracorporeal Membrane Oxygenation). ECMO is similar to cardiopulmonary bypass, but is designed for use over a longer time period and is used mainly in the Intensive Care Unit. The perfusion team provides a 24-hour on-call service for children who require urgent surgery and extracorporeal life support.
Queensland Paediatric Cardiac Service
Queensland Children’s Hospital
501 Stanley Street, South Brisbane
t: 07 3068 2597
t: 07 3068 1111 (general enquiries)
In an emergency, always call 000.
If it’s not an emergency but you have any concerns, contact 13 Health (13 43 2584). Qualified staff will give you advice on who to talk to and how quickly you should do it. You can phone 24 hours a day, seven days a week.