Cardiopulmonary bypass: What is it and how does it work?

Cardiopulmonary bypass uses a heart-lung machine to take over the work of the heart and lungs for a short time during surgery. The machine removes carbon dioxide from the blood and adds oxygen. It also keeps blood flowing through the body.

As the machine works, a healthcare team monitors blood flow, oxygen levels, blood pressure and body temperature. Examples of surgeries that use cardiopulmonary bypass include some heart valve and aortic surgeries as well as heart transplant and coronary artery bypass.

The care teams in these settings are specifically trained to do cardiopulmonary bypass. A specialist, called a perfusionist, operates the heart-lung machine. The care team uses checklists and processes to set up the machine. Team members check that the machine can do the work of the heart and lungs during surgery.

The surgeries that require cardiopulmonary bypass are often serious and complex. They have potential risks and complications. So while cardiopulmonary bypass has risks, the risks of the surgery itself are often more relevant. As a tool, cardiopulmonary bypass allows your surgeon to operate more safely. Your healthcare team talks with you about everything you should think about before you make an informed decision about your surgery.

In general, complications of cardiopulmonary bypass may include:

• Bleeding, including the need for transfusion.
• Stroke.
• Changes in emotions or the ability to think clearly, which are often short-term.
• Kidney injury.
• Changes in lung function.
• Irregular heartbeats, called arrhythmias.
• Inflammation caused by the body's reaction to the heart-lung machine.

Cardiopulmonary bypass is not the same as extracorporeal membrane oxygenation (ECMO). Cardiopulmonary bypass is used for a short time during surgery. ECMO may be used in an intensive care unit for longer term support.