Cardiopulmonary bypass


Cardiopulmonary bypass is a standard procedure frequently employed in various heart surgeries. It involves redirecting the circulation of blood away from the heart and lungs temporarily. During this process, blood is diverted from the natural path it would take through the heart and lungs and instead directed into a specialized machine located outside the body known as a cardiopulmonary bypass machine or heart-lung machine. This machine assumes the vital functions typically performed by the heart and lungs, such as oxygenating the blood, eliminating carbon dioxide, and then reintroducing the purified blood back into the body.

Reasons for undergoing the procedure.

Cardiopulmonary bypass may be required for individuals undergoing the following surgeries:

  • Coronary artery bypass grafting (CABG).
  • Surgery to treat aneurysms.
  • Heart transplantation.
  • Heart valve replacement or repair surgery.
  • Lung transplantation.

Cardiopulmonary bypass is a procedure frequently used to support CABG. Healthcare providers often perform these procedures simultaneously. Cardiopulmonary bypass establishes an alternate route for blood circulation, diverting it away from your heart and lungs. This aids your surgeon in performing CABG with greater ease and safety.


Discuss the potential risks associated with cardiopulmonary bypass with your healthcare provider, and ensure you understand how your surgical team plans to address them. Generally, the duration of time spent on the bypass machine can impact the likelihood of complications. Additionally, your pre-surgery health status plays a role in determining your individual risk profile.

The following risk includes:

  • Air embolism.
  • Bleeding.
  • Blood clots.
  • Brain injury.
  • Inflammation of the body
  • Lung injury
  • Kidney injury or kidney failure
  • Multi-organ failure.
  • Pancreatitis
  • Pleural effusion
  • Stroke


The heart-lung machine operates by establishing an extracorporeal circulatory route to oxygenate the blood. This process involves directing blood from the superior and inferior vena cava into tubing connected to a reservoir within the machine, where oxygenation takes place. The oxygenated blood is subsequently returned to the patient’s circulatory system via a tube linked to the aorta, the typical point of re-entry for oxygenated blood into the body after traversing the heart and lungs. This process is carefully supervised by a specialized surgical team comprising a surgeon, an anesthesiologist, and a perfusionist—a medical professional with specialized training in the supervision of cardiopulmonary bypass procedures.

During the procedure

During your surgical procedure, your healthcare team connects you to a heart-lung machine and closely monitors your condition. The process of conducting cardiopulmonary bypass involves several critical steps:

  • Preparation: To ensure the heart-lung machine is ready to manage your blood flow and prevent complications, any air inside its tubing is removed by filling it with a priming solution or compatible blood. This step is crucial in avoiding the formation of dangerous air embolisms (air bubbles).
  • Blood thinners: You are administered a blood-thinning medication called heparin. This medication helps reduce the risk of blood clots because, while on the heart-lung machine, your blood is flowing through artificial tubing that lacks the natural endothelial cells found in your blood vessels. These cells release substances that prevent abnormal clotting, which is not present in the artificial surface of the tubing.
  • Connection to heart-lung machine: You are then connected to the heart-lung machine, often referred to as “going on bypass.” At this stage, your heart and lungs are still functioning. Tubes are inserted into your blood vessels to redirect your blood into the machine. Before stopping your heart and lungs, the medical team ensures that everything is functioning correctly.
  • Stoppage of heart and lungs: Your medical team administers cardioplegia, a medication that temporarily stops your heart from beating. Simultaneously, the ventilator connecting to your lungs is turned off, allowing the heart-lung machine to completely take over for your heart and lungs.
  • Continuous monitoring: Throughout your surgical procedure, you remain on the heart-lung machine, and your surgeon performs the necessary surgical steps. The duration of this phase varies depending on the type of surgery you require. Your vital signs, including blood temperature and other critical parameters, are closely monitored by the medical team.
  • Gradual weaning: After completing the surgery, your healthcare team initiates the process of gradually transitioning you off the cardiopulmonary bypass machine. They start by restarting your heart and lungs, allowing them to regain their normal functions. Subsequently, the machine is gradually phased out, enabling your heart and lungs to fully resume their roles.

Once you are successfully disconnected from the heart-lung machine, your medical team continues to monitor your vital signs before transferring you to the intensive care unit (ICU) for post-surgery recovery.

After the procedure

Following surgery, the patient is gradually taken off cardiopulmonary bypass by the medical team. The heart and lungs are restarted first. Afterward, the machine is gradually turned off to allow the heart and lungs to take over completely.
Before the patient is moved to the intensive care unit (ICU) for recovery, the medical staff continues to check the patient’s levels while they are off the pump.

Consulting with your healthcare provider is the most advisable course of action for inquiries regarding your recovery, as it can be influenced by several factors including the specific procedure performed, your medical background, age, and the duration of time spent on the pump. Engaging in a conversation with your healthcare provider will provide you with a comprehensive understanding of what to anticipate following your surgical procedure.


Your healthcare provider will inform you about the necessary follow-up appointments. It’s essential to attend all scheduled appointments and adhere to your provider’s guidance diligently. Don’t hesitate to contact your provider whenever you have inquiries or concerns regarding your recovery.

In case you experience symptoms of a stroke, immediately call your local emergency number. These symptoms may include:

  • Difficulty maintaining balance or walking.
  • Numbness or weakness affecting one side of your body.
  • Slurred speech.
  • Sudden confusion.
  • Impaired vision.
  • Difficulty comprehending others’ speech.