Cardiopulmonary bypass is a technique that is widely used in open heart surgery, such as when replacing a valve, transplanting or revascularizing the heart muscle, as it replaces the work of the heart and lungs. Thus, the doctor can perform the surgery without worrying about blood circulation.
In addition, this technique also prevents the passage of blood through the lung, which reduces the chances of a pulmonary embolism, since there is no risk of trauma to the heart causing clots that end up being transported to the lungs.
How it works
Cardiopulmonary bypass is made by a set of machines that try to replace and imitate the functioning of blood circulation in the body. Thus, it is a technique that includes several steps and components:
- Removal of venous blood: a catheter is placed close to the heart to remove venous blood from the whole body, preventing it from reaching the right atrium of the heart; Reservoir: the removed blood is accumulated in a reservoir about 50 to 70 cm below the level of the heart, which maintains a continuous flow through the machine and which still allows the doctor to add medicines or blood transfusions to the circulation; Oxygenator: then the blood is sent to a device called an oxygenator, which removes excess carbon dioxide from the venous blood and adds oxygen to make it arterial blood; Temperature controller: after leaving the oxygenator, the blood goes to a temperature controller, which allows the doctor to maintain a temperature equal to that of the body or to reduce it, when it needs to cause a cardiac arrest, for example; Pump and filter: before returning to the body, the blood passes through a pump that replaces the strength of the heart, pushing the blood through a filter that removes clots and other gases that may have formed during circulation outside the body; Microfilters: after the filter, there is also a set of microfilters that remove smaller particles, which, although they do not cause problems in the circulation of the body, can pass through the blood-brain barrier and reach the brain; Arterial blood returns to the body: finally, the blood re-enters the body, directly into the aorta, being distributed throughout the body.
Throughout the process, there are several pumps that help the blood to circulate, so that it does not stand still and increases the risk of clots.
Possible complications
Although it is a widely used technique, relatively simple and with many benefits for cardiac surgery, cardiopulmonary bypass can cause some complications. One of the most frequent complications is the development of systemic inflammation, in which the body responds with blood cells to fight an infection. This is because the blood comes into contact with unnatural surfaces inside the machine, which ends up destroying several of the blood cells and causing the inflammatory response in the body.
In addition, due to changes in the speed and temperature that blood can pass into the device, it also increases the risk of clots and, therefore, after this type of surgery it is very important to be aware of the appearance of embolisms in the lung or even stroke.. However, since you have to stay in the ICU after surgery, normally all vital signs are being monitored to avoid this type of complications.
