Extracorporeal membrane oxygenation
Extracorporeal membrane oxygenation (ECMO)is a life support machine. People who need ECMO have a severe and life-threatening illness that stops their heart or lungs from working properly. For example, ECMO is used during life-threatening conditions such as severe lung damage from infection, or shock after a massive heart attack. The ECMO machine replaces the function of the heart and lungs. People who need support from an ECMO machine are cared for in a hospital’s intensive care unit (ICU). Typically, people are supported by an ECMO machine for only a few hours to days, but may require it for a few weeks, depending on how their condition progresses. There are many overlaps and differences between the use of ECMO in children and adults.
ECMO is used to help people whose:
Lungs cannot provide enough oxygen to the body even when given extra oxygen
Lungs cannot get rid of carbon dioxide even with help from a mechanical ventilator
Heart cannot pump enough blood to the body
ECMO may also be used to support people with heart or lung disease that cannot be cured while they wait for an organ transplant (e.g. new heart and/or lungs).
How does an ECMO machine work?
The ECMO machine is connected to a patient through plastic tubes (cannula). The tubes are placed in large veins and arteries in the legs, neck or chest. The procedure by which a healthcare provider places these tubes in a patient is called cannulation. The ECMO machine pumps blood from the patient’s body to an artificial lung (oxygenator) that adds oxygen to it and removes carbon dioxide. Thus, it replaces the function of the person’s own lungs. The ECMO machine then sends the blood back to the patient via a pump with the same force as the heart, replacing its function. The ECMO machine is controlled by a person called a perfusionist, or a nurse or respiratory therapist with advanced training called an ECMO specialist. The perfusionist or ECMO specialist will adjust the settings on the machine to give the patient the amount of heart and lung support they need.
How is a patient on an ECMO machine monitored?
Any patient connected to an ECMO machine in the ICU is also connected to monitors. These monitors measure heart rate, blood pressure, and oxygen levels. Patients on ECMO need their blood tested very often to measure the oxygen and carbon dioxide levels.These tests are called blood gases. Patients on ECMO are also given a medication to thin the blood so it does not clot. Thus, the blood is tested frequently to make sure it is thin enough. Members of the patient’s health care team use all these results to see how well the ECMO machine is helping the patient, and to make changes if needed.
How long is an ECMO machine used?
An ECMO machine can help save a patient’s life, but it does not treat the patient’s disease or injury. An ECMO machine simply provides support for a patient while the healthcare team works on treating the underlying disease or injury (such as an infection) or until organs for transplant become available. Healthcare providers will always try to help people get off the ECMO machine as soon as possible. Some diseases or injuries can be treated quickly, and patients only need the ECMO machine for a few hours. Other conditions may take longer to get better, in which case the patient may need the ECMO machine for several days to weeks. Unfortunately, in some cases, patients do not improve enough to be taken off the ECMO machine. ECMO does not save everyone but it has improved survival for many critically ill people who are not responding to usual life support options.
What are the risks of being on ECMO?
The healthcare team looking after patients on ECMO aim to avoid any complications that may occur from being on the machine. Some of the more serious problems that may occur when a patient is on ECMO include:
Bleeding: Because of the blood thinning medication that patients need while on ECMO, they can start bleeding in different parts of their body. This can be a very serious problem if the bleeding happens in their brain, lungs, insertion sites of cannulae or from their stomach. The healthcare team monitors patients very carefully by frequent physical exams and lab tests to make sure there is no bleeding. If there is bleeding, then medications can be given to help the blood to clot. Sometimes, surgery is needed to stop the bleeding. Blood and other blood products (such as platelets) may also need to be given if blood counts drop too low.
Kidney Failure: Patients who are on ECMO sometimes do not get enough blood flow to their kidneys. This can cause their kidneys to stop working, known as 「acute renal failure」. If the kidneys stop working, then a patient may need to be connected to a machine
that does the work of the kidneys. This is called dialysis. The kidney damage may get better. However, in some cases, patients may need dialysis for the rest of their life.
Infection: The tubes from the ECMO machine go from outside the patient’s body directly into their bloodstream. This increases the risk for infection, because the tubes are a way for germs to enter the body. The infection can reach the lungs, or any other part of the body. Infections in patients on ECMO can usually be treated with antibiotics. However, some patients who develop infections while on ECMO can get sicker and suffer organ damage.Leg Damage: Some patients are connected to the ECMO machine through a vein or artery in their thigh. In some cases, this can impair the blood flow down that leg, and the tissue in the leg can die.
Stroke: In patients on ECMO, certain areas of the brain may not get as much blood flow as they need because of small blood clots. This can cause a stroke, and parts of the brain may be permanently damaged. The area of the brain that is damaged will determine what problems a person has from a stroke. Some patients may not be able to move certain parts of their body, see, remember, speak, read or write. Sometimes a person will recover some function after a stroke, but that is not always the case. Fortunately, strokes are very rare and happen less than 5% of the time to patients on ECMO.
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