Common Questions about ECMO

ECMO stands for Extracorporeal Membrane Oxygenation, which means oxygenation outside the body. It can be used to support heart and/or lung function in babies and children. It is similar to bypass used in the operating room but can be used for longer periods of time.

ECMO is necessary when a child has severe lung or heart problems,and standard forms of treatment are not effective. ECMO is not a treatment but can provide time for the heart and lungs to improve. ECMO is only used when the child's condition can improve with rest.

Some of the illnesses for which ECMO is used include:

• Aspiration Pneumonia
• Asthma
• Congenital Diaphragmatic Hernia (CDH)
• Inborn Errors of Metabolism
• Meconium Aspiration Syndrome (MAS)
• Near-Drowning
• Post-Op Cardiac Surgery
• Pneumonia
• Pulmonary Hypertension (PPHN/PAH)
• Sepsis

Normally, the lungs provide oxygen and remove carbon dioxide from the blood. When the lungs are sick or injured, they are unable to do this even with maximum support from medication and machines. ECMO can supply oxygen and remove carbon dioxide while allowing the lungs to heal.

If the heart is unable to pump effectively, circulation of blood to the lungs may be affected resulting in low oxygen levels. Blood may not be pumped to the body adequately if the heart is damaged. ECMO can be used to pump the blood to the lungs and throughout the body, so the heart can rest and heal.

Parents are updated regularly on the progress of their child during ECMO treatment. Changes in medications or other treatments may be necessary. In some cases, these changes will not help the child. If a child shows no improvement, ECMO may have to be stopped.

The surgeon places cannula, or tubes, so that blood is able to drain out of the body and through the ECMO circuit. The site where these tubes are placed depends on the reason ECMO is needed and on the type of ECMO needed. The cannula may be placed in a vein and/or artery in the neck, the groin, or the chest. A cannula may also be placed in one vein or two different veins.

Once the cannulae are placed, the ECMO circuit is connected. The circuit has several components connected by different lengths of tubing. Initially the blood drains into a reservoir. The pump pushes the blood from the reservoir into the oxygenator, or artificial lung. Then the blood travels through a heat exchanger to be warmed before returning to the body. The rate the blood travels through the circuit is called the ECMO flow and is dependent on the size of the child.

Dark blood, without oxygen, drains into the circuit. After the blood passes through the oxygenator it becomes bright red due to the presence of oxygen. The oxygenated blood is returned to the child in either a vein or an artery.

Once ECMO flow is established, the ventilator settings may be turned down to allow the lungs to rest. Medications to help the heart function may or may not be decreased. The physician will change medications for each child based on individual needs. As the child improves, the ECMO flow can be decreased to allow the heart and/or lungs to do more of the work.

There are two types of ECMO: VA and VV. VA, or veno-arterial, ECMO supports heart and lung function. It is done using two cannulae. VV, or veno-venous, ECMO supports lung function. VV ECMO can be done with one or two cannulae.

With VA ECMO there are two cannula, one in a vein and one in an artery. Blood is drained from the vein and returned to the artery. Both of these cannula are usually placed in the neck. If the child develops problems with heart function soon after heart surgery, the cannulae are placed at the surgical site. Children who require ECMO shortly after surgery will have cannula in place with the chest incision unsutured and covered by a special dressing to prevent infection.

With VV ECMO, one or two cannula can be used. If one cannula is used, it has a double lumen, meaning two tubes in one. It is usually placed in a large vein in the child's neck. Blood drains from one side of the cannula and returns in the other side. If two cannula are used, blood drains from one cannula positioned in a vein and returns through a second cannula placed in a different vein.

Before ECMO a child with a critical condition requires many different tubes or wires to monitor vital signs and provide necessary medications. These will remain in place. Some  necessary equipment includes a ventilator, which breathes for the child. With ECMO the ventilator will stay in place, but the breathing rate and pressure used for each breath can be decreased. This will allow the lungs to rest.

Small tubes called central lines will monitor fluid status and allow access for different medications. A catheter will drain urine continuously. Wires that detect heart rhythm will be attached to electrodes taped to the skin. A small catheter in an artery in the hand, arm, or foot monitors blood pressure and provides access for blood draws. The ECMO cannula will be sutured in place, either in the neck, groin, or open chest incision.

If the child had problems getting oxygen before ECMO, there will be a bluish tint to the skin. Once ECMO has begun, color will improve. Low blood pressure, seen with poor heart function, can also cause skin color to be bluish or a pale gray. After ECMO is begun, color improves as circulation improves.

Children on ECMO may given medication to prevent movement. This is needed to prevent accidental dislodging of the ECMO cannula. The child is usually kept on the back. Position changes are generally only minimal, also due to the risk of accidental removal of the cannula. Blood drains into the ECMO circuit by gravity, making it necessary to raise the height of the bed. It would not be unusual for children to have three extra mattresses to add height. A stepladder will be at the bedside to allow parents to be near their child.

Bleeding may be seen from the site of cannula placement. This is not unusual and if necessary, blood will be given to replace what is lost. Other blood products will be given to help control the bleeding.

Before ECMO it may have been necessary to give large volumes of fluid to maintain blood pressure. This fluid can leak into the tissues, causing a swelling. This will decrease over several days and may not be gone until after ECMO is no longer necessary. A device can be connected to the ECMO circuit to help with the removal of extra fluid. This would be a slow process without a noticeable change in swelling.

Routine monitoring

• Vital signs, including heart rate, blood pressure, and temperature
• Specific monitoring of the ECMO circuit will also be done
• Pressure in the ECMO circuit
• Checks for leaks, kinks, or other signs of wear in the circuit
• Medication

Medications administered to children on ECMO may include those to aid heart function, improve urine output, prevent or treat infection, prevent blood clotting, manage sedation and pain relief, and prevent movement. All medications flow through an existing IV or into the ECMO circuit. No needle sticks are necessary. Sites attached to the ECMO circuit allow for blood draws.

Lab work

An hourly activated clotting time test measures use of the drug heparin. Blood gas tests  measure oxygen and carbon dioxide levels. These are are done hourly at first, but decrease as the child's condition stabilizes. Other routine lab work monitors amounts of blood components. Cultures may help spot infections.

Scans

Daily X-rays will check for changes in the lungs' appearance. Babies will have daily head ultrasounds to check for bleeding into the brain. If the child's condition is heart-related, an ECHO, which is an ultrasound of the heart, can tell the doctors if heart function is improving.

Most procedures can take place inside the PICU. In rare occasions a necessary procedure must be performed in another area of the hospital. The child can be safely moved while on ECMO.

Other routine care is unchanged after ECMO has begun. The ventilator will continue to breathe for the child, but at a much lower pressure and rate, allowing the lungs to rest. The tube into the child's lungs will be suctioned at intervals to clear them of secretions. Most children will be given special IV fluids to maintain nutrition. Some may be given formula through a feeding tube placed through the mouth into the stomach.

Frequent blood transfusions may be necessary. Other blood products are also given as needed. Platelets, a blood product that helps with clotting, can be depleted during ECMO. Blood and platelet counts are checked frequently and replaced as needed.

Because of the use of heparin, there is a risk of bleeding. This can occur anywhere, but is mostly seen at the site of cannula insertion. If the child has had heart surgery, bleeding may occur within the chest. If this happens, the surgeon will remove the dressing on the child's chest and look for possible areas of bleeding. This is not always possible to control while the child is being given heparin. Blood can be replaced as necessary if it cannot be stopped. Bleeding can also occur in the brain. If this occurs ECMO may have to be stopped to control it.

The use of ECMO can also cause the blood to clot too much. The blood within the ECMO circuit may produce clots at points where tubing is connected. These clots are observed and can be removed if necessary. Rarely, small pieces of these clots can break off and travel through the patients blood stream. If this happens, the clots could block blood supply to some areas of the patient, causing organ or tissue damage.

Tests routinely search for infections, with antibiotics administered as necessary.

Problems can occur with the equipment or with the circuit tubing. The ECMO specialists can recognize and correct these problems. A complete back-up circuit is available and can be changed out if necessary.

Several physicians may be involved in your child's care. A pediatric intensivist is primarily responsible for all children in the PICU. A cardiothoracic surgeon and a pediatric cardiologist will be involved with some children's care, and a pediatric surgeon with all others. Specially trained nurses care for the child, while ECMO specialists manage the ECMO circuit. The ECMO specialists can be either nurses or respiratory therapists. Others involved in each child's care include the social worker, pharmacist, nutritionist, and specialists in child development.

The decision to come off ECMO is made when all the doctors involved agree that the child is ready. The child's progress is evaluated to determine if there has been enough improvement or if more time is needed. If the child is on ECMO for respiratory reasons, an X-ray will help find improvement in the lungs' appearance. If a blood gas test show an improvement in oxygen and carbon dioxide levels, the ECMO flow can be decreased. This process may take several days or weeks.

When the ECMO flow is decreased to a certain point, the cannulae can be clamped, stopping blood flow from the circuit to the child. This allows the child's lungs to work without the support of ECMO. This is called a "trial off." Blood gases are checked at this time. If oxygen and carbon dioxide levels remain good, the child may be ready to come off ECMO.

When ECMO is used because of poor heart function, the weaning process would also require that the child's heart function support them without ECMO. There are several ways to monitor heart function. The blood pressure should be good without increasing medications. The doctors can do an ECHO, which would show how well the heart is beating. Blood gases and X-rays are also checked. The physicians will look at all of these things before making the decision to wean the ECMO flow. When the child is ready, there will also be a trial off before ECMO is stopped completely.

It is not uncommon for a child to have problems during the trial off. If this happens the ECMO flow is turned up, followed by another trial off a day or two later.

The trial off just described is only for VA ECMO. In VV ECMO the trial off periods involve weaning the ECMO flow to a specific point and then stopping the oxygen supply to the artificial lung. In this situation, the child's lungs are doing all the work. If the blood gases are good, ECMO can be stopped.

The procedure for stopping ECMO is similar to what was done to go on ECMO. The pediatric surgeon or the cardiothoracic surgeon will remove the cannulae. Following this the child will still be very sick and will remain in the PICU. The child's care will not change, except that ECMO will not be used. It may still take several more days or weeks for the child to be well enough to return home.

Parents and other family members can be involved in the child's care. Simple things such as bathing, diaper changing, and turning can be done with the nurses' help. As a parent, you know what your child likes and dislikes. You can bring your child's favorite music to be played at intervals throughout the day. A special stuffed animal can be put in the bed with your child. Pictures and cards can be hung at the bedside. Some families bring music for the child to listen to when they cannot visit. When you are at the bedside, just talking to your child can help both of you.

If your child is an infant, the nurse will help you understand what your baby needs. At first, babies need to be kept in a quiet environment. In the hours and days ahead, you will be able to enjoy more interaction with your baby. Your baby may benefit if you talk or sing. If you cannot visit as much as you would like, you can make audiotapes that can be played when you are not there.

Stroking may be better than patting. Classical music may be better than rattles or squeaky toys. Your baby may not even want to be touched. Noise can be irritating to your baby. The nurse can help you learn what will work best for your baby during this stressful time.

Your child will not be able to nurse or take a bottle while on ECMO. Nutrition is provided through a special type of fluid given in the blood stream. Breast-feeding can be done after the baby comes off ECMO. Until that time, mothers who wish to breast-feed can express milk and freeze it for use later. Your baby's nurse can explain how to do this.

Some babies have difficulty with feeding after ECMO. With help your baby may learn to nurse or take a bottle without problems. Due to the severity of problems before ECMO, there may be some children who continue to need oxygen even after going home. If this is the case, you will be taught what is needed before taking your child home.

Long-term follow-up of patients on ECMO is ongoing. The range of problems may extend from no problems at all to severe, long-term medical problems. Their severity often depends on many factors involving your child's disease process and treatment course.