Extracorporeal Membrane Oxygenation (ECMO) Program | Frequently Asked Questions

ECMO, which stands for extracorporeal membrane oxygenation, is a procedure during which blood oxygenation and cardiac function are performed by a mechanical pump outside the body.

ECMO is similar to heart-lung bypass machines used during open-heart surgery. It works by removing blood from the patient and pumping that blood through an artificial lung called a membrane oxygenator. The oxygenator takes over some of the work of the lungs, by exchanging oxygen and carbon dioxide, and the pump takes over some of the work of the heart. The blood is then pumped through a heat exchanger, where it is warmed and returned to the patient. The pressure and flow created by the mechanical pump help circulate blood in the body, thus supporting cardiac function.

ECMO is not a treatment or cure for a heart or lung disease, rather it substitutes for the work of the heart and lungs, thus allowing them to "rest" until time or additional procedures assist in reversing the problem that is causing reliance on ECMO.

Babies and children placed on ECMO have serious, but reversible, medical conditions that impair heart or lung function, or both. While a child awaits treatment or recovers from treatment, the ECMO machine does the work for the child's heart and lungs, until these vital organs recover and can function well independently. ECMO maintains blood flow and oxygenation to the vital organs (liver, kidney, brain), so that the function of these organs are maintained while the heart or the lungs recover.

At Boston Children's Hospital, ECMO has been successfully used in the following ways:

• For babies and children with severe lung conditions. Lungs provide oxygen to the body through blood, and remove carbon dioxide from blood. Sometimes, when lungs aren't functioning because of illness or injury, the problem is so severe it cannot be helped with support from medication or respirators. ECMO may be used to support lung function in the case of severe lung conditions such as neonatal respiratory distress syndrome, congenital diaphragmatic hernia, neonatal meconium aspiration syndrome, pulmonary hypertension, severe pneumonia, or respiratory failure.

• For children who go into sudden cardiac arrest. ECMO is sometimes used as a backup to revive patients whose hearts stop beating when other treatments, such as medications or a respirator, do not work.

• Other indications for ECMO.

  • as a bridge to cardiac surgery for newborns
  • post-operative support for children who undergo cardiac surgery
  • as a bridge to heart transplantation

The ECMO machine has many connecting pieces and moving parts. It consists primarily of a pump and a circuit made up of a membrane (artificial lung), a blood warmer, and a filter. The machine removes blue blood (without oxygen) from your child and pumps it through the membrane where it receives oxygen and becomes red. The blood is warmed, filtered, and returned to your child. ECMO is used in two different ways depending on your child's needs:

• Veno-arterial (VA) ECMO is used to support both heart and lung function. Blood is drained from a vein and returned to an artery which transports the oxygenated blood to organs and other body tissues where it is needed.

• Veno-venous (VV) ECMO is used to support lung function. Blood is drained from the vein, oxygenated, and then returned to the vein, where it is pumped through the heart to arteries that carry the oxygenated blood to organs and other body tissues.

ECMO support is established by the surgical placement of large IV-like catheters, known as cannulae, into veins and arteries. A team of surgeons inserts the cannulae, while a specially trained respiratory therapist prepares the ECMO circuit. Another team of ICU physicians and nurses closely monitors your child during the procedure and makes sure that your child remains stable and comfortable. Once the cannulae are inserted and secured, the ECMO circuit is connected to the cannulae and the pump is started.

The ICU team monitors your child while the ECMO specialist monitors the function of the ECMO pump and circuit. Your child will be put on general anesthesia before he or she is placed on ECMO. Since ECMO is used in very serious cases, children are usually already sedated, and additional analgesic agents are administered to augment the sedation. These agents are continued to keep patients asleep until they are weaned off of ECMO.

Where the cannulae are inserted can vary depending on age and circumstance. For instance:

• Infants that require ECMO support for respiratory failure typically have the cannulae inserted through arteries and veins located in the neck area.

• Older children have the cannulae placed in veins and arteries located in the groin. Patients that require ECMO support following cardiac surgery will typically have their cannulae placed through the surgical incision located in the center of the chest.

ECMO support is generally not painful. Your child will receive pain medications and sedatives during ECMO, and in some cases may require complete muscle relaxation with medications known as paralytics. These medications are only used when it is determined that your child needs to be completely still for safety reasons or during procedures. You will be able to talk to and touch your child while he or she is on ECMO support.

Your child may be on a specially designed and elevated bed during ECMO support. Routine monitoring equipment will be connected to measure your child's heart rate, respiratory rate, oxygen levels, and blood pressure. Your child will have a breathing tube inserted through his or her nose or mouth that will be connected to a ventilator, which is needed to prevent your child's lungs from collapsing while they heal. There will be intravenous catheters in place that will be connected to tubes providing continuous administration of medications. The ECMO pump and circuit will be next to your child's bed.

ECMO is generally continued until the underlying cardiac or lung problem is improved or resolved. The typical course is around five days, but in some cases, ECMO support has been continued for up to 25 to 30 days. Long-term ECMO support increases the chances of complications. The decision to discontinue ECMO support is determined after careful evaluation of the patient's lungs and heart, and their ability to resume near-normal function with minimal support and intervention. Your child's cardio-pulmonary function will be monitored through chest x-rays, echocardiography, and blood tests.

The most common complication associated with ECMO support is bleeding. Bleeding is prevalent because heparin, a blood-thinning medication, is continuously administered during ECMO. Heparin prevents the formation of blood clots and helps keep the ECMO circuit flowing smoothly. Bleeding may be visible at surgical sites, or it may not be, if it is internal. Every effort is made to minimize the use of heparin and reduce bleeding. The level of blood anticoagulation is monitored every hour at the bedside, and the dose of heparin used is carefully controlled to prevent bleeding complications.

Rarely, serious bleeding in the brain can occur. Infants are particularly susceptible to this kind of complication and therefore are routinely monitored by pediatric neurologists with head ultrasound and other examinations. Infections and problems with liver and kidney function can occur in patients who remain on ECMO over a long periods of time. All vital organs are routinely monitored with blood tests.

Mechanical complications with the circuit or pump also are possible. The ECMO circuit is composed of components that are interconnected to create a smooth-flowing support system for your child. If any of these parts malfunction, there is the risk of significant blood loss and/or the introduction of air into the system. These malfunctions are rare, but if they occur, significant damage may be done to the organs, including the brain. The ECMO specialist is trained to manage all ECMO-related emergencies.

Perhaps the most important thing you can do during this difficult time is to be in the room with your child as much as you can. Your child will be sleepy most of the time, but hearing your voice and knowing that you are there can be tremendously helpful. Your child will require rest, but there may be times when reading a story, playing music, or just talking to your child may be very helpful. You won't be able to hold your child, but holding you child's hand is encouraged. Talk to your child's nurse about other ways you can help, such as applying cream to your child's skin or moistening his or her lips.

If you are breastfeeding, you are strongly encouraged to pump your breasts and store the milk for your baby to use later, when off ECMO. For your convenience, you can use a lactation room that is fully equipped with an electric breast pump. A lactation specialist is on-site to assist you.

ECMO support is usually offered to children whose chances for a healthy recovery are considered to be very good. We have performed more than 900 ECMO runs at Boston Children's since 1986, making us one of the most experienced ECMO centers in the world. We track patient outcomes very closely, and the ICU physicians will discuss with you the possible outcomes, risks, and complications for your child while on ECMO. Because we have ECMO staff in house 24 hours each day, there are no delays using this life-saving technology.

There are potential long-term problems that can occur, such as developmental and neurologic disorders. Neurologic problems have been associated with low oxygen levels to the brain prior to ECMO, or intracranial hemorrhage. Your child's physician will discuss long-term problems that may occur as a result of your child requiring ECMO support. The Department of Neurology will provide ongoing follow-up after your child has been discharged.

If your child's doctors determine that your child's heart and/or lungs are able to function well without ECMO assistance, ECMO support will be reduced on a gradual schedule. Each time ECMO support is reduced, your child's oxygen and carbon dioxide levels will be checked to be sure the lungs are supplying the appropriate level of oxygen and the heart is effectively pumping.

If all goes well, doctors can stop ECMO entirely by clamping the tube, which will stop blood flow to the ECMO circuit. The cannulae then will be surgically removed. Your child will still require assistance of a ventilator. This will also be gradually decreased as your child's condition improves.

Your child's ECMO team is available 24 hours a day during your child's ECMO course. Please do not hesitate to ask any questions regarding any aspect of your child's care. There are also social workers, pastoral staff care, and a psychiatry staff available to you. Your child's nurse can get in touch with these individuals.