Overview of Extracorporeal Membrane Oxygenation in Children
Extracorporeal membrane oxygenation (ECMO), also known as extracorporeal life support (ECLS), is a life-saving machine that does the job of the heart and lungs when they aren’t working properly. It was first used in the 1970s during heart surgeries. Originally, it was mostly used for children, which is why much of what we know about ECMO comes from its use in children and newborns. Despite being a highly specialized technology with limited availability in children’s hospitals, it has been connected to improved survival rates.
The use of ECMO around the world is growing because it has been shown to improve survival rates in children who use it. However, it is a challenging treatment to use because it requires a lot of resources and highly skilled medical staff. An entire healthcare team is needed in order to manage a child on this machine, deal with any complications that arise and handle any technical problems that require a more intensive level of care.
Anatomy and Physiology of Extracorporeal Membrane Oxygenation in Children
The ECMO machine is a device that performs some of the heart and lungs’ functions when these organs are not working well. It consists of a pump, an artificial lung, and a device to adjust the blood temperature. The machine works by draining blood from the patient’s large blood vessels and pushing it towards the artificial lung. In this lung, the blood gets enriched with oxygen and gets rid of carbon dioxide, its temperature is adjusted, then it’s pumped back into the patient’s body.
The ECMO machine imitates the human lung thanks to the artificial lung being made up of tiny tubes that work similarly to the small air sacs in our lungs called alveoli where gases are exchanged. The machine ensures the patient’s body is functioning properly by controlling the pressure difference between the patient’s blood flow and the gas flow. This process involves removing carbon dioxide from the blood and adding oxygen, similar to what happens in our lungs when we breathe.
Doctors can adjust the machine to get the most of it based on the patient’s condition. They can control the flow of blood in the machine, for example, babies and small children require a different flow rate than bigger children. The oxygen-enriched blood is then returned to the patient’s body through a tube placed in a vessel.
Two primary modes or types of ECMO are based on the patient’s physical state. The first type, venoarterial (VA) ECMO, supports the patient’s heart and lungs when the heart’s function is not sufficient. The second type, venovenous (VV) ECMO, is used for patients whose lungs need support to recover, but whose heart function is okay. For this type, a catheter is placed in a vein, and blood is taken out, treated, and returned through the same or a different vein.
Recirculation, an issue where oxygen-enriched blood is taken back into the machine before it goes through the body, may occur with VV ECMO. Doctors can diagnose this problem when they see low oxygen levels in the patient and high oxygen levels before the artificial lung. They can solve it by adjusting the cannulae or tubes’ positions that take and return blood to the body.
Lastly, doctors have several methods to ensure adequate oxygen levels, including adjusting the machine’s blood flow, increasing the patient’s blood hemoglobin, reducing the body’s oxygen use, and readjusting the positions of the blood tubes to reduce recirculation.
Why do People Need Extracorporeal Membrane Oxygenation in Children
If your child or a newborn has a problem with their heart’s shape since birth (called structural congenital heart disease), they might need assistance around the time of surgery. This is done to ensure their heart continues to work properly.
Similarly, if your child has heart conditions that aren’t related to their heart’s shape, such as a weak heart muscle (cardiomyopathy), heart inflammation (myocarditis), heart attack (myocardial infarction), uncontrollable irregular heartbeat (intractable arrhythmias), sudden weakening of the right side of the heart due to high blood pressure in the lungs (acute right-sided heart failure secondary to pulmonary hypertension), worsening heart function due to poisoning, heart failure in serious infection (cardiac failure secondary to septic shock), they might need help for their heart to work better. If your child is awaiting a heart transplant, receiving long-term heart support systems such as a ventricular assist device (a mechanical pump inside the chest that helps pump blood from the lower chambers of your heart to the rest of your body), after a heart transplant, during a high-risk heart procedure or if they can’t be removed from heart-lung machine after surgery, this kind of support may be required.
If your child or newborn has trouble breathing due to an issue with oxygen exchange in their lungs, their doctor might consider a technique called ECMO (Extracorporeal Membrane Oxygenation). This is a treatment that uses a machine to take over the work of the lungs (and sometimes also the heart). This problem is calculated using a formula called an Oxygenation Index with no specific threshold value; if there’s no improvement by the second day of the illness, ECMO might be considered. If the body’s pH (a measure of how acidic your body’s fluids are) is less than 7, this is also a consideration for ECMO. Common conditions that might result in this problem include acute respiratory distress syndrome, pneumonia and being on a waiting list for lung transplantation.
In newborns, if the Oxygenation Index is greater than 40, ECMO is usually considered. If the Oxygenation Index is over 25, then the newborn might be transferred to a center where ECMO can be performed. Conditions that might lead to this problem include high blood pressure in the lungs, inhaling meconium (first stool) before or around the time of birth (meconium aspiration syndrome), congenital diaphragmatic hernia (a birth defect that allows the stomach and intestines to move into the chest cavity and cause breathing problems), air leak syndrome (a lung condition in newborns that leads to difficulty in breathing), and pneumonia.
When a Person Should Avoid Extracorporeal Membrane Oxygenation in Children
As doctors become more comfortable using ECMO (a treatment that uses a pump to circulate blood through an artificial lung back into the bloodstream), they are considering it for more and more patients. However, some patients might not be able to have this treatment due to certain health conditions, particularly those that make treatment pointless or highly risky, leading to severe illness or even death.
Some reasons why patients might not be able to have ECMO:
* Fatal genetic abnormalities like Trisomy 13 or 18. These are conditions where you have an extra chromosome, which can lead to a variety of health problems.
* Serious damage to the brain that can’t be reversed or severe bleeding in the brain (intraventricular hemorrhage grade III or more), or severe brain damage due to not enough oxygen or blood flow (hypoxic-ischemic encephalopathy).
* Uncontrollable bleeding that can’t be stopped.
* Cancer that can’t be cured.
* For newborns, if they were born too early (before 30 weeks of pregnancy) or are too small (birth weight less than 1 kg or 2.2 pounds).
Other factors that doctors consider but don’t necessarily disqualify a patient for ECMO:
* If the patient has been on a ventilator (a machine that helps you breathe) for more than 2 weeks before starting ECMO, it might pose a higher risk.
* If they had a recent brain surgery or bleeding in the brain within the past 7 days.
* If they have a chronic (long-term) illness with a poor prognosis (a predicted outcome).
* If they have received a bone marrow transplant from a donor.
* If they have solid organ tumors (cancers found in solid parts of the body, like the lungs, kidneys, or liver).
* Newborns with a birth weight less than 2 kg (4.4 pounds).
Equipment used for Extracorporeal Membrane Oxygenation in Children
An ECMO machine is a vital piece of equipment used in complicated procedures. It has certain components such as vascular cannulae, blood pumps, and monitoring devices. One important part of the ECMO machine is the membrane lung, which includes an oxygenator and heat exchanger. These instruments allow the machine to take over the function of the heart and lungs in pumping and oxygenating the blood.
These operations usually take place in a pediatric or neonatal intensive care unit, which is a specialized department in the hospital for treating newborns and children with severe illnesses or conditions.
These units work closely with a comprehensive clinical laboratory, which provides crucial information about the patient’s condition through different tests and analyses. This information is necessary for the doctors to make informed decisions about the patient’s treatment plan.
The procedures typically take place in a tertiary or quaternary hospital. These are high-level hospitals with a wide range of pediatric specialists and subspecialists. These professionals have more specific and refined knowledge and skills, which are necessary to effectively manage and treat complex medical conditions.
Echocardiography is another crucial part of the procedure. It is a medical test that uses sound waves to produce images of the heart. This allows the doctors to view the structure, function, and health of the heart and detect any abnormalities.
Who is needed to perform Extracorporeal Membrane Oxygenation in Children?
There’s a whole team of medical professionals working together to take care of children who are very sick, including pediatric intensivists (doctors specialized in caring for critically ill infants, children, and teenagers), and neonatologists (doctors who care for newborn babies, especially the ill or premature ones). Nurses who work specifically in critical care units, known as ICU nurses, are also part of the team.
The team may include different types of surgeons, like cardiothoracic surgeons (doctors who do heart and lung surgery), vascular surgeons (doctors who operate on the body’s network of blood vessels), and trauma or acute care surgeons (doctors who treat injuries and critical illnesses that need immediate attention).
Anesthesiology team members help put you to sleep before operations or procedures. The critical care transfer team is responsible for moving patients safely from one place to another within or between hospitals. The ECMO coordinator and technicians manage a special machine (ECMO) that supports the heart and lungs when they are not working properly.
There’s also a perfusionist who operates the heart-lung machine during heart surgery, and the radiology department uses medical imaging (like X-rays) to identify or monitor diseases or injuries. Echocardiography technicians work alongside the doctors for capturing images of the heart, and respiratory therapists try to improve lung function.
Finally, rehabilitation specialists are there to help children recover their physical or mental abilities that may have been affected by their illness or treatment.
Preparing for Extracorporeal Membrane Oxygenation in Children
Getting a child ready for ECMO, which is a special treatment that uses a machine to help a child’s heart or lungs work better, requires a lot team expertise. It’s really important this is done at a higher-level healthcare center because they are better equipped to manage any side effects or complications. If a child needs ECMO but is at a hospital that doesn’t provide this service, there’s a risk in keeping them there versus moving them to a specialized ECMO center. A well-coordinated critical care transfer team should always be available and ready to help.
Before starting ECMO, babies or children should have a very detailed checkup. This includes a full physical examination with a special focus on the brain, blood tests, a chest x-ray, a head ultrasound or CT scan, and heart scans. Also, it’s common to give sedatives to make sure the patient is comfortable and safe while making sure repeated checkups are accurate. Common medicines for pain and relaxation include morphine, fentanyl, midazolam, propofol, and dexmedetomidine.
When using ECMO, it could trick the body into reacting like there’s an injury and starts clotting the blood, so it’s crucial that we monitor the blood clotting and platelet count. To manage this, anticoagulants or blood thinners play a key role in ECMO treatment. The most commonly used blood thinner for ECMO is unfractionated heparin, but doctors are starting to use direct thrombin inhibitors as an alternative.
From a nutrition viewpoint, it’s very important to feed these children a balanced diet while they are on ECMO. Besides fulfilling their growth requirements, it’s been seen that underweight patients on ECMO have worse outcomes than patients who are properly nourished. Specifically for babies on ECMO, guidelines proposed by the American Society for Parenteral Enteral Nutrition recommend starting nutritional support quickly and providing food through the gut as soon as the patient’s condition is stable.
How is Extracorporeal Membrane Oxygenation in Children performed
In children and newborns, the equipment used during an Extracorporeal Membrane Oxygenation (ECMO) procedure, like the tubes or ‘cannulas’, must be chosen based on their weight. Also, where these cannulas are placed varies between adults and children. In adults, they are usually placed in the large blood vessels of the thigh, known as femoral vessels. In very young children, these vessels are not developed enough for ECMO, so the cannulas are preferably placed in the larger neck vessels instead. The best age to shift from using neck vessels to femoral vessels needs to be further researched.
Installing the cannula into the body can be done in two ways. One is by using a needle puncture technique known as the ‘Seldinger technique’. The other method is a minor surgical procedure to access the blood vessels.
The ECMO process uses a specific device called a ‘pump’ to move blood through the body. Two main types of pumps are used: roller pumps and centrifugal pumps. Roller pumps push blood through a tube to a plate with a rotating arm, creating pressure that moves the blood forward. This mechanism heavily depends on gravity. If there’s a blockage or bending in the tube, it may lead to a harmful burst. But safety measures are in place to stop the pump if the pressure gets too high. Roller pumps are commonly used in newborns, as they don’t need a specific flow rate to work effectively and are suitable for those with a lower birth weight.
Centrifugal pumps use quickly spinning motion to create pressure differences and push blood forward. This design significantly reduces the risk of a tube rupture. The newer models of centrifugal pumps lower the chances of blood clotting complications and damage to red blood cells.
In certain cases, the ECMO procedure can be carried out without a pump if the patient’s blood pressure can drive the blood flow or if the patient has severe lung-related high blood pressure.
Another part of the ECMO system is a component called a ‘bridge’. It’s positioned between the tubes that draw blood from and return blood to the body. It allows patients to be temporarily removed from the machine while keeping the system running. This might be necessary in cases like gradually ending the treatment, changing parts of the ECMO device, or in emergencies like severe bleeding or contamination in the system due to air or blood clots.
Possible Complications of Extracorporeal Membrane Oxygenation in Children
Extracorporeal Membrane Oxygenation (ECMO) is a treatment that uses a pump to circulate blood through an artificial lung and back into the bloodstream. This technique was first used successfully quite some time ago and there has been a lot of information collected about it since then by an organization known as the Extracorporeal Life Support Organization.
According to the data collected, around 57% of kids who needed ECMO for breathing problems were able to leave the hospital. For kids who needed ECMO for heart problems, this rate was around 50%.
However, this treatment also has some risks, which can be roughly divided into two categories: technical and medical complications.
Technical complications mean issues with the equipment. For instance, the tube that connects the patient to the ECMO machine might accidentally disconnect, the artificial lung might fail, the tubes might rupture or the pump might malfunction.
Medical complications are health related issues that might occur. Most commonly, these are neurological problems, which means they affect the brain. These might include bleeding within the brain, seizures, brain death, or a stroke. Blood related problems might also occur, like bleeding from the tube insertion site or surgical site, blood clot formation, injury to the blood vessels, and bleeding in the lungs or digestive tract. The ECMO could also affect other organs, causing kidney or liver failure.
We try to reduce these risks by monitoring the patients very closely. However, it’s important to understand that ECMO is typically used when all other treatments have failed and the patient’s condition is very serious, so it’s often worth taking these risks. Our main goal is always to get our patients healthy and back home as soon as possible.
What Else Should I Know About Extracorporeal Membrane Oxygenation in Children?
Extracorporeal Membrane Oxygenation (ECMO), which is particularly used in children’s treatment, is a complex medical procedure. It needs a deep understanding of how children’s and infants’ bodies work. Knowing the finest details about how oxygen is delivered to the body is vital for this procedure. ECMO can raise many tricky moral questions since it involves a lot of input from children’s families in making decisions about the treatment.
Usually, when ECMO is being considered urgently, there might be limited time to properly evaluate the progression of the patient’s health condition, the possibility of reversing the disease, whether the patient is suitable for a heart or lung transplant, and to balance concerns about the quality of life after survival with the family’s care goals.
Some challenges could include the emotional stress of caregivers and healthcare providers during extended ECMO treatment, deciding when to stop treatment, and allocating significant resources. It’s very important to understand the serious consequences tied to each clinical decision.
