By Emily Dovolis Thomson, MHA
The beeping vibrato of pressure monitors, mechanical rhythm of the blood pump, low hum of the oxygenator and metronomic beat measuring heart rate: These are the sounds that emanate from a complex circuit of pumps, tubes, filters and monitors called ECMO, or extracorporeal membrane oxygenation. ECMO moves blood outside of the body through cannulae, or tubes, to an oxygenator that provides a gas exchange in the blood, removing carbon dioxide and replacing it with oxygen. The oxygenated blood is then warmed to the appropriate temperature and returned to the body using rhythms that mimic a beating heart.
When disease or trauma prevent the body from performing these life-sustaining rhythms, ECMO can take over.
A complex intervention
According to Cambridge University, the first successful use of ECMO happened in Russia in 1929, when extracorporeal perfusion—pumping blood outside of the body—was used to sustain life in a dog. Following this initial accomplishment, specialists spent decades enhancing perfusion by developing a device that could exchange carbon dioxide for oxygen in blood. It wasn’t until the 1950s, though, with the invention of the heart-lung machine, that specialists began to use ECMO regularly and successfully in people.
In 1979, Robert Bartlett, MD—now known as the father of ECMO—and a team of clinicians used ECMO to save the life of a newborn. Born with nonfunctioning lungs, baby Esperanza was kept on an ECMO system for six days, giving her lungs time to fully develop.
However, during the 10 years following this successful use, the treatment was primarily used for pediatric patients, in good part because the need for ECMO intervention was more readily recognizable. In adults, too often the lungs sustained irreversible damage before the need for intervention was recognized. Because of this and other factors, the mortality rate for adults on ECMO was 90%. But in 1989, the new Extracorporeal Life Support Organization (ELSO) began to support and advocate for ECMO as medicine made advances that positively affected outcomes for adults.
These changes allowed ECMO to play an important role during the outbreak of H1N1 influenza in 2009. The virus caused extreme inflammation of the lungs, resulting in respiratory failure and profound lung damage. ECMO served a lifesaving role, treating some adults affected by the H1N1 virus whose lungs needed time to recover and repair.
ECMO and COVID-19
Like H1N1, the SARS-CoV-2 virus that causes COVID-19 infiltrates the lungs through the mucus membrane, potentially spreading infection and inflammation. In severe cases, the virus affects the upper and lower areas of the lungs, causing pneumonia that drowns the lungs’ alveoli sacs with fluid.
These sacs, situated at the end of the lung’s bronchi branches, exchange oxygen for carbon dioxide molecules. When the alveoli become flooded with fluid, they are unable to perform; the lungs, and then the body, begin to fail.
Some people with COVID-19 are given antiviral drugs, such as remdesivir, to prevent lung complications. And specialists may use a ventilator machine to help the lungs perform more effectively. Those with particularly severe COVID-19 disease, however, may have lung damage so severe that a ventilator cannot be used. In these cases, says Muhammad Faraz Masood, MD, a Washington University cardiothoracic surgeon at Barnes-Jewish Hospital, “the lungs become stiff and less compliant to air exchange.” Healthy lungs, he adds, expand and retract like balloons; COVID-19 can transform them into hard, leather-like pouches. “In very advanced stages of lung failure, ventilators are not able to sustain gas exchange, and we use ECMO to intervene.”
WHEN A PATIENT UNDERGOES EMCO FOR LUNG FAILURE, WE WANT TO MAKE SURE THAT THE REST OF THE BODY'S ORGANS ARE HEALTHY ENOUGH TO SUPPORT HEALING. WE USE EMCO TO BUY THE TIME THE BODY NEEDS TO RESTORE ITSELF.
However, Masood notes, not every person with life-threatening COVID-19 can be treated with ECMO. “We evaluate a patient carefully to determine whether ECMO can be beneficial,” he adds. Masood and fellow Washington University cardiothoracic surgeons Akinobu Itoh, MD, PhD, and Kunal Deepak Kotkar, MD, collaborated with other university specialists to develop the criteria used at Barnes-Jewish Hospital to determine eligibility. In addition to meeting other criteria, patients must be 70 years of age or younger, have a body mass index (BMI) below 45 and have no history of chronic organ failure or irreversible cardiac or pulmonary disease. “When a patient undergoes ECMO for lung failure, we want to make sure that the rest of the body’s organs are healthy enough to support healing,” Masood says. “We use ECMO to buy the time the body needs to restore itself.”
Because the criteria for ECMO qualification is strict—and because the equipment involved in the treatment is complex and the number of specialists it takes to manage an ECMO process is high—ECMO programs in the United States are scarce. In fact, currently there are only about 260 ECMO programs in the country, most of them located in cities with large hospital systems or academic medical centers. The ECMO program at Washington University School of Medicine and Barnes-Jewish Hospital is led by Masood, Itoh and Kotkar.
The complexity of the ECMO process means that the care team, made up of specialists in their fields of medicine, carefully coordinate their activities. Jane Goetz, RN, a critical care nurse in the cardiothoracic intensive care unit at Barnes-Jewish Hospital and a member of the ECMO team, says, “Whether it is cannulating a patient in preparation for ECMO, repositioning to help ensure lung function, or waking someone for the first time after ECMO, the process of caring for these patients really does take an entire village.”
Members of the cardiothoracic surgery team and the intensive care team have built relationships grounded in trust and respect. “We all work together toward the goal of a patient’s recovery,” Goetz says. For example, it took a team of at least 50 specialists working over a nine-week period to care for a recent patient with COVID-19 at Barnes-Jewish Hospital. “Some people with COVID have had a long, hard road to recovery,” says Goetz. “But thanks to ECMO—and the specialists who have provided care—we’ve seen people get a new chance at life.”
ECMO and the future
In 2019, Barnes-Jewish Hospital logged 3,000 hours of ECMO care for patients. Since March 2020 and the beginning of the SARS-CoV-2 pandemic, the hospital has recorded 30,000 hours of ECMO care.
Masood notes that ECMO often is used as a “last resort” option, a treatment for the sickest of the sick. He would like to see that change. As more clinicians become familiar with ECMO, he says, they may begin to see it as a viable option in a wider range of situations, resulting in an even greater potential to save lives. And frequency of use may improve the treatment itself, as well as expand the situations in which it is used. “If we were to use ECMO earlier in the treatment process, that would mitigate its reputation as the device of last chance,” Masood says. “And we likely would improve its rate of success while offering an effective way to care for people who are critically ill.”