Study: Adding Oxygen to Blood Helps Save COVID-19 Patients

An international study led by a researcher at the University of Michigan in Ann Arbor has shown that a last-resort life-support option is helping critically ill COVID-19 patients survive.
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ECMO diagram
U-M researchers have analyzed international data to find that treating near-death COVID-19 patients with ECMO, which adds oxygen to blood before pumping it back into the body, can save lives. // Image courtesy of the University of Michigan

An international study led by a researcher at the University of Michigan in Ann Arbor has shown that a last-resort life-support option is helping critically ill COVID-19 patients survive.

ECMO, or extracorporeal membrane oxygenation, is a system in which blood is channeled out of the body and into equipment that adds oxygen directly to the blood before pumping it back into the body’s circulation.

In the study, 1,035 patients faced a high risk of death as ventilators and other care failed to support their lungs. After they were placed on ECMO, their actual death rate was less than 40 percent, similar to the rate for patients treated with ECMO in past outbreaks of lung-damaging viruses and severe forms of viral pneumonia.

The study is published in The Lancet. The authors caution that patients who show signs of needing advanced life support should receive it at hospitals with experienced ECMO teams and that hospitals shouldn’t try to add ECMO capability in the middle of the pandemic.

A rapidly created international registry has given critical care experts near real-time data on the use of ECMO in COVID-19 patients since early in the year. Hosted by the Extracorporeal Life Support Organization (ELSO), the registry includes data submitted by 213 hospitals on four continents. The study includes data on patients 16 and older who were started on ECMO between Jan. 16 and May 1 and follows them until death, discharge from the hospital, or Aug. 5, whichever happened first.

“These results from hospitals experienced in providing ECMO are similar to past reports of ECMO-supported patients with other forms of acute respiratory distress syndrome or viral pneumonia,” says co-lead author Ryan Barbaro of Michigan Medicine, U-M’s academic medical center. “These results support recommendations to consider ECMO in COVID-19 if the ventilator is failing. We hope these findings help hospitals make decisions about this resource-intensive option.”

Graeme MacLaren of the National University Health System in Singapore, co-lead author, says most centers in the study did not need to use ECMO for COVID-19 very often.

Of the patients in the study, 70 percent were transferred to the hospital where they received ECMO. Half of these were started on ECMO – likely by the receiving hospitals’ team – before being transferred. The study could also help identify which patients will benefit most if they are placed on ECMO.

“Our findings also show that mortality risk rises significantly with patient age, and that those who are immunocompromised, have acute kidney injuries, worse ventilator outcomes, or COVID-19-related cardiac arrests are less likely to survive,” says Barbaro, who chairs ELSO’s COVID-19 registry committee and provides ECMO care as a pediatric intensive care physician at U-M’s C.S. Mott Children’s Hospital.

“Those who need ECMO to replace cardiac function as well as lung function also did worse. All of this knowledge can help centers and families understand what patients might face if they are placed on ECMO.”

The lack of reliable information early in the pandemic hampered the research team’s ability to understand the role of ECMO for COVID-19, says Daniel Brodie of New York Presbyterian Hospital and co-author.

“The results of this large-scale international registry study, while hardly definitive evidence, provide a real-world understanding of the potential for ECMO to save lives in a highly selected population of COVID-19 patients,” says Brodie, who shares senior authorship with Roberto Lorusso of the Maastricht University Medical Center in the Netherlands and Alain Combes of Sorbonne University in Paris.

Because the database doesn’t track what happens to patients once they are discharged, the study uses a statistical approach based on in-hospital mortality up to 90 days after the patient was put on ECMO. This also allowed the team to account for the 67 patients who were still in the hospital as of Aug. 5, regardless of whether they were still on ECMO, in the intensive care unit, or in step-down units.

“We used 90-day in-hospital mortality because this is the highest-risk period and because it allows us to use the information we have to the fullest, even if we don’t know the final outcome for every patient,” says Philip Boonstra of the U-M School of Public Health. He helped design the study.

While patients who were discharged to their homes or a rehabilitation facility are likely to survive, the fate of those who went to facilities that provide long-term care at a near ICU-level is less certain.

More than half of the patients in the study were treated in hospitals in the U.S. and Canada, including hospitals in the Michigan Medicine system.

Robert Bartlett, emeritus professor of surgery at U-M and co-author of the paper, is considered a key figure in the development of ECMO, including the first use in adults in the 1980s. He led the development of the initial guidance for the use of ECMO in COVID-19.

“ECMO is the final step in the algorithm for managing life-threatening lung failure in advanced ICUs,” Bartlett says. “Now we know it is effective in COVID-19.”

As of Aug. 5, 380 of the patients in the study had died in the hospital, more than 80 percent of them within 24 hours of a proactive decision to discontinue ECMO care because of a poor prognosis. Of the remaining patients, 57 percent had gone home or to a rehabilitation center (311 patients) or had been discharged to another to another hospital or a long-term acute care center (277 patients). The rest were still in the hospital but had reached 90 days after the start of ECMO.

The study adds to the information used to create the ECMO COVID-19 guidelines published by ELSO, which is in part based on past randomized controlled trials of ECMO’s use in acute respiratory distress syndrome.

Barbaro is studying the longer-term effects of ECMO care for any patient, leading a team that has recently received a National Institutes of Health grant for a long-term study of children who have survived after treatment with ECMO.

The ELSO registry continues to track the care of patients placed on ECMO because of COVID-19.

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