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The risk of dying while being treated for acute respiratory distress syndrome due to COVID-19 with extracorporeal membrane oxygenation (ECMO) -- often a last resort -- more than doubled during the second wave of the pandemic, researchers reported.

Of 28 patients placed on ECMO from April through September 2020, nine (32%) died. Among the 13 patients placed on ECMO during the second wave from November 2020 to March 2021, nine, or 69%, died (P=0.026), said Rohit Reddy, BS, of Thomas Jefferson University in Philadelphia, during a poster presentation at CHEST 2021, the American College of Chest Physicians' annual meeting, held virtually this year.

Of patients in the second wave, 85% were placed in a prone position while on ECMO compared with 11% of those in the first wave (P<0.001). Patients in the first wave spent a median 14 days on ECMO versus 20 days for second wave patients (P=0.728).

A similar proportion from both groups experienced acute renal failure (38% in the first wave vs 39% in the second wave), while sepsis occurred in 23% and 32%, bacterial pneumonia in 8% and 11%, gastrointestinal bleeding in 15% and 21%, and cerebral vascular accident in 23% and 4%, respectively.

Reddy suggested that poorer outcomes with ECMO in the second wave may have resulted from changing treatment standards as medical professionals learned how to deal with severe COVID.

"As treatment algorithms for COVID evolved, second wave patients were more often administered pre-ECMO immunomodulation therapy that potentially made these patients more susceptible to bacterial infection," Reddy told MedPage Today. "Sepsis was one of the leading causes of death in this study. Control of infection for patients on immunomodulation therapy is challenging, but necessary to improve outcomes in these patients."

In commenting on the study, Casey Cable, MD, of Virginia Commonwealth University in Richmond, sounded a note of caution: "This is an interesting study, but it is a single-institution study and the numbers of patients involved is small."

Cable told MedPage Today that one reason the mortality rate with ECMO could have been higher in the second wave was because patients were treated more extensively before turning to ECMO compared to patients in the first wave.

"We learn something every other week on how to treat COVID-19 patients, and in the interim between the two waves, there are other treatment strategies that have been developed," she said. "That might have had an impact on outcomes."

She said the study was potentially "hypothesis generating," but unlikely to change clinical practice. "We need larger studies with multiple institutions involved to determine how to use ECMO for the right patient," Cable said.

For the study, Reddy and colleagues looked at adult patients with acute respiratory distress syndrome due to COVID-19 included in a database approved by an institutional review board.

They identified 41 patients who were all treated with venovenous ECMO. Of the 28 patients stratified to the first wave group, median age was 52 and 68% were men. Of the 13 in the second wave group, median age was 45 and 69% were men. ECMO was not initiated during October 2020.

There were no significant differences in pre-ECMO comorbidities between the two groups, but pre-ECMO immunomodulators were more often given in the second wave. In the first wave group, 54% of patients were treated with steroids compared with all 13 in the second wave group (P=0.003). Remdesivir was administered to 39% of patients in the first wave and to 85% of those in the second wave (P=0.007).

"Despite improved pre-ECMO treatment, second wave patients with COVID-19 experienced higher mortality on ECMO than first wave patients," the authors wrote in their abstract. "More strict inclusion/exclusion criteria for ECMO may be necessary to improve outcomes."

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