麻豆传媒

Back in March, Chinese doctors who had provided critical care to patients with severe COVID-19 in Wuhan shared best practices with an international audience. In this follow-up, we take a look at how these lessons were applied and how critical care for these patients has evolved in the U.S. since then.

At the time New York City was just starting its first COVID-19 surge, the pandemic was already easing in Wuhan, China, where temporary COVID-designated hospitals were no longer needed and the country was starting to mandate quarantines for foreign travelers.

In the aftermath of the storm, Chinese doctors reflected on their Wuhan experience and discussed the strategies that had helped patients the most, during a joint webinar hosted mid-March by the American College of Cardiology and the Chinese Cardiovascular Association.

Speakers stressed that hypoxemic patients who are good candidates for extracorporeal membrane oxygenation (ECMO) get it early.

This advice still holds, said Kenneth Lyn-Kew, MD, co-director of the ECMO program at National Jewish Health in Denver, during an interview in December.

In September, international registry data showed that COVID-19 patients who go on ECMO have a 37.4% 90-day in-hospital mortality rate. This was viewed positively given the severe hypoxemia of these patients.

Both the Chinese group and Lyn-Kew pointed out that ECMO is of limited availability, however.

"ECMO is a finite resource and it consumes a lot of other resources, so you have to be selective about who you put on it," Lyn-Kew said.

In March, the Chinese doctors had suggested not giving ECMO to people over 70 years old. Subsequent guidelines also emphasized considering patient age, among other factors, when selecting ECMO candidates.

Clinicians still do not have all the tools to identify upfront which groups will share in the large benefits of ECMO that had been reported in the , Lyn-Kew cautioned. "When we're honest with ourselves, we don't always know who that [best] candidate is."

He urged critical care teams to continue hallmarks of good traditional critical care instead of relying on ECMO as a crutch. Proven strategies that are readily available for patients with respiratory failure include low-tidal volume settings on ventilators, prone positioning, and aggressive diuresis.

"The big thing that's changed is just understanding that a lot of the things we've learned over 30 years of critical care research are still applicable to COVID," he said of the past year. "When we stick to what we know and we stick to good care, we get good results. The only thing COVID does is increase the number of patients we have to do it for."

This revelation came in part as a result of clinicians answering the early question of whether COVID-19 patients with respiratory failure should be treated as having typical acute respiratory distress syndrome (ARDS) -- oddly, many of these patients have severe hypoxemia despite normal respiratory compliance.

"Does [COVID-19 ARDS] have unique features? Yes, but it's still ARDS. All these things we use for ARDS, like ECMO, still hold true in 2020," according to Lyn-Kew.

In August, two centers in Chicago shared particularly good results performing ECMO via a single-access, dual-stage right atrium-to-pulmonary artery cannula. The multiple advantages of this strategy include minimal cannula-associated complications or revisions, the group reported.

Another center is now testing awake, venovenous ECMO prior to intubation for severe COVID-19 ARDS, the rationale being to maximize ECMO's benefit while the patient can still be saved.

Nixing intubation had been discussed by a Chinese doctor during the March webinar. At that time, however, the suggestion had been met with hesitance from his peers.

Overall, ECMO was used aggressively in a small number of centers at the beginning of the pandemic, but has since been dialed back. In contrast, high flow nasal cannula (HFNC) and non-invasive ventilation have seen greater adoption, according to Richard Schwartzstein, MD, of Beth Israel Deaconess Medical Center and Harvard Medical School.

"We started in the winter/spring of 2020 by intubating patients early in their course and initiating mechanical ventilation. There was concern about using HFNC or non-invasive ventilation because of fears of 'aerosolizing' the virus," Schwartzstein told 麻豆传媒 in an email.

"It turns out they don't generate as much aerosol as people thought when put up on best testing, without putting COVID in people and have them breathe it out on one of those machines. It's not as dangerous as we thought," Lyn-Kew said.

Thus, he noted, these modalities have returned to their appropriate use in ICU care for people with COVID-19.

"What we learned over the past year is that early proning in concert with steroids for hypoxemic patients may prevent progression of disease," Schwartzstein wrote. "Consequently, we are not intubating patients early now, fewer patients are going to the ICU, and fewer patients are considered appropriate for ECMO."

Finally, Chinese doctors noted in March that the authorities did not allow colleagues over age 60 into COVID units over the winter for fear of them getting severely sick.

There has been no such age mandate in the U.S., though there have been older practitioners who decided to retire or take leave from the ICU, Lyn-Kew observed.

Even so, many others have chosen to remain on the front lines taking appropriate safety precautions -- Anthony Fauci at the NIH, for example (the nation's top infectious disease official just turned 80 years old).

"He's incredible," Lyn-Kew said. "I couldn't keep up with his schedule."

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