麻豆传媒

Pneumothorax and other barotrauma was more common in COVID-19 patients on invasive mechanical ventilation than seen for other patients on ventilators, a retrospective study showed.

Among invasive mechanical ventilation (IMV) patients at NYU Langone Health in New York City during the pandemic surge from March 1 to April 6, barotrauma occurred in (P<0.001), reported Georgeann McGuinness, MD, and colleagues at NYU Langone in Radiology.

That rate in COVID-19 was also higher than the 10% rate seen among acute respiratory distress syndrome (ARDS) patients on IMV over the prior 4 years at that institution (P<0.001).

"We saw some of these COVID patients, [air] was under the skin, in the chest wall, in the neck, out into the arms, in the breasts, it was just everywhere," McGuinness told 麻豆传媒.

Barotrauma in COVID-19 independently predicted death (OR 2.2, P=0.03) and longer hospital length of stay (OR 1.03, P<0.001).

"I think that there are probably going to be long-term sequelae for these patients, but it's speculative at this point because we don't have any chronic COVID patients," McGuinness said, noting the months rather than years of data available.

"Our observed high rate of barotrauma in patients with COVID-19 infection on IMV may support emerging theories of lung damage in SARS Co-V2 infection," the group wrote.

One such controversial theory, sparked by from Luciano Gattinoni, MD, of the University of Gottingen in Germany, is that there are -- some the typical stiff, high compliant lungs but others low compliant or spotty.

"Maybe high pressure air going in through mechanical ventilation is going to the areas of the lung that are more compliant and causing barotrauma -- pseudocysts or pneumatoceles in the lungs," McGuinness suggested.

On the other hand, it could be something about the coronavirus infection itself that uniquely increases risk, she noted.

"Interestingly, barotrauma rates were elevated during the SARS and MERS coronavirus outbreaks," her group wrote. Barotrauma rates varied between 12% and 34% during the 2003 SARS epidemic, and pneumothorax was reported in 30% of ICU intubated patients in one small study from the MERS epidemic.

Anecdotally with COVID-19, pseudocysts have even been seen in patients who have never been on a ventilator, McGuinness noted in an interview.

"These patients have very tenacious secretions in their airways," she said. "Maybe the formation of these pseudocysts in the lungs has to do with the fact that airway secretions are forming what we call a 'ball valve' -- they cause blockages in the airways and then patients are pushing air against the blockage."

Her group's next study is to correlate COVID-19 patients' mechanical ventilator type, settings, and time on ventilation with incidence of barotrauma.

Without such data, "it can't be anything other than hypothesis generating," cautioned C. Corey Hardin, MD, PhD, at Massachusetts General Hospital in Boston. "You could reproduce exactly that finding by just using inappropriate ventilatory settings."

Some of the speculation about not needing low tidal volume ventilation in COVID-19 could have led to differences in treatment compared with non-COVID patients, he noted. "If you use high tidal volumes with COVID patients, you would predict a lot of barotrauma."

Because more recent, larger series have demonstrated that lung compliance in COVID-19 is "fully consistent" with other causes of ARDS, treatment protocols should follow the same principles that have been known for years, he said: "Use as low a PEEP as you can consistent with oxygenation goals, and that you should try to individualize your vent settings to patient's compliance, because patients have a wide variety of compliance and a wide variety of recruitability. Details matter; paying attention to your individual patient matters."

The study included 601 COVID-19 patients (mean age 63, 71% men) and 196 contemporaneous patients without COVID-19 infection (mean age 64, 52% male). The historical cohort included 285 ARDS patients on IMV (mean age 68, 60% men) seen at the center from Feb. 1, 2016, through Feb. 1, 2020.

The COVID-19 patients were younger than the historical controls but not the contemporaneous ones, but were more likely to be male and minority ethnicity or race. Younger age has previously been associated with barotrauma in the ICU, McGuinness's group noted.

After excluding barotrauma events that followed line placement or a surgical procedure, a total of 145 temporally-distinct barotrauma events happened in the COVID-19 group for an overall rate of 24% among the 601 patients. That included a 9% rate of pneumothorax overall, 10% pneumomediastinum, nearly 8% subcutaneous emphysema, and 2% pneumopericardium.

"While only a small number of emergency patients without COVID-19 infection were hospitalized at [NYU Langone Health] at the height of the pandemic, this comparison mitigates potentially confounding management variations, as care was delivered in the same hospital system, with the same resources and management protocols," the researchers noted.

While the group suggested that the many new staff that came on-board during the pandemic didn't contribute to the high barotrauma rate -- because hospitalists and intensivists led the teams managing ventilators -- they still noted that "Barotrauma risk is particularly important to recognize as these critically ill patients may be managed by staff less familiar with the management of ventilator settings."

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