Lung Damage in Some COVID-19 Patients on Mechanical Ventilation

July 15, 2020

Lung damage has been observed in some patients with COVID-19 on invasive mechanical ventilation, according to a new study. In a series of 601 patients, 24% experienced barotrauma events (including pneumothorax and pneumomediastinum), compared with 11% of a historical control group of patients with acute respiratory distress syndrome (ARDS) on mechanical ventilation.

Barotrauma was an independent risk factor for death in COVID-19, and was also associated with a longer length of hospital stay, report Georgeann McGuinness, MD, Department of Radiology, NYU Grossman School of Medicine, New York, and colleagues in their article published online July 2 in Radiology.

In addition, barotrauma was more likely to occur in younger patients with COVID-19, the researchers found.

There was no correlation, however, between the rate of barotrauma and any specific ventilator settings, McGuinness and colleagues note in their article.

McGuinness told Medscape Medical News there is an important message here for those taking care of patients with COVID-19.

"Intensive care specialists need to be aware that there is a higher rate of barotrauma in patients with severe SARS-CoV-2 infection on invasive mechanical ventilation, occurring at a rate more than double that of patients with ARDS from other causes."

"This increased risk should be taken into consideration in patient management," she stressed. 

"Clinicians should also be aware that barotrauma contributes to the unpredictable course of the disease — an abrupt clinical deterioration in a relatively stable patient on invasive mechanical ventilation may indicate barotrauma and the need for interventions such as chest tubes to treat pneumothoraces."

In short, "The real thrust of this paper is to bring to light a serious potential complication in patients with severe respiratory failure related to SARS-CoV-2 infection, and to make sure that the clinicians in emerging hotspots are aware that in NYC during the height of the pandemic we saw elevated rates of barotrauma," McGuinness emphasized. 

Do Coronavirus Infections Uniquely Raise the Risk of Barotrauma?

In their retrospective study, McGuinness and colleagues examined the clinical and imaging data of over 600 patients who tested positive for COVID-19 who underwent invasive mechanical ventilation between March 1 and April 6, 2020, at their hospital. The average age of the patients was 63 years and 71% were men.

Barotrauma was evaluated using chest X-ray and most patients on invasive mechanical ventilation had at least daily radiographs.

They found that 89 of 601 patients (15%) had one or more barotrauma events, for a total of 145 events (24% overall events).

During the same period, 196 patients without COVID-19 (average age, 64 years, 52% men) with invasive mechanical ventilation had one barotrauma event (0.5%) (P < .001 vs the COVID-19 infection group).

Researchers say this comparison of barotrauma rates between contemporaneous patients on invasive mechanical ventilation with and without COVID-19 is "valuable" because although only a few patients without COVID-19 were admitted at the height of the pandemic, this "mitigates" potential confounding management variations, "as care was delivered in the same hospital system, with the same resources and management protocols."

They then compared patients with COVID-19 to 285 historical cases of ARDS on invasive mechanical ventilation over the prior 4 years (average age 68 years, 60% men). They found that 28 of these patients (10%) had 31 barotrauma events, with an overall barotrauma rate of 11% (P < .001 vs the COVID-19 infection group).

In patients with COVID-19, lung damage was an independent predictor of death (odds ratio, 2.2; P = .03) and was associated with longer hospital stay, the researchers note.

However, "it is not clear whether barotrauma caused prolonged hospitalization," or whether longer hospitalization is a risk factor for barotrauma, they note.  

In their discussion, McGuinness and team say that, "interestingly, barotrauma rates were elevated during the SARS and MERS coronavirus outbreaks," and cite research showing rates of barotrauma of 12%-34% during the 2002-2004 SARS outbreak.

During the MERS epidemic, one small study of ICU intubated patients reported a rate of pneumothorax of 30%, "higher than both our incident rate of 15% and overall rate of 24%."

"These high barotrauma rates raise questions of whether coronavirus infections uniquely increase barotrauma risk," they observe.    

Younger Patients Seem More Vulnerable to Barotrauma

The researchers go on to say that, in their study, "patients with COVID-19 infection with barotrauma were younger than those without barotrauma, suggesting an age-related risk for barotrauma."

"In fact, younger age in patients with COVID-19 infection after invasive mechanical ventilation is an independent risk factor for barotrauma."

They note, however, that younger age has also previously been associated with barotrauma in ICU patients.

The researchers comment that they do not have any clear answers as to what is  happening here.

Asked by Medscape Medical News whether doctors should try to avoid putting patients with COVID-19 on invasive mechanical ventilation, McGuinness said: "No, this is beyond the scope of the data in our paper — management of these patients is complex, and knowledge is evolving."

"We do not correlate the rate of barotrauma with specific ventilator settings," McGuinness and colleagues note in the article. "Rather, in this retrospective study reporting high barotrauma rates in patients with COVID-19 infection we speculate as to possible associations, among them, ventilator management."

"Examination of potential associations with ventilator parameters requires focused assessment," they add.

"Barotrauma risk is particularly important to recognize as these critically ill patients [with COVID-19] may be managed by staff less familiar with the management of ventilator settings."

Radiology. Published online July 2, 2020. Full text

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