NIV may reduce mortality but increase COVID-19 transmission in hospital workers

Use of noninvasive ventilation (NIV), similar to invasive mechanical ventilation (IMV), appears to lessen mortality but may increase the risk for transmission of the novel coronavirus disease (COVID-19) in healthcare workers, suggest the results of a study.

“[O]ur systematic review examined different streams of evidence, including original human studies evaluating different modalities of NIV, IMV, and high-flow oxygen by nasal cannula (HFNC) in COVID-19, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS); systematic reviews in other populations; mechanistic and laboratory evidence; and studies of aerosol-generating procedures (AGPs),” the researchers said.

“We found low-certainty evidence that NIV may have similar effects as IMV but reduce mortality compared with no IMV in patients with COVID-19,” they added.

Twenty-one standard World Health Organization-specific and COVID-19–specific databases were searched until 1 May 2020 with no language restrictions for studies comparing different oxygenation approaches in patients with coronavirus infections, including SARS or MERS, or with hypoxaemic respiratory failure.

The investigators gathered animal, mechanistic, laboratory, and preclinical evidence on aerosol dispersion of the coronavirus. Also included were studies assessing the risk for virus transmission to healthcare workers from AGPs.

A total of 123 studies (45 on COVID-19, 70 on SARS, and eight on MERS) met the eligibility criteria, but only five studies (one on COVID-19, three on SARS, and one on MERS) adjusted for important confounders. [Ann Intern Med 2020;doi:10.7326/M20-2306]

In one study of hospitalized patients with COVID-19, mortality was slightly higher with NIV than with IMV. However, two other studies (one in MERS patients and the other in SARS patients) reported a decrease in mortality with NIV compared with no mechanical ventilation (low-certainty evidence).

Additionally, two systematic reviews found a large decrease in mortality with NIV vs conventional oxygen therapy. Other studies included in this review reported higher risks of transmission from AGPs.

“This systematic review evaluating different ventilation strategies identified 28 original comparative studies in patients with SARS, MERS, and COVID-19,” the researchers said. “Although an additional 34 studies in patients with COVID-19 were found, their methods and reporting were too poor for us to synthesize data appropriately.”

Indirect evidence, including seven systematic reviews on other populations, showed that NIV may lower mortality or need for IMV, with similar effects to IMV. However, the researchers cautioned that NIV use and the choice of the ventilations strategy should be balanced against the potentially higher risk for infection of healthcare workers resulting from these AGPs.

“On the basis of this and other reviews, personal protective equipment may reduce for some the risk for transmission during AGPs, but it will not abolish it,” the researchers said. “The poor quality of conduct and reporting of studies on the effects of NIV on important outcomes in COVID-19 is striking.”

The current review was limited by direct studies in COVID-19 that are lacking and poorly reported.