COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Treatment Schunemann HJ, Khabsa J, Solo K, et al. Ventilation Techniques and Risk for Transmission of Coronavirus Disease, Including COVID-19: A Living Systematic Review of Multiple Streams of Evidence. Ann Intern Med. 2020 Aug 4;173(3):204-216. doi: 10.7326/M20-2306. Epub 2020 May 22.

BACKGROUND: Mechanical ventilation is used to treat respiratory failure in coronavirus disease 2019 (COVID-19).

PURPOSE: To review multiple streams of evidence regarding the benefits and harms of ventilation techniques for coronavirus infections, including that causing COVID-19.

DATA SOURCES: 21 standard, World Health Organization-specific and COVID-19-specific databases, without language restrictions, until 1 May 2020.

STUDY SELECTION: Studies of any design and language comparing different oxygenation approaches in patients with coronavirus infections, including severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), or with hypoxemic respiratory failure. Animal, mechanistic, laboratory, and preclinical evidence was gathered regarding aerosol dispersion of coronavirus. Studies evaluating risk for virus transmission to health care workers from aerosol-generating procedures (AGPs) were included.

DATA EXTRACTION: Independent and duplicate screening, data abstraction, and risk-of-bias assessment (GRADE for certainty of evidence and AMSTAR 2 for included systematic reviews).

DATA SYNTHESIS: 123 studies were eligible (45 on COVID-19, 70 on SARS, 8 on MERS), but only 5 studies (1 on COVID-19, 3 on SARS, 1 on MERS) adjusted for important confounders. A study in hospitalized patients with COVID-19 reported slightly higher mortality with noninvasive ventilation (NIV) than with invasive mechanical ventilation (IMV), but 2 opposing studies, 1 in patients with MERS and 1 in patients with SARS, suggest a reduction in mortality with NIV (very-low-certainty evidence). Two studies in patients with SARS report a reduction in mortality with NIV compared with no mechanical ventilation (low-certainty evidence). Two systematic reviews suggest a large reduction in mortality with NIV compared with conventional oxygen therapy. Other included studies suggest increased odds of transmission from AGPs.

LIMITATION: Direct studies in COVID-19 are limited and poorly reported.

CONCLUSION: Indirect and low-certainty evidence suggests that use of NIV, similar to IMV, probably reduces mortality but may increase the risk for transmission of COVID-19 to health care workers.

PRIMARY FUNDING SOURCE: World Health Organization. (PROSPERO: CRD42020178187).

Discipline / Specialty Area Score
Infectious Disease
Occupational and Environmental Health
Intensivist/Critical Care
Hospital Doctor/Hospitalists
Internal Medicine
Comments from MORE raters

Hospital Doctor/Hospitalists rater

This study suggests that intubation and NIV carry a higher risk for coronavirus transmission, and the use of PPE reduces it.

Hospital Doctor/Hospitalists rater

This is an important review of what is unfortunately incomplete and inadequate information of this very relevant topic. At this point, we still don't know what is the right thing to do for these patients and their health care workers.

Infectious Disease rater

It is helpful to have a systematic review, even though it shows what was generally expected: weak evidence, noninvasive ventilation may avoid endotracheal intubation in some patients but is more likely to transmit infection to healthcare workers.

Infectious Disease rater

Nice paper. It's methodological correct and provides useful information for ICU physicians.

Intensivist/Critical Care rater

This is a reasonable attempt at synthesizing these data, but there just aren't good data. There are numerous confounders and relatively small sample sizes. It's just hard to synthesize bad data into something useful. I don't really think this is all that useful for clinicians.

Intensivist/Critical Care rater

There is very low level of evidence showing that we need more RCT (well-designed and well-conducted) to answer to these important questions. A living systematic review is a perfect way to adapt to the published new evidence, and hopefully such new evidence will appear soon.

Occupational and Environmental Health rater

Of the multiple questions asked in this study, Stream 3 is most relevant for OM specialists. Unfortunately, it's of the lowest quality with very few studies allowing quantitative assessment. It's a lot of reading for information that is better suited to patient care choices than decisions related to HCW health and safety.