Effects of combined oxygen and surgical masks on inspired fraction of oxygen: relevance to COVID-19-induced respiratory failure

Editor—On March 11, 2020, WHO declared the novel coronavirus disease 2019 (COVID-19) outbreak a global pandemic.1World Health Organization. Coronavirus disease (COVID-19) pandemic. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019 (accessed March 2020).Google Scholar Some patients with COVID-19 present with acute hypoxaemic respiratory failure. In such cases, low-flow oxygen therapy through a nasal cannula or an...