Characteristics of the pragmatic definition of COVID-19 ARDS: “A patient receiving HFNO, NIV, or IMV for acute hypoxemic respiratory failure due to SARS-CoV-2 pneumonia”*.

Table 1: Characteristics of the pragmatic definition of COVID-19 ARDS: “A patient receiving HFNO, NIV, or IMV for acute hypoxemic respiratory failure due to SARS-CoV-2 pneumonia”*.

Feature of definition	Berlin criterion	COVID application
Associated with COVID-19	No restriction by pathogen	Limited to patients with SARS-CoV-2 pneumonia
Acute	< 7 days since onset	5-14 days is common; most important factor is that the respiratory failure be from COVID-19
Bilateral opacities	Bilateral opacities consistent with pulmonary edema “may be very mild, patchy, and asymmetric”	COVID-19 pneumonia is generally a bilateral process
Hypoxemic	Positive pressure ventilation with PEEP ≥ 5 cmH₂O and PaO₂:FIO₂< 300 (Kigali modification SpO₂:FIO₂< 315 and eliminates PEEP and positive pressure ventilation requirements)	Hypoxemic respiratory failure treated with HFNO, NIV, IMV (FIO₂ ≥ 0.35 guarantees SpO₂:FIO₂ < 315 regardless of SpO₂)
Not primarily cardiogenic/hydrostatic	Clinical assessment and judgment	Respiratory failure primarily due to COVID-19 pneumonia

*Brown SM, Peltan ID, Barkauskas C, Rogers AJ, Kan V, et al. (2021) What Does “ARDS” Mean during the COVID-19 Pandemic?. Ann Am Thorac Soc 18: 1948-1950.