Study	Reason for exclusion
Carlon 1983	Participant population had “acute respiratory failure” from a variety of reasons and included many requiring mechanical ventilation who would not necessarily fit modern criteria for ARDS
Dobyns 2002	Randomized on inhaled nitric oxide, not HFO
Fessler 2008	Randomized on frequency of oscillation, not HFO
Hurst 1984	Participants served as their own controls. Total of 9 participants randomized
Hurst 1990	Participants in the study who received HFO were only “at risk” of developing ARDS
Mentzelopoulos 2007a	Randomized on tracheal gas insufflation, not HFO. Cross‐over design
Mentzelopoulos 2010	Randomized on tracheal gas insufflation, not HFO. Cross‐over design
Vrettou 2014	Cross‐over design

ARDS = acute respiratory syndrome
 HFO = high‐frequency oscillation