Demory 2007.

Methods	Single‐centre RCT in France from November 2003 to December 2004
Participants	43 (28 included in this review) adults (mean age 49) with ARDS and PaO₂/FiO₂ < 150 and PEEP ≥ 5 cm H₂O
Interventions	3100B high‐frequency oscillatory ventilator (SensorMedics). Initial settings were FiO₂ 1.0, frequency of 5 Hz with inspiratory time of 33%, mPaw of CV+ 5 cm H₂O (but ≤ plateau pressure), pressure amplitude of oscillation = PaCO₂ during conventional mechanical ventilation (max 110) Controls were ventilated with volume‐assist control with tidal volume 6 ‐ 7 mL/kg predicted body weight. PEEP was adjusted according to the ARDSNet protocol Participants included in this review were randomized to receive conventional mechanical ventilation in the prone position for 12 hours prior to: supine HFO (intervention, n = 13), or supine conventional mechanical ventilation (control, n = 15). A third group (n = 15) was randomly assigned to conventional ventilation in the supine position for 12 hours, followed by HFO, and was not included in this review
Outcomes	Physiologic data including PaO₂/FiO₂, OI, venous admixture
Notes	Duration of HFO was limited to 12 hours; therefore we included only physiologic data (PaO₂/FiO₂ and OI) in pooled analyses Recruitment manoeuvres were performed at HFO initiation, but not during conventional mechanical ventilation. Sedation and paralysis were applied equally to both treatment groups
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated list of random numbers (email correspondence, L Papazian, 9 August 2011)
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes (email correspondence, L Papazian, 9 August 2011)
Blinding (performance bias and detection bias) All outcomes	Low risk	Although blinding of caregivers and family members was not possible, the use of protocols, equal application of sedation and paralysis, and short study duration, likely minimizes the risk of performance bias The primary outcome, PaO₂/FiO₂, was measured from arterial blood in a standardized manner, and is therefore not likely to be susceptible to detection bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	No incomplete outcome data
Selective reporting (reporting bias)	Low risk	All primary and secondary outcomes reported; authors provided additional physiologic data for this review after being contacted
Other bias	Low risk	No other source of bias identified