Derdak 2002.

Methods	Multi‐centre (13 university‐affiliated medical centres) RCT in the United States and Canada from October 1997 to December 2000
Participants	148 adults (mean age 49) with ARDS and PEEP > 10
Interventions	3100B high‐frequency oscillatory ventilator (SensorMedics). Initial settings of FiO₂ 0.80 ‐ 1.0, frequency of 5 Hz, mPaw of CV+5, pressure amplitude of oscillation set for “vibration down to level of mid‐thigh”, bias flow of 40 L/min. Switched back to CV when FiO₂ was 0.50 or less and mPaw was weaned to 24 cm H₂O or less with an SaO₂ of 88% or more Controls were ventilated using pressure control with an initial tidal volume of 6 ‐ 10 ml/kg actual body weight, RR adjusted for pH greater than 7.15, PEEP of 10, inspiratory time 33%. Subsequent adjustment of PEEP was according to study protocol (range 10 ‐ 14)
Outcomes	Survival without need for mechanical ventilation at 30 days from entry to study, 30‐day mortality, 6‐month mortality, need for mechanical ventilation at 30 days and 6 months. Physiologic endpoints and other clinical outcomes, including adverse events, were also obtained after author contact
Notes	Lung‐protective ventilation was not mandatory in the control group receiving conventional mechanical ventilation. Designed as an equivalence trial Rescue therapies used in 9% of the HFO group (nitric oxide 4/75; prone position 2/75, high‐dose steroids 1/75) and 16% of the CV group (nitric oxide 8/73;  prone position 3/73; high‐dose steroids 4/73) Lung‐volume recruitment manoeuvres were permitted, although not protocolized All participants who received HFO were paralysed; paralysis was not mandatory in participants receiving CV Partial industry support (SensorMedics)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐based randomization with a balanced block design, balanced with respect to baseline oxygenation index > 40 (email correspondence, S Derdak, T Bachmann, 20 April 2009)
Allocation concealment (selection bias)	Low risk	Computerized randomization programme (email correspondence, S Derdak, T Bachmann, 20 April 2009)
Blinding (performance bias and detection bias) All outcomes	Low risk	Study investigators and sponsors were blinded to overall results Although blinding of caregivers and family members was not possible due to the nature of the intervention, the use standardized ventilator settings in each study group reduces the risk of performance bias due to lack of blinding Because the primary outcome was death, detection bias was unlikely
Incomplete outcome data (attrition bias) All outcomes	Low risk	Mortality data for withdrawn participants (2/148) obtained after author contact
Selective reporting (reporting bias)	Low risk	All primary and secondary outcomes were reported; authors provided additional clinical and physiologic outcome data for this review after being contacted
Other bias	Low risk	No other source of bias identified