AECC	American‐European Consensus Conference definitions. ALI criteria: acute onset, PaO2/FIO2 ≤ 300 (regardless of PEEP level), bilateral pulmonary infiltrates and lack of evidence of left heart failure. ARDS has the same clinical characteristics as ALI, except that the PaO2/FIO2 in ARDS is ≤ 200 (Bernard 1994).
ALI	Acute lung injury.
APACHE II	Acute Physiology and Chronic Health Evaluation II. Classification system of severity of diseases.
ARDS	Acute respiratory distress syndrome.
Days‐free without organ failure	Number of days a participant was without organ failure from day 1 to day 28.
Days not spent in ICU	Number of days a participant was not in the ICU from day 1 to day 28.
Driving Pressure	Plateau pressure－PEEP.
FIO2	Fraction of inspired oxygen.
FRC	Functional residual capacity.
ICU	Intensive care unit.
LISS	Lung injury severity score (Murray 1988). Range 0 (normal) to 4 (most severe). LISS > 2.5 = ARDS.
LOS	Length of stay.
MV	Mechanical ventilation.
PaCO2	Partial pressure of arterial carbon dioxide.
PaO2	Partial pressure of arterial oxygen.
PaO2/FiO2	Relation between partial pressure of arterial/fractional inspired oxygen.
PBW	Predicted body weights.
PEEP	Positive end‐expiratory pressure.
Persistent ARDS	Participants with ARDS ventilated with standard setting for 24 hours who persist with PaO2/FIO2 ≤ 200.
Pflex	Upward shift in the slope of the pressure‐volume curve.
Pwedge	Pulmonary wedge pressure.
Recruitment manoeuvre	Manoeuvre for opening of collapsed alveoli to improve gas exchange and lung volume end‐expiration and decreased VILI.
RCT	Randomized controlled trial.
SpO2	Arterial oxygen saturation (measured via pulse oximetry).
Static compliance (Cst)	Determined by dividing tidal volume by the difference between pressure at the end of inflation hold and PEEP.
Strain	Ratio between the amount of gas volume delivered during tidal breath and the amount of aerated lung receiving it.
VFD	Number of days between successful weaning from mechanical ventilation and day 28 after study enrolment (Schoenfeld 2002).
VILI	Ventilator‐induced lung injury.
VT	Volume tidal.