AECC	American‐European Consensus Conference definitions ALI criteria: acute onset, PaO₂/FIO₂≤ 300 (regardless of PEEP level), bilateral pulmonary infiltrates, lack of evidence of left heart failure ARDS has the same clinical characteristics as ALI, except that 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 disease
ARDS	Acute respiratory distress syndrome
AUC	Area under the curve
Berlin definition	Mild ARDS: 200 mmHg < PaO₂/FIO₂ ≤ 300 mmHg with PEEP or CPAP ≥ 5 cmH₂O Moderate ARDS: 100 mmHg < PaO₂/FIO₂ ≤ 200 mmHg with PEEP ≥ 5 cmH₂O Severe ARDS: PaO₂/FIO₂ ≤ 100 mmHg with PEEP ≥ 5 cmH₂O (Ranieri 2012)
BMI	Body mass index
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
Decremental PEEP trial	PEEP titration along deflation limb of the pressure/volume curve with observation of changes in oxygenation and/or respiratory mechanics (Gernoth 2009)
Driving pressure	Plateau pressure ‐ PEEP
ECMO	Extracorporeal membrane oxygenation
Established ARDS	Patients who meet ARDS criteria after 24 hours of standard ventilatory setting
FIO₂	Fraction of inspired oxygen
FRC	Functional residual capacity
HFO	High‐frequency oscillatory ventilation
ICU	Intensive care unit
LIS	Lung Injury Severity score (Murray 1988). Range 0 (normal) to 4 (most severe). LIS > 2.5 = ARDS
LOS	Length of stay
Minute ventilation	Product of tidal volume and respiratory rate
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 weight
PEEP	Positive end‐expiratory pressure
Persistent ARDS	ARDS ventilated at standard setting for 24 hours that persists with PaO₂/FIO₂≤ 200
Pflex	Upward shift in slope of the pressure‐volume curve
Pplat	End‐inspiratory plateau pressure
Pwedge	Pulmonary wedge pressure: pulmonary capillary wedge pressure; frequently used to assess left ventricular filling. It is measured by inserting a balloon into a branch of the pulmonary artery. The balloon is then inflated, which occludes the branch of the pulmonary artery, providing a pressure reading that is equivalent to pressure of the left atrium
Recruitment manoeuvre	Manoeuvre for opening of collapsed alveoli to improve gas exchange and lung volume end‐expiration and to decrease VILI
RCT	Randomised 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 the inflation hold and PEEP
Strain	Ratio between the amount of gas volume delivered during tidal breath and the amount of aerated lung receiving it
VFDs	Ventilator‐free days: (28 ‐ x): if the patient is successfully weaned from mechanical ventilation within 28 days, where x is the number of days spent receiving mechanical ventilation
VILI	Ventilator‐induced lung injury
Transpulmonary pressure	Airway pressure minus pleural pressure
TV	Tidal volume