Table 1

Study flow chart

Procedures and assessments	Inclusion and randomisation	Follow-up and data collection			End of study
		H₁,H₆, H_12–H_24–48	ICU stay	Day 28	ICU discharge and day 90
Screening inclusion/non-inclusion criteria	X			X	X
Information and consent	X
Treatment allocation	X
Clinical characteristics
Demographic data, comorbidity, reason for respiratory failure*	X			X
Clinical data	X	X	X
Chest X-ray	X
SOFA score, SAPS II, McCabe score	X			SOFA (daily during the 2 days after intubation)	SOFA (daily during the 2 days after intubation)
Evaluation of oxygenation therapy
Arterial blood gas and FiO₂ estimation2	X	X
VAS for respiratory discomfort	X	X
Dyspnoea score, pattern of breathing		X
Duration of oxygen strategies		X	X	X	X
Use of alternative oxygen therapy		X	X	X	X
Criteria of intubation and description of intubation procedure		X	X	X	X
Outcomes and complications
Outcomes (death, intubation, ventilation-free day at 28 days, ICU and hospital length of stay) Complications during ICU stay			X	X (phone contact)	X (phone contact)

*Reasons for respiratory failure will be collected in the electronic case-report form and classified as follows: pneumonia (community-acquired pneumonia, hospital-acquired pneumonia and documentation if available), other common risks (non-pulmonary sepsis, aspiration of gastric content, major trauma, pulmonary contusion, inhalation injury, severe burns, non-cardiogenic shock, drug overdose, multiple transfusions or transfusion-associated acute lung injury, pancreatitis, drowning), other non-common risks (connective tissue disease, small-vessel vasculitis, hypersensitivity pneumonitis, drug-induced pneumonia, haematology malignancy, solid tumour, lymphangitic carcinomatosis, organising pneumonia, diffuse alveolar haemorrhage, massive haemoptysis, no aetiology identified, other).
FiO₂, fractional inspired oxygen; ICU, intensive care unit; SAPS II, Simplified Acute Physiology Score II; SOFA, Sequential-related Organ Failure Assessment; VAS, visual analogue scale.