Secondary outcome measures
| Key domains | Outcome | Time frame for assessment |
| Parameters related to VFDs | ||
| Duration of NIV sessions (hours) | 28 days postrandomisation | |
| Number of days between the day of initially achieving unassisted ventilation and day 28 postrandomisation (ie, after having successfully spent 48 consecutive hours of unassisted breathing) | 28 days postrandomisation | |
| Number of days between the day the patient first meets criteria for NIV cessation and day 28 postrandomisation | 28 days postrandomisation | |
| Proportion of patients achieving 48 consecutive hours of unassisted breathing | 28 days postrandomisation | |
| Proportion of patients requiring NIV resumption after 48 consecutive hours of unassisted breathing | 28 days postrandomisation | |
| Number of NIV sessions | 28 days postrandomisation | |
| Tolerance/comfort | ||
| Patient self-assessment of comfort during each NIV period measured by VAS (score range 0–10, higher values represent a better outcome) | After 1 hour of NIV, up to 28 days postrandomisation | |
| Nurse assessment of comfort during each NIV period measured by Likert scale (score range 1–5; higher values represent a better outcome) | After 1 hour of NIV, up to 28 days postrandomisation | |
| Patient self-assessment of comfort during each SB period measured by VAS (score range 0–10, higher values represent a better outcome) | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter, up to 28 days postrandomisation | |
| Nurse assessment of comfort during each SB period measured by Likert scale (score range 1–5; higher values represent a better outcome) | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter, up to 28 days postrandomisation | |
| Patient self-assessment of dyspnoea during each NIV period measured by VAS (range 0–10; higher values represent a worst outcome) | After 1 hour of NIV, up to 28 days postrandomisation | |
| Nurse assessment of dyspnoea during each NIV period measured by Likert scale (score range 1–5; higher values represent a worst outcome) | After 1 hour of NIV, up to 28 days postrandomisation | |
| Patient self-assessment of dyspnoea during each SB period measured by VAS (range 0–10; higher values represent a worst outcome) | After 2 hours of SB in the 48 first hours, and every 4 hours thereafter, up to 28 days | |
| Nurse assessment of dyspnoea during each SB period measured by Likert scale (score range 1–5; higher values represent a worst outcome) | After 2 hours of SB in the 48 first hours, and every 4 hours thereafter, up to 28 days postrandomisation | |
| Respiratory rate during NIV periods | After 1 hour of NIV, up to 28 days postrandomisation | |
| Respiratory rate during SB periods | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter, up to 28 days postrandomisation | |
| Proportion of patients using accessory muscles during NIV periods | After 1 hour of NIV, up to 28 days postrandomisation | |
| Daily ABGs (in terms of pH, PaCO2 and PaO2 measured between 8:00 and 10:00) | Up to 28 days postrandomisation | |
| Proportion of patients with premature NIV cessation (intolerance, defined by agitation and/or mask removal, and/or patient’s wish to interrupt session before) | 28 days postrandomisation | |
| Proportion of patients refusing to resume NIV (despite meeting criteria) | 28 days postrandomisation | |
| Proportion of patients who need secondary intubation and IMV | 28 days postrandomisation | |
| Proportion of patients who need secondary intubation and IMV | 28 days postrandomisation | |
| Side effects | ||
| Proportion of patients with nasal bridge ulceration | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with facial skin erythema and/or ulceration | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with eye irritation | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with nasal congestion | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with nasal/oral dryness | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with gastric distension | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with nosocomial pneumonia | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with pneumothorax | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with arterial hypotension | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with nostril ulceration (including nasolabial angle, columella, nostril sill) | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Proportion of patients with nose bleeding | After 2 hours of SB in the first 48 hours, and every 4 hours thereafter; and after 1 hour of NIV; up to 28 days postrandomisation | |
| Hospital length of stay | ||
| Overall hospital length of stay (defined as the duration from hospital admission to hospital discharge) | 28 days postrandomisation | |
| Length of stay in the unit where the patient has been first admitted (either ICU, intermediate care or respiratory care unit) | 28 days postrandomisation | |
| Length of stay in the units where the patient has received NIV | 28 days postrandomisation | |
| Mortality | ||
| All-cause mortality | 28 days postrandomisation | |
| All cause in-hospital mortality | 28 days postrandomisation | |
| All cause inpatient mortality in the unit where the patient has been first admitted (either ICU, intermediate care or respiratory care unit) | 28 days postrandomisation | |
| All cause inpatient mortality in the unit where the patient has been transferred to further receive NIV (eg, from ICU to intermediate care for those who provide NIV in intermediate care) | 28 days postrandomisation |
ABG, arterial blood gas; ICU, intensive care unit; IMV, invasive mechanical ventilation; NIV, non-invasive ventilation; PaCO2, alveolar carbon dixoide tension; PaO2, arterial oxygen tension; SB, spontaneous breathing; VAS, Visual Analogue Scale; VFDs, ventilator-free days.