Longhini 2019.

Study characteristics
Methods	RCT, cross‐over design. Multicentre study
Participants	Total number of randomized participants: 32 Setting: 2 ICUs; Italy Inclusion criteria: COPD, NIV > 24 hours; fully co‐operative; pH ≥ 7.35 during NIV; respiratory rate ≤ 30 breaths/min; improvement of condition (no dyspnoea, no agitation, no fever) Exclusion criteria: diaphragm paralysis; clinical signs of distress or impending respiratory muscle failure; haemodynamic instability; life‐threatening cardiac arrhythmia; ECG signs of ischaemia; impaired renal function; inclusion in other studies; refusal to consent Baseline characteristics (overall, for analysed participants only): Age, mean (SD): 72.5 (± 8.2) years Gender, M/F: 17/13 BMI, mean (SD): not reported SAPS II, mean (SD) : 31.5 (± 6.2) PaCO2, mean (SD): not reported PaO2/FiO2, mean (SD): not reported
Interventions	Cross‐over study design, with 30 minutes for each 5 intervention stages. Three intervention stages, which were all NIV, were not randomized. Two randomized interventions were given as interruptions to the NIV stages: HFNO delivered using Optiflow via nasal cannula connected to a heated humidifier (MR850) Standard oxygen treatment using Venturi mask Randomized participants, n = 32; losses, n = 2 (insufficient ultrasound imaging quality); analysed, n = 30
Outcomes	Evaluation of right hemidiaphragm; respiratory rate; pH; PaO2; PaCO2; comfort (using 11‐point NRS) Note: we did not include outcome data in the review because study authors did not report outcome data from the first period.
Notes	Funding/declarations of interest: some authors received fees or institutional funding from one or more of the following: Chiesi; AIM ITALY SRL; Fisher and Paykel Healthcare Ltd; Maquet Critical Care; Draeger; Intersurgical SpA; Orionpharma; Phils; Resmed; Merck Sharp and Dohme; Novartis Study dates: December 2015 to March 2017 Note: we did not complete 'Risk of bias' assessments for this study because we did not report outcome data in the review.