Yang 2019.

Methods	RCT, parallel‐group design
Participants	Total number of participants: 74 Setting: China Inclusion criteria: acute exacerbation of COPD (Grade I/II) Exclusion criteria: none reported
Interventions	Intervention group (HFNC): n = 37; flow = 40 L/min Control group (standard oxygen therapy): n = 37; nasal cannula; flow = 3 L/min
Outcomes	All outcomes measured: ultrasound measure of diaphragm movement (shallow and deep breathing); diaphragmatic fast breathing index; PaO2;PaCO2 Outcomes relevant to this review: PaO2; PaCO2
Notes	Contact: Yang Shengqiang, Department of Intensive Medicine, Huxi Hospital (Shan County Central Hospital), Jining Medical College We did not source the full text of this study which was published in Chinese; we have taken the current information from the English abstract. This study requires translation into English in order to be incorporated into the review. We will seek translation when completing the next review update.