Zhou 2001.

Methods	Country: China Design: Randomised controlled trial, but no information about randomisation method or allocation concealment provided Study site: Single centre at the Second Xiangya Hospital, Central South University, Changsha, China Setting: Not stated whether conducted in ICU or on ward Methods of analysis: Means for before and after intervention were compared by t‐test. Chi2 analysis was used for differences in rates of intubation between 2 groups Aim: To observe effects of NIV on gas exchange and on patients’ transformation, and to evaluate clinical value
Participants	Eligible for study: Not mentioned Recruited: Total of 60 participants with COPD were randomised to 2 groups: 30 to NIV group and 30 to usual care group. No differences in baseline characteristics between 2 groups; P > 0.05 Completed: Unsure, not mentioned in text or table. Presumed all 60 participants completed study. Intention‐to‐treat data were analysed with 30 participants on each arm Age: NIV group: 63.5 ± 9.1 years. Usual care group: 64.3 ± 9.4 years Gender: NIV group: 22 male and 8 female. Usual care group: 24 male and 6 female Criteria used to define COPD: No details available Inclusion criteria: Patients with COPD admitted to hospital with respiratory failure of PaCO2 > 50 mmHg Exclusion criteria: Patients who were hypotensive with SBP < 90 mmHg, with cardiac arrhythmias, or comatose
Interventions	Intervention description: NIV was provided via Respironics, Inc. BiPAP ST‐D model with nasal/face mask. S/T mode was selected with IPAP 8 to 14 cmH2O , EPAP 2 to 6 cmH2O. All participants also received oxygen FiO2 22% to 33%, antibiotics, mucolytics, bronchodilator, glucocorticoids, and nutrients that required improving treatments and respiratory stimulants for patients with pulmonary encephalopathy Control description: Oxygen FiO2 22% to 33%, antibiotics, mucolytics, bronchodilator, glucocorticoids, and nutrients that required improving treatments and respiratory stimulants for patients with pulmonary encephalopathy Duration of intervention: 2 days with ≥ 4 hours of NIV each day Intervention delivery by: Not reported in text
Outcomes	Method of outcome data collection: Data were collected at baseline and throughout hospital stay Prespecified primary outcome: Protocol not available. In text outcomes: ABG, heart rate and respiratory rate changes Prespecified secondary outcome: Protocol not available. In text outcome: Intubation rate Validation: ABG, HR, RR Follow‐up period: Throughout admission, until discharged or endpoint reached Number of follow‐up periods reported on during study: Not mentioned in text Indications for intubation: PaCO2 > 70 mmHg or PaCO2 increased by 5 to 10 mmHg, pH decreased by 0.05 to 0.1, reduced GCS or PaO2 < 45 mmHg
Notes	ABGs and vital signs changes were compared from baseline to 2 days post treatment. No data available 1 hour post NIV. Hence data not included in meta‐analysis Paper written in Chinese, with limited translation by translator. Attempts to contact study authors for more information were met with no reply Funder: Not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not mentioned in the paper; stated only that participants were randomly assigned to control vs intervention group
Allocation concealment (selection bias)	Unclear risk	Not mentioned in the paper; stated only that participants were randomly assigned to control vs intervention group
Blinding of participants and personnel (performance bias) All outcomes	High risk	No sham NIV used
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned in paper who delivered NIV and who collected data
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information available
Selective reporting (reporting bias)	Unclear risk	Insufficient information available
Imbalance of outcome measures at baseline All outcomes	Unclear risk	Insufficient information available
Comparability of intervention and control group characteristics at baseline	Unclear risk	Insufficient information available
Protection against contamination All outcomes	Unclear risk	Insufficient information available
Selective recruitment of participants	Unclear risk	Insufficient information available
Other bias	Unclear risk	Insufficient information reported in paper. Attempts to contact study authors were met with no response

ABG: Arterial blood gases; AECOPD: Acute exacerbation of chronic obstructive pulmonary disease; AHRF: Acute hypercapnic respiratory failure; APO: Acute pulmonary oedema; BiPAP: bi‐level positive airway pressure; BMI: Body mass index; BP: blood pressure; CHF: Congestive heart failure; cmH₂O: centimetres of water; COPD: Chronic obstructive pulmonary disease; CXR: chest x‐ray; DIC: disseminated intravascular coagulation; ECG: electrocardiography; ED: Emergency department; EMG: electromyography; EPAP: Expiratory positive pressure; FEV₁: Forced expiratory volume in one second; FiO₂: Fraction of inspired oxygen; GCS: Glasgow Coma Scale; GI: gastrointestinal; HR: Heart rate; ICU: Intensive care unit; IV: intravenously; IPAP: Inspiratory positive pressure; LOS: length of stay; mmHg: millimetres of mercury; NIPPV: non‐invasive positive pressure ventilation; NIV: Non‐invasive ventilation; PE: Pulmonary embolism; PaO₂: Partial pressure of oxygen (arterial); PaCO₂: Partial pressure of carbon dioxide (arterial); PEEP: Positive expiratory end pressure; PFT: pulmonary function test; PS: pressure support; RR: Respiratory rate; SaO₂: arterial oxygen saturation; SAPS: simplified acute physiology score; SCM: sternocleidomastoid; SD: Standard deviation; SE: standard error; SpO₂: peripheral oxygen saturation; SPSS: Statistical Package for the Social Sciences; TV: tidal volume; VAS: Visual analogue scale.