Table 1.

Summary of basic characteristics of studies selected for inclusion in meta-analysis

Study	Study design	Disease	Causes	Patients, n	Interventions	Content of therapy	Mean age, years	Male	Severity of illness	PaO ₂/FiO ₂, mmHg	Comorbidity
Zhu³²	RCT	ARF	ACPE, ALI, lobar atelectasis, pneumonia, COPD, RMF	48	NPPV	Bilevel positive airways pressure S/T mode (BiPAP) via a face mask via a face mask	62	67%	17.2*	NA	HT, DM
				47	Control	Standard medical care and oxygen therapy as needed	61	57%	17.6*
Zhan²⁴	RCT	ALI	Pulmonary infection, acute pancreatitis, multiple trauma, sepsis	21	NPPV	Bilevel positive airways pressure S/T mode (BiPAP) via a face mask	44	76%	11.8*	225.4 (17.4)	HT, immunosuppres-sion, DM, chronic renal insufficiency, cancer
				19	Control	High-concentration oxygen therapy through a Venturi mask	49	42%	13.4*	234.4 (26.6)
Uçgun²⁵	Prospective	ARDS	NA	10	NPPV	A BiPAP vision ventilator device was used in BIPAP mode via a CPAP full-face mask	43	90%	17.4*	110	NA
				10	Control	Standard therapy (such as oxygen, antibiotics, and bronchodilators)	47	80%	18.8*	103.3
De Santo²⁶	Prospective	ARF	Post-cardiopulmonary bypass lung injury, cardiogenic oedema, pneumonia	43	NPPV	Helmet	66	74%	NA	357 (60.4)	DM, COPD, low LVEF
				422	Control	NA	62	69%	NA	381 (41)
Yañez³¹	RCT	ARF	NA	25	NIV	Positive airways pressure STD 30 mode (BiPAP) via a face mask	16	68%	NA	Median (IQR): 150 (110-383)	Moderate asthma, viral pneumonia and/or bronchiolitis, bacterial pneumonia, RSV pneumonia, bronchiolitis, parainfluenza, pneumonia
				25	Control	Standard treatment (mask oxygen)	18	52%	NA	Median (IQR): 190 (101-400)
Thys²⁸	RCT	ARF	Acute pulmonary oedema, acute exacerbation of COPD	10	NPPV	Bilevel positive airways pressure S/TD 30 mode (BiPAP) via a face mask via a face mask	71	70%	NA	NA	NA
				10	Control	Oxygen therapy + Placebo-device	76	40%
Auriant34	RCT	ARF	Interstitial pulmonary oedema, atelectasis, documented pneumonia	24	NPPV	Bilevel positive airways pressure S/TD 30 mode (BiPAP) via an nasal mask	59	NA	16.9^	126.8 (42.1)	NA
				24	Control	Standard therapy (oxygen, bronchodilatators, patient controlled analgesia, chest physiotherapy)	63	NA	16.8^	127.1 (42.5)
Antonelli¹⁶	RCT	ARF	Pneumonia, ACPE, ARDS, mucous plugging or atelectasis, pulmonary embolism	20	NPPV	Bilevel positive airway pressure via a full face mask	45	65%	13^	129 (30)	NA
				20	Control	Oxygen supplementation	44	60%	13^	129 (30)
Martin33	RCT	ARF	Hypercapnic, hypoxemic	32	NPPV	Bilevel positive airways pressure S/TD mode (BiPAP) via an nasal mask	64	47%	58^#	Hypercapnic ARF: 190(68) Hypoxemic ARF:103 (35)	COPD, Non-COPD-related pulmonary disease
				29	Control	Usual medical care	58	48%	65^#	Hypercapnic ARF: 208 (90) Hypoxemic ARF:110 (43)
Confalonieri²⁷	RCT	ARF	Severe community-acquired pneumonia	28	NPPV	Continuous positive airway pressure through full-face mask	66	82%	20*	183 (36)	COPD
				28	Control	Standard treatment with oxygen supplementation delivered by a Venturi mask	61	61%	18*	167 (47)
Wood²⁹	RCT	ARDS	ACPE, COPD, pneumonia, interstitial lung disease, sepsis	16	NPPV	Hospital-grade ventilatory support systems (BiPAP) stationed in the ED. via an nasal mask	56	69%	18.1*	NA	NA
				11	Control	Conventional medical therapy (supplemental oxygen and pharmacologic therapy)	62	46%	15.6*
Wysocki³⁰	RCT	ARF	Pneumonia, ACPE, Laryngeal dyspnea, chest wall impairment	21	NIPSV	NIPSV was delivered to the patient through a full-face mask	64	57%	17^	NA	NA
				20	Control	Medications related to the cause of respiratory distress (antibiotics, diuretics, inotropics, etc) and oxygen supplementation	62	60%	12^

↵*APACHE (Acute Physiology and Chronic Health Evaluation) II score
^SAPS II (Simplified Acute Physiology Score)
↵#APACHE III score
ACPE = acute cardiogenic pulmonary oedema; ALI = acute lung injury; ARDS = acute respiratory distress syndrome; ARF = acute respiratory failure; COPD = chronic obstructive pulmonary disease; DM = diabetes mellitus; HT = hypertension; LVEF = left ventricular ejection fraction; NA = not available; NIV = non-invasive ventilation; NIPSV = non-invasive pressure support ventilation; NPPV = non-invasive positive-pressure ventilation; RCT = randomised controlled trial; RMF = respiratory muscle fatigue; RSV = respiratory syncytial virus