Background Respiratory muscle fatigue plays an important role in acute exacerbations of chronic obstructivepulmonary disease (AECOPD)·In previous clinical studies, non-invasive positive pressure ventilation (NPPV)was proved to be successful only for AECOPD patients with severe respiratory failure·We hypothesized that, theoutcomes of AECOPD would be improved if NPPVis early (within 24 to 48 hours of admission) administered inthose patients with respiratory muscle fatigue and mild respiratory insufficiency, especially in patients withoutfulfilling the conventional criteria of mechanical ventilatory support·Methods Aprospective multicentre randomized controlled trial was conducted in19 hospitals in China over16months·Three hundred and forty-two AECOPD patients with pH≥7·25 and PaCO2>45 mmHg were recruitedon general ward and randomly assigned to standard medical treatment (control group) or early administration ofadditional NPPV (NPPV group)·Results The characteristics of two groups on admission were similar·The number of AECOPD patientsrequiring intubations in NPPV group was much fewer than that of the control group (8/171 vs 26/71,P=0·002)·Subgroup analysis showed the needs for intubation in mildly (pH≥7·35) and severe (pH<7·30)acidotic patients in NPPVgroup were both decreased (9/80 vs2/71,P=0·047 and 8/30 vs3/43,P=0·048,respectively)·The mortality in hospital was reduced slightly by NPPV but with no significant difference (7/171vs 12/171,P=0·345)·Respiratory rate (RR),scale for accessory muscle use and arterial pHimproved rapidlyat the first 2 hours only in patients of NPPV group·After 24 hours, the differences of pH, PaO2, scale foraccessory muscle use and RR in NPPV group [(7·36±0·06) mmHg, (72±22) mmHg, (2·5±0·9) /min,(22±4) /min] were statistically significant compared with control group (7·37±0·05) mmHg, (85±34)mmHg, (2·3±1·1) /min, (21±4) /min,P<0·01 for all comparisons]·Conclusions The early use of NPPV on general ward improves arterial blood gas and respiratory pattern,decreases the rate of need for intubation in AECOPD patients·NPPV is indicative for alleviating respiratorymuscle fatigue and preventing respiratory failure from exacerbation· Background Respiratory muscle fatigue plays an important role in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) · In previous clinical studies, non-invasive positive pressure ventilation (NPPV) was proved to be successful only for AECOPD patients with severe respiratory failure · We hypothesized that , the outcomes of AECOPD would be improved if NPPVis early (within 24 to 48 hours of admission) administered in those patients with respiratory muscle fatigue and mild respiratory insufficiency, especially in patients withoutfulfilling the conventional criteria of mechanical ventilatory support · Methods Aprospective multicentre randomized controlled trial was conducted in19 hospitals in China over16months · Three hundred and forty-two AECOPD patients with pH ≥7.25 and PaCO2> 45 mmHg were recruitedon general ward and randomly assigned to standard medical treatment (control group) or early administration ofadditional NPPV (NPPV group) Results The characteristics of two groups s on admission were similar · The number of AECOPD patients who recruit intubations in NPPV group was much fewer than that of the control group (8/171 vs 26/71, P = 0.002) · Subgroup analysis showed the needs for intubation in mildly ( (pH <7.30) and severe (pH <7.30) acidotic patients in NPPVgroup both both decreased (9/80 vs 2/71, P = 0 · 047 and 8/30 vs 3/43, respectively ) · The mortality in hospital was reduced slightly by NPPV but with no significant difference (7/171 vs 12/171, P = 0 · 345) · Respiratory rate (RR), scale for accessory muscle use and arterial pH during rapid first the first 2 hours only in patients of NPPV group · After 24 hours, the differences of pH, PaO2, scale foraccessory muscle use and RR in NPPV group [(7.336 ± 0.06) mmHg, (72 ± 22) mmHg, (2.5 (22 ± 4) / min] were statistically significant compared with the control group (7.37 ± 0.05) mmHg, (85 ± 34) mmHg, (2.3 ± 1.1) / min, (21 ± 4) / min, P <0 · 01 for all comparisons · Conclusions The early use of NPPV on general ward i mproves arterial blood gas and respiratory pattern, decreases the rate of need for intubation in AECOPD patients · NPPV is indicative for alleviating respiratorymuscle fatigue and preventing respiratory failure from exacerbation ·