title: Early use of non-invasive positive pressure ventilation for acute exacerbations of chronic obstructive pulmonary disease: a multicentre randomized controlled trial.
abstract: 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 NPPV is early (within 24 to 48 hours of admission) administered in those patients with respiratory muscle fatigue and mild respiratory insufficiency, especially in patients without fulfilling the conventional criteria of mechanical ventilatory support.
  
  
  METHODS
  A prospective multicentre randomized controlled trial was conducted in 19 hospitals in China over 16 months. Three hundred and forty-two AECOPD patients with pH > or = 7.25 and PaCO2 > 45 mmHg were recruited on general ward and randomly assigned to standard medical treatment (control group) or early administration of additional NPPV (NPPV group).
  
  
  RESULTS
  The characteristics of two groups on admission were similar. The number of AECOPD patients requiring 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 > or = 7.35) and severe (pH < 7.30) acidotic patients in NPPV group were both decreased (9/80 vs 2/71, P = 0.047 and 8/30 vs 3/43, P = 0.048, 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 improved rapidly at the first 2 hours only in patients of NPPV group. After 24 hours, the differences of pH, PaO2, scale for accessory 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 respiratory muscle fatigue and preventing respiratory failure from exacerbation.
mesh_terms: D000208:Acute Disease; D000368:Aged; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011446:Prospective Studies