title: High-intensity versus low-intensity non-invasive ventilation in patients with stable hypercapnic COPD: a randomised crossover trial.
abstract: BACKGROUND
  The conventional approach of low-intensity non-invasive positive pressure ventilation (NPPV) produces only minimal physiological and clinical benefits in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD).
  
  
  OBJECTIVE
  To determine whether the novel approach of high-intensity NPPV is superior to low-intensity NPPV in controlling nocturnal hypoventilation.
  
  
  METHODS
  A randomised controlled crossover trial comparing 6 weeks of high-intensity NPPV (using controlled ventilation with mean inspiratory pressures of 28.6+/-1.9 mbar) with low-intensity NPPV (using assisted ventilation with mean inspiratory pressures of 14.6+/-0.8 mbar) was performed in 17 patients with severe stable hypercapnic COPD.
  
  
  RESULTS
  Two patients refused low-intensity NPPV and two patients dropped out while on low-intensity NPPV. Thirteen patients (mean forced expiratory volume in 1 s (FEV(1)) 0.76+/-0.29 l) completed the trial. High-intensity NPPV produced higher pneumotachographically-measured expiratory volumes, with a mean treatment effect of 96 ml (95% CI 23 to 169) (p=0.015). This resulted in a mean treatment effect on nocturnal arterial carbon dioxide tension (Paco(2)) of -9.2 mm Hg (95% CI -13.7 to -4.6) (p=0.001) in favour of high-intensity NPPV. Daily use of NPPV was increased in high-intensity NPPV compared with low-intensity NPPV, with a mean difference of 3.6 h/day (95% CI 0.6 to 6.7) (p=0.024). In addition, compared with baseline, only high-intensity NPPV resulted in significant improvements in exercise-related dyspnoea, daytime Paco(2), FEV(1), vital capacity and the Severe Respiratory Insufficiency Questionnaire Summary Score.
  
  
  CONCLUSIONS
  High-intensity NPPV is better tolerated by patients with severe chronic hypercapnic COPD and has been shown to be superior to the conventional and widely-used form of low-intensity NPPV in controlling nocturnal hypoventilation. High-intensity NPPV therefore offers a new promising therapeutic option for these patients.
authors.affiliation: Department of Pneumology, University Hospital Freiburg, Killianstrasse 5, D-79106 Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Dreher
authors.forename: Jan H
authors.initials: JH
authors.lastname: Storre
authors.forename: Claudia
authors.initials: C
authors.lastname: Schmoor
authors.forename: Wolfram
authors.initials: W
authors.lastname: Windisch
mesh_terms: D002245:Carbon Dioxide / Q000097:blood; D018592:Cross-Over Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D010313:Partial Pressure; D011175:Positive-Pressure Respiration / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome; D014797:Vital Capacity
chemical_list: D002245:Carbon Dioxide