title: Noninvasive ventilation in COPD: impact of inspiratory pressure levels on sleep quality.
abstract: BACKGROUND
  Although high-intensity noninvasive positive pressure ventilation (HI-NPPV) is superior to low-intensity noninvasive positive pressure ventilation (LI-NPPV) in controlling nocturnal hypoventilation in stable hypercapnic patients with COPD, it produces higher amounts of air leakage, which, in turn, could impair sleep quality. Therefore, the present study assessed the difference in sleep quality during HI-NPPV and LI-NPPV.
  
  
  METHODS
  A randomized, controlled, crossover trial comparing sleep quality during HI-NPPV (mean inspiratory positive airway pressure 29 ± 4 mbar) and LI-NPPV (mean inspiratory positive airway pressure 14 mbar) was performed in 17 stable hypercapnic patients with COPD who were already familiar with HI-NPPV.
  
  
  RESULTS
  Thirteen patients (mean FEV(1) 27% ± 11% predicted) completed the trial; four patients refused to sleep under LI-NPPV. There was no significant difference in sleep quality between the treatment groups (all P > .05), with a mean difference of -3.0% (95% CI, -10.0 to 3.9; P = .36) in the primary outcome, namely non-rapid eye movement sleep stages 3 and 4. However, nocturnal Paco(2) was lower during HI-NPPV compared with LI-NPPV, with a mean difference of -6.4 mm Hg (95% CI, -10.9 to -1.8; P = .01).
  
  
  CONCLUSIONS
  In patients with COPD, high inspiratory pressures used with long-term HI-NPPV produce acceptable sleep quality that is no worse than that produced by lower inspiratory pressures, which are more traditionally applied in conjunction with LI-NPPV. In addition, higher pressures are more successful in maintaining sufficient alveolar ventilation compared with low pressures. Thus, HI-NPPV is a very promising new approach, but still requires large, longer-term trials to determine the impact on outcomes such as exacerbation rates and longevity.
  
  
  BACKGROUND
  German Clinical Trials Register (DRKS); No.: DRKS00000520; URL: www.drks.de.
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany. Electronic address: michael.dreher@uniklinik-freiburg.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Dreher
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany.
authors.forename: Emelie
authors.initials: E
authors.lastname: Ekkernkamp
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Walterspacher
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Walker
authors.affiliation: Clinical Trials Unit, University Medical Center, Freiburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Schmoor
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Storre
authors.affiliation: Department of Pneumology, University Medical Center, Freiburg, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Windisch
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D002908:Chronic Disease; D018592:Cross-Over Studies; D006801:Humans; D006935:Hypercapnia / Q000628:therapy; D001239:Inhalation / Q000502:physiology*; D007385:Intermittent Positive-Pressure Ventilation; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology* / Q000628:therapy*; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D016896:Treatment Outcome