title: Six-month nocturnal nasal positive pressure ventilation improves respiratory muscle capacity and exercise endurance in patients with chronic hypercapnic respiratory failure.
abstract: OBJECTIVE
  This study was designed to investigate the effects of 6 months of nocturnal nasal positive pressure ventilation (NNPPV) on respiratory muscle function and exercise capacity in patients with chronic respiratory failure.
  
  
  METHODS
  A prospective, randomized, controlled design was used. Twenty-nine patients with chronic respiratory failure were enrolled and allocated to either the NNPPV (n = 14) or control group (n = 15). Patients in the NNPPV group received bi-level positive pressure ventilation via nasal mask for 6 consecutive months. Arterial blood gas, respiratory muscle assessment and 6-minute walk test (6MWT) were performed before and after the 6-month NNPPV intervention. Respiratory muscle function was assessed using the variables of maximal inspiratory pressure (Pimax), maximal expiratory pressure (Pemax), and maximum voluntary ventilation (MVV).
  
  
  RESULTS
  Subjects in the NNPPV group showed a significant improvement in blood gas exchange and increased 6-minute walk distance (6MWD) compared to baseline and the control group. The 6MWD was significantly increased from 257.1 +/- 114.1 to 345.2 +/- 109.9 m (34.3%) in the NNPPV group. NNPPV also significantly improved MVV and Pimax relative to baseline. MVV was significantly increased from 19.2 +/- 6.5 to 22.3 +/- 7.1 L/min (16.1%) in the NNPPV group (p < 0.05). Furthermore, there was a significant correlation between the magnitude of MVV improvement and 6MWD change.
  
  
  CONCLUSIONS
  The 6-month NNPPV treatment significantly decreased the partial pressure of carbon dioxide and improved daytime respiratory muscle function, thus contributing to exercise-capacity increase in patients with chronic respiratory failure.
authors.affiliation: School of Respiratory Therapy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Chiang
authors.forename: Chih-Teng
authors.initials: CT
authors.lastname: Yu
authors.forename: Chien-Ying
authors.initials: CY
authors.lastname: Liu
authors.forename: Yu-Lun
authors.initials: YL
authors.lastname: Lo
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
authors.forename: Horng-Chyuan
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000368:Aged; D002908:Chronic Disease; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012131:Respiratory Insufficiency / Q000628:therapy*; D012132:Respiratory Muscles