title: Decline in Lung Volume With Duchenne Muscular Dystrophy Is Associated With Ventilation Inhomogeneity.
abstract: BACKGROUND
  Advanced stages of Duchenne muscular dystrophy (DMD) result in severe lung volume decline and are associated with high respiratory morbidity and mortality. The aim of this study was to investigate whether lung volume decline in subjects with DMD is associated with ventilation inhomogeneity measured with the multiple-breath washout technique.
  
  
  METHODS
  This cross-sectional study of lung function included 45 subjects with DMD and 16 healthy controls using multiple-breath washout, spirometry, and cough peak flow.
  
  
  RESULTS
  Subjects with DMD exhibited an elevated lung clearance index (> 7.0) defined as the cumulative exhaled volume divided by the functional residual capacity to lower the sulfur hexafluoride concentration below 2.5% compared with controls (8.16 ± 2.55 vs 6.23 ± 0.46, P < .001). Lung clearance index elevation was negatively correlated with vital capacity (% predicted: r = -0.79, P < .001) and cough peak flow (L/min: r = -0.41, P = .005). Furthermore, dead-space ventilation (dead-space-to-tidal-volume ratio) and functional residual capacity showed a positive correlation with lung clearance index elevation (r = 0.81 and 0.48, P < .001). An FVC of < 24% predicted lung clearance index elevation with a sensitivity of 96% and a specificity of 80%.
  
  
  CONCLUSIONS
  Moderate-to-severe lung volume decline in subjects with DMD is associated with ventilation inhomogeneity. Lung clearance index elevation may be the result of altered ventilation geometry or retention of airway secretions in the infection-free DMD subject.
authors.affiliation: Department of Pediatric Respiratory Medicine florian.stehling@uk-essen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Stehling
authors.affiliation: Department of Pediatric Respiratory Medicine Department of Pediatric Intensive Care Medicine, University Children's Hospital Essen, Essen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Dohna-Schwake
authors.affiliation: Department of Pediatric Respiratory Medicine.
authors.forename: Uwe
authors.initials: U
authors.lastname: Mellies
authors.affiliation: Department of Pediatric Respiratory Medicine Department of Pediatric Intensive Care Medicine, University Children's Hospital Essen, Essen, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Große-Onnebrink
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000503:physiopathology*; D010366:Peak Expiratory Flow Rate; D012123:Pulmonary Ventilation / Q000502:physiology*; D012126:Respiratory Dead Space / Q000502:physiology; D012129:Respiratory Function Tests; D013147:Spirometry; D013990:Tidal Volume; D014797:Vital Capacity; D055815:Young Adult
keywords: lung function; neuromuscular disorders; respiratory function; respiratory insufficiency