title: Clinical implications of maximal respiratory pressure determinations for individuals with Duchenne muscular dystrophy.
abstract: OBJECTIVE
  To analyze the relationship between disease progression, pulmonary volumes, respiratory muscle strength (maximum inspiratory [MIP] and expiratory [MEP] pressure), and arterial blood gases for patients with Duchenne muscular dystrophy (DMD).
  
  
  METHODS
  An inception cohort study of pulmonary volumes, MIPs, and MEPs, correlated with age and PaCO2 levels and with each other using linear and nonlinear regression analyses.
  
  
  METHODS
  Outpatient clinic.
  
  
  METHODS
  Fifty-two consecutive DMD patients who presented for regular evaluations at a regional DMD center.
  
  
  RESULTS
  Maximum expiratory pressures were 47.7% +/- 10.9% of normal in the 167- to 14-year-old patients and decreased linearly thereafter (MEP% = -2.7 x age +73.8; p < .001). Declines in MEP also correlated linearly with expiratory reserve volume (p < .001) and inversely with residual volume (p < .001). By contrast, MIP was 66.3% +/- 19.0% in the 357- to 14-year-old patients and then declined to 30.2% +/- 19.5% after age 14. No linear relationships were found with age but declines did correlate linearly with inspiratory reserve volume (p < .001) and total lung capacity (p < .001). PaCO2 elevations correlated best with decreases in MIP (p < .0001) and appeared when MIP was below 30cmH2O.
  
  
  CONCLUSIONS
  Lung volume changes in DMD patients correlate with respiratory muscle weakness, and although inspiratory muscle dysfunction plays a key role in the development of chronic ventilatory insufficiency, reductions in expiratory muscle strength are the first signs of dysfunction and lead to the first episodes of respiratory failure.
authors.affiliation: Department of Neuropediatrics, University of Kiel, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hahn
authors.forename: J R
authors.initials: JR
authors.lastname: Bach
authors.forename: A
authors.initials: A
authors.lastname: Delaubier
authors.forename: A
authors.initials: A
authors.lastname: Renardel-Irani
authors.forename: C
authors.initials: C
authors.lastname: Guillou
authors.forename: Y
authors.initials: Y
authors.lastname: Rideau
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D015331:Cohort Studies; D006801:Humans; D009136:Muscular Dystrophies / Q000150:complications / Q000503:physiopathology*; D012044:Regression Analysis; D012120:Respiration Disorders / Q000209:etiology / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012600:Scoliosis / Q000150:complications