title: Nutritional status is an important predictor of diaphragm strength in young patients with cystic fibrosis.
abstract: BACKGROUND
  The effect of nutritional status and lung disease progression on diaphragm strength in young patients with cystic fibrosis remains unclear.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of nutritional status and airway obstruction on diaphragm strength.
  
  
  METHODS
  Twitch transdiaphragmatic pressure (Tw Pdi) obtained by bilateral anterior magnetic phrenic nerve stimulation, body mass index (BMI) z score, fat mass, fat-free mass (FFM), arm muscle circumference (AMC), forced expiratory volume in 1 s (FEV(1)), and functional residual capacity (FRC) were measured in 20 patients aged 15.1 +/- 2.8 y (x +/- SD). Values were expressed as a percentage of predicted values.
  
  
  RESULTS
  Mean (+/-SD) Tw Pdi was 24.3 +/- 5.5 cm H(2)O. Univariate regression analysis showed positive correlations between Tw Pdi and nutrition scores (BMI z score: r = 0.63, P = 0.003; FFM: r = 0.47, P = 0.04; AMC: r = 0.45, P = 0.04), airway obstruction (FEV(1): r = 0.68, P = 0.001), and arterial oxygen partial pressure (r = 0.68, P = 0.001). Negative correlations were observed between Tw Pdi and dynamic hyperinflation (FRC: r = -0.65, P = 0.005) and arterial carbon dioxide pressure (r = -0.50, P = 0.03). Furthermore, stepwise regression analysis showed that Tw Pdi correlated with BMI z score (r = 0.75, P = 0.0002) and FEV(1) (r = 0.69, P = 0.001).
  
  
  CONCLUSIONS
  Diaphragm strength is relatively well preserved in young patients with cystic fibrosis. However, the strength of the diaphragm decreases with the progression of malnutrition and airway obstruction.
authors.affiliation: Respiratory Muscle Laboratory, Royal Brompton Hospital, Fulham Road, London, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hart
authors.forename: Patrick
authors.initials: P
authors.lastname: Tounian
authors.forename: Annick
authors.initials: A
authors.lastname: Clément
authors.forename: Michèle
authors.initials: M
authors.lastname: Boulé
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lofaso
authors.forename: Brigitte
authors.initials: B
authors.lastname: Fauroux
mesh_terms: D000293:Adolescent; D000402:Airway Obstruction; D001823:Body Composition; D003550:Cystic Fibrosis / Q000503:physiopathology*; D003964:Diaphragm; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008170:Lung Compliance; D008297:Male; D024510:Muscle Development; D009752:Nutritional Status; D010791:Phrenic Nerve