title: Acidosis and raised norepinephrine levels are associated with exercise dyspnoea in idiopathic pulmonary fibrosis.
abstract: OBJECTIVE
  Exertional dyspnoea limits patients with IPF in their activities of daily living. The mechanism, however, has not been elucidated. This study tested the hypothesis in IPF that exertional dyspnoea correlates with cardiopulmonary exercise responses, specifically changes in arterial blood pH and plasma norepinephrine (NE).
  
  
  METHODS
  Cardiopulmonary exercise testing with measurements of dyspnoea (Borg scale), plasma NE, plasma lactate and arterial blood gases were performed in 29 patients with IPF and in nine controls.
  
  
  RESULTS
  Both groups showed obvious break points in dyspnoea changes during exercise. In IPF, an abrupt change in the Borg scale, pH, PaCO(2) and plasma NE occurred in the late exercise phase after the 'break point'. Compared with controls, patients with IPF had significantly higher HCO(3)(-) levels and physiologic dead space/tidal volume during exercise. In IPF, during both exercise phases, the dyspnoea slope (DeltaBorg scale/Deltaminute ventilation) correlated with the pH slope (DeltapH/Deltaoxygen uptake) (before the break point: r = -0.537, P = 0.0022; r = -0.886, P < 0.0001, after the break point) and the NE slope (DeltaNE/Deltaoxygen uptake) (before the break point: r = 0.481, P = 0.0075; R = 0.784, P < 0.0001, after the break point).
  
  
  CONCLUSIONS
  In patients with IPF, exercise-induced acidosis and increases in circulating NE levels were associated with intensity of exertional dyspnoea.
authors.affiliation: Department of Internal Medicine, National Hospital Organization Toneyama National Hospital, Toyonaka, Osaka, Japan. mikisuke@toneyama.go.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Miki
authors.forename: Ryoji
authors.initials: R
authors.lastname: Maekura
authors.forename: Toru
authors.initials: T
authors.lastname: Hiraga
authors.forename: Hisako
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Seigo
authors.initials: S
authors.lastname: Kitada
authors.forename: Mari
authors.initials: M
authors.lastname: Miki
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tateishi
authors.forename: Kenji
authors.initials: K
authors.lastname: Fushitani
authors.forename: Masaharu
authors.initials: M
authors.lastname: Motone
mesh_terms: D000138:Acidosis / Q000097:blood*; D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D016022:Case-Control Studies; D004417:Dyspnea / Q000097:blood* / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D054990:Idiopathic Pulmonary Fibrosis / Q000097:blood* / Q000503:physiopathology*; D007773:Lactates / Q000097:blood; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood*; D012129:Respiratory Function Tests
chemical_list: D007773:Lactates; D009638:Norepinephrine