title: Repeated breathlessness experiences induced by hypercapnia: differential effects on intensity and unpleasantness.
abstract: BACKGROUND
  The present study investigated the effect of repeated hypercapnic challenges on the sensory (intensity [I]) and affective (unpleasantness [U]) dimensions of breathlessness.
  
  
  METHODS
  Three subsequent rebreathing trials (Read, 1968) were administered to healthy men and women (n = 39). The I and U of breathlessness were rated every 20 s during the baseline, rebreathing, and recovery phases. Breathing behavior (fractional end-tidal CO(2) [Fetco(2)] and minute ventilation [Ve]) was monitored continuously. Intraindividual linear regression slopes for Fetco(2) and Ve] were calculated and standardized, separately for both rating dimensions.
  
  
  RESULTS
  Both the absolute magnitude and the slope of the I of breathlessness were higher compared to U (p < 0.05). Across-trial habituation of the peak I and U of breathlessness occurred in both genders (p < 0.001), but habituation was larger for the U than for the I (p = 0.05).
  
  
  CONCLUSIONS
  The findings show that the sensory and affective dimensions of breathlessness can meaningfully be distinguished during hypercapnic challenges and that repeated exposures have different effects on both dimensions.
authors.affiliation: Department of Psychology, University of Leuven, Leuven, Belgium.
authors.forename: Li
authors.initials: L
authors.lastname: Wan
authors.affiliation: Department of Psychology, University of Leuven, Leuven, Belgium.
authors.forename: Ilse
authors.initials: I
authors.lastname: Van Diest
authors.affiliation: Department of Psychology, University of Leuven, Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: De Peuter
authors.affiliation: Department of Psychology, University of Leuven, Leuven, Belgium.
authors.forename: Katleen
authors.initials: K
authors.lastname: Bogaerts
authors.affiliation: Department of Psychology, University of Leuven, Leuven, Belgium. Electronic address: omer.vandenbergh@psy.kuleuven.be.
authors.forename: Omer
authors.initials: O
authors.lastname: Van den Bergh
mesh_terms: D000293:Adolescent; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D055809:Illness Behavior; D001239:Inhalation / Q000502:physiology; D008297:Male; D012016:Reference Values; D018570:Risk Assessment; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds; D012737:Sex Factors; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide