title: Repeatability of the evaluation of perception of dyspnea in normal subjects assessed through inspiratory resistive loads.
abstract: OBJECTIVE
  Study the repeatability of the evaluation of the perception of dyspnea using an inspiratory resistive loading system in healthy subjects.
  
  
  METHODS
  We designed a cross sectional study conducted in individuals aged 18 years and older. Perception of dyspnea was assessed using an inspiratory resistive load system. Dyspnea was assessed during ventilation at rest and at increasing resistive loads (0.6, 6.7, 15, 25, 46.7, 67, 78 and returning to 0.6 cm H2O/L/s). After breathing in at each level of resistive load for two minutes, the subject rated the dyspnea using the Borg scale. Subjects were tested twice (intervals from 2 to 7 days).
  
  
  RESULTS
  Testing included 16 Caucasian individuals (8 male and 8 female, mean age: 36 years). The median scores for dyspnea rating in the first test were 0 at resting ventilation and 0, 2, 3, 4, 5, 7, 7 and 1 point, respectively, with increasing loads. The median scores in the second test were 0 at resting and 0, 0, 2, 2, 3, 4, 4 and 0.5 points, respectively. The intra-class correlation coefficient was 0.57, 0.80, 0.74, 0.80, 0.83, 0.86, 0.91, and 0.92 for each resistive load, respectively. In a generalized linear model analysis, there was a statistically significant difference between the levels of resistive loads (p<0.001) and between tests (p=0.003). Dyspnea scores were significantly lower in the second test.
  
  
  CONCLUSIONS
  The agreement between the two tests of the perception of dyspnea was only moderate and dyspnea scores were lower in the second test. These findings suggest a learning effect or an effect that could be at least partly attributed to desensitization of dyspnea sensation in the brain.
authors.affiliation: Programa de Pós-Graduação em Ciências Pneumológicas, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil.
authors.forename: Andréia K
authors.initials: AK
authors.lastname: Fernandes
authors.affiliation: Programa de Pós-Graduação em Ciências Pneumológicas, UFRGS, Brazil.
authors.forename: Bruna
authors.initials: B
authors.lastname: Ziegler
authors.affiliation: Programa de Pós-Graduação em Ciências Pneumológicas, UFRGS, Brazil.
authors.forename: Glauco L
authors.initials: GL
authors.lastname: Konzen
authors.affiliation: Serviço de Engenharia Biomédica do Hospital de Clínicas de Porto Alegre (HCPA), Brazil.
authors.forename: Paulo R S
authors.initials: PR
authors.lastname: Sanches
authors.affiliation: Serviço de Engenharia Biomédica do Hospital de Clínicas de Porto Alegre (HCPA), Brazil.
authors.forename: André F
authors.initials: AF
authors.lastname: Müller
authors.affiliation: Faculdade de Medicina, UFRGS; Serviço de Pneumologia, HCPA, Brazil.
authors.forename: Rosemary P
authors.initials: RP
authors.lastname: Pereira
authors.affiliation: Faculdade de Medicina, UFRGS; Serviço de Pneumologia, HCPA, Brazil.
authors.forename: Paulo de Tarso R
authors.initials: Pde T
authors.lastname: Dalcin
keywords: Dyspnea; inspiratory resistive loading system; normal subjects; perception; repeatability.