title: Ventilation distribution and small airway function in patients with systemic sclerosis.
abstract: BACKGROUND
  Despite the importance of traditional pulmonary function tests (PFTs) in managing systemic sclerosis (SSc), many patients with pulmonary disease diagnosed by computed tomography (CT) present with normal PFTs.
  
  
  OBJECTIVE
  To evaluate the efficacy of the nitrogen single-breath washout (N2SBW) test in diagnosing SSc and to correlate N2SBW parameters with the PFT indexes used in the follow-up of these patients, clinical data, and CT findings.
  
  
  METHODS
  Cross-sectional study in which 52 consecutive SSc patients were subjected to spirometry, body plethysmography, analysis of the diffusing capacity for carbon monoxide (DLCO), analysis of respiratory muscle strength, N2SBW testing, and CT analysis.
  
  
  RESULTS
  Twenty-eight patients had a forced vital capacity (FVC) that was <70% of the predicted value. In the N2SBW test, 44 patients had a phase III slope (Phase III slopeN2SBW) that was >120% of the predicted value, while 15 patients had a closing volume/vital capacity (CV/VC) that was >120% of the predicted value. A significant difference in Phase III slopeN2SBWwas observed when the patients with predominant traction bronchiectasis and honeycombing were compared to the patients with other CT patterns (p<0.0001). The Phase III slopeN2SBWwas correlated with FVC (rs=-0.845, p<0.0001) and DLCO (rs=-0.600, p<0.0001), and the CV/VC was correlated with FVC (rs=-0.460, p=0.0006) and residual volume/total lung capacity (rs=0.328, p=0.017).
  
  
  CONCLUSIONS
  Ventilation heterogeneity is a frequent finding in SSc patients that is associated with restrictive damage, changes in pulmonary diffusion, and CT patterns. In addition, approximately one-third of the patients presented with findings that were compatible with small airway disease.
authors.affiliation: Laboratory of Respiratory Physiology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: B R A
authors.initials: BRA
authors.lastname: Silva
authors.affiliation: Department of Pulmonology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Rufino
authors.affiliation: Department of Pulmonology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: C H
authors.initials: CH
authors.lastname: Costa
authors.affiliation: Department of Rheumatology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: V S
authors.initials: VS
authors.lastname: Vilela
authors.affiliation: Department of Rheumatology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: R A
authors.initials: RA
authors.lastname: Levy
authors.affiliation: Laboratory of Respiratory Physiology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: phel.lop@uol.com.br.
authors.forename: A J
authors.initials: AJ
authors.lastname: Lopes
mesh_terms: D000328:Adult; D001944:Breath Tests; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012119:Respiration; D012129:Respiratory Function Tests; D012595:Scleroderma, Systemic / Q000503:physiopathology*
keywords: Nitrogen single-breath washout test; Respiratory function tests; Systemic sclerosis