title: Volumetric capnography as a tool to detect early peripheric lung obstruction in cystic fibrosis patients.
abstract: OBJECTIVE
  To compare spirometry and volumetric capnography (VCap) to determine if the capnographic values add more information about early lung disease in cystic fibrosis (CF) patients.
  
  
  METHODS
  This was a cross-sectional study involving CF patients: Group I (42 patients, 6-12 years of age); and Group II (22 patients, 13-20 years of age). The corresponding control groups were comprised of 30 and 50 healthy subjects, respectively. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), and the FEV(1)/FVC ratio was determined by spirometry. Using VCap, we measured peripheral oxygen saturation (SpO(2)), respiratory rate (RR), inspiratory time (IT), expiratory time (ET), and the phase III slope normalized by expiratory volume (phase III slope/Ve).
  
  
  RESULTS
  In comparison with control groups, all CF patients presented higher phase III slope/Ve values (p < 0.001) independent of the pulmonary disease stage. The phase III slope/Ve was significantly higher in the 24 patients who presented normal spirometry results (p = 0.018). The Group II patients showed lower FVC, FEV(1), FEV(1)/FVC (p < 0.05), and also lower SpO(2) values (p < 0.001) when compared with Group I patients. In comparison with Control Group II, the Group II patients presented higher RR (p < 0.001), and lower IT and ET values (p < 0.001).
  
  
  CONCLUSIONS
  Compared to the controls, all studied CF patients showed an increase in phase III slope/Ve values. VCap identified the heterogeneity of the ventilation distribution in the peripheral airways of CF patients who presented normal spirometry.
authors.affiliation: Saúde da Criança e do Adolescente, Universidade Estadual de Campinas, Campinas, SP, Brazil. ribeiromago@gmail.com
authors.forename: Maria Ângela G O
authors.initials: MÂ
authors.lastname: Ribeiro
authors.forename: Marcos T N
authors.initials: MT
authors.lastname: Silva
authors.forename: José Dirceu
authors.initials: JD
authors.lastname: Ribeiro
authors.forename: Marcos M
authors.initials: MM
authors.lastname: Moreira
authors.forename: Celize C B
authors.initials: CC
authors.lastname: Almeida
authors.forename: Armando A
authors.initials: AA
authors.lastname: Almeida-Junior
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Ribeiro
authors.forename: Monica C
authors.initials: MC
authors.lastname: Pereira
authors.forename: Gabriel
authors.initials: G
authors.lastname: Hessel
authors.forename: Ilma A
authors.initials: IA
authors.lastname: Paschoal
mesh_terms: D000293:Adolescent; D019296:Capnography / Q000379:methods*; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D042241:Early Diagnosis; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008173:Lung Diseases, Obstructive / Q000175:diagnosis*; D008297:Male; D013147:Spirometry / Q000379:methods*; D013990:Tidal Volume; D055815:Young Adult