title: Dynamic hyperinflation, arterial blood oxygen, and airway oxidative stress in stable patients with COPD.
abstract: BACKGROUND
  There is considerable evidence that oxidative stress is increased in patients with COPD, although little information is available about its relationship with the structural and functional alterations produced by COPD. In this study, we evaluated the relationship between 8-isoprostane in exhaled breath condensate (EBC) of stable patients with COPD and the main parameters of the disease (such as dyspnea), stages of severity, lung parenchyma densities, lung function impairment, and exercise tolerance in order to identify the predictors of airway oxidative stress.
  
  
  METHODS
  In a cross-sectional study, we included 76 men with moderate to very severe COPD. 8-Isoprostane levels in EBC were measured by enzyme immunoassay. Regional lung densities were measured by lung densitometry with high-resolution CT scanning. Arterial blood gas levels, lung volumes, and diffusing capacity were determined. Patients performed a 6-min walk test and an incremental exercise test with measurement of breathing pattern and operating lung volumes.
  
  
  RESULTS
  Significant severity-related differences in 8-isoprostane were identified according to the BMI, obstruction, dyspnea, and exercise (BODE) index. 8-Isoprostane levels were related to smoking intensity, lung densities in expiration, static lung volumes, PaO(2), diffusion capacity, distance walked in 6 min, peak oxygen uptake, and anaerobic threshold. Concentration of 8-isoprostane was higher in the 60 patients (79%) who developed dynamic hyperinflation than in the remaining 16 (21%) who did not. In a multivariate linear regression analysis using 8-isoprostane as a dependent variable, end-expiratory lung volume change and PaO(2) were retained in the prediction model (r(2) = 0.734, P < .001).
  
  
  CONCLUSIONS
  In stable patients with COPD, oxygen level and dynamic hyperinflation are related to airway oxidative stress.
authors: Servicio de Neumología, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain. Electronic address: fgr01m@gmail.com.
authors: Francisco
authors: F
authors: García-Rio
authors: Servicio de Neumología, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: David
authors: D
authors: Romero
authors: Sección de Neumología, Hospital Infanta Leonor, Madrid, Spain.
authors: Vanesa
authors: V
authors: Lores
authors: Servicio de Neumología, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: Raquel
authors: R
authors: Casitas
authors: Servicio de Bioquímica, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: Angel
authors: A
authors: Hernanz
authors: Servicio de Neumología, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: Raul
authors: R
authors: Galera
authors: Servicio de Neumología, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: Rodolfo
authors: R
authors: Alvarez-Sala
authors: Servicio de Radiodiagnóstico, Hospital Universitario La Paz, IdiPAZ, Madrid, Spain.
authors: Isabel
authors: I
authors: Torres
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D015237:Dinoprost / Q000031:analogs & derivatives / Q000378:metabolism; D004417:Dyspnea / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D017079:Exercise Tolerance / Q000502:physiology; D045853:Exhalation / Q000502:physiology; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000503:physiopathology*; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed
chemical_list: C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost; D010100:Oxygen