title: Peripheral endothelial dysfunction is associated with gas exchange inefficiency in smokers.
abstract: OBJECTIVE
  To assess the cross-sectional association between exercise capacity, gas exchange efficiency and endothelial function, as measured by flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) of the brachial artery, in a large-scale population-based survey.
  
  
  METHODS
  The study population was comprised of 1416 volunteers 25 to 85 years old. Oxygen uptake at anaerobic threshold (VO2@AT), peak exercise (peakVO2) and ventilatory efficiency (VE vs. VCO2 slope and VE/VCO2@AT) were assessed on a breath-by-breath basis during incremental symptom-limited cardiopulmonary exercise. FMD and NMD measurements at rest were performed using standardised ultrasound techniques.
  
  
  RESULTS
  Multivariable logistic regression analyses revealed a significant association between FMD and ventilatory efficiency in current smokers but not in ex-smokers or non-smokers. There was no association between FMD and VO2@AT or peak VO2. In current smokers, for each one millimetre decrement in FMD, VE/VCO2@AT improved by -3.6 (95% CI -6.8, -0.4) in the overall population [VE vs. VCO2 slope -3.9 (-7.1, -0.6)]. These results remained robust after adjusting for all major influencing factors. Neither exercise capacity nor ventilatory efficiency was significantly associated with NMD.
  
  
  CONCLUSIONS
  In current smokers, FMD is significantly associated with ventilatory efficiency. This result may be interpreted as a potential clinical link between smoking and early pulmonary vasculopathy due to smoking.
authors.affiliation: Medical Faculty of the Ernst-Moritz-Arndt University, Department of Internal Medicine B-Cardiology, Intensive Care, Pulmonary Medicine and Infectious Diseases, Friedrich-Loeffler-Str, 23, D-17475 Greifswald, Germany. glaeser.sven@gmail.com
authors.forename: Sven
authors.initials: S
authors.lastname: Gläser
authors.forename: Anne
authors.initials: A
authors.lastname: Obst
authors.forename: Christian F
authors.initials: CF
authors.lastname: Opitz
authors.forename: Marcus
authors.initials: M
authors.lastname: Dörr
authors.forename: Stephan B
authors.initials: SB
authors.lastname: Felix
authors.forename: Klaus
authors.initials: K
authors.lastname: Empen
authors.forename: Henry
authors.initials: H
authors.lastname: Völzke
authors.forename: Ralf
authors.initials: R
authors.lastname: Ewert
authors.forename: Christoph
authors.initials: C
authors.lastname: Schäper
authors.forename: Beate
authors.initials: B
authors.lastname: Koch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005858:Germany; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin; D010101:Oxygen Consumption; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D014463:Ultrasonography; D014664:Vasodilation; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin