title: Influence of smoking and obesity on alveolar-arterial gas pressure differences and dead space ventilation at rest and peak exercise in healthy men and women.
abstract: OBJECTIVE
  Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations.
  
  
  RESULTS
  Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given.
  
  
  CONCLUSIONS
  Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study.
authors.affiliation: Department of Internal Medicine B-Cardiology, Intensive Care, Pulmonary Medicine and Infectious Diseases, University of Greifswald, Greifswald, Germany. sven.glaeser@uni-greifswald.de
authors.forename: Sven
authors.initials: S
authors.lastname: Gläser
authors.forename: Till
authors.initials: T
authors.lastname: Ittermann
authors.forename: Beate
authors.initials: B
authors.lastname: Koch
authors.forename: Christoph
authors.initials: C
authors.lastname: Schäper
authors.forename: Stephan B
authors.initials: SB
authors.lastname: Felix
authors.forename: Henry
authors.initials: H
authors.lastname: Völzke
authors.forename: Raik
authors.initials: R
authors.lastname: Könemann
authors.forename: Ralf
authors.initials: R
authors.lastname: Ewert
authors.forename: James E
authors.initials: JE
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012126:Respiratory Dead Space / Q000502:physiology*; D012907:Smoking / Q000097:blood / Q000503:physiopathology*; D013990:Tidal Volume / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen