title: Abnormal end-tidal PO(2) and PCO(2) at the anaerobic threshold correlate well with impaired exercise gas exchange in patients with left ventricular dysfunction.
abstract: BACKGROUND
  The aim of the present study was to compare the end-tidal O(2) pressure (PETO(2)) to end-tidal CO(2) pressure (PETCO(2)) in cardiac patients during rest and during 2 states of exercise: at anaerobic threshold (AT) and at peak. The purpose was to see which metabolic state, PETO(2) or PETCO(2), best correlated with exercise limitation.
  
  
  RESULTS
  Thirty-eight patients with left ventricular (LV) ejection fraction <40% underwent cardiopulmonary exercise testing (CPX). PETO(2) and PETCO(2) were measured during CPX, along with peak O(2) uptake (VO(2)), AT, slope of the increase in ventilation (VE) relative to the increase in CO(2) output (VCO(2)) (VE vs. VCO(2) slope), and the ratio of the increase in VO(2) to the increase in work rate (ΔVO(2)/ΔWR). Both PETO(2) and PETCO(2) measured at AT were best correlated with peakVO(2), AT, ΔVO(2)/ΔWR and VE vs. VCO(2) slope. PETO(2) at AT correlated with reduced peak VO(2) (r=-0.60), reduced AT (r=-0.52), reduced ΔVO(2)/ΔWR (r=-0.55) and increased VE vs. VCO(2) slope (r=0.74). PETCO(2) at AT correlated with reduced peak VO(2) (r=0.67), reduced AT (r=0.61), reduced ΔVO(2)/ΔWR (r=0.58) and increased VE vs. VCO(2) slope (r=-0.80).
  
  
  CONCLUSIONS
  PETCO(2) and PETO(2) at AT correlated with peak VO(2), AT and ΔVO(2)/ΔWR, but best correlated with increased VE vs. VCO(2) slope. PETO(2) and PETCO(2) at AT can be used as a prime index of impaired cardiopulmonary function during exercise in patients with LV failure.
authors.affiliation: Cardiovascular Institute, Tokyo, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kano
authors.forename: Akira
authors.initials: A
authors.lastname: Koike
authors.forename: Masayo
authors.initials: M
authors.lastname: Hoshimoto-Iwamoto
authors.forename: Osamu
authors.initials: O
authors.lastname: Nagayama
authors.forename: Koji
authors.initials: K
authors.lastname: Sakurada
authors.forename: Takeya
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tsuneoka
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sawada
authors.forename: Tadanori
authors.initials: T
authors.lastname: Aizawa
authors.forename: Karlman
authors.initials: K
authors.lastname: Wasserman
mesh_terms: D000368:Aged; D015308:Anaerobic Threshold / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013318:Stroke Volume / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen