title: Reduced confounding by impaired ventilatory function with oxygen uptake efficiency slope and VE/VCO2 slope rather than peak oxygen consumption to assess exercise physiology in suspected heart failure.
abstract: Heart failure and ventilatory disease often coexist; both create abnormalities in cardiopulmonary exercise test measurements. The authors evaluated the relative dependency of a well-recognized index of heart failure, peak oxygen consumption (VO(2)), and 2 newer indices, the minute ventilation (VE)/carbon dioxide production (VCO(2)) slope and oxygen uptake efficiency slope (OUES), on standard markers of impaired cardiac and ventilatory function. One hundred twenty-four patients (median age, 65.8; range, 22.6-84.9), with functional limitation from clinical heart failure were exercised. Peak VO(2) was 17.14 ± 7.58 mL/kg/min, VE/VCO(2) slope 50.1 ± 20.1, OUES 1.46 ± 0.68 L/min, and forced expiratory volume in 1 second (FEV(1) ) 1.88 ± 0.75 L. Peak VO(2) is substantially more sensitive to FEV(1) than ejection fraction (4.0 mL/kg/min difference between above- and below-median FEV(1) and 1.5 mL/kg/min between above- and below-median ejection fraction). OUES does not share this peculiar excess sensitivity to FEV(1) (0.12 L/min difference between above- and below-median FEV(1) and 0.01 L/min between above- and below-median ejection fraction). VE/VCO(2) slope has a borderline effect by FEV(1) (7.07 difference between above- and below-median FEV(1) and 2.07 between above- and below-median ejection fraction). Although widely used as a marker of heart failure severity, peak VO(2) is very sensitive to spirometry status and is indeed more affected by FEV(1) than by ejection fraction. OUES in contrast does not show this preferential sensitivity to impaired FEV(1).
authors.affiliation: International Centre for Circulatory Health, Imperial College London and Imperial College NHS Trust, London, UK. anthonybarron@hotmail.co.uk
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Barron
authors.forename: Katharine I
authors.initials: KI
authors.lastname: Medlow
authors.forename: Alberto
authors.initials: A
authors.lastname: Giannoni
authors.forename: Beth
authors.initials: B
authors.lastname: Unsworth
authors.forename: Andrew J S
authors.initials: AJ
authors.lastname: Coats
authors.forename: Jamil
authors.initials: J
authors.lastname: Mayet
authors.forename: Luke S
authors.initials: LS
authors.lastname: Howard
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000378:metabolism; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume; D006333:Heart Failure / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000503:physiopathology*; D012189:Retrospective Studies; D013147:Spirometry; D013223:Statistics as Topic; D013318:Stroke Volume; D014463:Ultrasonography; D016277:Ventricular Function, Left; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide