title: Better parameters of ventilation-CO₂output relationship predict death in CHF patients.
abstract: OBJECTIVE
  Measures of ventilation-CO₂output relationship have been shown to be more prognostic than peak O₂uptake in assessing life expectancy in patients with chronic heart failure (CHF). Because both the ratios (VE/Vco₂) and slopes (VE-vs-Vco₂) of ventilation-co₂ output of differing durations can be used, we aim to ascertain which measurements best predicted CHF life expectancy.
  
  
  METHODS
  Two hundred and seventy-one CHF patients with NYHA class II-IV underwent incremental cardiopulmonary exercise testing (CPET) and were followed-up for a median duration of 479 days. Four different linear regression VE-vs- Vco₂ slopes were calculated from warm-up exercise onset to: 180 s, anaerobic threshold (AT), ventilatory compensation point (VCP); and peak exercise. Five VE/Vco₂ ratios were calculated for the following durations: rest (120 s), warm-up (30 s), AT (60 s), lowest value (90 s), and peak exercise (30 s). Death or heart transplant were considered end-points. Multiple statistical analyses were performed.
  
  
  RESULTS
  CHF patients had high lowest VE/Vco₂ (41.0 ± 9.2, 141 ± 30%pred), high VE/Vco₂ at AT (42.5 ± 10.4, 145 ± 35%pred), and high VE-vs-Vco₂ slope to VCP (37.6 ± 12.1, 126 ± 41%pred). The best predictor of death was a higher lowest VE/Vco₂ (≥ 42, ≥ 141%pred), whereas the VE-vs-Vco₂slope to VCP was less variable than other slopes. For death prognosis in 6 months, %pred values were superior: for longer times, absolute values were superior.
  
  
  CONCLUSIONS
  The increased lowest VE/Vco₂ ratio easily identifiable and simply measured during exercise, is the best measurement to assess the ventilation-co₂output relationship in prognosticating death in CHF patients.
authors.forename: You-xiu
authors.initials: YX
authors.lastname: Yao
authors.forename: Xing-guo
authors.initials: XG
authors.lastname: Sun
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zheng
authors.forename: Gui-zhi
authors.initials: GZ
authors.lastname: Wang
authors.forename: James E
authors.initials: JE
authors.lastname: Hansen
authors.forename: William W
authors.initials: WW
authors.lastname: Stringer
authors.forename: Karlman
authors.initials: K
authors.lastname: Wasserman
authors.forename: Sheng-shou
authors.initials: SS
authors.lastname: Hu
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D002908:Chronic Disease; D018450:Disease Progression; D005080:Exercise Test; D006333:Heart Failure / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D006801:Humans; D008017:Life Expectancy; D012129:Respiratory Function Tests
chemical_list: D002245:Carbon Dioxide