title: [Thoracic fluid content - a possible determinant of ventilatory efficiency in patients with heart failure].
abstract: Ventilatory efficiency, evaluated by cardiopulmonary exercise testing (CPET), has considerable prognostic value in patients with chronic heart failure (CHF) due to left ventricular systolic dysfunction (LVSD). Its determinants nevertheless remain controversial.
  
  
  OBJECTIVE
  To investigate the possible correlation between parameters of ventilatory efficiency obtained by CPET and thoracic fluid content (TFC), assessed by thoracic electrical bioimpedance (TEB), in patients with CHF due to LVSD.
  
  
  METHODS
  We studied 120 patients with LVSD and CHF, referred to our laboratory for CPET: 76% male, age 52.1 ± 12.1 years, 37% of ischemic etiology, left ventricular ejection fraction 27.6 ± 7.9%, 83% in sinus rhythm, 96% receiving ACEIs and/or ARBs and 79% beta-blockers, and 20% treated with a cardiac resynchronization device. TEB studies were performed after 15 minutes of rest, prior to symptom-limited treadmill CPET, using the modified Bruce protocol. CPET-derived peak oxygen consumption (pVO(2)), the slope of the relationship between minute ventilation (VE) and carbon dioxide production (VCO(2)), VE/VCO(2) at the anaerobic threshold (AT), and TFC assessed by TEB were considered for analysis.
  
  
  RESULTS
  TFC ranged between 20.6 and 45.8kOhm-1, mean 32.2, SD=5.7, median 32.7, pVO(2) 8.9-40.6 ml/kg/min, mean 21.0, SD 6.2, median 20.2, VE/VCO(2) slope 19.8-60.7, mean 30.7, SD 7.9, median 29.1 and VE/VCO(2) at AT 21-62, mean 33.1, SD 7.5, median 31.5. By linear regression, TFC did not correlate with pVO(2) (r=0.05, p=0.58), but showed correlation with parameters of ventilatory efficiency: r=0.20, p=0.032, r(2)=0.04 for VE/VCO(2) slope and r=0.25, p=0.009, r(2)=0.06 for VE/VCO(2) at AT.
  
  
  CONCLUSIONS
  TFC correlates with CPET parameters of ventilatory efficiency in patients with CHF due to LVSD, suggesting that it may be one of its determinants.
authors.affiliation: Serviço de Cardiologia, Centro Hospitalar de Lisboa Central, Lisboa, Portugal. bvalente@lycos.com
authors.forename: Bruno
authors.initials: B
authors.lastname: Tereno Valente
authors.forename: Joana
authors.initials: J
authors.lastname: Feliciano
authors.forename: Rui
authors.initials: R
authors.lastname: Soares
authors.forename: Alexandra
authors.initials: A
authors.lastname: Toste
authors.forename: Filipa
authors.initials: F
authors.lastname: Ferreira
authors.forename: Hamad
authors.initials: H
authors.lastname: Hamad
authors.forename: Ninel
authors.initials: N
authors.lastname: Santos
authors.forename: Sofia
authors.initials: S
authors.lastname: Silva
authors.forename: Ana
authors.initials: A
authors.lastname: Abreu
authors.forename: Rui
authors.initials: R
authors.lastname: Ferreira
mesh_terms: D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010490:Pericardial Effusion / Q000209:etiology*; D010996:Pleural Effusion / Q000209:etiology*; D012123:Pulmonary Ventilation