Document Detail

Causes of breathing inefficiency during exercise in heart failure.
MedLine Citation:
PMID:  20932466     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Patients with heart failure (HF) develop abnormal pulmonary gas exchange; specifically, they have abnormal ventilation relative to metabolic demand (ventilatory efficiency/minute ventilation in relation to carbon dioxide production [V(E)/VCO₂]) during exercise. The purpose of this investigation was to examine the factors that underlie the abnormal breathing efficiency in this population.
METHODS AND RESULTS: Fourteen controls and 33 moderate-severe HF patients, ages 52 ± 12 and 54 ± 8 years, respectively, performed submaximal exercise (∼65% of maximum) on a cycle ergometer. Gas exchange and blood gas measurements were made at rest and during exercise. Submaximal exercise data were used to quantify the influence of hyperventilation (PaCO₂) and dead space ventilation (V(D)) on V(E)/VCO₂. The V(E)/VCO₂ relationship was lower in controls (30 ± 4) than HF (45 ± 9, P < .01). This was the result of hyperventilation (lower PaCO₂) and higher V(D)/V(T) that contributed 40% and 47%, respectively, to the increased V(E)/VCO₂ (P < .01). The elevated V(D)/V(T) in the HF patients was the result of a tachypneic breathing pattern (lower V(T), 1086 ± 366 versus 2003 ± 504 mL, P < .01) in the presence of a normal V(D) (11.5 ± 4.0 versus 11.9 ± 5.7 L/min, P = .095).
CONCLUSIONS: The abnormal ventilation in relation to metabolic demand in HF patients during exercise was due primarily to alterations in breathing pattern (reduced V(T)) and excessive hyperventilation.
Paul R Woods; Thomas P Olson; Robert P Frantz; Bruce D Johnson
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-06-16
Journal Detail:
Title:  Journal of cardiac failure     Volume:  16     ISSN:  1532-8414     ISO Abbreviation:  J. Card. Fail.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-11     Completed Date:  2011-02-15     Revised Date:  2014-09-18    
Medline Journal Info:
Nlm Unique ID:  9442138     Medline TA:  J Card Fail     Country:  United States    
Other Details:
Languages:  eng     Pagination:  835-42     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier Inc. All rights reserved.
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MeSH Terms
Carbon Dioxide / metabolism
Data Interpretation, Statistical
Exercise Test
Exercise Tolerance
Heart Failure* / blood,  complications,  physiopathology
Hyperventilation* / blood,  diagnosis,  etiology
Middle Aged
Oxygen / metabolism
Oxygen Consumption / physiology
Respiratory Function Tests / methods*
Respiratory Insufficiency / blood,  complications,  diagnosis
Respiratory Rate / physiology
Severity of Illness Index
Statistics as Topic
Grant Support
Reg. No./Substance:
142M471B3J/Carbon Dioxide; S88TT14065/Oxygen

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