Document Detail

Metabolic gas kinetics depend upon the level of exercise performed.
MedLine Citation:
PMID:  16115799     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The kinetics of oxygen and carbon dioxide at the onset of and recovery from exercise are slowed in patients with chronic heart failure (CHF). The aim of the present study was to establish whether the kinetics of O2 are influenced by the work rate.
METHODS: Thirteen CHF patients and 12 control subjects underwent bicycle-based peak exercise testing with metabolic gas exchange analysis. Each subject then exercised at 15%, 25% and 50% of the maximal workload achieved until reaching steady state. Time constants for onset (T(onset)) and offset (T(offset)) for O2 uptake and CO2 output were correlated to the workload and the percentage of peak V(O2) performed during the steady state tests.
RESULTS: Patients had lower peak oxygen uptake (pV(O2)) and the relation between ventilation and carbon dioxide output was steeper in patients than controls. T(offset) for both oxygen (O2) and carbon dioxide (CO(2)) from peak exercise was significantly greater in the patients than the controls and correlated with peak V(O2) (r=0.56, p<0.005 and r=0.58, p<0.005). T(onset) and T(offset) for O2 were increased in patients for each of the steady state tests and peak V(O2) correlated with T for recovery of O2 (r=0.44; p<0.05 from 15%, r=0.35; p= or <0.05 from 25%, and r=0.54; p<0.01 from 50%). There was a correlation between the T(onset) (r=0.42; p<0.0005 for O2 and r=0.23; p<0.05 for CO2) and T(offset) (r=0.49; p<0.0001 for O2 and r=0.42; p<0.0005 for CO2) and oxygen uptake as a percentage of peak exercise.
CONCLUSIONS: This study demonstrates that the time constants of onset and offset for oxygen are dependent upon the degree of exertion performed relative to the individual's peak capacity.
Klaus K A Witte; Simon D R Thackray; Kenneth A Lindsay; John G F Cleland; Andrew L Clark
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2005-08-22
Journal Detail:
Title:  European journal of heart failure     Volume:  7     ISSN:  1388-9842     ISO Abbreviation:  Eur. J. Heart Fail.     Publication Date:  2005 Oct 
Date Detail:
Created Date:  2005-10-17     Completed Date:  2006-01-23     Revised Date:  2011-06-08    
Medline Journal Info:
Nlm Unique ID:  100887595     Medline TA:  Eur J Heart Fail     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  991-6     Citation Subset:  IM    
Department of Academic Cardiology, Castle Hill Hospital, Castle Road, Cottingham, Hull HU16 5JQ, United Kingdom.
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MeSH Terms
Blood Gas Analysis
Carbon Monoxide / blood,  metabolism*
Case-Control Studies
Exercise Test*
Exercise Tolerance / physiology*
Heart Failure / diagnosis*
Middle Aged
Oxygen / blood*
Oxygen Consumption / physiology
Physical Exertion / physiology
Pulmonary Gas Exchange
Reference Values
Risk Assessment
Severity of Illness Index
Reg. No./Substance:
630-08-0/Carbon Monoxide; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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