Document Detail


Inspiratory muscle relaxation rate slows during exhaustive treadmill walking in patients with chronic heart failure.
MedLine Citation:
PMID:  11371408     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Exercise intolerance is a feature of chronic heart failure (CHF). We hypothesized that excessive loading of the respiratory muscle pump might contribute to exertional breathlessness. One marker of excessive muscle-loading is slowing of maximum relaxation rate (MRR) and, therefore, to test our hypothesis, we investigated the effect of exhaustive treadmill walking on inspiratory muscle MRR in patients with CHF. We studied eight stable patients with mild-moderate CHF walking on a treadmill until termination because of severe dyspnea. Inspiratory muscle MRR was determined from esophageal pressure (Pes) change during submaximal sniffs (Sn) before and immediately after exercise to a mean (SD) minute ventilation of 77 () L/min. For comparison, nine healthy subjects performed a similar protocol; exercise was terminated either by severe dyspnea or when minute ventilation reached 100 L/min. There were no significant differences in terms of heart rate, respiratory rate, tidal volume, or inspiratory duty cycle at cessation of exercise. The mean slowing of Sn Pes MRR in the first minute after termination of exercise in the CHF group was 22.4% and in the normal control group it was 2.8% (p < 0.01). Our data show that slowing of inspiratory muscle relaxation rate occurs in patients with CHF walking to severe breathlessness. We conclude that severe loading of the inspiratory muscles is a feature of exertional dyspnea in CHF.
Authors:
P D Hughes; N Hart; C H Hamnegård; M Green; A J Coats; J Moxham; M I Polkey
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  163     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2001 May 
Date Detail:
Created Date:  2001-05-23     Completed Date:  2001-06-28     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1400-3     Citation Subset:  AIM; IM    
Affiliation:
Respiratory Muscle Laboratory, Royal Brompton Hospital, Fulham Rd., London SW3 6NP, United Kingdom.
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MeSH Terms
Descriptor/Qualifier:
Adult
Case-Control Studies
Chronic Disease
Dyspnea / etiology*
Exercise Test*
Forced Expiratory Volume
Heart Failure / complications,  diagnosis,  physiopathology*
Heart Rate
Humans
Inspiratory Capacity*
Middle Aged
Muscle Relaxation*
Respiratory Muscles / physiopathology*
Spirometry
Tidal Volume
Time Factors
Walking*

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


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