Document Detail

Influence of expiratory loading and hyperinflation on cardiac output during exercise.
MedLine Citation:
PMID:  14729724     Owner:  NLM     Status:  MEDLINE    
Patients with obstructive lung disease are exposed to expiratory loads (ELs) and dynamic hyperinflation as a consequence of expiratory flow limitation. To understand how these alterations in lung mechanics might affect cardiac function, we examined the influence of a 10-cm H2O EL, alone and in combination with voluntary hyperinflation (ELH), on pulmonary pressures [esophageal (Pes) and gastric (Pg)] and cardiac output (CO) in seven healthy subjects. CO was determined by using an acetylene method at rest and at 40 and 70% of peak work. At rest and during exercise, EL resulted in an increase in Pes and Pg (7-18 cm H2O; P < 0.05) and a decrease in CO (from 5.3 +/- 1.8 to 4.5 +/- 1.4, 12.2 +/- 2.2 to 11.2 +/- 2.2, and 16.3 +/- 3.3 to 15.2 +/- 3.2 l/min for rest, 40% peak work, and 70% peak work, respectively; P < 0.05), which remained depressed after an additional 2 min of EL. With ELH, CO increased at rest and both exercise loads (relative to EL only) but remained below control values. The changes in CO were due to a reduction in stroke volume with a tendency for stroke volume to fall further with prolonged EL. There was a negative correlation between CO and the increase in expiratory Pes and Pg with EL (R = -0.58 and -0.60; P < 0.01), whereas the rise in CO with subsequent hyperinflation was related to a more negative Pes (R = 0.72; P < 0.01). In conclusion, EL leads to a reduction in CO, which appears to be primarily related to increases in expiratory abdominal and intrathoracic pressure, whereas ELH resulted in an improved CO, suggesting that lung inflation has little impact on cardiac function.
Kristy N Stark-Leyva; Ken C Beck; Bruce D Johnson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2004-01-16
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  96     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2004 May 
Date Detail:
Created Date:  2004-04-12     Completed Date:  2004-12-14     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1920-7     Citation Subset:  IM    
Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
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MeSH Terms
Cardiac Output*
Cardiovascular Physiological Phenomena
Exercise / physiology*
Heart / physiology
Middle Aged
Pulmonary Ventilation*
Reference Values
Respiratory Mechanics
Respiratory Muscles / physiology
Work of Breathing*
Grant Support

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