Document Detail

Tracking variations in airway caliber by using total respiratory vs. airway resistance in healthy and asthmatic subjects.
MedLine Citation:
PMID:  12692146     Owner:  NLM     Status:  MEDLINE    
An index of airway caliber can be tracked in near-real time by measuring airway resistance (Raw) as indicated by lung resistance at 8 Hz. These measurements require the placing of an esophageal balloon. The objective of this study was to establish whether total respiratory system resistance (Rrs) could be used rather than Raw to track airway caliber, thereby not requiring an esophageal balloon. Rrs includes the resistance of the chest wall (Rcw). We used a recursive least squares approach to track Raw and Rrs at 8 Hz in seven healthy and seven asthmatic subjects during tidal breathing and a deep inspiration (DI). In both subject groups, Rrs was significantly higher than Raw during tidal breathing at baseline and postchallenge. However, at total lung capacity, Raw and Rrs became equivalent. Measured with this approach, Rcw appears volume dependent, having a magnitude of 0.5-1.0 cmH2O. l-1. s during tidal breathing and decreasing to zero at total lung capacity. When resistances are converted to an effective diameter, Rrs data overestimate the increase in diameter during a DI. Simulation studies suggest that the decrease in apparent Rcw during a DI is a consequence of airway opening flow underestimating chest wall flow at increased lung volume. We conclude that the volume dependence of Rcw can bias the presumed net change in airway caliber during tidal breathing and a DI but would not distort assessment of maximum airway dilation.
L D Black; R Dellaca; K Jung; H Atileh; E Israel; E P Ingenito; K R Lutchen
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.     Date:  2003-04-11
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  95     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-07-09     Completed Date:  2004-03-19     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:  511-8     Citation Subset:  IM    
Department of Biomedical Engineering, 44 Cummington St, Boston, MA 02215, USA.
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MeSH Terms
Airway Resistance*
Asthma / physiopathology*
Case-Control Studies
Computer Simulation
Least-Squares Analysis
Middle Aged
Models, Biological
Respiratory Mechanics*
Respiratory System / physiopathology*
Thorax / physiopathology
Tidal Volume
Total Lung Capacity

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

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