Document Detail

Association of chest wall motion and tidal volume responses during CO2 rebreathing.
MedLine Citation:
PMID:  8904564     Owner:  NLM     Status:  MEDLINE    
The purpose of this study is to investigate the effect of chest wall configuration at end expiration on tidal volume (VT) response during CO2 rebreathing. In a group of 11 healthy male subjects, the changes in end-expiratory and end-inspiratory volume of the rib cage (delta Vrc,E and delta Vrc,I, respectively) and abdomen (delta Vab,E and delta Vab,I, respectively) measured by linearized magnetometers were expressed as a function of end-tidal PCO2 (PETCO2. The changes in end-expiratory and end-inspiratory volumes of the chest wall (delta Vcw,E and delta Vcw,I, respectively) were calculated as the sum of the respective rib cage and abdominal volumes. The magnetometer coils were placed at the level of the nipples and 1-2 cm above the umbilicus and calibrated during quiet breathing against the VT measured from a pneumotachograph. The delta Vrc,E/delta PETCO2 slope was quite variable among subjects. It was significantly positive (P < 0.05) in five subjects, significantly negative in four subjects (P < 0.05), and not different from zero in the remaining two subjects. The delta Vab,E/delta PETCO2 slope was significantly negative in all subjects (P < 0.05) with a much smaller intersubject variation, probably suggesting a relatively more uniform recruitment of abdominal expiratory muscles and a variable recruitment of rib cage muscles during CO2 rebreathing in different subjects. As a group, the mean delta Vrc,E/delta PETCO2, delta Vab,E/delta PETCO2, and delta Vcw,E/delta PETCO2, slopes were 0.010 +/- 0.034, -0.030 +/- 0.007, and -0.020 +/- 0.032 1/Torr, respectively; only the delta Vab,E/delta PETCO2, slope was significantly different from zero. More interestingly, the individual delta VT/delta PETCO2 slope was negatively associated with the delta Vcr,E/delta PETCO2 (r = 0.68, P = 0.021) and delta Vcw,E/delta PETCO2 slopes (r = 0.63, P = 0.037) but was not associated with the delta Vab,E/delta PETCO2 slope (r = 0.40, P = 0.223). There was no correlation of the delta Vrc,E/delta PETCO2 and delta Vcw,E/delta PETCO2 slopes with age, body size, forced expiratory volume in 1 s, or expiratory time. The group delta Vab,I/delta PETCO2 slope (0.004 +/- 0.014 1/Torr) was not significantly different from zero despite the VT nearly being tripled at the end of CO2 rebreathing. In conclusion, the individual VT response to CO2, although independent of delta Vab,E, is a function of delta Vrc,E to the extent that as the delta Vrc,E/delta PETCO2 slope increases (more positive) among subjects, the VT response to CO2 decreases. These results may be explained on the basis of the respiratory muscle actions and interactions on the rib cage.
S Yan; P Sliwinski; P T Macklem
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  81     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 Oct 
Date Detail:
Created Date:  1997-02-19     Completed Date:  1997-02-19     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:  1528-34     Citation Subset:  IM; S    
Montreal Chest Institute Research Centre, McGill University, Montreal, Quebec, Canada.
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MeSH Terms
Abdominal Muscles / physiology
Carbon Dioxide / metabolism*
Forced Expiratory Volume / physiology
Middle Aged
Respiratory Function Tests
Respiratory Mechanics / physiology*
Respiratory Muscles / physiology
Thorax / physiology*
Tidal Volume / physiology*
Vital Capacity / physiology
Reg. No./Substance:
124-38-9/Carbon Dioxide

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