Document Detail

Control of expiratory time in conscious humans.
MedLine Citation:
PMID:  7649930     Owner:  NLM     Status:  MEDLINE    
Combinations of 17 normal awake humans breathed mildly hyperoxic and hypercapnic gas mixtures via a pneumotachograph into an open circuit. Respiratory pattern was measured for each breath in real time by computer. Use of computer-controlled auditory feedback at a constant end-tidal PCO2 (PETCO2) allowed prolonged changes of 1) inspiratory time (TI) at constant inspired tidal volume (VTI), 2) VTI up and down in repeated steps at constant TI, and 3) expiratory time (TE) at constant VTI. The remaining variables were free to be determined by the subjects' automatic respiratory control mechanisms. We showed that TE changed in parallel with the change in TI despite constant VTI, TE did not change in response to step changes in VTI at constant TI, and large changes in TE had no influence on the subsequent TI, but VTI increased slightly as TE lengthened despite clamping. Time for expiratory flow (TE--end-expiratory pause) changed in parallel with TE in all protocols. Thus, in conscious humans, inspiratory timing has a direct influence on expiratory timing, independent of volume change and chemical drive, but expiratory timing has no influence on the inspiratory timing of the subsequent breath but has a small influence on volume.
G F Rafferty; J Evans; W N Gardner
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:  78     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1995 May 
Date Detail:
Created Date:  1995-09-27     Completed Date:  1995-09-27     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:  1910-20     Citation Subset:  IM    
Department of Physiology, King's College London, United Kingdom.
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MeSH Terms
Carbon Dioxide / blood,  pharmacology
Feedback / physiology
Oxygen / pharmacology
Oxygen Consumption / physiology
Respiratory Mechanics / physiology*
Stimulation, Chemical
Tidal Volume / physiology
Time Factors
Grant Support
//Wellcome Trust
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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