Document Detail

Breathing responses to small inspiratory threshold loads in humans.
MedLine Citation:
PMID:  10066699     Owner:  NLM     Status:  MEDLINE    
To investiage the effect of inspiratory threshold load (ITL) on breathing, all previous work studied loads that were much greater than would be encountered under pathophysiological conditions. We hypothesized that mild ITL from 2.5 to 20 cmH2O is sufficient to modify control and sensation of breathing. The study was performed in healthy subjects. The results demonstrated that with mild ITL 1) inspiratory difficulty sensation could be perceived at an ITL of 2.5 cmH2O; 2) tidal volume increased without change in breathing frequency, resulting in hyperpnea; and 3) although additional time was required for inspiratory pressure to attain the threshold before inspiratory flow was initiated, the total inspiratory muscle contraction time remained constant. This resulted in shortening of the available time for inspiratory flow, so that the tidal volume was maintained or increased by significant increase in mean inspiratory flow. On the basis of computer simulation, we conclude that the mild ITL is sufficient to increase breathing sensation and alter breathing control, presumably aiming at maintaining a certain level of ventilation but minimizing the energy consumption of the inspiratory muscles.
S Yan; J H Bates
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  86     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-05-07     Completed Date:  1999-05-07     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:  874-80     Citation Subset:  IM; S    
Meakins-Christie Laboratories, Department of Biomedical Engineering, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada H2X 2P4.
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MeSH Terms
Air Pressure
Blood Volume / physiology
Computer Simulation
Linear Models
Models, Biological
Posture / physiology
Respiratory Mechanics / physiology*
Respiratory Muscles / physiology
Tidal Volume / physiology

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