Document Detail


Respiratory control during volume-cycled ventilation in normal humans.
MedLine Citation:
PMID:  8727563     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The purpose of this study was to evaluate the extent of inhibition to respiratory rhythm associated with high volumes of ventilation during volume-cycled mechanical ventilation (neuromechanical inhibition). Two approaches were used. 1) In 18 normal awake subjects, ventilator tidal volume (VT) in the assist/control mode (A/C) was increased in steps from the minimum tolerable level up to 80% of the subject's inspiratory capacity or ventilator's maximum VT. We looked for appearance of intermittent apnea or a reduction in spontaneous rate (f). 2) Another 18 normal awake subjects were placed on controlled mechanical ventilation (CMV). When apnea was established, we abruptly terminated CMV and measured the time before the appearance of the next spontaneous effort. In the assist mode (protocol 1), we did not observe intermittent apnea because VT was increased from [from 944 +/- 198 to 1,867 +/- 277 (SD) ml], and there was only a modest reduction in f (14.1 +/- 3.9 to 12.4 +/- 4.0 breaths/min). End-tidal PCO2 (PETCO2) decreased precipitously as VT was increased. In protocol 2, we did not observe apnea after discontinuation of CMV in any subject. Total breath duration of the first breath after discontinuation did not differ significantly from total breath duration during A/C in the same subjects (4.84 +/- 2.2 vs. 5.2 +/- 2.0 s). This similarly applied regardless of route of breathing (nose vs. mouth) or PETCO2 level at time of discontinuation. We conclude that neuromechanical inhibition is quite weak and provides very little negative feedback that may help control PCO2 in the face of excessive VT and f demands of the subject.
Authors:
A Puddy; W Patrick; K Webster; M Younes
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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:  80     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 May 
Date Detail:
Created Date:  1996-12-03     Completed Date:  1996-12-03     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:  1749-58     Citation Subset:  IM    
Affiliation:
Respiratory Investigation Unit, University of Manitoba, Winnipeg, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adult
Female
Humans
Male
Pulmonary Ventilation / physiology*
Respiration / physiology*
Tidal Volume / physiology*

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


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