Document Detail

Central airway occlusion underestimates intrinsic positive end-expiratory pressure: a numerical and physical simulation.
MedLine Citation:
PMID:  19916859     Owner:  NLM     Status:  MEDLINE    
Intrinsic positive end-expiratory pressure (PEEP) occurs when airway outflow is higher than zero at end-expiration. Differences in the time constant among alveolar units may result in an uneven distribution of intrinsic PEEP. The authors conducted a computer simulation of a 2-compartment respiratory system and calculated intrinsic PEEP for each alveolar unit and confirmed it with a test-lung experiment. Ventilator settings, including respiratory rate, inspiratory time, pause time, and external PEEP, were tested at various values in combination with various airway resistance and alveolar compliance values. The simulation was performed by calculating the flow, pressure, and volume every millisecond. The data demonstrated that the larger the difference of time constant between 2 respiratory units, the greater the difference in intrinsic PEEP between the units. A higher respiratory frequency and a larger percentage of inspiratory time resulted in an increase in the intrinsic PEEP at the central airway, as well as a wide difference in the intrinsic PEEP between airway units. These phenomena were confirmed by a 2-compartment test-lung study. The authors demonstrated and verified an uneven distribution of intrinsic PEEP in 2 different experiments, which raised a warning that some respiratory units might have much higher intrinsic PEEP than the intrinsic PEEP measured clinically.
Kiyoyasu Kurahashi; Masahide Ohtsuka; Yutaka Usuda
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Experimental lung research     Volume:  35     ISSN:  1521-0499     ISO Abbreviation:  Exp. Lung Res.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-17     Completed Date:  2010-01-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8004944     Medline TA:  Exp Lung Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  756-69     Citation Subset:  IM    
Department of Anesthesiology and Critical Care Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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MeSH Terms
Airway Obstruction / physiopathology*
Computer Simulation*
Models, Biological*
Positive-Pressure Respiration, Intrinsic / physiopathology*
Pulmonary Alveoli
Respiratory Rate
Respiratory System
Ventilators, Mechanical

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

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