Document Detail


Dynamics of tidal volume and ventilation heterogeneity under pressure-controlled ventilation during bronchoconstriction: a simulation study.
MedLine Citation:
PMID:  20671035     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The difference in effectiveness between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on mechanically ventilated patients during bronchoconstriction is not totally clear. PCV is thought to deliver a more uniform distribution of ventilation than VCV, but the delivered tidal volume could be unstable and affected by changes in the degree of constriction. To explore the magnitude of these effects, we ran numerical simulations with both modes of ventilation in a network model of the lung in which we incorporated not only the pressure and flow dynamics along the airways but also the effect of cycling pressures and tissue tethering forces during breathing on the dynamic equilibrium of the airway smooth muscle (ASM) (Venegas et al., Nature 434: 777-782). These simulations provided an illustration of changes in airway radii, the total delivered tidal volume stability, and distribution of ventilation following a transition from VCV to PCV and during progressively increasing ASM activation level. These simulations yielded three major results. First, the ventilation heterogeneity and patchiness in ventilation during steady-state VCV were substantially reduced after the transition to PCV. Second, airway radius, tidal volume, and the distribution of ventilation under severe bronchoconstriction were highly sensitive to the setting of inspiratory pressure selected for PCV and to the degree of activation of the ASM. Third, the dynamic equilibrium of active ASM exposed to cycling forces is the major contributor to these effects. These insights may provide a theoretical framework to guide the selection of ventilation mode, the adjustment of ventilator settings, and the interpretation of clinical observations in mechanically ventilated asthmatic patients.
Authors:
Chanikarn Wongviriyawong; Tilo Winkler; R Scott Harris; Jose G Venegas
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-07-29
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  109     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-13     Completed Date:  2011-05-23     Revised Date:  2014-09-19    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1211-8     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Asthma / pathology,  physiopathology,  therapy*
Bronchoconstriction*
Computer Simulation*
Humans
Lung / pathology,  physiopathology*
Models, Biological*
Pressure
Pulmonary Ventilation*
Respiration, Artificial / methods*
Respiratory Mechanics
Tidal Volume*
Time Factors
Grant Support
ID/Acronym/Agency:
HL-068011/HL/NHLBI NIH HHS; HL-087281/HL/NHLBI NIH HHS; R01 HL086717/HL/NHLBI NIH HHS
Comments/Corrections

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