| Optimal expiratory volume profile in tidal liquid ventilation under steady state conditions, based on a symmetrical lung model. | |
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MedLine Citation:
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PMID: 19092655 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Liquid-assisted ventilation (LAV) using perfluorochemicals (PFC) offers clear theoretical advantages over gas ventilation. During tidal liquid ventilation (TLV) the residual capacity of the lungs is filled with PFC and a liquid ventilator is necessary to inhale and exhale the tidal volume of PFC. However, during the expiration phase, a flow limitation (choked flow) can be observed, which compromises minute ventilation and consequently the gas exchange. The hypothesis of the presented works is that the choked flow can be avoided by profiling the expiratory volume. To validate this concept, an elastic symmetrical lung numerical model, used to characterize forced expiration in gas ventilation, was transposed to TLV. The parameters of the developed numerical model were fitted from experimental data obtained on a newborn lamb. The results obtained demonstrate that general observations made with gas ventilation still hold, however, in TLV: flow limitation in the central airways is the result of a coupling between viscous pressure losses and airway compliance, and the flow limiting segment is located in the central airways. Using the model results, an optimal theoretical expiratory profile seems to be exponential as first approximation, and its time constant is dependent on the chocked flow mechanism and not on the product of resistance by compliance. This optimal profile is used to compute the maximal minute ventilation allowable with an acceptable risk of collapse. Also, the sensitivity of minute ventilation to different parameter variations were analyzed and practical recommendations are proposed. |
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Authors:
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Raymond Robert; Philippe Micheau; Hervé Walti |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: ASAIO journal (American Society for Artificial Internal Organs : 1992) Volume: 55 ISSN: 1538-943X ISO Abbreviation: ASAIO J. Publication Date: 2009 Jan-Feb |
Date Detail:
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Created Date: 2009-01-13 Completed Date: 2009-03-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9204109 Medline TA: ASAIO J Country: United States |
Other Details:
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Languages: eng Pagination: 63-72 Citation Subset: IM |
Affiliation:
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Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, Quebec, Canada. raymond.robert@usherbrooke.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Humans Infant Liquid Ventilation* Lung / physiology* Models, Biological* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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