| Effects of surfactant depletion on regional pulmonary metabolic activity during mechanical ventilation. | |
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MedLine Citation:
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PMID: 21799132 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Inflammation during mechanical ventilation is thought to depend on regional mechanical stress. This can be produced by concentration of stresses and cyclic recruitment in low-aeration dependent lung. Positron emission tomography (PET) with (18)F-fluorodeoxyglucose ((18)F-FDG) allows for non-invasive assessment of regional metabolic activity, an index of neutrophilic inflammation. We tested the hypothesis that, during mechanical ventilation, surfactant-depleted low-aeration lung regions present increased regional (18)F-FDG uptake suggestive of in vivo increased regional metabolic activity and inflammation. Sheep underwent unilateral saline lung lavage, and were ventilated supine for 4 hours (positive end-expiratory pressure=10 cmH(2)O, tidal volume adjusted to plateau pressure=30 cmH2O). We used PET scans of: injected (13)N-nitrogen to compute regional perfusion and ventilation; and injected (18)F-FDG to calculate (18)F-FDG uptake rate. Regional aeration was quantified with transmission scans. Whole-lung (18)F-FDG uptake was approximately twice higher in lavaged than in non-lavaged lungs (2.9±0.6 vs. 1.5±0.3 10(-3)/min; P<0.05). The increased (18)F-FDG uptake was topographically heterogeneous, highest in dependent low-aeration regions (gas fraction 10-50%, P<0.001), even after correction for lung density and wet-to-dry lung ratios. (18)F-FDG uptake in low-aeration regions of lavaged lungs was higher than that in low-aeration regions of non-lavaged lungs (P<0.05). This occurred despite lower perfusion and ventilation to dependent regions in lavaged than non-lavaged lungs (P<0.001). In contrast, (18)F-FDG uptake in normally-aerated regions was low and similar between lungs. Surfactant depletion produces increased and heterogeneously distributed pulmonary (18)F-FDG uptake after 4 hours of supine mechanical ventilation. Metabolic activity is highest in poorly-aerated dependent regions suggesting local increased inflammation. |
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Authors:
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Nicolas de Prost; Eduardo L Costa; Tyler Wellman; Guido Musch; Tilo Winkler; Mauro R Tucci; Robert Scott Harris; Jose G Venegas; Marcos F Vidal Melo |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-7-28 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Jul |
Date Detail:
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Created Date: 2011-7-29 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1Massachusetts General Hospital and Harvard Medical School. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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