Document Detail

Pulmonary impedance and alveolar instability during injurious ventilation in rats.
MedLine Citation:
PMID:  15831795     Owner:  NLM     Status:  MEDLINE    
The mechanical derangements in the acutely injured lung have long been ascribed, in large part, to altered mechanical function at the alveolar level. This has not been directly demonstrated, however, so we investigated the issue in a rat model of overinflation injury. After thoracotomy, rats were mechanically ventilated with either 1) high tidal volume (Vt) or 2) low Vt with periodic deep inflations (DIs). Forced oscillations were used to measure pulmonary impedance every minute, from which elastance (H) and hysteresivity (eta) were derived. Subpleural alveoli were imaged every 15 min using in vivo video microscopy. Cross-sectional areas of individual alveoli were measured at peak inspiration and end exhalation, and the percent change was used as an index of alveolar instability (%I-EDelta). Low Vt never led to an increase in %I-EDelta but did result in progressive atelectasis that coincided with an increase in H but not eta. DI reversed atelectasis due to low Vt, returning H to baseline. %I-EDelta, H, and eta all began to rise by 30 min of high Vt and were not reduced by DI. We conclude that simultaneous increases in both H and eta are reflective of lung injury in the form of alveolar instability, whereas an isolated and reversible increase in H during low Vt reflects merely derecruitment of alveoli.
Gilman B Allen; Lucio A Pavone; Joseph D DiRocco; Jason H T Bates; Gary F Nieman
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2005-04-14
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  99     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-15     Completed Date:  2005-09-30     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:  723-30     Citation Subset:  IM    
Department of Medicine, Vermont Lung Center, 149 Beaumont Avenue, Burlington, VT 05405-0075, USA.
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MeSH Terms
Plethysmography, Impedance
Pulmonary Alveoli / injuries*,  pathology,  physiopathology*
Rats, Sprague-Dawley
Respiration, Artificial / adverse effects*
Respiratory Distress Syndrome, Adult / etiology*,  pathology,  physiopathology*
Tidal Volume*
Grant Support

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

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