Document Detail


The value of electrical impedance tomography in assessing the effect of body position and positive airway pressures on regional lung ventilation in spontaneously breathing subjects.
MedLine Citation:
PMID:  16195908     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Functional electrical impedance tomography (EIT) measures relative impedance changes in lung tissue during tidal breathing and creates images of local ventilation distribution. A novel approach to analyse the effect of body position and positive pressure ventilation on intrapulmonary tidal volume distribution was evaluated in healthy adult subjects. DESIGN AND SETTING: Prospective experimental study in healthy adult subjects in the intensive care unit at university hospital. SUBJECTS: Ten healthy male adults. INTERVENTIONS: Change in body position from supine to prone, left and right lateral during spontaneous breathing and positive pressure support ventilation. MEASUREMENTS AND RESULTS: EIT measurements and multiple-breath sulphur hexafluoride (SF6) washout were performed. Profiles of average relative impedance change in regional lung areas were calculated. Relative impedance time course analysis and Lissajous figure loop analysis were used to calculate phase angles between dependent or independent lung and total lung (phi). EIT data were compared to SF6 data washout measuring the lung clearance index (LCI). Proposed EIT profiles allowed inter-individual comparison of EIT data and identified areas with reduced regional tidal volume using pressure support ventilation. Phase angle phi of dependent lung in supine position was 11.7+/-1.4 degrees, in prone 5.3+/-0.5 degrees, in right lateral 11.0+/-1.3 degrees and in left lateral position 10.8+/-1.0 degree. LCI increased in supine position from 5.63+/-0.43 to 7.13+/-0.64 in prone position. Measured phi showed inverse relationship to LCI in the four different body positions. CONCLUSIONS: EIT profiles and phi of functional EIT are new methods to describe regional ventilation distribution with EIT allowing inter-individual comparison.
Authors:
Thomas Riedel; Tanya Richards; Andreas Schibler
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-09-30
Journal Detail:
Title:  Intensive care medicine     Volume:  31     ISSN:  0342-4642     ISO Abbreviation:  Intensive Care Med     Publication Date:  2005 Nov 
Date Detail:
Created Date:  2005-11-11     Completed Date:  2006-01-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7704851     Medline TA:  Intensive Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1522-8     Citation Subset:  IM    
Affiliation:
Queensland Paediatric Intensive Care Service, Mater Children's Hospital, Mater Misericordiae Hospitals, 41010, South Brisbane, QLD, Australia.
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MeSH Terms
Descriptor/Qualifier:
Adult
Continuous Positive Airway Pressure*
Electric Impedance*
Humans
Male
Middle Aged
Prone Position
Respiration*
Supine Position
Tidal Volume
Tomography, X-Ray Computed
Comments/Corrections
Comment In:
Intensive Care Med. 2005 Nov;31(11):1474-5   [PMID:  16195907 ]

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


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