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

Riedel, Thomas, Richards, Tanya and Schibler, Andreas (2005) 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. Intensive Care Medicine, 31 11: 1522-1528. doi:10.1007/s00134-005-2734-x


Author Riedel, Thomas
Richards, Tanya
Schibler, Andreas
Title 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
Journal name Intensive Care Medicine   Check publisher's open access policy
ISSN 0342-4642
Publication date 2005
Sub-type Article (original research)
DOI 10.1007/s00134-005-2734-x
Volume 31
Issue 11
Start page 1522
End page 1528
Total pages 7
Editor L. Brochard
Place of publication Germany
Publisher Springer-Verlag
Collection year 2005
Language eng
Subject C1
321019 Paediatrics
730204 Child health
Formatted abstract
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 ø. 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 phgr of dependent lung in supine position was 11.7±1.4°, in prone 5.3±0.5°, in right lateral 11.0±1.3° and in left lateral position 10.8±1.0°. LCI increased in supine position from 5.63±0.43 to 7.13±0.64 in prone position. Measured phgr showed inverse relationship to LCI in the four different body positions.

Conclusions EIT profiles and phgr of functional EIT are new methods to describe regional ventilation distribution with EIT allowing inter-individual comparison.
Keyword Critical Care Medicine
Body Position
Electrical Impedance Tomography
Intrapulmonary Tidal Volume Distribution
Multiple-breath Nitrogen Washout
Positive Airway Pressures
Regional Lung Ventilation
Ultrasonic Flow Meter
Tidal Volume
Mechanics
Gas
Eit
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
2006 Higher Education Research Data Collection
School of Medicine Publications
 
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Created: Wed, 15 Aug 2007, 07:50:03 EST