Assessment of regional ventilation distribution: comparison of vibration response imaging (VRI) with electrical impedance tomography (EIT).
BACKGROUND
Vibration response imaging (VRI) is a bedside technology to monitor ventilation by detecting lung sound vibrations. It is currently unknown whether VRI is able to accurately monitor the local distribution of ventilation within the lungs. We therefore compared VRI to electrical impedance tomography (EIT), an established technique used for the assessment of regional ventilation.


RESULTS
Simultaneous EIT and VRI measurements were performed in the healthy and injured lungs (ALI; induced by saline lavage) at different PEEP levels (0, 5, 10, 15 mbar) in nine piglets. Vibration energy amplitude (VEA) by VRI, and amplitudes of relative impedance changes (rel.ΔZ) by EIT, were evaluated in seven regions of interest (ROIs). To assess the distribution of tidal volume (VT) by VRI and EIT, absolute values were normalized to the VT obtained by simultaneous spirometry measurements. Redistribution of ventilation by ALI and PEEP was detected by VRI and EIT. The linear correlation between pooled VT by VEA and rel.ΔZ was R(2) = 0.96. Bland-Altman analysis showed a bias of -1.07±24.71 ml and limits of agreement of -49.05 to +47.36 ml. Within the different ROIs, correlations of VT-distribution by EIT and VRI ranged between R(2) values of 0.29 and 0.96. ALI and PEEP did not alter the agreement of VT between VRI and EIT.


CONCLUSIONS
Measurements of regional ventilation distribution by VRI are comparable to those obtained by EIT.
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany ; Beijing Institute of Pharmacology and Toxicology, National Beijing Center for Drug Safety Evaluation and Research, Beijing, China.
Chang
C
Shi
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany ; Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
Stefan
S
Boehme
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany.
Alexander H
AH
Bentley
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany.
Erik K
EK
Hartmann
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany ; Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
Klaus U
KU
Klein
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany.
Marc
M
Bodenstein
Oscillogy LLC, Folsom, Pennsylvania, United States of America.
James E
JE
Baumgardner
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany.
Matthias
M
David
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
Roman
R
Ullrich
Department of Anaesthesiology, Medical Centre of the Johannes Gutenberg-University, Mainz, Germany ; Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
Klaus
K
Markstaller
D000704:Analysis of Variance; D000818:Animals; D003952:Diagnostic Imaging / Q000379:methods*; D017097:Electric Impedance; D015233:Models, Statistical; D012123:Pulmonary Ventilation / Q000502:physiology*; D013147:Spirometry; D013552:Swine; D014054:Tomography / Q000379:methods*; D014732:Vibration