Assessment of regional ventilation distribution: comparison of vibration response imaging (VRI) with electrical impedance tomography (EIT)

PLoS One. 2014 Jan 27;9(1):e86638. doi: 10.1371/journal.pone.0086638. eCollection 2014.


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.

Methodology/principal findings: 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/significance: Measurements of regional ventilation distribution by VRI are comparable to those obtained by EIT.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Diagnostic Imaging / methods*
  • Electric Impedance
  • Models, Statistical
  • Pulmonary Ventilation / physiology*
  • Spirometry
  • Swine
  • Tomography / methods*
  • Vibration*

Grants and funding

The study was funded by German Research Foundation grant No. DFG PAK 415; Ma 2398/6-1, Ma 2398/7-1 and in part by G.E. Healthcare Inc., Milwaukee, USA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.