Monitoring pulmonary perfusion by electrical impedance tomography

An evaluation in a pig model

A. Fagerberg, O. Stenqvist, A. Åneman*

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Background: Electrical impedance tomography (EIT) is a non-invasive technique that generates images of impedance distribution. Changes in the pulmonary content of air and blood are major determinants of thoracic impedance. This study was designed to evaluate EIT in monitoring pulmonary perfusion in a wide range of cardiac output. Methods: Eight anaesthetised, mechanically ventilated pigs were fitted with a 16-electrode belt at the mid-thoracic level to generate EIT images that were analysed to determine pulse-synchronous systolic changes in impedance (ΔZsys). Stroke volume (SV) was derived using a pulmonary artery catheter. Reductions in cardiac pre-load, and thus pulmonary perfusion, were induced either by inflating the balloon of a Fogarty catheter positioned in the inferior caval vein or by increasing the positive end-expiratory pressure (PEEP). All measurements were performed in a steady state during a short apnoea. Results: Pulse-synchronous changes in ΔZsys were easily discernable during apnoea. Balloon inflation reduced SV to 36% of the baseline, with a corresponding decrease in ΔZsys to 45% of baseline. PEEP reduced SV and ΔZ sys to 52% and 44% of the baseline, respectively. Significant correlations between SV and ΔZsys were demonstrated during all measurements (ρ=0.62) as well as during balloon inflation (ρ=0.73) and increased PEEP (ρ=0.40). A Bland-Altman comparison of relative changes in SV and ΔZsys demonstrated a bias of -7%, with 95% limits of agreement at -51% and 36%. Conclusions: EIT provided beat-to-beat approximations of pulmonary perfusion that significantly correlated to a wide range of SV values achieved during both extra and intrapulmonary interventions to change cardiac output.

Original languageEnglish
Pages (from-to)152-158
Number of pages7
JournalActa Anaesthesiologica Scandinavica
Volume53
Issue number2
DOIs
Publication statusPublished - Feb 2009

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