A Unified Approach for EIT Imaging of Regional Overdistension and Atelectasis in Acute Lung Injury

Camille Gomez-Laberge,Gerhard K. Wolf,John H. Arnold

doi:10.1109/tmi.2012.2183641

Camille Gomez-Laberge, Gerhard K. Wolf + Show 1 more

Open Access

https://doi.org/10.1109/tmi.2012.2183641

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Journal: IEEE Transactions on Medical Imaging	Publication Date: Jan 10, 2012
Citations: 94	License type: cc-by

Affiliation: Harvard University

Abstract

Patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) are vulnerable to ventilator-induced lung injury. Although this syndrome affects the lung heterogeneously, mechanical ventilation is not guided by regional indicators of potential lung injury. We used electrical impedance tomography (EIT) to estimate the extent of regional lung overdistension and atelectasis during mechanical ventilation. Techniques for tidal breath detection, lung identification, and regional compliance estimation were combined with the Graz consensus on EIT lung imaging (GREIT) algorithm. Nine ALI/ARDS patients were monitored during stepwise increases and decreases in airway pressure. Our method detected individual breaths with 96.0% sensitivity and 97.6% specificity. The duration and volume of tidal breaths erred on average by 0.2 s and 5%, respectively. Respiratory system compliance from EIT and ventilator measurements had a correlation coefficient of 0.80. Stepwise increases in pressure could reverse atelectasis in 17% of the lung. At the highest pressures, 73% of the lung became overdistended. During stepwise decreases in pressure, previously-atelectatic regions remained open at sub-baseline pressures. We recommend that the proposed approach be used in collaborative research of EIT-guided ventilation strategies for ALI/ARDS.

Highlights

M ECHANICAL ventilation is an essential part of caring for critically-ill patients with acute lung injury (ALI) or its more severe form acute respiratory distress syndrome (ARDS)
Building upon a decade of experimental validation of electrical impedance tomography (EIT) regional lung volume measurements [19], [25]–[29], there has been a recent surge in EIT research about mechanical ventilation of the ALI/ARDS lung [15], [30]–[35]
The following methods have been proposed: an intra-tidal respiratory system compliance index [15], functional EIT (fEIT) changes between PEEP settings [30], a respiratory system compliance percentile change from a scaled baseline value [31], a regional lung state classification index based on changes between PEEP settings [32], the dorsoventral center-of-mass coordinate of a spectral power EIT image [33], an intra-tidal global ventilation inhomogeneity index [34], and ventilator-calibrated regional distributions of end-expiratory lung volume and potentially-recruitable lung volume [35]

Summary

Introduction

M ECHANICAL ventilation is an essential part of caring for critically-ill patients with acute lung injury (ALI) or its more severe form acute respiratory distress syndrome (ARDS). It has become clear after two decades of research that mechanical ventilation itself can exacerbate lung injury and, increase the chance of death [1], [2]. Multicenter trials attempting to reduce the mortality among ALI/ARDS patients by strategic selection of ventilation parameters have led to mixed results [3]–[6] Their goal was to find a lung protective tidal volume ( ) and positive end-expiratory pressure (PEEP) according to measurements that characterize the lung as a whole.

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