Abstract
Introduction: Electrical impedance tomography (EIT) is able to trace ventilation-related changes in electrical properties of lung tissue. Previous studies using computed tomography (CT) suggested a good correlation between regional EIT data and lung tissue density. However, no validation data exist in regional acute lung injury (ALI).
Objective: To validate EIT measurements of regional ventilation (rVa) by dynamic Xenon-multidetector-row CT (Xe-MDCT) in two animal models of regional ALI.
Methods: 9 anaesthetized mechanically ventilated pigs were examined before and after induction of ALI within two adjacent sub-lobar lung segments by repetitive saline lavage (n=4) or endotoxin sepsis injury (n=5). EIT data were acquired at 25 scans/s (GoeMF II system, CareFusion, Höchberg, Germany). Xe-MDCT (Sensation 64, Siemens AG, Forchheim, Germany) was performed at the same thoracic region. EIT and Xe-MDCT rVa images during control and ALI were divided into 32 regions of interest (ROI) in each hemithorax. rVa differences for both methods were obtained by subtracting the corresponding values in each ROI. EIT and CT measurements were compared by Spearman's Rho correlation.
Results: In 4 of 9 animals analyzed so far, rVa difference images revealed a ventilation decrease in the injured (right) lung and an increase in the non-injured (left) lung compared to control. rVa changes occurred in spatially similar locations. Spearman's rho ranged from 0.931-0.936 for the right and 0.943-0.979 for the left hemithorax in control. In ALI, ranges were 0.857-0.933 and 0.948-0.981, respectively (p<0.001).
Conclusion: A good correlation existed of rVa determined by EIT and Xe-MDCT in the 4 animals with regional ALI compared to date.
- © 2011 ERS