Literature List Electrical Impedance Tomography

Breathing moves volumes of electrically insulating air into and out of the lungs, producing conductivity changes which can be seen by electrical impedance tomography. It has thus been apparent, since the early days of EIT research, that imaging of ventilation could become a key clinical application of EIT. In this paper, we review the current state and future prospects for lung EIT, by a synthesis of the presentations of the authors at the ‘special lung sessions’ of the annual biomedical EIT conferences on 2009-2011. We argue that lung EIT research has arrived at an important transition. It is now clear that valid and reproducible physiological information is available from EIT lung images. We must now ask the question: How can these data be used to help improve patient outcomes? To answer this question, we develop a classification of possible clinical scenarios in which EIT could play an important role, and we identify clinical and experimental research programs and engineering developments required to turn EIT into a clinically useful tool for lung monitoring. ES Muders T et al. Tidal recruitment assessed by electrical impedance tomography and computed tomography in a porcine model of lung injury Crit Care Med. 2012 Mar;40(3):903-11 Objectives: To determine the validity of electrical impedance tomography to detect and quantify the amount of tidal recruitment caused by different positive end-expiratory pressure levels in a porcine acute lung injury model. Design: Randomized, controlled, prospective experimental study. Setting: Academic research laboratory. Subjects: Twelve anesthetized and mechanically ventilated pigs. Interventions: Acute lung injury was induced by a central venous oleic acid injection and abdominal hypertension in seven animals. Five healthy pigs served as control group. Animals were ventilated with positive end-expiratory pressure of 0, 5, 10, 15, 20, 25 cm H2O, respectively, in a randomized order. Measurements and Main Results: At any positive end-expiratory pressure level. Electrical impedance tomography was obtained during a slow inflation of 12 mL/kg of body weight. Regional-ventilation-delay indices quantifying the time until a lung region reaches a certain amount of impedance change were calculated for lung quadrants and for every single electrical impedance tomography pixel, respectively. Pixel-wise calculated regional-ventilation-delay indices were plotted in a color-coded regional-ventilation-delay map. Regional-ventilation-delay inhomogeneity that quantifies heterogeneity of ventilation time courses was evaluated by calculating the scatter of all pixel-wise calculated regional-ventilation-delay indices. End-expiratory and end-ins piratory computed tomography scans were performed at each positive end-expiratory pressure level to quantify tidal recruitment of the lung. Tidal recruitment showed a moderate inter-individual (r= 0.54; p<0.05) and intra-individual linear correlation (r= 0.46 up to 0.73 and p < 0.05, respectively) with regional-ventilation-delay obtained from lung quadrants. Regional-ventilation-delay inhomogeneity was excellently correlated with tidal recruitment intra(r=0.90 up to r 0 0.99 and p<0.05, respectively) and inter-individually (r=0.90; p<0.001). Conclusions: Regional-ventilation-delay can be noninvasively measured by electrical impedance tomography during a slow inflation of 12 mL/kg of body weight and visualized using ventilation delay maps. Our experimental data suggest that the impedance tomography-based analysis of regional-ventilation-delay inhomogeneity provides a good estimate of the amount of tidal recruitment and may be useful to individualize ventilatory settings. Electrical Impedance Tomography (EIT) Literature List