Regional Ventilation by Electrical Impedance Tomography

Hinz, José; Neumann, Peter; Dudykevych, Taras; Andersson, Lars; Wrigge, Hermann; Burchardi, H.; Hedenstierna, Göran

doi:10.1378/chest.124.1.314

Cited by 149 publications

(56 citation statements)

References 26 publications

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“…This might be regarded as a limitation, however, the feasibility of EIT to assess regional ventilation has been previously validated with multiple standard imaging techniques [47]–[49].…”

Section: Discussionmentioning

confidence: 99%

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

Zick¹,

Elke²,

Becher³

et al. 2013

PLoS ONE

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IntroductionLung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (CRS), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation.MethodsEIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional CRS and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels.ResultsIn healthy animals, high compared to low VT increased CRS and ventilation in dependent lung regions implying tidal recruitment. ALI reduced CRS and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in CRS in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional CRS differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH2O PEEP.ConclusionsTidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional CRS.

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“…This might be regarded as a limitation, however, the feasibility of EIT to assess regional ventilation has been previously validated with multiple standard imaging techniques [47]–[49].…”

Section: Discussionmentioning

confidence: 99%

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

Zick¹,

Elke²,

Becher³

et al. 2013

PLoS ONE

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“…EIT proved its ability to monitor gas content in any region-of-interest (ROI) in numerous validation studies. It was compared to positron emission tomography [2], single photon emission computed tomography [3], ventilation and perfusion scintigraphy [4], dynamic computed tomography (CT) [5], electron beam CT [6] and spirometry [7]. …”

Section: Introductionmentioning

confidence: 99%

Determination of respiratory gas flow by electrical impedance tomography in an animal model of mechanical ventilation

et al. 2014

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BackgroundA recent method determines regional gas flow of the lung by electrical impedance tomography (EIT). The aim of this study is to show the applicability of this method in a porcine model of mechanical ventilation in healthy and diseased lungs. Our primary hypothesis is that global gas flow measured by EIT can be correlated with spirometry. Our secondary hypothesis is that regional analysis of respiratory gas flow delivers physiologically meaningful results.MethodsIn two sets of experiments n = 7 healthy pigs and n = 6 pigs before and after induction of lavage lung injury were investigated. EIT of the lung and spirometry were registered synchronously during ongoing mechanical ventilation. In-vivo aeration of the lung was analysed in four regions-of-interest (ROI) by EIT: 1) global, 2) ventral (non-dependent), 3) middle and 4) dorsal (dependent) ROI. Respiratory gas flow was calculated by the first derivative of the regional aeration curve. Four phases of the respiratory cycle were discriminated. They delivered peak and late inspiratory and expiratory gas flow (PIF, LIF, PEF, LEF) characterizing early or late inspiration or expiration.ResultsLinear regression analysis of EIT and spirometry in healthy pigs revealed a very good correlation measuring peak flow and a good correlation detecting late flow. PIFEIT = 0.702 · PIFspiro + 117.4, r2 = 0.809; PEFEIT = 0.690 · PEFspiro-124.2, r2 = 0.760; LIFEIT = 0.909 · LIFspiro + 27.32, r2 = 0.572 and LEFEIT = 0.858 · LEFspiro-10.94, r2 = 0.647. EIT derived absolute gas flow was generally smaller than data from spirometry. Regional gas flow was distributed heterogeneously during different phases of the respiratory cycle. But, the regional distribution of gas flow stayed stable during different ventilator settings. Moderate lung injury changed the regional pattern of gas flow.ConclusionsWe conclude that the presented method is able to determine global respiratory gas flow of the lung in different phases of the respiratory cycle. Additionally, it delivers meaningful insight into regional pulmonary characteristics, i.e. the regional ability of the lung to take up and to release air.

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“…This idea is based on the assumption that EIT could provide immediate feedback information on regional lung ventilation and aeration in response to changes in ventilator settings and/or imposed maneuvers. This hypothesis has been supported by several experimental and clinical studies showing that EIT is able to trace changes in regional lung air content [8,9,10]. …”

Section: Introductionmentioning

confidence: 71%

Assessment of Changes in Distribution of Lung Perfusion by Electrical Impedance Tomography

Frerichs¹,

Pulletz²,

Elke³

et al. 2009

Respiration

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Background: Electrical impedance tomography (EIT) is able to detect variations in regional lung electrical impedance associated with changes in both air and blood content and potentially capable of assessing regional ventilation-perfusion relationships. However, regional lung perfusion is difficult to determine because the impedance changes synchronous with the heart rate are of very small amplitude. Objectives: The aim of our study was to determine the redistribution of lung perfusion elicited by one-lung ventilation using EIT with a novel region-of-interest analysis. Methods: Ten patients (65 ± 9 years, mean age ± SD) scheduled for elective chest surgery were studied after intubation with a double-lumen endotracheal tube during bilateral and unilateral ventilation of the right and left lungs. EIT data were acquired at a rate of 25 scans/s. Relative impedance changes synchronous with the heart rate were evaluated in the right and left lung regions. Results: During bilateral ventilation, the mean right-to-left lung ratio of the sum of heart rate-related impedance changes was 1.12 ± 0.20, but the ratio significantly changed (0.81 ± 0.16 and 1.48 ± 0.37) during unilateral left- and right-lung ventilation with reduced perfusion of the non-ventilated lung. Increased perfusion most likely occurred in the ventilated lung because the impedance values summed over both regions did not change (0.62 ± 0.23 vs. 0.58 ± 0.22) compared with bilateral ventilation. Conclusions: Our results indicate that redistribution of regional lung perfusion can be assessed by EIT during one-lung ventilation. The performance of EIT in detecting changes in lung perfusion in even smaller lung regions remains to be established.

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Regional Ventilation by Electrical Impedance Tomography

Cited by 149 publications

References 26 publications

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

Determination of respiratory gas flow by electrical impedance tomography in an animal model of mechanical ventilation

Assessment of Changes in Distribution of Lung Perfusion by Electrical Impedance Tomography

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