Regional Lung Perfusion Analysis in Experimental ARDS by Electrical Impedance and Computed Tomography

Kircher, Michael; Elke, Gunnar; Stender, Birgit; Mesa, María Hernández; Schuderer, Felix; Dössel, Olaf; Fuld, Matthew K.; Halaweish, Ahmed F.; Hoffman, Eric A.; Weiler, Norbert; Frerichs, Inéz

doi:10.1109/tmi.2020.3025080

Cited by 38 publications

(26 citation statements)

References 51 publications

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“…For the image entries a similarity measure of the respective pulsatility signal was evaluated mutually in combination with criteria regarding signal power and statistical information on shape and location of the region of interest in humans. An indicator-based heart region was determined by K-Means clustering using three features of the indicator signal, as previously described[ 19 ]. The underlying assumption is that three functional compartments are involved: cardiac chambers and large vessels upstream of the lung, the lungs as second compartment and a compartment downstream of the lungs.…”

Section: Methodsmentioning

confidence: 99%

“…Electrical impedance tomography (EIT) is a dynamic bedside monitor of lung volume changes [ 12 ], able to accurately assess regional ventilation distribution in ARDS patients [ 13 , 14 ]. EIT-based method that quantitatively estimates regional lung perfusion based on first-pass kinetics of a bolus of hypertonic saline contrast has been developed [ 15 ], validated in experimental studies [ 16 – 19 ], and recently increasingly applied in critically ill patients [ 20 – 24 ]. EIT might identify only ventilated (i.e., ventilated but not perfused) units and only perfused (i.e., perfused non-ventilated) units expressed as a percentage of total lung volume.…”

Section: Introductionmentioning

confidence: 99%

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Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS

Spinelli,

Kircher,

Stender

et al. 2021

Crit Care

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Background In acute respiratory distress syndrome (ARDS), non-ventilated perfused regions coexist with non-perfused ventilated regions within lungs. The number of unmatched regions might reflect ARDS severity and affect the risk of ventilation-induced lung injury. Despite pathophysiological relevance, unmatched ventilation and perfusion are not routinely assessed at the bedside. The aims of this study were to quantify unmatched ventilation and perfusion at the bedside by electrical impedance tomography (EIT) investigating their association with mortality in patients with ARDS and to explore the effects of positive end-expiratory pressure (PEEP) on unmatched ventilation and perfusion in subgroups of patients with different ARDS severity based on PaO2/FiO2 and compliance. Methods Prospective observational study in 50 patients with mild (36%), moderate (46%), and severe (18%) ARDS under clinical ventilation settings. EIT was applied to measure the regional distribution of ventilation and perfusion using central venous bolus of saline 5% during end-inspiratory pause. We defined unmatched units as the percentage of only ventilated units plus the percentage of only perfused units. Results Percentage of unmatched units was significantly higher in non-survivors compared to survivors (32[27–47]% vs. 21[17–27]%, p < 0.001). Percentage of unmatched units was an independent predictor of mortality (OR 1.22, 95% CI 1.07–1.39, p = 0.004) with an area under the ROC curve of 0.88 (95% CI 0.79–0.97, p < 0.001). The percentage of ventilation to the ventral region of the lung was higher than the percentage of ventilation to the dorsal region (32 [27–38]% vs. 18 [13–21]%, p < 0.001), while the opposite was true for perfusion (28 [22–38]% vs. 36 [32–44]%, p < 0.001). Higher percentage of only perfused units was correlated with lower dorsal ventilation (r = − 0.486, p < 0.001) and with lower PaO2/FiO2 ratio (r = − 0.293, p = 0.039). Conclusions EIT allows bedside assessment of unmatched ventilation and perfusion in mechanically ventilated patients with ARDS. Measurement of unmatched units could identify patients at higher risk of death and could guide personalized treatment.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS

Spinelli,

Kircher,

Stender

et al. 2021

Crit Care

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“…More recently, Kircher et al optimized an EIT-gamma function fitting based on a linear piecewise approximation of the drift model in a porcine acute respiratory distress syndrome (ARDS) model, simplifying the quantization algorithm for potential clinical applications (Kircher et al, 2021). Simultaneously, following the administration of a saline bolus, by calculating the SD of each pixel and plotting them at the relevant image position, a new type of EIT image presenting the exact position, into which the indicator is carried by the bloodstream and visualizing the temporal variation in perfusion distribution can be generated (Frerichs et al, 2002).…”

Section: Principles Of the Conductivity Contrast Bolus Eit Methodsmentioning

confidence: 99%

“…The experimental and clinical studies using the saline bolus EIT method to visually assess lung perfusion are summarized in Tables 2-4 (Frerichs et al, 2002;Borges et al, 2012;Nguyen et al, 2013Nguyen et al, , 2015Reinius et al, 2015;Hentze et al, 2018;Bluth et al, 2019;Grassi et al, 2020;He et al, 2020aHe et al, ,b,c, 2021bMauri et al, 2020;Safaee Fakhr et al, 2020;Kircher et al, 2021;Spinelli et al, 2021;Yuan et al, 2021). The administration of saline boluses, data analyses, precision, and cutoff values differ among…”

Section: Implementation Of the Saline Bolus Methodsmentioning

confidence: 99%

Lung Perfusion Assessment by Bedside Electrical Impedance Tomography in Critically Ill Patients

Long

2021

Front. Physiol.

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As a portable, radiation-free imaging modality, electrical impedance tomography (EIT) technology has shown promise in the bedside visual assessment of lung perfusion distribution in critically ill patients. The two main methods of EIT for assessing lung perfusion are the pulsatility and conductivity contrast (saline) bolus method. Increasing attention is being paid to the saline bolus EIT method in the evaluation of regional pulmonary perfusion in clinical practice. This study seeks to provide an overview of experimental and clinical studies with the aim of clarifying the progress made in the use of the saline bolus EIT method. Animal studies revealed that the saline bolus EIT method presented good consistency with single-photon emission CT (SPECT) in the evaluation of lung regional perfusion changes in various pathological conditions. Moreover, the saline bolus EIT method has been applied to assess the lung perfusion in a pulmonary embolism and the effect of positive end-expiratory pressure (PEEP) on regional ventilation/perfusion ratio (V/Q) and acute respiratory distress syndrome (ARDS) in several clinical studies. The implementation of saline boluses, data analyses, precision, and cutoff values varied among different studies, and a consensus must be reached regarding the clinical application of the saline bolus EIT method. Further study is required to validate the impact of the described saline bolus EIT method on decision-making, therapeutic management, and outcomes in critically ill patients.

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“…To evaluate lung perfusion, apnea time does not need to be as long as PTT. Animal studies suggested that the time from saline injection to saline entering and concentrating in the lungs was about 3–5 seconds ( 2 , 3 ). For the patients with pulmonary embolism (PE) evaluated in our study ( 1 ), the trough value of global impedance was observed at 2–5 seconds after saline bolus injection.…”

mentioning

confidence: 99%

Reply to Wang and Zhong: Bedside Evaluation of Pulmonary Embolism by Saline Contrast–enhanced Electrical Impedance Tomography: Considerations for Future Research

Long

Chi

et al. 2021

Am J Respir Crit Care Med

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Regional Lung Perfusion Analysis in Experimental ARDS by Electrical Impedance and Computed Tomography

Cited by 38 publications

References 51 publications

Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS

Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS

Lung Perfusion Assessment by Bedside Electrical Impedance Tomography in Critically Ill Patients

Reply to Wang and Zhong: Bedside Evaluation of Pulmonary Embolism by Saline Contrast–enhanced Electrical Impedance Tomography: Considerations for Future Research

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