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Article ; Online: A Rotational Invariant Neural Network for Electrical Impedance Tomography Imaging without Reference Voltage

Jöran Rixen / Benedikt Eliasson / Benjamin Hentze / Thomas Muders / Christian Putensen / Steffen Leonhardt / Chuong Ngo

Diagnostics, Vol 12, Iss 777, p

RF-REIM-NET

2022 Volume 777

Abstract: Background : Electrical Impedance Tomography (EIT) is a radiation-free technique for image reconstruction. However, as the inverse problem of EIT is non-linear and ill-posed, the reconstruction of sharp conductivity images poses a major problem. With the ...

Abstract	Background : Electrical Impedance Tomography (EIT) is a radiation-free technique for image reconstruction. However, as the inverse problem of EIT is non-linear and ill-posed, the reconstruction of sharp conductivity images poses a major problem. With the emergence of artificial neural networks (ANN), their application in EIT has recently gained interest. Methodology : We propose an ANN that can solve the inverse problem without the presence of a reference voltage. At the end of the ANN, we reused the dense layers multiple times, considering that the EIT exhibits rotational symmetries in a circular domain. To avoid bias in training data, the conductivity range used in the simulations was greater than expected in measurements. We also propose a new method that creates new data samples from existing training data. Results : We show that our ANN is more robust with respect to noise compared with the analytical Gauss–Newton approach. The reconstruction results for EIT phantom tank measurements are also clearer, as ringing artefacts are less pronounced. To evaluate the performance of the ANN under real-world conditions, we perform reconstructions on an experimental pig study with computed tomography for comparison. Conclusions : Our proposed ANN can reconstruct EIT images without the need of a reference voltage.
Keywords	artificial intelligence ; deep learning ; Electrical Impedance Tomography ; lung imaging ; cardiopulmonary monitoring ; Medicine (General) ; R5-920
Subject code	006
Language	English
Publishing date	2022-03-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Electrical Impedance Tomography for Cardio-Pulmonary Monitoring

Christian Putensen / Benjamin Hentze / Stefan Muenster / Thomas Muders

Journal of Clinical Medicine, Vol 8, Iss 8, p

2019 Volume 1176

Abstract: Electrical impedance tomography (EIT) is a bedside monitoring tool that noninvasively visualizes local ventilation and arguably lung perfusion distribution. This article reviews and discusses both methodological and clinical aspects of thoracic EIT. ... ...

Abstract	Electrical impedance tomography (EIT) is a bedside monitoring tool that noninvasively visualizes local ventilation and arguably lung perfusion distribution. This article reviews and discusses both methodological and clinical aspects of thoracic EIT. Initially, investigators addressed the validation of EIT to measure regional ventilation. Current studies focus mainly on its clinical applications to quantify lung collapse, tidal recruitment, and lung overdistension to titrate positive end-expiratory pressure (PEEP) and tidal volume. In addition, EIT may help to detect pneumothorax. Recent studies evaluated EIT as a tool to measure regional lung perfusion. Indicator-free EIT measurements might be sufficient to continuously measure cardiac stroke volume. The use of a contrast agent such as saline might be required to assess regional lung perfusion. As a result, EIT-based monitoring of regional ventilation and lung perfusion may visualize local ventilation and perfusion matching, which can be helpful in the treatment of patients with acute respiratory distress syndrome (ARDS).
Keywords	electrical impedance tomography ; bioimpedance ; image reconstruction ; thorax ; regional ventilation ; regional perfusion ; monitoring ; Medicine ; R
Language	English
Publishing date	2019-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Measurement of Electrical Impedance Tomography-Based Regional Ventilation Delay for Individualized Titration of End-Expiratory Pressure

Thomas Muders / Benjamin Hentze / Stefan Kreyer / Karin Henriette Wodack / Steffen Leonhardt / Göran Hedenstierna / Hermann Wrigge / Christian Putensen

Journal of Clinical Medicine, Vol 10, Iss 2933, p

2021 Volume 2933

Abstract: Rationale: Individualized positive end-expiratory pressure (PEEP) titration might be beneficial in preventing tidal recruitment. To detect tidal recruitment by electrical impedance tomography (EIT), the time disparity between the regional ventilation ... ...

Abstract	Rationale: Individualized positive end-expiratory pressure (PEEP) titration might be beneficial in preventing tidal recruitment. To detect tidal recruitment by electrical impedance tomography (EIT), the time disparity between the regional ventilation curves (regional ventilation delay inhomogeneity [RVDI]) can be measured during controlled mechanical ventilation when applying a slow inflation of 12 mL/kg of body weight (BW). However, repeated large slow inflations may result in high end-inspiratory pressure (P EI ), which might limit the clinical applicability of this method. We hypothesized that PEEP levels that minimize tidal recruitment can also be derived from EIT-based RVDI through the use of reduced slow inflation volumes. Methods: Decremental PEEP trials were performed in 15 lung-injured pigs. The PEEP level that minimized tidal recruitment was estimated from EIT-based RVDI measurement during slow inflations of 12, 9, 7.5, or 6 mL/kg BW. We compared RVDI and P EI values resulting from different slow inflation volumes and estimated individualized PEEP levels. Results: RVDI values from slow inflations of 12 and 9 mL/kg BW showed excellent linear correlation ( R 2 = 0.87, p < 0.001). Correlations decreased for RVDI values from inflations of 7.5 ( R 2 = 0.68, p < 0.001) and 6 ( R 2 = 0.42, p < 0.001) mL/kg BW. Individualized PEEP levels estimated from 12 and 9 mL/kg BW were comparable (bias −0.3 cm H 2 O ± 1.2 cm H 2 O). Bias and scatter increased with further reduction in slow inflation volumes (for 7.5 mL/kg BW, bias 0 ± 3.2 cm H 2 O; for 6 mL/kg BW, bias 1.2 ± 4.0 cm H 2 O). P EI resulting from 9 mL/kg BW inflations were comparable with P EI during regular tidal volumes. Conclusions: PEEP titration to minimize tidal recruitment can be individualized according to EIT-based measurement of the time disparity of regional ventilation courses during slow inflations with low inflation volumes . This sufficiently decreases P EI and may reduce potential clinical risks.
Keywords	acute respiratory distress syndrome ; positive end-expiratory pressure ; individualized therapy ; electrical impedance tomography ; monitoring ; functional imaging ; Medicine ; R
Subject code	333
Language	English
Publishing date	2021-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: A Modified Method to Assess Tidal Recruitment by Electrical Impedance Tomography

Thomas Muders / Benjamin Hentze / Philipp Simon / Felix Girrbach / Michael R.G. Doebler / Steffen Leonhardt / Hermann Wrigge / Christian Putensen

Journal of Clinical Medicine, Vol 8, Iss 8, p

2019 Volume 1161

Abstract: Avoiding tidal recruitment and collapse during mechanical ventilation should reduce the risk of lung injury. Electrical impedance tomography (EIT) enables detection of tidal recruitment by measuring regional ventilation delay inhomogeneity (RVDI) during ... ...

Abstract	Avoiding tidal recruitment and collapse during mechanical ventilation should reduce the risk of lung injury. Electrical impedance tomography (EIT) enables detection of tidal recruitment by measuring regional ventilation delay inhomogeneity (RVDI) during a slow inflation breath with a tidal volume (V T ) of 12 mL/kg body weight (BW). Clinical applicability might be limited by such high V T s resulting in high end-inspiratory pressures (P EI ) during positive end-expiratory pressure (PEEP) titration. We hypothesized that RVDI can be obtained with acceptable accuracy from reduced slow inflation V T s. In seven ventilated pigs with experimental lung injury, tidal recruitment was quantified by computed tomography at PEEP levels changed stepwise between 0 and 25 cmH 2 O. RVDI was measured by EIT during slow inflation V T s of 12, 9, 7.5, and 6 mL/kg BW. Linear correlation of tidal recruitment and RVDI was excellent for V T s of 12 ( R 2 = 0.83, p < 0.001) and 9 mL/kg BW ( R 2 = 0.83, p < 0.001) but decreased for V T s of 7.5 ( R 2 = 0.76, p < 0.001) and 6 mL/kg BW ( R 2 = 0.71, p < 0.001). With any reduction in slow inflation V T , P EI decreased at all PEEP levels. Receiver-Operator-Characteristic curve analyses revealed that RVDI-thresholds to predict distinct amounts of tidal recruitment differ when obtained from different slow inflation V T s. In conclusion, tidal recruitment can sufficiently be monitored by EIT-based RVDI-calculation with a slow inflation of 9 mL/kg BW.
Keywords	acute respiratory distress syndrome ; positive end-expiratory pressure ; electrical impedance tomography ; computed tomography ; monitoring ; functional imaging ; Medicine ; R
Subject code	333 ; 290
Language	English
Publishing date	2019-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Secondary ARDS Following Acute Pancreatitis

Mathias Schmandt / Tim R. Glowka / Stefan Kreyer / Thomas Muders / Stefan Muenster / Nils Ulrich Theuerkauf / Jörg C. Kalff / Christian Putensen / Jens-Christian Schewe / Stefan Felix Ehrentraut

Journal of Clinical Medicine, Vol 10, Iss 5, p

Is Extracorporeal Membrane Oxygenation Feasible or Futile?

2021 Volume 1000

Abstract: Objective: To assess the feasibility of extracorporeal membrane oxygenation (ECMO) or life support (ECLS) as last resort life support therapy in patients with acute pancreatitis and subsequent secondary acute respiratory distress syndrome (ARDS). Methods: ...

Abstract	Objective: To assess the feasibility of extracorporeal membrane oxygenation (ECMO) or life support (ECLS) as last resort life support therapy in patients with acute pancreatitis and subsequent secondary acute respiratory distress syndrome (ARDS). Methods: Retrospective analysis from January 2013, to April 2020, of ECMO patients with pancreatitis-induced ARDS at a German University Hospital. Demographics, hospital and ICU length of stay, duration of ECMO therapy, days on mechanical ventilation, fluid balance, need for decompressive laparotomy, amount of blood products, prognostic scores (CCI (Charlson Comorbidity Index), SOFA (Sequential Organ Failure Assessment), RESP(Respiratory ECMO Survival Prediction), SAVE (Survival after Veno-Arterial ECMO)), and the total known length of survival were assessed. Results: A total of n = 495 patients underwent ECMO. Eight patients with acute pancreatitis received ECLS (seven veno-venous, one veno-arterial). Five (71%) required decompressive laparotomy as salvage therapy due to abdominal hypertension. Two patients with acute pancreatitis (25%) survived to hospital discharge. The overall median length of survival was 22 days. Survivors required less fluid in the first 72 h of ECMO support and showed lower values for all prognostic scores. Conclusion: ECLS can be performed as a rescue therapy in patients with pancreatitis and secondary ARDS, but nevertheless mortality remains still high. Thus, this last-resort therapy may be best suited for patients with fewer pre-existing comorbidities and no other organ failure.
Keywords	extra corporeal life support (ECLS) ; extra corporeal membrane oxygenation (ECMO) ; pancreatitis ; acute respiratory distress syndrome (ARDS) ; Medicine ; R
Subject code	610
Language	English
Publishing date	2021-03-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Extensive Therapeutic Drug Monitoring of Colistin in Critically Ill Patients Reveals Undetected Risks

Stefan Felix Ehrentraut / Stefan Muenster / Stefan Kreyer / Nils Ulrich Theuerkauf / Christian Bode / Folkert Steinhagen / Heidi Ehrentraut / Jens-Christian Schewe / Matthias Weber / Christian Putensen / Thomas Muders

Microorganisms, Vol 8, Iss 3, p

2020 Volume 415

Abstract: 1) Background: With the rise of multi-/pan-drug resistant (MDR/PDR) pathogens, the less utilized antibiotic Colistin has made a comeback. Colistin fell out of favor due to its small therapeutic range and high potential for toxicity. Today, it is used ... ...

Abstract	(1) Background: With the rise of multi-/pan-drug resistant (MDR/PDR) pathogens, the less utilized antibiotic Colistin has made a comeback. Colistin fell out of favor due to its small therapeutic range and high potential for toxicity. Today, it is used again as a last resort substance in treating MDR/PDR pathogens. Although new guidelines with detailed recommendations for Colistin dosing are available, finding the right dose in critically ill patients with renal failure remains difficult. Here, we evaluate the efficiency of the current guidelines’ recommendations by using high resolution therapeutic drug monitoring of Colistin. (2) Methods: We analyzed plasma levels of Colistin and its prodrug colisthimethate sodium (CMS) in 779 samples, drawn from eight PDR-infected ICU patients, using a HPLC-MS/MS approach. The impact of renal function on proper Colistin target levels was assessed. (3) Results: CMS levels did not correlate with Colistin levels. Over-/Underdosing occurred regardless of renal function and mode of renal replacement therapy. Colistin elimination half-time appeared to be longer than previously reported. (4) Conclusion: Following dose recommendations from the most current guidelines does not necessarily lead to adequate Colistin plasma levels. Use of Colistin without therapeutic drug monitoring might be unsafe and guideline adherence does not warrant efficient target levels in critically ill patients.
Keywords	colistin ; sepsis ; colistin methanosulfate ; therapeutic drug monitoring ; intensive care medicine ; renal failure ; polymyxin e ; acinetobacter baumannii ; carbapenem resistant ; Biology (General) ; QH301-705.5
Subject code	610 ; 616
Language	English
Publishing date	2020-03-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: CT fatty muscle fraction as a new parameter for muscle quality assessment predicts outcome in venovenous extracorporeal membrane oxygenation

Anton Faron / Stefan Kreyer / Alois M. Sprinkart / Thomas Muders / Stefan F. Ehrentraut / Alexander Isaak / Rolf Fimmers / Claus C. Pieper / Daniel Kuetting / Jens-Christian Schewe / Ulrike Attenberger / Christian Putensen / Julian A. Luetkens

Scientific Reports, Vol 10, Iss 1, Pp 1-

2020 Volume 9

Abstract: Abstract Impaired skeletal muscle quality is a major risk factor for adverse outcomes in acute respiratory failure. However, conventional methods for skeletal muscle assessment are inapplicable in the critical care setting. This study aimed to determine ... ...

Abstract	Abstract Impaired skeletal muscle quality is a major risk factor for adverse outcomes in acute respiratory failure. However, conventional methods for skeletal muscle assessment are inapplicable in the critical care setting. This study aimed to determine the prognostic value of computed tomography (CT) fatty muscle fraction (FMF) as a biomarker of muscle quality in patients undergoing extracorporeal membrane oxygenation (ECMO). To calculate FMF, paraspinal skeletal muscle area was obtained from clinical CT and separated into areas of fatty and lean muscle based on densitometric thresholds. The cohort was binarized according to median FMF. Patients with high FMF displayed significantly increased 1-year mortality (72.7% versus 55.8%, P = 0.036) on Kaplan–Meier analysis. A multivariable logistic regression model was built to test the impact of FMF on outcome. FMF was identified as a significant predictor of 1-year mortality (hazard ratio per percent FMF, 1.017 [95% confidence interval, 1.002–1.033]; P = 0.031), independent of anthropometric characteristics, Charlson Comorbidity Index, Simplified Acute Physiology Score, Respiratory Extracorporeal Membrane Oxygenation Survival Prediction Score, and duration of ECMO support. To conclude, FMF predicted 1-year mortality independently of established clinical prognosticators in ECMO patients and may have the potential to become a new muscle quality imaging biomarker, which is available from clinical CT.
Keywords	Medicine ; R ; Science ; Q
Language	English
Publishing date	2020-12-01T00:00:00Z
Publisher	Nature Portfolio
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Mechanical Ventilation Strategies Targeting Different Magnitudes of Collapse and Tidal Recruitment in Porcine Acid Aspiration-Induced Lung Injury

Juliane Haase / Dorina C. Buchloh / Sören Hammermüller / Peter Salz / Julia Mrongowius / Nadja C. Carvalho / Alessandro Beda / Anna Rau / Henning Starke / Peter M. Spieth / Claudia Gittel / Thomas Muders / Hermann Wrigge / Andreas W. Reske

Journal of Clinical Medicine, Vol 8, Iss 8, p

2019 Volume 1250

Abstract: Reducing ventilator-associated lung injury by individualized mechanical ventilation (MV) in patients with Acute Respiratory Distress Syndrome (ARDS) remains a matter of research. We randomly assigned 27 pigs with acid aspiration-induced ARDS to three ... ...

Abstract	Reducing ventilator-associated lung injury by individualized mechanical ventilation (MV) in patients with Acute Respiratory Distress Syndrome (ARDS) remains a matter of research. We randomly assigned 27 pigs with acid aspiration-induced ARDS to three different MV protocols for 24 h, targeting different magnitudes of collapse and tidal recruitment (collapse&TR): the ARDS-network (ARDSnet) group with low positive end-expiratory pressure (PEEP) protocol (permissive collapse&TR); the Open Lung Concept (OLC) group, PaO 2 /FiO 2 >400 mmHg, indicating collapse&TR <10%; and the minimized collapse&TR monitored by Electrical Impedance Tomography (EIT) group, standard deviation of regional ventilation delay, SD RVD . We analyzed cardiorespiratory parameters, computed tomography (CT), EIT, and post-mortem histology. Mean PEEP over post-randomization measurements was significantly lower in the ARDSnet group at 6.8 ± 1.0 cmH 2 O compared to the EIT (21.1 ± 2.6 cmH 2 O) and OLC (18.7 ± 3.2 cmH 2 O) groups (general linear model (GLM) p < 0.001). Collapse&TR and SD RVD , averaged over all post-randomization measurements, were significantly lower in the EIT and OLC groups than in the ARDSnet group (collapse p < 0.001, TR p = 0.006, SD RVD p < 0.004). Global histological diffuse alveolar damage (DAD) scores in the ARDSnet group (10.1 ± 4.3) exceeded those in the EIT (8.4 ± 3.7) and OLC groups (6.3 ± 3.3) ( p = 0.16). Sub-scores for edema and inflammation differed significantly (ANOVA p < 0.05). In a clinically realistic model of early ARDS with recruitable and nonrecruitable collapse, mechanical ventilation involving recruitment and high-PEEP reduced collapse&TR and resulted in improved hemodynamic and physiological conditions with a tendency to reduced histologic lung damage.
Keywords	acute respiratory distress syndrome ; lung protective mechanical ventilation ; positive end-expiratory pressure ; lung recruitment ; electrical impedance tomography ; Medicine ; R
Subject code	290 ; 333
Language	English
Publishing date	2019-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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