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Torsani V, Cardoso PFG, Borges JB, Gomes S, Moriya HT, Cruz AFD, Santiago RRDS, Nagao CK, Fitipaldi MF, Beraldo MDA, Junior MHV, Mlček M, Pego-Fernandes PM, Amato MBP. First real-time imaging of bronchoscopic lung volume reduction by electrical impedance tomography. Respir Res 2024; 25:264. [PMID: 38965590 PMCID: PMC11225379 DOI: 10.1186/s12931-024-02877-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024] Open
Abstract
BACKGROUND Bronchoscopic lung volume reduction (BLVR) with one-way endobronchial valves (EBV) has better outcomes when the target lobe has poor collateral ventilation, resulting in complete lobe atelectasis. High-inspired oxygen fraction (FIO2) promotes atelectasis through faster gas absorption after airway occlusion, but its application during BLVR with EBV has been poorly understood. We aimed to investigate the real-time effects of FIO2 on regional lung volumes and regional ventilation/perfusion by electrical impedance tomography (EIT) during BLVR with EBV. METHODS Six piglets were submitted to left lower lobe occlusion by a balloon-catheter and EBV valves with FIO2 0.5 and 1.0. Regional end-expiratory lung impedances (EELI) and regional ventilation/perfusion were monitored. Local pocket pressure measurements were obtained (balloon occlusion method). One animal underwent simultaneous acquisitions of computed tomography (CT) and EIT. Regions-of-interest (ROIs) were right and left hemithoraces. RESULTS Following balloon occlusion, a steep decrease in left ROI-EELI with FIO2 1.0 occurred, 3-fold greater than with 0.5 (p < 0.001). Higher FIO2 also enhanced the final volume reduction (ROI-EELI) achieved by each valve (p < 0.01). CT analysis confirmed the denser atelectasis and greater volume reduction achieved by higher FIO2 (1.0) during balloon occlusion or during valve placement. CT and pocket pressure data agreed well with EIT findings, indicating greater strain redistribution with higher FIO2. CONCLUSIONS EIT demonstrated in real-time a faster and more complete volume reduction in the occluded lung regions under high FIO2 (1.0), as compared to 0.5. Immediate changes in the ventilation and perfusion of ipsilateral non-target lung regions were also detected, providing better estimates of the full impact of each valve in place. TRIAL REGISTRATION Not applicable.
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Affiliation(s)
- Vinicius Torsani
- Divisao de Pneumologia, Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Paulo Francisco Guerreiro Cardoso
- Division of Thoracic Surgery, Thoracic Surgery Research Laboratory (LIM 61), Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - João Batista Borges
- Institute of Physiology, First Faculty of Medicine, Charles University, Albertov 5, Prague, 128 00, Czech Republic.
| | - Susimeire Gomes
- Divisao de Pneumologia, Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Henrique Takachi Moriya
- Biomedical Engineering Laboratory, Escola Politecnica da Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Andrea Fonseca da Cruz
- Biomedical Engineering Laboratory, Escola Politecnica da Universidade de Sao Paulo, Sao Paulo, Brasil
| | | | - Cristopher Kengo Nagao
- Division of Thoracic Surgery, Thoracic Surgery Research Laboratory (LIM 61), Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Mariana Fernandes Fitipaldi
- Division of Thoracic Surgery, Thoracic Surgery Research Laboratory (LIM 61), Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Marcelo do Amaral Beraldo
- Divisao de Pneumologia, Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Marcus Henrique Victor Junior
- Divisao de Pneumologia, Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Mikuláš Mlček
- Institute of Physiology, First Faculty of Medicine, Charles University, Albertov 5, Prague, 128 00, Czech Republic
| | - Paulo Manuel Pego-Fernandes
- Division of Thoracic Surgery, Thoracic Surgery Research Laboratory (LIM 61), Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - Marcelo Britto Passos Amato
- Divisao de Pneumologia, Instituto do Coracao, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brasil
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Lee H, Johnson Z, Denton S, Liu N, Akinwande D, Porter E, Kireev D. A non-invasive approach to skin cancer diagnosis via graphene electrical tattoos and electrical impedance tomography. Physiol Meas 2024; 45:055003. [PMID: 38599226 DOI: 10.1088/1361-6579/ad3d26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 04/10/2024] [Indexed: 04/12/2024]
Abstract
Objective.Making up one of the largest shares of diagnosed cancers worldwide, skin cancer is also one of the most treatable. However, this is contingent upon early diagnosis and correct skin cancer-type differentiation. Currently, methods for early detection that are accurate, rapid, and non-invasive are limited. However, literature demonstrating the impedance differences between benign and malignant skin cancers, as well as between different types of skin cancer, show that methods based on impedance differentiation may be promising.Approach.In this work, we propose a novel approach to rapid and non-invasive skin cancer diagnosis that leverages the technologies of difference-based electrical impedance tomography (EIT) and graphene electronic tattoos (GETs).Main results.We demonstrate the feasibility of this first-of-its-kind system using both computational numerical and experimental skin phantom models. We considered variations in skin cancer lesion impedance, size, shape, and position relative to the electrodes and evaluated the impact of using individual and multi-electrode GET (mGET) arrays. The results demonstrate that this approach has the potential to differentiate based on lesion impedance, size, and position, but additional techniques are needed to determine shape.Significance.In this way, the system proposed in this work, which combines both EIT and GET technology, exhibits potential as an entirely non-invasive and rapid approach to skin cancer diagnosis.
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Affiliation(s)
- Hannah Lee
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
| | - Zane Johnson
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, United States of America
| | - Spencer Denton
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
| | - Ning Liu
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
| | - Deji Akinwande
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX, United States of America
| | - Emily Porter
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
- Department of Biomedical Engineering, McGill University, Montreal, Canada
| | - Dmitry Kireev
- Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States of America
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX, United States of America
- Department of Biomedical Engineering, The University of Massachusetts Amherst, Amherst, MA, United States of America
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Yildirim S, Saygili SM, Süneçli O, Kirakli C. Comparison of the effects of open and closed aspiration on end-expiratory lung volume in acute respiratory distress syndrome. Korean J Anesthesiol 2024; 77:115-121. [PMID: 37211764 PMCID: PMC10834727 DOI: 10.4097/kja.23194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/20/2023] [Accepted: 05/21/2023] [Indexed: 05/23/2023] Open
Abstract
BACKGROUND Alveoli tend to collapse in patients with acute respiratory distress syndrome (ARDS). Endotracheal aspiration may increase alveolar collapse due to the loss of end-expiratory lung volume (EELV). We aimed to compare the loss of EELV after open and closed suction in patients with ARDS. METHODS This randomized crossover study included 20 patients receiving invasive mechanical ventilation for ARDS. Open and closed suction were applied in a random order. Lung impedance was measured using electric impedance tomography. The change in end-expiratory lung impedance end of suction and at 1, 10, 20, and 30 min after suction, was used to represent the change in EELV. Arterial blood gas analyses and ventilatory parameters such as the plateau pressure (Pplat), driving pressure (Pdrive), and compliance of the respiratory system (CRS) were also recorded. RESULTS Less volume loss was noted after closed suction than after open suction (mean ΔEELI: -2661 ± 1937 vs. -4415 ± 2363; mean difference: -1753; 95% CI [-2662, -844]; P = 0.001). EELI returned to baseline 10 min after closed suction but did not return to baseline even 30 min after open suction. After closed suction, the Pplat and Pdrive decreased while the CRS increased. Conversely, the Pplat and Pdrive increased while the CRS decreased after open suction. CONCLUSIONS Endotracheal aspiration may result in alveolar collapse due to loss of EELV. Given that closed suction is associated with less volume loss at end-expiration without worsening ventilatory parameters, it should be chosen over open suction in patients with ARDS.
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Affiliation(s)
- Süleyman Yildirim
- Intensive Care Unit, University of Health Sciences Turkey, İzmir School of Medicine, Dr. Suat Seren Chest Disease and Surgery Training and Research Hospital, İzmir, Turkey
| | - Saba Mukaddes Saygili
- Intensive Care Unit, University of Health Sciences Turkey, İzmir School of Medicine, Dr. Suat Seren Chest Disease and Surgery Training and Research Hospital, İzmir, Turkey
| | - Onur Süneçli
- Department of Physiotherapy, University of Health Sciences Turkey, İzmir School of Medicine, Dr. Suat Seren Chest Disease and Surgery Training and Research Hospital, İzmir, Turkey
| | - Cenk Kirakli
- Intensive Care Unit, University of Health Sciences Turkey, İzmir School of Medicine, Dr. Suat Seren Chest Disease and Surgery Training and Research Hospital, İzmir, Turkey
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Martin KT, Xin Y, Gaulton TG, Victor M, Santiago RR, Kim T, Morais CCA, Kazimi AA, Connell M, Gerard SE, Herrmann J, Mueller AL, Lenart A, Shen J, Khan SS, Petrov M, Reutlinger K, Rozenberg K, Amato M, Berra L, Cereda M. Electrical Impedance Tomography Identifies Evolution of Regional Perfusion in a Porcine Model of Acute Respiratory Distress Syndrome. Anesthesiology 2023; 139:815-826. [PMID: 37566686 PMCID: PMC10840641 DOI: 10.1097/aln.0000000000004731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
BACKGROUND Bedside electrical impedance tomography could be useful to visualize evolving pulmonary perfusion distributions when acute respiratory distress syndrome worsens or in response to ventilatory and positional therapies. In experimental acute respiratory distress syndrome, this study evaluated the agreement of electrical impedance tomography and dynamic contrast-enhanced computed tomography perfusion distributions at two injury time points and in response to increased positive end-expiratory pressure (PEEP) and prone position. METHODS Eleven mechanically ventilated (VT 8 ml · kg-1) Yorkshire pigs (five male, six female) received bronchial hydrochloric acid (3.5 ml · kg-1) to invoke lung injury. Electrical impedance tomography and computed tomography perfusion images were obtained at 2 h (early injury) and 24 h (late injury) after injury in supine position with PEEP 5 and 10 cm H2O. In eight animals, electrical impedance tomography and computed tomography perfusion imaging were also conducted in the prone position. Electrical impedance tomography perfusion (QEIT) and computed tomography perfusion (QCT) values (as percentages of image total) were compared in eight vertical regions across injury stages, levels of PEEP, and body positions using mixed-effects linear regression. The primary outcome was agreement between QEIT and QCT, defined using limits of agreement and Pearson correlation coefficient. RESULTS Pao2/Fio2 decreased over the course of the experiment (healthy to early injury, -253 [95% CI, -317 to -189]; early to late injury, -88 [95% CI, -151 to -24]). The limits of agreement between QEIT and QCT were -4.66% and 4.73% for the middle 50% quantile of average regional perfusion, and the correlation coefficient was 0.88 (95% CI, 0.86 to 0.90]; P < 0.001). Electrical impedance tomography and computed tomography showed similar perfusion redistributions over injury stages and in response to increased PEEP. QEIT redistributions after positional therapy underestimated QCT in ventral regions and overestimated QCT in dorsal regions. CONCLUSIONS Electrical impedance tomography closely approximated computed tomography perfusion measures in experimental acute respiratory distress syndrome, in the supine position, over injury progression and with increased PEEP. Further validation is needed to determine the accuracy of electrical impedance tomography in measuring perfusion redistributions after positional changes. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Kevin T Martin
- Department of Anesthesia and Perioperative Care, University of California San Francisco, CA, USA
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi Xin
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Timothy G Gaulton
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Marcus Victor
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Electronics Engineering Division, Aeronautics Institute of Technology, São Paulo, Brazil
| | - Roberta R Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Taehwan Kim
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Caio C A Morais
- Department of Physical Therapy, Federal University of Pernambuco, Recife, Brazil
| | - Aubrey A Kazimi
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc Connell
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
| | - Sarah E Gerard
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Jacob Herrmann
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Ariel L Mueller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Austin Lenart
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Jiacheng Shen
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Sherbano S Khan
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Mihail Petrov
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristan Reutlinger
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Karina Rozenberg
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Marcelo Amato
- Department of Cardio-Pulmonary, University of São Paulo, São Paulo, Brazil
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
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Cai C, Chen S, Liu L. Detection of Fatigue Cracks for Concrete Structures by Using Carbon Ink-Based Conductive Skin and Electrical Resistance Tomography. SENSORS (BASEL, SWITZERLAND) 2023; 23:8382. [PMID: 37896476 PMCID: PMC10610693 DOI: 10.3390/s23208382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/29/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023]
Abstract
Concrete is among the most widely used structural materials in buildings and bridges all over the world. During their service life, concrete structures may inevitably display cracks due to long-term fatigue loads, leading to the degradation of structural integrity. Thus, it is very important to detect cracks and their growth in concrete structures using an automated structural health monitoring system. In this paper, experimental research on crack detection and imaging of concrete structures by using sensing skin and electrical resistance tomography (ERT) is presented. Carbon ink is screen-printed on the surface of concrete as a conductive material to form sensing skins. With these sensing skins, when cracks occur on or near the surface, it breaks the continuity of the sensing skins and significantly reduces conductivity in cracking areas. Then, after exciting small currents in sensing skins and measuring related voltage data, an inverse analysis based on total variation (TV) regularization is adopted to reconstruct tomographic images showing conductivity changes in sensing skins, to detect the occurrence and growth of cracks. The effectiveness of conductive sensing skins and our related crack detection method is validated in experimental studies on a concrete beam subjected to fatigue tests.
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Affiliation(s)
| | - Shaolin Chen
- College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China; (C.C.)
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Pessoa D, Rocha BM, Strodthoff C, Gomes M, Rodrigues G, Petmezas G, Cheimariotis GA, Kilintzis V, Kaimakamis E, Maglaveras N, Marques A, Frerichs I, Carvalho PD, Paiva RP. BRACETS: Bimodal repository of auscultation coupled with electrical impedance thoracic signals. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 240:107720. [PMID: 37544061 DOI: 10.1016/j.cmpb.2023.107720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/27/2023] [Accepted: 07/10/2023] [Indexed: 08/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Respiratory diseases are among the most significant causes of morbidity and mortality worldwide, causing substantial strain on society and health systems. Over the last few decades, there has been increasing interest in the automatic analysis of respiratory sounds and electrical impedance tomography (EIT). Nevertheless, no publicly available databases with both respiratory sound and EIT data are available. METHODS In this work, we have assembled the first open-access bimodal database focusing on the differential diagnosis of respiratory diseases (BRACETS: Bimodal Repository of Auscultation Coupled with Electrical Impedance Thoracic Signals). It includes simultaneous recordings of single and multi-channel respiratory sounds and EIT. Furthermore, we have proposed several machine learning-based baseline systems for automatically classifying respiratory diseases in six distinct evaluation tasks using respiratory sound and EIT (A1, A2, A3, B1, B2, B3). These tasks included classifying respiratory diseases at sample and subject levels. The performance of the classification models was evaluated using a 5-fold cross-validation scheme (with subject isolation between folds). RESULTS The resulting database consists of 1097 respiratory sounds and 795 EIT recordings acquired from 78 adult subjects in two countries (Portugal and Greece). In the task of automatically classifying respiratory diseases, the baseline classification models have achieved the following average balanced accuracy: Task A1 - 77.9±13.1%; Task A2 - 51.6±9.7%; Task A3 - 38.6±13.1%; Task B1 - 90.0±22.4%; Task B2 - 61.4±11.8%; Task B3 - 50.8±10.6%. CONCLUSION The creation of this database and its public release will aid the research community in developing automated methodologies to assess and monitor respiratory function, and it might serve as a benchmark in the field of digital medicine for managing respiratory diseases. Moreover, it could pave the way for creating multi-modal robust approaches for that same purpose.
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Affiliation(s)
- Diogo Pessoa
- University of Coimbra Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal.
| | - Bruno Machado Rocha
- University of Coimbra Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - Claas Strodthoff
- Department of Anesthesiology, and Intensive Care Medicine, University Medical Center Schleswig-Holstein Campus Kiel, Kiel 24105, Schleswig-Holstein, Germany
| | - Maria Gomes
- Lab3R - Respiratory Research and Rehabilitation Laboratory, School of Health Sciences (ESSUA), University of Aveiro, 3810-193 Aveiro, Portugal
| | - Guilherme Rodrigues
- Lab3R - Respiratory Research and Rehabilitation Laboratory, School of Health Sciences (ESSUA), University of Aveiro, 3810-193 Aveiro, Portugal
| | - Georgios Petmezas
- 2nd Department of Obstetrics and Gynaecology, The Medical School, 54124 Thessaloniki, Greece
| | | | - Vassilis Kilintzis
- 2nd Department of Obstetrics and Gynaecology, The Medical School, 54124 Thessaloniki, Greece
| | - Evangelos Kaimakamis
- 1st Intensive Care Unit, "G. Papanikolaou" General Hospital of Thessaloniki, 57010 Pilea Hortiatis, Greece
| | - Nicos Maglaveras
- 2nd Department of Obstetrics and Gynaecology, The Medical School, 54124 Thessaloniki, Greece
| | - Alda Marques
- Lab3R - Respiratory Research and Rehabilitation Laboratory, School of Health Sciences (ESSUA), University of Aveiro, 3810-193 Aveiro, Portugal; Institute of Biomedicine (iBiMED), University of Aveiro, 3810-193 Aveiro, Portugal
| | - Inéz Frerichs
- Department of Anesthesiology, and Intensive Care Medicine, University Medical Center Schleswig-Holstein Campus Kiel, Kiel 24105, Schleswig-Holstein, Germany
| | - Paulo de Carvalho
- University of Coimbra Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
| | - Rui Pedro Paiva
- University of Coimbra Centre for Informatics and Systems of the University of Coimbra, Department of Informatics Engineering, 3030-290 Coimbra, Portugal
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Ribeiro De Santis Santiago R, Xin Y, Gaulton TG, Alcala G, León Bueno de Camargo ED, Cereda M, Britto Passos Amato M, Berra L. Lung Imaging Acquisition with Electrical Impedance Tomography: Tackling Common Pitfalls. Anesthesiology 2023; 139:329-341. [PMID: 37402247 DOI: 10.1097/aln.0000000000004613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2023]
Abstract
Electrical impedance tomography is a powerful tool for lung imaging that can be employed at the bedside in multiple clinical scenarios. Diagnosing and preventing interpretation pitfalls will ensure reliable data and allow for appropriate clinical decision-making.
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Affiliation(s)
- Roberta Ribeiro De Santis Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yi Xin
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Timothy G Gaulton
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Glasiele Alcala
- Pulmonary Division, Heart Institute (InCor), University of São Paulo, São Paulo, Brazil
| | - Erick Dario León Bueno de Camargo
- Federal University of ABC/Engineering, Modeling and Applied Social Sciences Centre, Biomedical Engineering, São Bernardo do Campo, Brazil
| | - Maurizio Cereda
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Reza MS, Jin L, Jeong YJ, Oh TI, Kim H, Kim KJ. Electrospun Rubber Nanofiber Web-Based Dry Electrodes for Biopotential Monitoring. SENSORS (BASEL, SWITZERLAND) 2023; 23:7377. [PMID: 37687833 PMCID: PMC10490276 DOI: 10.3390/s23177377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/10/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023]
Abstract
This study aims to find base materials for dry electrode fabrication with high accuracy and without reducing electrode performance for long-term bioelectric potential monitoring after electroless silver plating. Most applications of dry electrodes that have been developed in the past few decades are restricted by low accuracy compared to commercial Ag/AgCl gel electrodes, as in our previous study of PVDF-based dry electrodes. In a recent study, however, nanoweb-based chlorinated polyisoprene (CPI) and poly(styrene-b-butadiene-b-styrene) (SBS) rubber were selected as promising candidates due to their excellent elastic properties, as well as their nanofibril nature, which may improve electrode durability and skin contact. The electroless silver plating technique was employed to coat the nanofiber web with silver, and silver nanoweb(AgNW)-based dry electrodes were fabricated. The key electrode properties (contact impedance, step response, and noise characteristics) for AgNW dry electrodes were investigated thoroughly using agar phantoms. The dry electrodes were subsequently tested on human subjects to establish their realistic performance in terms of ECG, EMG monitoring, and electrical impedance tomography (EIT) measurements. The experimental results demonstrated that the AgNW dry electrodes, particularly the SBS-AgNW dry electrodes, performed similarly to commercial Ag/AgCl gel electrodes and were outperformed in terms of long-term stability.
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Affiliation(s)
- Mohammad Shamim Reza
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Yongin 17104, Gyeonggi-do, Republic of Korea; (M.S.R.); (L.J.)
| | - Lu Jin
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Yongin 17104, Gyeonggi-do, Republic of Korea; (M.S.R.); (L.J.)
| | - You Jeong Jeong
- Department of Biomedical Engineering, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; (Y.J.J.); (T.I.O.)
| | - Tong In Oh
- Department of Biomedical Engineering, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea; (Y.J.J.); (T.I.O.)
| | - Hongdoo Kim
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Yongin 17104, Gyeonggi-do, Republic of Korea; (M.S.R.); (L.J.)
| | - Kap Jin Kim
- Department of Advanced Materials Engineering for Information & Electronics, Kyung Hee University, Yongin 17104, Gyeonggi-do, Republic of Korea; (M.S.R.); (L.J.)
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Zeng S, Kwok WC, Cao P, Zouari F, Yun Lee PT, Chan RW, Touboul A. Deep learning based reconstruction enables high-resolution electrical impedance tomography for lung function assessment. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083133 DOI: 10.1109/embc40787.2023.10340392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Recently, deep learning based methods have shown potential as alternative approaches for lung time difference electrical impedance tomography (tdEIT) reconstruction other than traditional regularized least square methods, that have inherent severe ill-posedness and low spatial resolution posing challenges for further interpretation. However, the validation of deep learning reconstruction quality is mainly focused on simulated data rather than in vivo human chest data, and on image quality rather than clinical indicator accuracy. In this study, a variational autoencoder is trained on high-resolution human chest simulations, and inference results on an EIT dataset collected from 22 healthy subjects performing various breathing paradigms are benchmarked with simultaneous spirometry measurements. The deep learning reconstructed global conductivity is significantly correlated with measured volume-time curves with correlation > 0.9. EIT lung function indicators from the reconstruction are also highly correlated with standard spirometry indicators with correlation > 0.75.Clinical Relevance- Our deep learning reconstruction method of lung tdEIT can predict lung volume and spirometry indicators while generating high-resolution EIT images, revealing potential of being a competitive approach in clinical settings.
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Chen R, Krueger-Ziolek S, Battistel A, Rupitsch SJ, Moeller K. Effect of a Patient-Specific Structural Prior Mask on Electrical Impedance Tomography Image Reconstructions. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094551. [PMID: 37177755 PMCID: PMC10181649 DOI: 10.3390/s23094551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/27/2023] [Accepted: 05/06/2023] [Indexed: 05/15/2023]
Abstract
Electrical Impedance Tomography (EIT) is a low-cost imaging method which reconstructs two-dimensional cross-sectional images, visualising the impedance change within the thorax. However, the reconstruction of an EIT image is an ill-posed inverse problem. In addition, blurring, anatomical alignment, and reconstruction artefacts can hinder the interpretation of EIT images. In this contribution, we introduce a patient-specific structural prior mask into the EIT reconstruction process, with the aim of improving image interpretability. Such a prior mask ensures that only conductivity changes within the lung regions are reconstructed. To evaluate the influence of the introduced structural prior mask, we conducted numerical simulations with two scopes in terms of their different ventilation statuses and varying atelectasis scales. Quantitative analysis, including the reconstruction error and figures of merit, was applied in the evaluation procedure. The results show that the morphological structures of the lungs introduced by the mask are preserved in the EIT reconstructions and the reconstruction artefacts are decreased, reducing the reconstruction error by 25.9% and 17.7%, respectively, in the two EIT algorithms included in this contribution. The use of the structural prior mask conclusively improves the interpretability of the EIT images, which could facilitate better diagnosis and decision-making in clinical settings.
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Affiliation(s)
- Rongqing Chen
- Institute for Technical Medicine (ITeM), Hochschule Furtwangen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany
- Faculty of Engineering, University of Freiburg, Georges-Koehler-Allee 101, 79110 Freiburg, Germany
| | - Sabine Krueger-Ziolek
- Institute for Technical Medicine (ITeM), Hochschule Furtwangen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany
| | - Alberto Battistel
- Institute for Technical Medicine (ITeM), Hochschule Furtwangen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany
| | - Stefan J Rupitsch
- Faculty of Engineering, University of Freiburg, Georges-Koehler-Allee 101, 79110 Freiburg, Germany
| | - Knut Moeller
- Institute for Technical Medicine (ITeM), Hochschule Furtwangen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany
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Chen R, Krueger-Ziolek S, Lovas A, Benyó B, Rupitsch SJ, Moeller K. Structural priors represented by discrete cosine transform improve EIT functional imaging. PLoS One 2023; 18:e0285619. [PMID: 37167237 PMCID: PMC10174522 DOI: 10.1371/journal.pone.0285619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 04/26/2023] [Indexed: 05/13/2023] Open
Abstract
Structural prior information can improve electrical impedance tomography (EIT) reconstruction. In this contribution, we introduce a discrete cosine transformation-based (DCT-based) EIT reconstruction algorithm to demonstrate a way to incorporate the structural prior with the EIT reconstruction process. Structural prior information is obtained from other available imaging methods, e.g., thorax-CT. The DCT-based approach creates a functional EIT image of regional lung ventilation while preserving the introduced structural information. This leads to an easier interpretation in clinical settings while maintaining the advantages of EIT in terms of bedside monitoring during mechanical ventilation. Structural priors introduced in the DCT-based approach are of two categories in terms of different levels of information included: a contour prior only differentiates lung and non-lung region, while a detail prior includes information, such as atelectasis, within the lung area. To demonstrate the increased interpretability of the EIT image through structural prior in the DCT-based approach, the DCT-based reconstructions were compared with reconstructions from a widely applied one-step Gauss-Newton solver with background prior and from the advanced GREIT algorithm. The comparisons were conducted both on simulation data and retrospective patient data. In the simulation, we used two sets of forward models to simulate different lung conditions. A contour prior and a detail prior were derived from simulation ground truth. With these two structural priors, the reconstructions from the DCT-based approach were compared with the reconstructions from both the one-step Gauss-Newton solver and the GREIT. The difference between the reconstructions and the simulation ground truth is calculated by the ℓ2-norm image difference. In retrospective patient data analysis, datasets from six lung disease patients were included. For each patient, a detail prior was derived from the patient's CT, respectively. The detail prior was used for the reconstructions using the DCT-based approach, which was compared with the reconstructions from the GREIT. The reconstructions from the DCT-based approach are more comprehensive and interpretable in terms of preserving the structure specified by the priors, both in simulation and retrospective patient data analysis. In simulation analysis, the ℓ2-norm image difference of the DCT-based approach with a contour prior decreased on average by 34% from GREIT and 49% from the Gauss-Newton solver with background prior; for reconstructions of the DCT-based approach with detail prior, on average the ℓ2-norm image difference is 53% less than GREIT and 63% less than the reconstruction with background prior. In retrospective patient data analysis, the reconstructions from both the DCT-based approach and GREIT can indicate the current patient status, but the DCT-based approach yields more interpretable results. However, it is worth noting that the preserved structure in the DCT-based approach is derived from another imaging method, not from the EIT measurement. If the structural prior is outdated or wrong, the result might be misleadingly interpreted, which induces false clinical conclusions. Further research in terms of evaluating the validity of the structural prior and detecting the outdated prior is necessary.
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Affiliation(s)
- Rongqing Chen
- Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
- Faculty of Engineering, University of Freiburg, Freiburg, Germany
| | - Sabine Krueger-Ziolek
- Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
| | - András Lovas
- Department of Anaesthesiology and Intensive Therapy, Kiskunhalas Semmelweis Hospital, Kiskunhalas, Hungary
| | - Balázs Benyó
- Department of Control Engineering and Information Technology, Faculty of Electrical Engineering and Informatics, Budapest University of Technology and Economics, Budapest, Hungary
| | | | - Knut Moeller
- Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany
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Grivans C, Stenqvist O. Gas distribution by EIT during PEEP inflation: PEEP response and optimal PEEP with lowest trans-pulmonary driving pressure can be determined without esophageal pressure during a rapid PEEP trial in patients with acute respiratory failure. Physiol Meas 2022; 43. [PMID: 36007512 DOI: 10.1088/1361-6579/ac8ccc] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/25/2022] [Indexed: 02/07/2023]
Abstract
Objective. Protective ventilation should be based onlungmechanics and transpulmonary driving pressure (ΔPTP), as this 'hits' the lung directly.Approach. The change in end-expiratory lung volume (ΔEELV) is determined by the size of the PEEP step and the elastic properties of the lung (EL), ΔEELV/ΔPEEP. Consequently, EL can be determined as ΔPEEP/ΔEELV. By calibration of tidal inspiratory impedance change with ventilator inspiratory tidal volume, end-expiratory lung impedance changes were converted to volume changes and lung P/V curves were obtained during a PEEP trial in ten patients with acute respiratory failure. The PEEP level where ΔPTP was lowest (optimal PEEP) was determined as the steepest point of the lung P/V curve.Main results. Over-all EL ranged between 7.0-23.2 cmH2O/L. Optimal PEEP was 12.9 cmH2O (10-16) with ΔPTP of 4.1 cmH2O (2.8-7.6). Patients with highest EL were PEEP non-responders, where EL increased in non-dependent and dependent lung at high PEEP, indicating over-distension in all lung. Patients with lower EL were PEEP responders with decreasing EL in dependent lung when increasing PEEP.Significance. PEEP non-responders could be identified by regional lung P/V curves derived from ventilator calibrated EIT. Optimal PEEP could be determined from the equation for the lung P/V curve.
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Affiliation(s)
| | - Ola Stenqvist
- Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
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13
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Nascimento MS, do Prado C, Costa ELV, Alcala GC, Corrêa LC, Rossi FS, Amato MBP, Rebello CM. Effect of flow rate on the end-expiratory lung volume in infants with bronchiolitis using high-flow nasal cannula evaluated through electrical impedance tomography. Pediatr Pulmonol 2022; 57:2681-2687. [PMID: 35931651 DOI: 10.1002/ppul.26082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVES To evaluate the effects of four flow rates on the functional residual capacity (FRC) and pulmonary ventilation distribution while using a high-flow nasal cannula (HFNC). WORKING HYPOTHESIS Our hypothesis is that flow rates below 1.5 L·kg-1 ·min-1 lead to FRC loss and respiratory distress. STUDY DESIGN A single-center, prospective clinical study. PATIENT SELECTION Infants diagnosed with acute viral bronchiolitis were given HFNC. METHODOLOGY Through a prospective clinical study, the effects of four different flow rates, 2.0, 1.5, 1.0, and 0.5 L·kg-1 ·min-1 , on FRC and the pulmonary ventilation pattern were evaluated using electrical impedance tomography. The impedance variation (delta Z), end-expiratory lung volume (EELZ), respiratory rate, heart rate, respiratory distress score, and saturation/fraction of inspired oxygen ratio (SpO2 /FI O2 ), were also evaluated at each flow rate. RESULTS Among the 11 infants included, There was a decrease in respiratory distress score at a flow rate of 1.5 L·kg-1 ·min-1 (*p = 0.021), and at a flow rate of 2.0 L·kg-1 ·min-1 (**p = 0.003) compared to 0.5 L·kg-1 ·min-1 . There was also a small but significant increase in SpO2 /FiO2 at flow rates of 1.5 (*p = 0.023), and 2.0 L·kg-1 ·min-1 (**p = 0.008) compared to 0.5 L·kg-1 ·min-1 . There were no other significant changes in the clinical parameters. In the global EELZ measurements, there was a significant increase under a flow rate of 2.0 L·kg-1 ·min-1 as compared to 0.5 L·kg-1 ·min-1 (p = 0.03). In delta Z values, there were no significant variations between the different flow rates. CONCLUSION The ∆EELZ increases at the highest flow rates were accompanied by decreased distress scores and improved oxygenation.
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Affiliation(s)
- Milena S Nascimento
- Maternal-Child Department, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Cristiane do Prado
- Maternal-Child Department, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | | | - Glasiele C Alcala
- Divisão de Pneumologia, Departamento Cardiopulmonar, Instituto do Coração (INCOR), Sao Paulo City, Sao Paulo, Brazil
| | - Letícia C Corrêa
- Divisão de Pneumologia, Departamento Cardiopulmonar, Instituto do Coração (INCOR), Sao Paulo City, Sao Paulo, Brazil
| | - Felipe S Rossi
- Maternal-Child Department, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Marcelo B P Amato
- Divisão de Pneumologia, Departamento Cardiopulmonar, Instituto do Coração (INCOR), Sao Paulo City, Sao Paulo, Brazil
| | - Celso M Rebello
- Maternal-Child Department, Hospital Israelita Albert Einstein, São Paulo, Brazil
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Liu J, Zhu Z, Xiong H, Li C, Chen Y. A new current injection and voltage measurement strategy of 3D electrical impedance tomography based on scanning electrode. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:094704. [PMID: 36182463 DOI: 10.1063/5.0105317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
Electrical impedance tomography (EIT) technology is an important imaging approach to show the conductivity distribution of the area noninvasively. Recently, 3D EIT has been extensively studied for its more comprehensive display of electrical properties. Nonetheless, most 3D EIT electrode models are based on multilayer ring electrodes and only suitable for specific scenarios. In order to overcome its limitations and alleviate the ill-condition of 3D EIT, we propose a new current injection and voltage measurement strategy based on scanning row electrodes (SRE) called the back electrode excitation (BEEM) strategy and select the optimal number of excitation electrodes according to different imaging effects. A 3D electrical impedance imaging system based on SRE is designed. Then, the traditional excitation measurement strategy is introduced, and the two strategies are compared through simulation and actual experiments. The results show that the BEEM strategy with SRE can not only obtain rich potential information in the finite field but also significantly improve the imaging detection depth, accuracy, and noise immunity compared with the flat electrode array.
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Affiliation(s)
- Jinzhen Liu
- School of Control Science and Engineering, Tiangong University, Tianjin, China
| | - Zhaoqi Zhu
- School of Control Science and Engineering, Tiangong University, Tianjin, China
| | - Hui Xiong
- School of Control Science and Engineering, Tiangong University, Tianjin, China
| | - Chunchan Li
- Engineering Teaching Practice Training Center, Tiangong University, Tianjin, China
| | - Yunjun Chen
- School of Control Science and Engineering, Tiangong University, Tianjin, China
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Yap DYH, Ma EKY, Oon WY, Lee WH, Li WH, Ho CM, Gautama B, Chan RW, Wong EC. Bio-conductivity characteristics of chronic kidney disease stages examined by portable frequency-difference electrical impedance tomography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:3378-3381. [PMID: 36086019 DOI: 10.1109/embc48229.2022.9871377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chronic kidney disease (CKD) is an escalating global health concern, and non-invasive means for early CKD detection is eagerly awaited. Here, we explore the potential of using home-based frequency-difference electrical impedance tomography (fdEIT) to evaluate CKD based on bio-conductivity characteristics. We first verified the feasibility of using portable EIT capturing bio-conductivity in fresh pig kidneys ex vivo. We further performed bio-conductivity measurement in vivo paired with standard eGFR measurements on CKD patients by EIT and traditional blood test, respectively. Our results showed a significant correlation between renal bio-conductivity changes captured by fdEIT and standard eGFR scores. These results hold promise to be developed into a non-invasive and portable device for early CKD detection and longitudinal CKD treatment monitoring in clinical, community and home-based settings. Clinical Relevance - A novel non-invasive bio-conductivity approach was developed for CKD classification. The renal assessment with portable EIT device demonstrated the potential to ameliorate the detection and classification of CKD into a portable, accessible, self-administrable home-based process.
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Honkoop P, Usmani O, Bonini M. The Current and Future Role of Technology in Respiratory Care. Pulm Ther 2022; 8:167-179. [PMID: 35471689 PMCID: PMC9039604 DOI: 10.1007/s41030-022-00191-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/05/2022] [Indexed: 11/29/2022] Open
Abstract
Over the past few decades, technology and improvements in artificial intelligence have dramatically changed major sectors of our day-to-day lives, including the field of healthcare. E-health includes a wide range of subdomains, such as wearables, smart-inhalers, portable electronic spirometers, digital stethoscopes, and clinical decision support systems. E-health has been consistently shown to enhance the quality of care, improve adherence to therapy, and allow early detection of worsening in chronic pulmonary diseases. The present review addresses the current and potential future role of major e-health tools and approaches in respiratory medicine, with the aim of providing readers with trustful and updated evidence to increase their awareness of the topic, and to allow them to optimally benefit from the latest innovation technology. Collected literature evidence shows that the potential of technology tools in respiratory medicine mainly relies on three fundamental interactions: between clinicians, between clinician and patient, and between patient and health technology. However, it would be desirable to establish widely agreed and adopted standards for conducting trials and reporting results in this area, as well as to take into proper consideration potentially relevant pitfalls related to privacy protection and compliance with regulatory procedures.
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Affiliation(s)
- Persijn Honkoop
- Dept of Biomedical Data Sciences, Section of Medical Decision Making, Leiden University Medical Centre, Leiden, The Netherlands
| | - Omar Usmani
- National Heart and Lung Institute (NHLI), Imperial College London, Guy Scadding Building, Dovehouse Street, London, SW3 6LY, UK.
| | - Matteo Bonini
- National Heart and Lung Institute (NHLI), Imperial College London, Guy Scadding Building, Dovehouse Street, London, SW3 6LY, UK.,Department of Cardiovascular and Thoracic Sciences, Università Cattolica del Sacro Cuore, Rome, Italy.,Department of Clinical and Surgical Sciences, Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
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Zong Z, Wang Y, He S, Wei Z. Adaptively Regularized Bases-Expansion Subspace Optimization Methods for Electrical Impedance Tomography. IEEE Trans Biomed Eng 2022; 69:3098-3108. [PMID: 35344482 DOI: 10.1109/tbme.2022.3161526] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE In this work, to deal with the difficulties in choosing regularization weighting parameters and low spatial resolution problems in difference electrical impedance tomography (EIT), we propose two adaptively regularized bases-expansion subspace optimization methods (AR-BE-SOMs). METHODS Firstly, an adaptive L1-norm based total variation (TV) regularization is introduced under the framework of BE-SOM. Secondly, besides the additive regularization, an adaptive weighted L2-norm multiplicative regularization is further proposed. The regularized objective functions are optimized by conjugate gradient method, where the unknowns in both methods are update alternatively between induced contrast current (ICC) and conductivity domain. CONCLUSION Both numerical and experimental tests are conducted to validate the proposed methods, where AR-BE-SOMs show better edge-preserving, anti-noise performance, lower relative errors, and higher structure similarity indexes than BE-SOM. SIGNIFICANCE Unlike the common regularization techniques in EIT, the proposed regularization factors can be obtained adaptively during the optimization process. More importantly, ARBE-SOMs perform well in reconstructions of some challenging geometry with sharp corners such as the heart and lung phantoms, deformation phantoms, triangles and even rectangles. It is expected that the proposed AR-BE-SOMs will find their applications for high-quality lung health monitoring and other clinical applications.
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Li Z, Qin S, Chen C, Mei S, Yao Y, Zhao Z, Li W, Deng Y, Gao Y. Emerging Trends and Hot Spots of Electrical Impedance Tomography Applications in Clinical Lung Monitoring. Front Med (Lausanne) 2022; 8:813640. [PMID: 35174185 PMCID: PMC8841839 DOI: 10.3389/fmed.2021.813640] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/28/2021] [Indexed: 12/14/2022] Open
Abstract
Objective This study explores the emerging trends and hot topics concerning applications on electrical impedance tomography (EIT) in clinical lung monitoring. Methods Publications on EIT applications in clinical lung monitoring in 2001–2021 were extracted from the Web of Science Core Collection (WoSCC). The search strategy was “electrical impedance tomography” and “lung.” CiteSpace, a VOS viewer was used to study the citation characteristics, cooperation, and keyword co-occurrence. Moreover, co-cited reference clustering, structural variation analysis (SVA), and future research trends were presented. Results Six hundred and thirty-six publications were included for the final analysis. The global annual publications on clinical lung monitoring gradually increased in the last two decades. Germany contributes 32.2% of total global publications. University Medical Center Schleswig-Holstein (84 publications, cited frequency 2,205), Physiological Measurement (105 publications, cited frequency 2,056), and Inéz Frerichs (116 articles, cited frequency 3,609) were the institution, journal, and author with the largest number of article citations in the research field. “Electrical impedance tomography” (occurrences, 304), “mechanical ventilation” (occurrences, 99), and “acute respiratory distress syndrome” (occurrences, 67) were the top most three frequent keywords, “noninvasive monitoring” (Avg, pub, year: 2008.17), and “extracorporeal membrane oxygenation” (Avg, pub, year: 2019.60) were the earliest and latest keywords. The keywords “electrical impedance tomography” (strength 7.88) and co-cited reference “Frerichs I, 2017, THORAX” (strength 47.45) had the highest burst value. “Driving pressure,” “respiratory failure,” and “titration” are the three keywords still maintaining a high brush value until now. The largest and smallest cluster of the co-cited references are “obstructive lung diseases” (#0, size: 97) and “lung perfusion” (#20, size: 5). Co-cited reference “Frerichs I, 2017, THORAX” (modularity change rate: 98.49) has the highest structural variability. Categories with most and least interdisciplinary crossing are “ENGINEERING” and “CRITICAL CARE MEDICINE.” Conclusions EIT is a valuable technology for clinical lung monitoring, gradually converting from imaging techniques to the clinic. Research hot spots may continue monitoring techniques, the ventilation distribution of acute respiratory distress syndrome (ARDS), and respiratory therapy strategies. More diversified lung function monitoring studies, such as lung perfusion and interdisciplinary crossing, are potentially emerging research trends.
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Affiliation(s)
- Zhe Li
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shaojie Qin
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Chen
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shuya Mei
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yulong Yao
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Wen Li
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Wen Li
| | - Yuxiao Deng
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Yuxiao Deng
| | - Yuan Gao
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Yuan Gao
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Nascimento MS, Alcala GC, Guzman AIA, Corrêa LC, Baggio DM, Rossi FS, Fascina LP, Amato MBP, do Prado C. Electrical impedance tomography in pediatric patients with COVID-19, the first reports. BMC Pulm Med 2021; 21:357. [PMID: 34749685 PMCID: PMC8573758 DOI: 10.1186/s12890-021-01716-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/25/2021] [Indexed: 11/16/2022] Open
Abstract
Introduction Electrical impedance tomography (EIT) is a noninvasive, radiation-free, bedside tool to monitor ventilation distribution in real time. Objective To evaluate, in pediatric COVID-19 patients, the ventilation distribution using EIT and compare it to thoracic computed tomography (TCT) or chest radiograph results obtained in these patients. Methods This was a prospective, observational clinical study including pediatric patients admitted to the intensive care unit of a private hospital. The patients monitored with EIT tested positive for COVID-19 and were submitted to the previously mentioned radiation exams. EIT monitoring lasted 15 min and no sedation was used. Results Six patients were included in this study. The main differences observed in the EIT were in the right-left distribution and were compatible with the morphological changes found in the TCT or radiograph images due to COVID-19 infection. Conclusion We conclude that EIT is ready to investigate the ventilatory profile present at different lung diseases, including COVID-19, and might postpone or mitigate the need of repeated ionizing radiation exams in the pediatric population, although larger pediatric cohorts comparing to standard radiological imaging are needed.
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Affiliation(s)
- Milena S Nascimento
- Department of Pediatrics, Hospital Israelita Albert Einstein, Albert Einstein Avenue, 627-701, São Paulo, SP, 05651-901, Brazil.
| | | | | | | | - Diana M Baggio
- Department of Pediatrics, Hospital Israelita Albert Einstein, Albert Einstein Avenue, 627-701, São Paulo, SP, 05651-901, Brazil
| | - Felipe S Rossi
- Department of Pediatrics, Hospital Israelita Albert Einstein, Albert Einstein Avenue, 627-701, São Paulo, SP, 05651-901, Brazil
| | - Linus P Fascina
- Department of Pediatrics, Hospital Israelita Albert Einstein, Albert Einstein Avenue, 627-701, São Paulo, SP, 05651-901, Brazil
| | - Marcelo B P Amato
- Divisão de Pneumologia, Cardiopulmonary Department, Heart Institute (INCOR), São Paulo, SP, Brazil
| | - Cristiane do Prado
- Department of Pediatrics, Hospital Israelita Albert Einstein, Albert Einstein Avenue, 627-701, São Paulo, SP, 05651-901, Brazil
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Lin BS, Yu HR, Kuo YT, Liu YW, Chen HY, Lin BS. Wearable Electrical Impedance Tomography Belt With Dry Electrodes. IEEE Trans Biomed Eng 2021; 69:955-962. [PMID: 34495826 DOI: 10.1109/tbme.2021.3110527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electrical impedance tomography (EIT) is a noninvasive imaging technology used to reconstruct the conductivity distribution in objects and the human body. In recent years, numerous EIT systems and image reconstruction algorithms have been developed. However, most of these EIT systems require conventional electrodes with conductive gels (wet electrodes) and cannot be adapted to different body types, resulting in limited applicability. In this study, a wearable wireless EIT belt with dry electrodes was designed to enable EIT imaging of the human body without using wet electrodes. The specific design of the belt mechanism and dry electrodes provide the advantages of easy wear and adaptation to different body sizes. Additionally, the GaussNewton method was used to optimize the EIT image. Finally, experiments were performed on the phantom and human body to validate the performance of the proposed EIT belt. The results demonstrate that the proposed system can provide accurate location information of the objects in the EIT image and the system can be successfully applied for noninvasive measurement of the human body.
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Poni R, Neufeld E, Capstick M, Bodis S, Samaras T, Kuster N. Feasibility of Temperature Control by Electrical Impedance Tomography in Hyperthermia. Cancers (Basel) 2021; 13:3297. [PMID: 34209300 PMCID: PMC8268554 DOI: 10.3390/cancers13133297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 11/17/2022] Open
Abstract
We present a simulation study investigating the feasibility of electrical impedance tomography (EIT) as a low cost, noninvasive technique for hyperthermia (HT) treatment monitoring and adaptation. Temperature rise in tissues leads to perfusion and tissue conductivity changes that can be reconstructed in 3D by EIT to noninvasively map temperature and perfusion. In this study, we developed reconstruction methods and investigated the achievable accuracy of EIT by simulating HT treatmentlike scenarios, using detailed anatomical models with heterogeneous conductivity distributions. The impact of the size and location of the heated region, the voltage measurement signal-to-noise ratio, and the reference model personalization and accuracy were studied. Results showed that by introducing an iterative reconstruction approach, combined with adaptive prior regions and tissue-dependent penalties, planning-based reference models, measurement-based reweighting, and physics-based constraints, it is possible to map conductivity-changes throughout the heated domain, with an accuracy of around 5% and cm-scale spatial resolution. An initial exploration of the use of multifrequency EIT to separate temperature and perfusion effects yielded promising results, indicating that temperature reconstruction accuracy can be in the order of 1 ∘C. Our results suggest that EIT can provide valuable real-time HT monitoring capabilities. Experimental confirmation in real-world conditions is the next step.
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Affiliation(s)
- Redi Poni
- Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland; (R.P.); (N.K.)
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland; (M.C.); (S.B.)
| | - Esra Neufeld
- Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland; (R.P.); (N.K.)
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland; (M.C.); (S.B.)
| | - Myles Capstick
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland; (M.C.); (S.B.)
| | - Stephan Bodis
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland; (M.C.); (S.B.)
- Center of Radiation Oncology KSA-KSB, Kantonsspital Aarau, 5001 Aarau, Switzerland
| | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
| | - Niels Kuster
- Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland; (R.P.); (N.K.)
- Foundation for Research on Information Technologies in Society (IT’IS), 8004 Zurich, Switzerland; (M.C.); (S.B.)
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Low Power Contactless Bioimpedance Sensor for Monitoring Breathing Activity. SENSORS 2021; 21:s21062081. [PMID: 33809602 PMCID: PMC7999750 DOI: 10.3390/s21062081] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/07/2021] [Accepted: 03/11/2021] [Indexed: 11/17/2022]
Abstract
An electronic circuit for contactless detection of impedance changes in a tissue is presented. It operates on the principle of resonant frequency change of the resonator having the observed tissue as a dielectric. The operating frequency reflects the tissue dielectric properties (i.e., the tissue composition and on the tissue physiological changes). The sensor operation was tested within a medical application by measuring the breathing of a patient, which was an easy detectable physiological process. The advantage over conventional contact bioimpedance measurement methods is that no direct contact between the resonator and the body is required. Furthermore, the sensor's wide operating range, ability to adapt to a broad range of measured materials, fast response, low power consumption, and small outline dimensions enables applications not only in the medical sector, but also in other domains. This can be extended, for example, to food industry or production maintenance, where the observed phenomena are reflected in dynamic dielectric properties of the observed object or material.
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Xia F, Pan C, Wang L, Liu L, Liu S, Guo F, Yang Y, Huang Y. Physiological effects of different recruitment maneuvers in a pig model of ARDS. BMC Anesthesiol 2020; 20:266. [PMID: 33087066 PMCID: PMC7576861 DOI: 10.1186/s12871-020-01164-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 09/16/2020] [Indexed: 12/16/2022] Open
Abstract
Background In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. Methods ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the ratio of arterial partial pressure of oxygen (PaO2) of fraction of inspired oxygen (P/F) was < 100 mmHg and remained stable for 30 min (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation, increments of positive end-expiratory pressure (PEEP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and electrical impedance tomography were recorded at baseline, TARDS, and before and after each recruitment maneuver. Results In all ten pigs, ARDS was successfully induced with a mean 2.8 ± 1.03 L bronchoalveolar lavages. PaO2, P/F, and compliance were significantly improved after recruitment with sustained inflation, increments of PEEP or PCV (all p < 0.05), and there were no significant differences between maneuvers. Global inhomogeneity index significantly decreased after recruitment with sustained inflation, increments of PEEP, or PCV. There were no significant differences in global inhomogeneity before or after recruitment with the different maneuvers. The decrease in global inhomogeneity index (ΔGI) was significantly greater after recruitment with increments of PEEP compared to sustained inflation (p = 0.023), but there was no significant difference in ΔGI between increments of PEEP and PCV or between sustained inflation and PCV. Conclusion Sustained inflation, increments of PEEP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. Increments of PEEP significantly improved inhomogeneity of the lung compared to sustained inflation, while there was no difference between increments of PEEP and PCV or between sustained inflation and PCV.
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Affiliation(s)
- Feiping Xia
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Chun Pan
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Lihui Wang
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Ling Liu
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Songqiao Liu
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Fengmei Guo
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Yi Yang
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China
| | - Yingzi Huang
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, No.87, Dingjiaqiao Road, Gulou District, Nanjing, 210009, Jiangsu, China.
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Kao TJ, Amm B, Ashe J, Davenport D. Pulmonary Ventilation and Pulsatile Perfusion Imaging on Premature Neonates using Simultaneous Multi-Source EIT. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:1444-1447. [PMID: 33018262 DOI: 10.1109/embc44109.2020.9176446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We applied our Simultaneous Multi-Source Electrical Impedance Tomography (SMS-EIT) system to detect pulmonary ventilation and pulsatile perfusion on 5 preterm newborns with respiratory distress syndrome under the nasal continuous positive airway pressure (CPAP) treatment. The results show that derived impedance changes have a potential for clinical application to evaluate effects in spontaneously breathing preterm infants with and without CPAP.
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Munir B, Murphy EK, Mallick A, Gutierrez H, Zhang F, Verga S, Smith C, Levy S, McIlduff C, Sarbesh P, Halter RJ, Rutkove SB. A robust and novel electrical impedance metric of pulmonary function in ALS patients. Physiol Meas 2020; 41:044005. [PMID: 32240997 DOI: 10.1088/1361-6579/ab85cf] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Pulmonary function tests (PFTs) are important for assessing respiratory function in amyotrophic lateral sclerosis (ALS) patients. However, weakness of oral and glottal closure, due to concomitant bulbar dysfunction, may result in unreliable PFT values stemming from leakage of air around the breathing tube and through the glottis. In this study, we assessed whether standard thoracic electrical impedance tomography (EIT) could serve as a surrogate measure for PFTs. APPROACH Thoracic EIT was performed simultaneously with standard PFTs on seven ALS patients without clinical bulbar weakness (six men and one woman, mean age of 63 years) and ten healthy volunteers (seven men and three women, mean age of 57 years). A raw impedance metric along with more standard EIT measures were computed and correlated with the normalized forced vital capacity (FVC). Additionally, test/re-test metrics and EIT images were analyzed. MAIN RESULTS The impedance metric was found to be robust and sensitive to lung activity. We also identified qualitative EIT differences between healthy volunteers and ALS patients, with the ALS images showing greater heterogeneity. Significant correlations with FVC were found for both impedance and EIT metrics in ALS patients (r2 = 0.89) and for the impedance metric only in healthy volunteers (r2 = 0.49). SIGNIFICANCE This suggests that EIT, using our novel impedance metric, has the potential to serve as an alternative technology to standard PFTs for assessing pulmonary function in patients with ALS, offering new metrics of disease status for those with bulbar weakness.
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Affiliation(s)
- Badria Munir
- Department of Neurology, Beth Israel Deaconess Medical Center (BIDMC), Boston, MA 02215, United States of America. Harvard Medical School, Boston, MA 02115, United States of America
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Li H, Liu X, Xu C, Yang B, Fu D, Dong X, Fu F. Managing erroneous measurements of dynamic brain electrical impedance tomography after reconnection of faulty electrodes. Physiol Meas 2020; 41:035002. [PMID: 32000152 DOI: 10.1088/1361-6579/ab71f4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrode detachment may occur during dynamic brain electrical impedance tomography (EIT) measurements. After the faulty electrodes have been reset, EIT can restore to steady monitoring but the corrupted data, which will challenge interpretation of the results, are notoriously difficult to recover. APPROACH Here, a piecewise processing method (PPM) is introduced to manage the erroneous EIT data after reattachment of faulty electrodes. In the PPM, we define the three phases before, during and after reconnection of the faulty electrode as PI, PII and PIII, respectively. Using this definition, an empirical mode decomposition-based interpolation method is introduced to compensate the corrupted data in PII, using the valid measurements in PI and PIII. Then, the compensated data in PII are spliced at the end of PI. Thus, there will be a surge at the junction of PII and PIII due to the changes in contact state of the repositioned electrodes. Finally, to ensure all the EIT data are obtained under constant electrode settings, we calculate the above changes and eliminate them from the data after PII. To verify the performance of the PPM, experiments based on head models, with anatomical structures and with human subjects were conducted. Metrics including permutation entropy (PE) and image correlation (IC) were proposed to measure the stability of the signal and the quality of the reconstructed EIT images, respectively. MAIN RESULTS The results demonstrated that the PE of the processed data was reduced to 0.25 and the IC improved to 0.78. SIGNIFICANCE Without iterative calculations the PPM could efficiently manage the erroneous EIT data after reattachment of the faulty electrodes.
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Affiliation(s)
- Haoting Li
- Haoting Li and Xuechao Liu contributed equally to this work
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27
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Liang G, Ren S, Dong F. A Shape-Based Statistical Inversion Method for EIT/URT Dual-Modality Imaging. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2020; 29:4099-4113. [PMID: 32011255 DOI: 10.1109/tip.2020.2969077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A shape-based statistical inversion method is proposed for Electrical Impedance Tomography (EIT) and Ultrasound Reflection Tomography (URT) dual-modality imaging. It is promising to improve the imaging accuracy in inclusion detection problems. The proposed image reconstruction method is based on the statistical shape inversion framework. The likelihood function is derived from EIT and URT forward models. The prior distribution is constructed using the Markov random field (MRF) prior. The measurement uncertainty is modeled by conditional error model method. The statistical shape inversion problem is solved by the Maximum a posterior (MAP) method with conventional error model. A set of numerical and experimental tests are carried out to evaluate the performance of the proposed method. The results show that the proposed EIT/URT dual-modality imaging method has obvious improvement in imaging accuracy compared to the traditional single-modality EIT and URT methods.
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28
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A theoretical study on real time monitoring of single cell mitosis with micro electrical impedance tomography. Biomed Microdevices 2019; 21:102. [PMID: 31768642 DOI: 10.1007/s10544-019-0452-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Real time monitoring of cell division, mitosis, at the single cell level, has value for many biomedical applications; such as developing optimal cancer treatments that target the cell division process. The goal of this theoretical study is to explore the feasibility of using Micro Electrical Impedance Tomography (MEIT) for real time monitoring of mitosis in a single cell, through imaging. MEIT employs a micro (single cell) scale electrode cage with electrodes placed around the cell. The electrodes deliver subsensory current and the consequential voltages on the electrodes are measured. An inverse image reconstruction algorithm uses the electric data from the electrodes to generate a map of electrical conductivity distribution in the chamber, which is the image. EIT is a well-known medical imaging technology that is simple to use but lacks good resolution. Therefore, it is not a-priori obvious that EIT has sufficient resolution to monitor single cell mitosis. To accomplish the goal of this study we have developed a mathematical model of MEIT of single cell mitosis, in which an in silico experiment provided the data for the MEIT image reconstruction. This theoretical study shows that MEIT can detect the outlines of the dividing cell during the various stages of mitosis (metaphase, anaphase and telophase) and, therefore, has potential as a technology for real time monitoring of single cell mitosis.
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Milne S, Huvanandana J, Nguyen C, Duncan JM, Chapman DG, Tonga KO, Zimmermann SC, Slattery A, King GG, Thamrin C. Time-based pulmonary features from electrical impedance tomography demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease. J Appl Physiol (1985) 2019; 127:1441-1452. [PMID: 31556831 DOI: 10.1152/japplphysiol.00304.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pulmonary electrical impedance tomography (EIT) is a functional imaging technique that allows real-time monitoring of ventilation distribution. Ventilation heterogeneity (VH) is a characteristic feature of chronic obstructive pulmonary disease (COPD) and has previously been quantified using features derived from tidal variations in the amplitude of the EIT signal. However, VH may be better described by time-based metrics, the measurement of which is made possible by the high temporal resolution of EIT. We aimed 1) to quantify VH using novel time-based EIT metrics and 2) to determine the physiological relevance of these metrics by exploring their relationships with complex lung mechanics measured by the forced oscillation technique (FOT). We performed FOT, spirometry, and tidal-breathing EIT measurements in 11 healthy controls and 9 volunteers with COPD. Through offline signal processing, we derived 3 features from the impedance-time (Z-t) curve for each image pixel: 1) tE, mean expiratory time; 2) PHASE, mean time difference between pixel and global Z-t curves; and 3) AMP, mean amplitude of Z-t curve tidal variation. Distribution was quantified by the coefficient of variation (CV) and the heterogeneity index (HI). Both CV and HI of the tE and PHASE features were significantly increased in COPD compared with controls, and both related to spirometry and FOT resistance and reactance measurements. In contrast, distribution of the AMP feature showed no relationships with lung mechanics. These novel time-based EIT metrics of VH reflect complex lung mechanics in COPD and have the potential to allow real-time visualization of pulmonary physiology in spontaneously breathing subjects.NEW & NOTEWORTHY Pulmonary electrical impedance tomography (EIT) is a real-time imaging technique capable of monitoring ventilation with exquisite temporal resolution. We report novel, time-based EIT measurements that not only demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease (COPD), but also reflect oscillatory lung mechanics. These EIT measurements are noninvasive, radiation-free, easy to obtain, and provide real-time visualization of the complex pathophysiology of COPD.
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Affiliation(s)
- Stephen Milne
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Central Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St. Leonards, New South Wales, Australia.,Centre for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jacqueline Huvanandana
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - Chinh Nguyen
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia
| | - Joseph M Duncan
- Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St. Leonards, New South Wales, Australia
| | - David G Chapman
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Translational Airways Group, School of Life Sciences, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Katrina O Tonga
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine, the University of New South Wales, Kensington, New South Wales, Australia
| | - Sabine C Zimmermann
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St. Leonards, New South Wales, Australia
| | - Alexander Slattery
- Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St. Leonards, New South Wales, Australia
| | - Gregory G King
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Northern Clinical School, University of Sydney, Sydney, New South Wales, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St. Leonards, New South Wales, Australia.,Centre of Excellence in Severe Asthma, New Lambton, New South Wales, Australia
| | - Cindy Thamrin
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health, Central Clinical School, University of Sydney, Sydney, New South Wales, Australia
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Grune J, Tabuchi A, Kuebler WM. Alveolar dynamics during mechanical ventilation in the healthy and injured lung. Intensive Care Med Exp 2019; 7:34. [PMID: 31346797 PMCID: PMC6658629 DOI: 10.1186/s40635-019-0226-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 02/13/2019] [Indexed: 02/12/2023] Open
Abstract
Mechanical ventilation is a life-saving therapy in patients with acute respiratory distress syndrome (ARDS). However, mechanical ventilation itself causes severe co-morbidities in that it can trigger ventilator-associated lung injury (VALI) in humans or ventilator-induced lung injury (VILI) in experimental animal models. Therefore, optimization of ventilation strategies is paramount for the effective therapy of critical care patients. A major problem in the stratification of critical care patients for personalized ventilation settings, but even more so for our overall understanding of VILI, lies in our limited insight into the effects of mechanical ventilation at the actual site of injury, i.e., the alveolar unit. Unfortunately, global lung mechanics provide for a poor surrogate of alveolar dynamics and methods for the in-depth analysis of alveolar dynamics on the level of individual alveoli are sparse and afflicted by important limitations. With alveolar dynamics in the intact lung remaining largely a "black box," our insight into the mechanisms of VALI and VILI and the effectiveness of optimized ventilation strategies is confined to indirect parameters and endpoints of lung injury and mortality.In the present review, we discuss emerging concepts of alveolar dynamics including alveolar expansion/contraction, stability/instability, and opening/collapse. Many of these concepts remain still controversial, in part due to limitations of the different methodologies applied. We therefore preface our review with an overview of existing technologies and approaches for the analysis of alveolar dynamics, highlighting their individual strengths and limitations which may provide for a better appreciation of the sometimes diverging findings and interpretations. Joint efforts combining key technologies in identical models to overcome the limitations inherent to individual methodologies are needed not only to provide conclusive insights into lung physiology and alveolar dynamics, but ultimately to guide critical care patient therapy.
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Affiliation(s)
- Jana Grune
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, 10117 Berlin, Germany
| | - Arata Tabuchi
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Wolfgang M. Kuebler
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, 10117 Berlin, Germany
- The Keenan Research Centre for Biomedical Science at St. Michael’s, Toronto, Canada
- Departments of Surgery and Physiology, University of Toronto, Toronto, Canada
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31
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Nguyen DM, Qian P, Barry T, McEwan A. Self-weighted NOSER-prior electrical impedance tomography using internal electrodes in cardiac radiofrequency ablation. Physiol Meas 2019; 40:065006. [DOI: 10.1088/1361-6579/ab1937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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32
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Rahmel T, Koniusch A, Schwertner M, Oprea G, Adamzik M, Nowak H. Evaluation of inhaled salbutamol effectiveness under supportive use of electrical impedance tomography in ventilated ICU patients: study protocol for a randomised controlled clinical trial. BMJ Open 2019; 9:e026038. [PMID: 30862635 PMCID: PMC6429886 DOI: 10.1136/bmjopen-2018-026038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
INTRODUCTION The inhalative administration of drugs is a non-invasive application form that is regularly used in the treatment of ventilated patients in critical care setting. However, assessment of effectiveness or distribution of nebulised drugs is one of the lacking cornerstones of modern intensive care monitoring. Electrical impedance tomography (EIT) may provide a promising new monitoring and guiding tool for an adequate optimisation of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and evaluate associated pathologies at bedside. This study aims to elucidate the extent to which the effectiveness of inhaled salbutamol can be increased by the additional use of EIT for optimisation of respirator settings. METHODS AND ANALYSIS This study is a randomised, open-label, superiority trial conducted on an intensive care unit of a German university hospital, comparing two groups of mechanically ventilated patients with an acute or chronic bronchial airway obstruction according to the effectiveness of inhaled salbutamol with (intervention) or without (control) additional use of EIT for optimising ventilator settings. The primary outcome is change in airway resistance 30 min after salbutamol inhalation. ETHICS AND DISSEMINATION The study has received approval from the Ethics Committee of the Medical Faculty of Ruhr-University Bochum (17-6306). The results will be made available to critical care survivors, their caregivers, the funders, the critical care societies and other researchers by publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER DRKS00014706; Pre-results.
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Affiliation(s)
- Tim Rahmel
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Alexandra Koniusch
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Martin Schwertner
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Günther Oprea
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Michael Adamzik
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Hartmuth Nowak
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
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Ngo C, Spagnesi S, Munoz C, Lehmann S, Vollmer T, Misgeld B, Leonhardt S. Assessing regional lung mechanics by combining electrical impedance tomography and forced oscillation technique. ACTA ACUST UNITED AC 2019; 63:673-681. [PMID: 28850542 DOI: 10.1515/bmt-2016-0196] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 07/17/2017] [Indexed: 11/15/2022]
Abstract
There is a lack of noninvasive pulmonary function tests which can assess regional information of the lungs. Electrical impedance tomography (EIT) is a radiation-free, non-invasive real-time imaging that provides regional information of ventilation volume regarding the measurement of electrical impedance distribution. Forced oscillation technique (FOT) is a pulmonary function test which is based on the measurement of respiratory mechanical impedance over a frequency range. In this article, we introduce a new measurement approach by combining FOT and EIT, named the oscillatory electrical impedance tomography (oEIT). Our oEIT measurement system consists of a valve-based FOT device, an EIT device, pressure and flow sensors, and a computer fusing the data streams. Measurements were performed on five healthy volunteers at the frequencies 3, 4, 5, 6, 7, 8, 10, 15, and 20 Hz. The measurements suggest that the combination of FOT and EIT is a promising approach. High frequency responses are visible in the derivative of the global impedance index ΔZeit(t,fos). $\Delta {Z_{{\text{eit}}}}(t,{f_{{\text{os}}}}).$ The oEIT signals consist of three main components: forced oscillation, spontaneous breathing, and heart activity. The amplitude of the oscillation component decreases with increasing frequency. The band-pass filtered oEIT signal might be a new tool in regional lung function diagnostics, since local responses to high frequency perturbation could be distinguished between different lung regions.
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Affiliation(s)
- Chuong Ngo
- Philips Chair of Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Sarah Spagnesi
- Philips Chair of Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Carlos Munoz
- Philips Chair of Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Sylvia Lehmann
- Department of Pediatric Pulmonology, University Hospital RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Thomas Vollmer
- Philips GmbH Innovative Technologies Aachen, Pauwelsstr. 17, 52074 Aachen, Germany
| | - Berno Misgeld
- Philips Chair of Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Steffen Leonhardt
- Philips Chair of Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
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EIT Imaging of Upper Airway to Estimate Its Size and Shape Changes During Obstructive Sleep Apnea. Ann Biomed Eng 2019; 47:990-999. [PMID: 30693441 DOI: 10.1007/s10439-019-02210-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/17/2019] [Indexed: 10/27/2022]
Abstract
Noninvasive continuous imaging of the upper airway during natural sleep was conducted for patients with obstructive sleep apnea (OSA) using the electrical impedance tomography (EIT) technique. A safe amount of alternating current (AC) was injected into the lower head through multiple surface electrodes. Since the air is an electrical insulator, upper airway narrowing during OSA altered internal current pathways and changed the induced voltage distribution. Since the measured voltage data from the surface of the lower head were influenced not only by upper airway narrowing but respiratory motions, head motions, and blood flows, we developed a pre-processing algorithm to extract the voltage component originated from upper airway closing and opening. Using an EIT image reconstruction algorithm, time-series of EIT images of the upper airway were produced with a temporal resolution of 50 frames per second. Applying a postprocessing algorithm to the reconstructed EIT images, we could extract quantitative information about changes in the size and shape during upper airway closing and opening. Results of the clinical studies with seven normal subjects and ten OSA patients show the feasibility of the new method for OSA phenotyping and treatment planning.
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Moridani MK, Choopani F, Kia M. Recognition of Lung Volume Condition based on Phase Space Mapping Using Electrical Impedance Tomography. JOURNAL OF ELECTRICAL BIOIMPEDANCE 2019; 10:34-39. [PMID: 33584880 PMCID: PMC7531212 DOI: 10.2478/joeb-2019-0005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Indexed: 06/12/2023]
Abstract
The purpose of this paper is to identify differences between abnormal and normal lung signals gathered by an EIT device, which is a new, non-invasive system that seeks the electrical conductivity and permittivity inside a body. Lung performances in patients are investigated using Phase Space Mapping technique on Electrical EIT signals. The database used in this paper contains 82 registered records of 52 individuals with proper lung volume. The results of this paper show that as the delay parameter (τ) increases, the SD1 parameter of phase space mapping indicates a significant difference between normal and abnormal lung volumes. The value of the SD1 parameter with τ = 6 in the case that the lung volume is in a normal condition is 342.57 ± 32.75 while it is 156.71 ± 26.01 in non-optimal mode. This method can be used to identify the patients' lung volumes with chronic respiratory illnesses and is an accurate assessment of the diverse methods to treat respiratory system illnesses in addition to saving various therapeutic costs and dangerous consequences that are likely to occur by using improper treatment methods. It can also reduce the required treatment durations.
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Affiliation(s)
- Mohammad Karimi Moridani
- Department of Biomedical Engineering, Faculty of Health, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Fatemeh Choopani
- Department of Biomedical Engineering, Faculty of Health, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mandana Kia
- Department of Biomedical Engineering, Faculty of Health, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
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Shang Y, Dong J, Tian L, Inthavong K, Tu J. Detailed computational analysis of flow dynamics in an extended respiratory airway model. Clin Biomech (Bristol, Avon) 2019; 61:105-111. [PMID: 30544055 DOI: 10.1016/j.clinbiomech.2018.12.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 11/27/2018] [Accepted: 12/06/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Understanding respiratory physiology can aid clinicians in diagnosing the cause of respiratory symptoms or shed light on drug delivery inhaler device optimisation. However, the sheer complexity of the human lung prohibits a full-scale study. METHODS In this study, a realistic respiratory airway model including large-to-small conducting airways was built. This airway model consists of subject-specific upper and lower airways, extending from nasal and oral openings to terminal bronchioles (up to the 15th generation). Based on the subject-specific airway model, topological information was extracted and a digital reference model that exhibits strong asymmetry and multi-fractal properties was provided. Inhalation flow rates 18 L/min and 50 L/min were adopted to understand inspiratory conditions subjecting to resting and light exercise inhalation modes. Regional airflow in terms of axial velocity and secondary flow vortices along the lung airway model was extracted. FINDINGS Obvious secondary flow currents were seen in the larynx-trachea segment and left main bronchus, while for the terminal conducting airway in the right lower lobe, the airflow tends to be much smoother with no secondary flow currents. INTERPRETATION This paper provides insights on respiratory physiology, especially in the lower lung airways, and will be potentially useful for diagnosis of lower airway diseases.
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Affiliation(s)
- Yidan Shang
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Jingliang Dong
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Lin Tian
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia.
| | - Kiao Inthavong
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Jiyuan Tu
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia; Key Laboratory of Ministry of Education for Advanced Reactor Engineering and Safety, Institute of Nuclear and New Energy Technology, Tsinghua University, PO Box 1021, Beijing 100086, China.
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Lee MH, Jang GY, Kim YE, Yoo PJ, Wi H, Oh TI, Woo EJ. Portable multi-parameter electrical impedance tomography for sleep apnea and hypoventilation monitoring: feasibility study. Physiol Meas 2018; 39:124004. [PMID: 30523963 DOI: 10.1088/1361-6579/aaf271] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Quantitative ventilation monitoring and respiratory event detection are needed for the diagnosis of sleep apnea and hypoventilation. We developed a portable device with a chest belt, nasal cannula and finger sensor to continuously acquire multi-channel signals including tidal volume, nasal pressure, respiratory effort, body position, snoring sound, ECG and SpO2. The unique feature of the device is the continuous tidal volume signal obtained from real-time lung ventilation images produced by the electrical impedance tomography (EIT) technique. APPROACH The chest belt includes 16 electrodes for real-time time-difference EIT imaging and ECG data acquisitions. It also includes a microphone, accelerometer, gyroscope, magnetometer and pressure sensor to acquire, respectively, snoring sound, respiratory effort, body position and nasal pressure signals. A separate finger sensor is used to measure SpO2. The minute ventilation signal is derived from the tidal volume signal and respiration rate. MAIN RESULTS The experimental results from a conductivity phantom, four swine subjects and one human volunteer show that the developed multi-parameter EIT device could supplement existing polysomnography (PSG) and home sleep test (HST) devices to improve the accuracy of sleep apnea diagnosis. The portable device could be also used as a new tool for continuous hypoventilation monitoring of non-intubated patients with respiratory depression. SIGNIFICANCE Following the feasibility study in this paper, future validation studies in comparison with in-lab PSG, HST and end-tidal CO2 devices are suggested to find its clinical efficacy as a sleep apnea diagnosis and hypoventilation monitoring tool.
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Affiliation(s)
- Min Hyoung Lee
- Department of Biomedical Engineering, Graduate School, Kyung Hee University, Yongin, Republic of Korea
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Zhang C, Dai M, Liu W, Bai X, Wu J, Xu C, Xia J, Fu F, Shi X, Dong X, Jin F, You F. Global and regional degree of obstruction determined by electrical impedance tomography in patients with obstructive ventilatory defect. PLoS One 2018; 13:e0209473. [PMID: 30571739 PMCID: PMC6301672 DOI: 10.1371/journal.pone.0209473] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 12/06/2018] [Indexed: 11/19/2022] Open
Abstract
Background Electrical impedance tomography is a continuous imaging method capable of measuring lung volume changes. The purpose of this study was to examine whether EIT was capable of evaluating the degree of obstructive ventilatory defect (OVD) on the global and regional level. Methods 41 healthy subjects with no lung diseases and 67 subjects suffering from obstructive lung diseases were examined using EIT and spirometry during forced vital capacity (FVC) maneuver. The subjects were divided into control group (n = 41), early airway obstruction group (n = 26), mild group (n = 17), moderate group (n = 16) and severe group (n = 8) according to the degree of obstruction. Forced expiratory volume in 1 second (FEV1) and FEV1/FVC were determined by EIT. The mode index (MI) was proposed to evaluate the degree of global and regional obstruction; the effectiveness of MI was validated by evaluating posture related change of lung emptying capacity in sitting and supine postures; the degree of regional obstruction was determined according to the cut-off values of MI obtained from receiver operating characteristic (ROC) analysis; regional obstruction was located in the four-quadrant region of interest (ROI) and the contour-map ROI with contour lines at the cut-off values of MI. Results Significant differences were found between different groups (P<0.05) and the global MI was 0.93±0.03, 0.86±0.05, 0.81±0.09, 0.73±0.09 and 0.60±0.11 (mean ±SD), respectively. The cut-off MI value was 0.90, 0.83, 0.77, and 0.65, respectively. Conclusion The results indicated the potential of EIT to evaluate the degree of obstruction in patients with obstructive ventilatory defect on the global and regional level.
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Affiliation(s)
- Chao Zhang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China.,Medical Engineering Section, General Hospital of Shenyang Military Region, Shenyang, Liaoning, China
| | - Meng Dai
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Wei Liu
- Department of respiratory medicine, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Xiaohui Bai
- The Fifth People's Hospital of Baoji City, Baoji, Shaanxi, China
| | - Jiaming Wu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China.,Department of Medical Technology, Bethune Military Medical NCO Academy of PLA, Shijiazhuang, Hebei, China
| | - Canhua Xu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Junying Xia
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Xuetao Shi
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Xiuzhen Dong
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Faguang Jin
- Department of respiratory medicine, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Fusheng You
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi, China
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Alex A, Ramasubba Reddy M. Application of meshless local Petrov Galerkin method (MLPG5) for EIT forward problem. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aace4e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Rutkove SB, Kwon H, Guasch M, Wu JS, Sanchez B. Electrical impedance imaging of human muscle at the microscopic scale using a multi-electrode needle device: A simulation study. Clin Neurophysiol 2018; 129:1704-1708. [PMID: 29804914 DOI: 10.1016/j.clinph.2018.04.746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/23/2018] [Accepted: 04/29/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To use a standard modeling approach to evaluate the feasibility of imaging healthy and diseased skeletal muscle at the microscopic scale with a novel electrical impedance imaging (EII) needle. METHODS We modeled an EII needle containing 16 impedance electrodes arranged circumferentially around the shaft of a non-conductive 19-gauge needle in 4 planes. We then combined the finite element method approach with a reconstruction algorithm to create imaging simulations of the electrical properties of the triceps brachii by localized intramuscular fat (as might be seen in any chronic neuromuscular disease) and by localized edema (as in inflammatory myositis or after direct muscle injury). RESULTS We were able to image a 1 cm radial region of interest with a resolution of 200 µm. Modeling localized deposition of fat and pockets of inflammatory cells, showing clear differences between the two modeled clinical states. CONCLUSIONS This modeling study shows needle EII's ability to image the internal composition of muscle. These results can serve as an initial guide in designing and manufacturing prototype EII needles for experimental testing in animals and eventually in humans. SIGNIFICANCE Needle EII could serve as a new minimally invasive technique for imaging human muscle at the microscopic scale, potentially serving as a new biomarker to assess disease response to therapy.
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Affiliation(s)
- Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5491, USA
| | - Hyeuknam Kwon
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5491, USA
| | - Maria Guasch
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5491, USA
| | - Jim S Wu
- Department Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5491, USA
| | - Benjamin Sanchez
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215-5491, USA.
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Ngo C, Dippel F, Tenbrock K, Leonhardt S, Lehmann S. Flow-volume loops measured with electrical impedance tomography in pediatric patients with asthma. Pediatr Pulmonol 2018; 53:636-644. [PMID: 29405616 DOI: 10.1002/ppul.23962] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/15/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Electrical impedance tomography (EIT) provides information on global and regional ventilation during tidal breathing and mechanical ventilation. During forced expiration maneuvers, the linearity of EIT and spirometric data has been documented in healthy persons. The present study investigates the potential diagnostic use of EIT in pediatric patients with asthma. METHODS EIT and spirometry were performed in 58 children with asthma (average age ± SD: 11.86 ± 3.13 years), and 58 healthy controls (average age ± SD: 12.12 ± 2.9 years). The correlation between EIT data and simultaneously acquired spirometric data were tested for FEV1, FEV0.5 , MEF75 , MEF50 , and MEF25 . Binary classification tests were performed for the EIT-derived Tiffeneau index FEV1 /FVC and the bronchodilator test index ΔFEV1 . Average flow-volume (FV) loops were generated for patients with pathologic spirometry to demonstrate the feasibility of EIT for graphic diagnosis of asthma. RESULTS Spirometry and global EIT-based FV loops showed a strong correlation (P < 0.001, r > 0.9 in FEV1 and FEV0.5 ). In all criteria, the binary classification tests yielded high specificity (>93%), a high positive predictive value (≥75%) and a high negative predictive value (>80%), while sensitivity was higher in ΔFEV1 (86.67%) and lower in FEV1 /FVC (25% and 35.29%). A typical concave shape of the EIT-derived average FV loops was observed for asthmatic children with improvement after bronchospasmolysis. CONCLUSIONS Global FV loops derived from EIT correlate well with spirometry. Positive bronchospasmolysis can be observed in EIT-derived FV loops. Flow-volume loops originated from EIT have a potential to visualize pulmonary function.
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Affiliation(s)
- Chuong Ngo
- Philips Chair for Medical Information Technology, RWTH Aachen, Aachen, Germany
| | - Falk Dippel
- Philips Chair for Medical Information Technology, RWTH Aachen, Aachen, Germany
| | - Klaus Tenbrock
- Department of Pediatric Pulmonology, RWTH Aachen University Hospital, Aachen, Germany
| | - Steffen Leonhardt
- Philips Chair for Medical Information Technology, RWTH Aachen, Aachen, Germany
| | - Sylvia Lehmann
- Department of Pediatric Pulmonology, RWTH Aachen University Hospital, Aachen, Germany
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Abstract
OBJECTIVE The most commonly used EIT paradigm (time division multiplexing) limits the temporal resolution of impedance images due to the need to switch between injection electrodes. Advances have previously been made using frequency division multiplexing (FDM) to increase temporal resolution, but in cases where a fixed range of frequencies is available, such as imaging fast neural activity, an upper limit is placed on the total number of simultaneous injections. The use of phase division multiplexing (PDM) where multiple out of phase signals can be injected at each frequency is investigated to increase temporal resolution. APPROACH TDM, FDM and PDM were compared in head tank experiments, to compare transfer impedance measurements and spatial resolution between the three techniques. A resistor phantom paradigm was established to investigate the imaging of one-off impedance changes, of magnitude 1% and with durations as low as 500 µs (similar to those seen in nerve bundles), using both PDM and TDM approaches. MAIN RESULTS In head tank experiments, a strong correlation (r > 0.85 and p < 0.001) was present between the three sets of measured transfer impedances, and no statistically significant difference was found in reconstructed image quality. PDM was able to image impedance changes down to 500 µs in the phantom experiments, while the minimum duration imaged using TDM was 5 ms. SIGNIFICANCE PDM offers a possible solution to the imaging of fast moving impedance changes (such as in nerves), where the use of triggering or coherent averaging is not possible. The temporal resolution presents an order of magnitude improvement of the TDM approach, and the approach addresses the limited spatial resolution of FDM by increasing the number of simultaneous EIT injections.
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Affiliation(s)
- T Dowrick
- Department of Medical Physics & Biomedical Engineering, University College London, London, United Kingdom
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Vogt B, Löhr S, Zhao Z, Falkenberg C, Ankermann T, Weiler N, Frerichs I. Regional lung function testing in children using electrical impedance tomography. Pediatr Pulmonol 2018; 53:293-301. [PMID: 29136345 DOI: 10.1002/ppul.23912] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/03/2017] [Accepted: 10/22/2017] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To evaluate regional lung function in lung-healthy children before and after exercise challenge using electrical impedance tomography (EIT). METHODS Regional lung function was examined using EIT in 100 lung-healthy children (three age subgroups: 74-121, 122-155, 156-195 months) at baseline and 10 min after exercise. Global lung function was assessed by spirometry using Z-Scores of FEV1 , FVC, FEV1 /FVC, and FEF75 . The same lung function measures were determined in 912 EIT image pixels to enable the spatial and temporal ventilation distribution analysis. Coefficients of variation (CV) of these pixel values were calculated and histograms of pixel FEV1 /FVC and times required to exhale 50% and 75% of pixel FVC (t50 and t75 ) generated. Additionally, we compared the findings of the studied population with three cystic fibrosis (CF) children. FINDINGS Z-Scores corresponded to the worldwide reference values in all studied age groups at baseline. Global lung function was not affected by exercise, only the youngest group exhibited higher FVC and lower FEF75 , FEV1 /FVC attributable to the training effect. The overall degree of ventilation heterogeneity assessed by CV showed no exercise dependency. The histograms of pixel values of FEV1 /FVC, t50 , and t75 revealed a slight modulating effect of exercise on regional ventilation distribution in all subgroups. EIT identified the distinctly higher ventilation heterogeneity in the CF children. CONCLUSION Global and regional lung functions were not affected by exercise in lung-healthy children. Exercise did not increase ventilation inhomogeneity. The obtained EIT-derived regional lung parameters can serve as reference values for future studies in children with lung diseases.
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Affiliation(s)
- Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Sarah Löhr
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany
| | - Christian Falkenberg
- Rehabilitation Center for Children and Adolescents, Fachklinik Satteldüne, Nebel, Germany
| | - Tobias Ankermann
- Department of Pediatric Pulmonology, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Krueger-Ziolek S, Schullcke B, Gong B, Müller-Lisse U, Moeller K. EIT based pulsatile impedance monitoring during spontaneous breathing in cystic fibrosis. Physiol Meas 2018; 38:1214-1225. [PMID: 28530203 DOI: 10.1088/1361-6579/aa69d5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Evaluating the lung function in patients with obstructive lung disease by electrical impedance tomography (EIT) usually requires breathing maneuvers containing deep inspirations and forced expirations. Since these maneuvers strongly depend on the patient's co-operation and health status, normal tidal breathing was investigated in an attempt to develop continuous maneuver-free measurements. APPROACH Ventilation related and pulsatile impedance changes were systematically analyzed during normal tidal breathing in 12 cystic fibrosis (CF) patients and 12 lung-healthy controls (HL). Tidal breaths were subdivided into three inspiratory (In1, In2, In3) and three expiratory (Ex1, Ex2, Ex3) sections of the same amplitude of global impedance change. Maximal changes of the ventilation and the pulsatile impedance signal occurring during these sections were determined (▵I V and ▵I P). Differences in ▵I V and ▵I P among sections were ascertained in relation to the first inspiratory section. In addition, ▵I V/▵I P was calculated for each section. MAIN RESULTS Medians of changes in ▵I V were <0.05% in all sections for both subject groups. Both groups showed a similar pattern of ▵I P changes during tidal breathing. Changes in ▵I P first decreased during inspiration (In2), then increased towards the end of inspiration (In3) and reached a maximum at the beginning of expiration (Ex1). During the last two sections of expiration (Ex2, Ex3) ▵I P changes decreased. The CF patients showed higher variations in ▵I P changes compared to the controls (CF: -426.5%, HL: -158.1%, coefficient of variation). Furthermore, ▵I V/▵I P significantly differed between expiratory sections for the CF patients (Ex1-Ex2, p < 0.01; Ex1-Ex3, p < 0.001; Ex2-Ex3, p < 0.05), but not for the controls. No significant differences in ▵I V/▵I P between inspiratory sections were determined for both groups. SIGNIFICANCE Differences in ▵I P changes and in ▵I V/▵I P between both subject groups were speculated to be caused by higher breathing efforts of the CF patients due to airway obstruction leading to higher intrathoracic pressures, and thus to greater changes in lung perfusion.
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Affiliation(s)
- Sabine Krueger-Ziolek
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Straße 17, 78054 Villingen-Schwenningen, Germany. Department of Radiology, LMU University of Munich, Ziemssenstrasse 1, 80336 Munich, Germany3
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Lobo B, Hermosa C, Abella A, Gordo F. Electrical impedance tomography. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:26. [PMID: 29430443 PMCID: PMC5799136 DOI: 10.21037/atm.2017.12.06] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 11/30/2017] [Indexed: 11/06/2022]
Abstract
Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way.
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Affiliation(s)
- Beatriz Lobo
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Cecilia Hermosa
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Ana Abella
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Federico Gordo
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
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Electrical impedance tomography: Amplitudes of cardiac related impedance changes in the lung are highly position dependent. PLoS One 2017; 12:e0188313. [PMID: 29145478 PMCID: PMC5690592 DOI: 10.1371/journal.pone.0188313] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 11/03/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Electrical impedance tomography (EIT) is used on the thorax to measure impedance changes due to the presence of air and blood in the lung. This experimental study was performed to investigate the effect of posture on cardiac and respiratory related impedance changes. METHODS EIT measurements were performed on 14 healthy subjects in left-, right lateral, prone, supine and upright positions. Simultaneously, tidal volume was recorded with an ultrasonic flowmeter. For image reconstruction, the classic Sheffield back-projection and three variants of the modern GREIT algorithm were applied with two different reference frames. Amplitudes of cardiac- and respiratory impedance changes were extracted and compared between the positions. RESULTS We found significant differences in both cardiac and respiratory amplitudes between postures. Especially, supine and upright positions showed dramatic changes in amplitude. These differences between postures were unaffected by the change of reference frames in all reconstruction methods except of the classic Sheffield back projection. Possible sources that explain the observed posture dependency are discussed. CONCLUSION Researchers and clinicians need to be aware of this phenomenon when comparing EIT amplitudes in different body positions.
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Cambiaghi B, Vasques F, Mörer O, Ritter C, Mauri T, Kunze-Szikszay N, Holke K, Collino F, Maiolo G, Rapetti F, Schulze-Kalthoff E, Tonetti T, Hahn G, Quintel M, Gattinoni L. Effects of regional perfusion block in healthy and injured lungs. Intensive Care Med Exp 2017; 5:46. [PMID: 29030751 PMCID: PMC5640557 DOI: 10.1186/s40635-017-0161-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/04/2017] [Indexed: 11/30/2022] Open
Abstract
Background Severe hypoperfusion can cause lung damage. We studied the effects of regional perfusion block in normal lungs and in the lungs that had been conditioned by lavage with 500 ml saline and high VT (20 ml kg−1) ventilation. Methods Nineteen pigs (61.2 ± 2.5 kg) were randomized to five groups: controls (n = 3), the right lower lobe block alone (n = 3), lavage and high VT (n = 4), lung lavage, and high VT plus perfusion block of the right (n = 5) or left (n = 4) lower lobe. Gas exchange, respiratory mechanics, and hemodynamics were measured hourly. After an 8-h observation period, CT scans were obtained at 0 and 15 cmH2O airway pressure. Results Perfusion block did not damage healthy lungs. In conditioned lungs, the left perfusion block caused more edema in the contralateral lung (777 ± 62 g right lung vs 484 ± 204 g left; p < 0.05) than the right perfusion block did (581 ± 103 g right lung vs 484 ± 204 g left; p n.s.). The gas/tissue ratio, however, was similar (0.5 ± 0.3 and 0.8 ± 0.5; p n.s.). The lobes with perfusion block were not affected (gas/tissue ratio right 1.6 ± 0.9; left 1.7 ± 0.5, respectively). Pulmonary artery pressure, PaO2/FiO2, dead space, and lung mechanics were more markedly affected in animals with left perfusion block, while the gas/tissue ratios were similar in the non-occluded lobes. Conclusions The right and left perfusion blocks caused the same “intensity” of edema in conditioned lungs. The total amount of edema in the two lungs differed because of differences in lung size. If capillary permeability is altered, increased blood flow may induce or increase edema. Electronic supplementary material The online version of this article (10.1186/s40635-017-0161-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Barbara Cambiaghi
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany.,Dipartimento di Medicina e Chirurgia, Università Degli Studi Milano-Bicocca, Monza, Italy
| | - Francesco Vasques
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Onnen Mörer
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Christian Ritter
- Department of Radiology, Georg-August-University Göttingen, Göttingen, Germany
| | - Tommaso Mauri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Nils Kunze-Szikszay
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Karin Holke
- Department of Pathology, University of Göttingen, Göttingen, Germany
| | - Francesca Collino
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Giorgia Maiolo
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Francesca Rapetti
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Elias Schulze-Kalthoff
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Tommaso Tonetti
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Günter Hahn
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Michael Quintel
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany
| | - Luciano Gattinoni
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany.
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Schullcke B, Krueger-Ziolek S, Gong B, Jörres RA, Mueller-Lisse U, Moeller K. Ventilation inhomogeneity in obstructive lung diseases measured by electrical impedance tomography: a simulation study. J Clin Monit Comput 2017; 32:753-761. [PMID: 29019006 DOI: 10.1007/s10877-017-0069-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 09/23/2017] [Indexed: 12/01/2022]
Abstract
Electrical impedance tomography (EIT) has mostly been used in the Intensive Care Unit (ICU) to monitor ventilation distribution but is also promising for the diagnosis in spontaneously breathing patients with obstructive lung diseases. Beside tomographic images, several numerical measures have been proposed to quantitatively assess the lung state. In this study two common measures, the 'Global Inhomogeneity Index' and the 'Coefficient of Variation' were compared regarding their capability to reflect the severity of lung obstruction. A three-dimensional simulation model was used to simulate obstructed lungs, whereby images were reconstructed on a two-dimensional domain. Simulations revealed that minor obstructions are not adequately recognized in the reconstructed images and that obstruction above and below the electrode plane may result in misleading values of inhomogeneity measures. EIT measurements on several electrode planes are necessary to apply these measures in patients with obstructive lung diseases in a promising manner.
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Affiliation(s)
- B Schullcke
- Institute of Technical Medicine, Furtwangen University, VS-Schwenningen, Germany. .,Department of Radiology, Ludwig-Maximilians-Universität, Munich, Germany.
| | - S Krueger-Ziolek
- Institute of Technical Medicine, Furtwangen University, VS-Schwenningen, Germany.,Department of Radiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - B Gong
- Institute of Technical Medicine, Furtwangen University, VS-Schwenningen, Germany.,Department of Radiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - R A Jörres
- Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - U Mueller-Lisse
- Department of Radiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - K Moeller
- Institute of Technical Medicine, Furtwangen University, VS-Schwenningen, Germany
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Abstract
In the future, diagnostic devices will be able to monitor a patient’s physiological or biochemical parameters continuously, under natural physiological conditions and in any environment through wearable biomedical sensors. Together with apps that capture and interpret data, and integrated enterprise and cloud data repositories, the networks of wearable devices and body area networks will constitute the healthcare’s Internet of Things. In this review, four main areas of interest for respiratory healthcare are described: pulse oximetry, pulmonary ventilation, activity tracking and air quality assessment. Although several issues still need to be solved, smart wearable technologies will provide unique opportunities for the future or personalised respiratory medicine. Smart wearable technologies provide unique opportunities for assessing and monitoring respiratory functionhttp://ow.ly/BHXY30cEfBl
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Affiliation(s)
- Andrea Aliverti
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
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