1
|
Leali M, Marongiu I, Spinelli E, Chiavieri V, Perez J, Panigada M, Grasselli G, Mauri T. Absolute values of regional ventilation-perfusion mismatch in patients with ARDS monitored by electrical impedance tomography and the role of dead space and shunt compensation. Crit Care 2024; 28:241. [PMID: 39010228 PMCID: PMC11251389 DOI: 10.1186/s13054-024-05033-8] [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: 04/15/2024] [Accepted: 07/11/2024] [Indexed: 07/17/2024] Open
Abstract
BACKGROUND Assessment of regional ventilation/perfusion (V'/Q) mismatch using electrical impedance tomography (EIT) represents a promising advancement for personalized management of the acute respiratory distress syndrome (ARDS). However, accuracy is still hindered by the need for invasive monitoring to calibrate ventilation and perfusion. Here, we propose a non-invasive correction that uses only EIT data and characterized patients with more pronounced compensation of V'/Q mismatch. METHODS We enrolled twenty-one ARDS patients on controlled mechanical ventilation. Cardiac output was measured invasively, and ventilation and perfusion were assessed by EIT. Relative V'/Q maps by EIT were calibrated to absolute values using the minute ventilation to invasive cardiac output (MV/CO) ratio (V'/Q-ABS), left unadjusted (V'/Q-REL), or corrected by MV/CO ratio derived from EIT data (V'/Q-CORR). The ratio between ventilation to dependent regions and perfusion reaching shunted units ( V D ' /QSHUNT) was calculated as an index of more effective hypoxic pulmonary vasoconstriction. The ratio between perfusion to non-dependent regions and ventilation to dead space units (QND/ V DS ' ) was calculated as an index of hypocapnic pneumoconstriction. RESULTS Our calibration factor correlated with invasive MV/CO (r = 0.65, p < 0.001), showed good accuracy and no apparent bias. Compared to V'/Q-ABS, V'/Q-REL maps overestimated ventilation (p = 0.013) and perfusion (p = 0.002) to low V'/Q units and underestimated ventilation (p = 0.011) and perfusion (p = 0.008) to high V'/Q units. The heterogeneity of ventilation and perfusion reaching different V'/Q compartments was underestimated. V'/Q-CORR maps eliminated all these differences with V'/Q-ABS (p > 0.05). HigherV D ' / Q SHUNT correlated with higher PaO2/FiO2 (r = 0.49, p = 0.025) and lower shunt fraction (ρ = - 0.59, p = 0.005). HigherQ ND / V DS ' correlated with lower PEEP (ρ = - 0.62, p = 0.003) and plateau pressure (ρ = - 0.59, p = 0.005). Lower values of both indexes were associated with less ventilator-free days (p = 0.05 and p = 0.03, respectively). CONCLUSIONS Regional V'/Q maps calibrated with a non-invasive EIT-only method closely approximate the ones obtained with invasive monitoring. Higher efficiency of shunt compensation improves oxygenation while compensation of dead space is less needed at lower airway pressure. Patients with more effective compensation mechanisms could have better outcomes.
Collapse
Affiliation(s)
- Marco Leali
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Ines Marongiu
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Valentina Chiavieri
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Joaquin Perez
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Mauro Panigada
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giacomo Grasselli
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Tommaso Mauri
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
| |
Collapse
|
2
|
Rutkove SB, McIlduff CE, Stommel E, Levy S, Smith C, Gutierrez H, Verga S, Samaan S, Yator C, Nanda A, Pastel L, Doussan A, Phipps K, Murphy E, Halter R. Assessing pulmonary function in ALS using electrical impedance tomography. Amyotroph Lateral Scler Frontotemporal Degener 2024:1-8. [PMID: 38576194 DOI: 10.1080/21678421.2024.2334075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 03/18/2024] [Indexed: 04/06/2024]
Abstract
Objective: We sought to determine whether thoracic electrical impedance tomography (EIT) could characterize pulmonary function in amyotrophic lateral sclerosis (ALS) patients, including those with facial weakness. Thoracic EIT is a noninvasive, technology in which a multi-electrode belt is placed across the chest, producing real-time impedance imaging of the chest during breathing. Methods: We enrolled 32 ALS patients and 32 age- and sex-matched healthy controls (HCs) without underlying lung disease. All participants had EIT measurements performed simultaneously with standard pulmonary function tests (PFTs), including slow and forced vital capacity (SVC and FVC) in upright and supine positions and maximal inspiratory and expiratory pressures (MIPs and MEPs, respectively). Intraclass correlation coefficients (ICCs) were calculated to assess the immediate reproducibility of EIT measurements and Pearson's correlations were used to explore the relationships between EIT and PFT values. Results: Data from 30 ALS patients and 27 HCs were analyzed. Immediate upright SVC reproducibility was very high (ICC 0.98). Correlations were generally strongest between EIT and spirometry measures, with R values ranging from 0.64 to 0.82 (p < 0.001) in the ALS cohort. There were less robust correlations between EIT values and both MIPs and MEPs in the ALS patients, with R values ranging from 0.33 to 0.44. There was no significant difference for patients with and without facial weakness. There were no reported adverse events. Conclusion: EIT-based pulmonary measures hold the promise of providing an alternative approach for lung function assessment in ALS patients. Based on these early results, further development and study of this technology are warranted.
Collapse
Affiliation(s)
- Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Courtney E McIlduff
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Elijah Stommel
- Department of Neurology, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Sean Levy
- Department of Medicine, Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA, and
| | - Christy Smith
- Department of Medicine, Division of Pulmonary and Critical Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA, and
| | - Hilda Gutierrez
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Sarah Verga
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Soleil Samaan
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Chebet Yator
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Ajitesh Nanda
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Lisa Pastel
- Department of Neurology, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Allaire Doussan
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Kathy Phipps
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Ethan Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Ryan Halter
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| |
Collapse
|
3
|
Hyun CM, Kim TG, Lee K. Unsupervised sequence-to-sequence learning for automatic signal quality assessment in multi-channel electrical impedance-based hemodynamic monitoring. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 247:108079. [PMID: 38394789 DOI: 10.1016/j.cmpb.2024.108079] [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: 05/23/2023] [Revised: 11/08/2023] [Accepted: 02/11/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND AND OBJECTIVE This study proposes an unsupervised sequence-to-sequence learning approach that automatically assesses the motion-induced reliability degradation of the cardiac volume signal (CVS) in multi-channel electrical impedance-based hemodynamic monitoring. The proposed method attempts to tackle shortcomings in existing learning-based assessment approaches, such as the requirement of manual annotation for motion influence and the lack of explicit mechanisms for realizing motion-induced abnormalities under contextual variations in CVS over time. METHOD By utilizing long-short term memory and variational auto-encoder structures, an encoder-decoder model is trained not only to self-reproduce an input sequence of the CVS but also to extrapolate the future in a parallel fashion. By doing so, the model can capture contextual knowledge lying in a temporal CVS sequence while being regularized to explore a general relationship over the entire time-series. A motion-influenced CVS of low-quality is detected, based on the residual between the input sequence and its neural representation with a cut-off value determined from the two-sigma rule of thumb over the training set. RESULT Our experimental observations validated two claims: (i) in the learning environment of label-absence, assessment performance is achievable at a competitive level to the supervised setting, and (ii) the contextual information across a time series of CVS is advantageous for effectively realizing motion-induced unrealistic distortions in signal amplitude and morphology. We also investigated the capability as a pseudo-labeling tool to minimize human-craft annotation by preemptively providing strong candidates for motion-induced anomalies. Empirical evidence has shown that machine-guided annotation can reduce inevitable human-errors during manual assessment while minimizing cumbersome and time-consuming processes. CONCLUSION The proposed method has a particular significance in the industrial field, where it is unavoidable to gather and utilize a large amount of CVS data to achieve high accuracy and robustness in real-world applications.
Collapse
Affiliation(s)
- Chang Min Hyun
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; School of Mathematics and Computing (Computational Science and Engineering), Yonsei University, Seoul, Republic of Korea.
| | - Tae-Geun Kim
- Department of Physics, Yonsei University, Seoul, Republic of Korea
| | - Kyounghun Lee
- Medical Science Research Institute, Kyung Hee University Medical Center, Seoul 02447, Republic of Korea.
| |
Collapse
|
4
|
Murphy EK, Smith J, Kokko MA, Rutkove SB, Halter RJ. Rapid patient-specific FEM meshes from 3D smart-phone based scans. Physiol Meas 2024; 45:025008. [PMID: 38320323 PMCID: PMC10901069 DOI: 10.1088/1361-6579/ad26d2] [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: 10/17/2023] [Accepted: 02/06/2024] [Indexed: 02/08/2024]
Abstract
Objective.The objective of this study was to describe and evaluate a smart-phone based method to rapidly generate subject-specific finite element method (FEM) meshes. More accurate FEM meshes should lead to more accurate thoracic electrical impedance tomography (EIT) images.Approach.The method was evaluated on an iPhone®that utilized an app called Heges, to obtain 3D scans (colored, surface triangulations), a custom belt, and custom open-source software developed to produce the subject-specific meshes. The approach was quantitatively validated via mannequin and volunteer tests using an infrared tracker as the gold standard, and qualitatively assessed in a series of tidal-breathing EIT images recorded from 9 subjects.Main results.The subject-specific meshes can be generated in as little as 6.3 min, which requires on average 3.4 min of user interaction. The mannequin tests yielded high levels of precision and accuracy at 3.2 ± 0.4 mm and 4.0 ± 0.3 mm root mean square error (RMSE), respectively. Errors on volunteers were only slightly larger (5.2 ± 2.1 mm RMSE precision and 7.7 ± 2.9 mm RMSE accuracy), illustrating the practical RMSE of the method.Significance.Easy-to-generate, subject-specific meshes could be utilized in the thoracic EIT community, potentially reducing geometric-based artifacts and improving the clinical utility of EIT.
Collapse
Affiliation(s)
- Ethan K Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America
| | - Joel Smith
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America
| | - Michael A Kokko
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America
| | - Seward B Rutkove
- 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
| | - Ryan J Halter
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America
- Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, United States of America
| |
Collapse
|
5
|
Chung CR, Ko RE, Jang GY, Lee K, Suh GY, Kim Y, Woo EJ. Comparison of noninvasive cardiac output and stroke volume measurements using electrical impedance tomography with invasive methods in a swine model. Sci Rep 2024; 14:2962. [PMID: 38316842 PMCID: PMC10844629 DOI: 10.1038/s41598-024-53488-0] [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: 06/28/2023] [Accepted: 02/01/2024] [Indexed: 02/07/2024] Open
Abstract
Pulmonary artery catheterization (PAC) has been used as a clinical standard for cardiac output (CO) measurements on humans. On animals, however, an ultrasonic flow sensor (UFS) placed around the ascending aorta or pulmonary artery can measure CO and stroke volume (SV) more accurately. The objective of this paper is to compare CO and SV measurements using a noninvasive electrical impedance tomography (EIT) device and three invasive devices using UFS, PAC-CCO (continuous CO) and arterial pressure-based CO (APCO). Thirty-two pigs were anesthetized and mechanically ventilated. A UFS was placed around the pulmonary artery through thoracotomy in 11 of them, while the EIT, PAC-CCO and APCO devices were used on all of them. Afterload and contractility were changed pharmacologically, while preload was changed through bleeding and injection of fluid or blood. Twenty-three pigs completed the experiment. Among 23, the UFS was used on 7 pigs around the pulmonary artery. The percentage error (PE) between COUFS and COEIT was 26.1%, and the 10-min concordance was 92.5%. Between SVUFS and SVEIT, the PE was 24.8%, and the 10-min concordance was 94.2%. On analyzing the data from all 23 pigs, the PE between time-delay-adjusted COPAC-CCO and COEIT was 34.6%, and the 10-min concordance was 81.1%. Our results suggest that the performance of the EIT device in measuring dynamic changes of CO and SV on mechanically-ventilated pigs under different cardiac preload, afterload and contractility conditions is at least comparable to that of the PAC-CCO device. Clinical studies are needed to evaluate the utility of the EIT device as a noninvasive hemodynamic monitoring tool.
Collapse
Affiliation(s)
- Chi Ryang Chung
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ryoung Eun Ko
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Geuk Young Jang
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Kyounghun Lee
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Gee Young Suh
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yongmin Kim
- Department of Convergence IT Engineering, POSTECH, Pohang, Korea
| | - Eung Je Woo
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea.
| |
Collapse
|
6
|
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
Collapse
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
| |
Collapse
|
7
|
Putensen C, Gattinoni L, Leonhardt S. Electrical Impedance Tomography: Is It Ready to Measure Pulmonary Perfusion Distribution at the Bedside? Anesthesiology 2023; 139:722-725. [PMID: 37934108 DOI: 10.1097/aln.0000000000004770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Affiliation(s)
- Christian Putensen
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany
| | - Luciano Gattinoni
- Department of Anesthesiology, University Medical Center Göttingen, Göttingen, Germany
| | - Steffen Leonhardt
- Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Rein A, Ngo C, van den Berg M, Böll S, Lassay L, Kontny U, Wagner N, Leonhardt S, Tenbrock K, Verjans E. Evaluation of lung function in a German single center cohort of young patients with sickle cell disease using EIT and standard techniques. Front Med (Lausanne) 2023; 10:1100180. [PMID: 36993804 PMCID: PMC10040809 DOI: 10.3389/fmed.2023.1100180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/21/2023] [Indexed: 03/15/2023] Open
Abstract
Background and objectiveSickle cell disease (SCD) is a very common autosomal recessive hemoglobinopathy leading to multiple pulmonary complications that are closely associated with mortality. The pathophysiology of chronic pulmonary involvement is not yet fully understood and no specific therapies are available.MethodsThe aim of this cross-sectional study was to characterize the lung function of children and young adolescents with SCD in a German single-center cohort and to extend conventional lung function testing by the use of a new imaging method. We performed spirometry and body plethysmography in 35 children and young adults with hemoglobin SS, SC, S/β-thalassemia as well as 50 controls. These data were compared with clinical characteristics and typical laboratory parameters of hemolysis and disease activity in SCD. To identify lung inhomogeneities, for example due to atelectasis, hyperinflation, air trapping or vascular occlusions, we used the promising new method of electrical impedance tomography (EIT) and calculated global inhomogeneity indices.ResultsLung function of patients with SCD was significantly reduced compared to that of healthy controls. When the result was found to be pathological, the most commonly observed type of breathing disorder was classified as restrictive. Laboratory parameters showed typical features of SCD including decreased levels of hemoglobin and hematocrit and elevated levels of leucocytes, platelets, lactate dehydrogenase and total bilirubin. However, there was no correlation between blood values and reduced lung function. Electrical impedance tomography (EIT) revealed no abnormalities in SCD patients compared to healthy controls. In particular, we were unable to demonstrate any regional inhomogeneities in lung ventilation.ConclusionIn our study, SCD patients showed impaired lung function, with a relevant percentage of patients suffering from restrictive breathing disorder. Signs of obstruction could not be detected. Electrical impedance tomography (EIT) measurements revealed no unevenness that would suggest air entrapment, blockage of blood vessels, excessive inflation, obstruction, or other forms of lung disease. Additionally, the reduction in lung function observed in SCD patients was not related to the disease severity or laboratory test results.
Collapse
Affiliation(s)
- Alina Rein
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Chuong Ngo
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Maike van den Berg
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Svenja Böll
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Lisa Lassay
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Udo Kontny
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Norbert Wagner
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Steffen Leonhardt
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Klaus Tenbrock
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
| | - Eva Verjans
- Department of Pediatrics, Medical Faculty, RWTH Aachen University, University Hospital Aachen, Aachen, Germany
- *Correspondence: Eva Verjans,
| |
Collapse
|
10
|
Min Hyun C, Jun Jang T, Nam J, Kwon H, Jeon K, Lee K. Machine learning-based signal quality assessment for cardiac volume monitoring in electrical impedance tomography. MACHINE LEARNING: SCIENCE AND TECHNOLOGY 2023. [DOI: 10.1088/2632-2153/acc637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023] Open
Abstract
Abstract
Owing to recent advances in thoracic electrical impedance tomography (EIT), a patient’s hemodynamic function can be noninvasively and continuously estimated in real-time by surveilling a cardiac volume signal (CVS) associated with stroke volume and cardiac output. In clinical applications, however, a CVS is often of low quality, mainly because of the patient’s deliberate movements or inevitable motions during clinical interventions. This study aims to develop a signal quality indexing method that assesses the influence of motion artifacts on transient CVSs. The assessment is performed on each cardiac cycle to take advantage of the periodicity and regularity in cardiac volume changes. Time intervals are identified using the synchronized electrocardiography system. We apply divergent machine-learning methods, which can be sorted into discriminative-model and manifold-learning approaches. The use of machine-learning could be suitable for our real-time monitoring application that requires fast inference and automation as well as high accuracy. In the clinical environment, the proposed method can be utilized to provide immediate warnings so that clinicians can minimize confusion regarding patients’ conditions, reduce clinical resource utilization, and improve the confidence level of the monitoring system. Numerous experiments using actual EIT data validate the capability of CVSs degraded by motion artifacts to be accurately and automatically assessed in real-time by machine learning. The best model achieved an accuracy of 0.95, positive and negative predictive values of 0.96 and 0.86, sensitivity of 0.98, specificity of 0.77, and AUC of 0.96.
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Zhang K, Li M, Liang H, Wang J, Yang F, Xu S, Abubakar A. Deep feature-domain matching for cardiac-related component separation from a chest electrical impedance tomography image series: proof-of-concept study. Physiol Meas 2022; 43. [PMID: 36265475 DOI: 10.1088/1361-6579/ac9c44] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 10/20/2022] [Indexed: 02/07/2023]
Abstract
Objectives.The cardiac-related component in chest electrical impedance tomography (EIT) measurement is of potential value to pulmonary perfusion monitoring and cardiac function measurement. In a spontaneous breathing case, cardiac-related signals experience serious interference from ventilation-related signals. Traditional cardiac-related signal-separation methods are usually based on certain features of signals. To further improve the separation accuracy, more comprehensive features of the signals should be exploited.Approach.We propose an unsupervised deep-learning method called deep feature-domain matching (DFDM), which exploits the feature-domain similarity of the desired signals and the breath-holding signals. This method is characterized by two sub-steps. In the first step, a novel Siamese network is designed and trained to learn common features of breath-holding signals; in the second step, the Siamese network is used as a feature-matching constraint between the separated signals and the breath-holding signals.Main results.The method is first tested using synthetic data, and the results show satisfactory separation accuracy. The method is then tested using the data of three patients with pulmonary embolism, and the consistency between the separated images and the radionuclide perfusion scanning images is checked qualitatively.Significance.The method uses a lightweight convolutional neural network for fast network training and inference. It is a potential method for dynamic cardiac-related signal separation in clinical settings.
Collapse
Affiliation(s)
- Ke Zhang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Maokun Li
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Haiqing Liang
- TEDA International Cardiovascular Hospital, Tianjin 300457, People's Republic of China
| | - Juan Wang
- National Laboratory of Pattern Recognition (NLPR), Institute of Automation, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fan Yang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shenheng Xu
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Aria Abubakar
- Schlumberger, Houston, TX 77056, United States of America
| |
Collapse
|
13
|
Electrical Impedance Tomography Can Be Used to Quantify Lung Hyperinflation during HFOV: The Pilot Study in Pigs. Diagnostics (Basel) 2022; 12:diagnostics12092081. [PMID: 36140483 PMCID: PMC9497761 DOI: 10.3390/diagnostics12092081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/16/2022] Open
Abstract
Dynamic hyperinflation is reported as a potential risk during high-frequency oscillatory ventilation (HFOV), and its existence has been documented both by physical models and by CT. The aim of this study is to determine the suitability of electrical impendence tomography (EIT) for the measurement of dynamic lung hyperinflation and hypoinflation during HFOV. Eleven healthy pigs were anaesthetized and ventilated using HFOV. The difference between the airway pressure at the airway opening and alveolar space was measured by EIT and esophageal balloons at three mean airway pressures (12, 18 and 24 cm H2O) and two inspiratory to expiratory time ratios (1:1, 1:2). The I:E ratio was the primary parameter associated with differences between airway and alveolar pressures. All animals showed hyperinflation at a 1:1 ratio (median 1.9 cm H2O) and hypoinflation at a 1:2 (median –4.0 cm H2O) as measured by EIT. EIT measurements had a linear correlation to esophageal balloon measurements (r2 = –0.915, p = 0.0085). EIT measurements were slightly higher than that of the esophageal balloon transducer with the mean difference of 0.57 cm H2O. Presence of a hyperinflation or hypoinflation was also confirmed independently by chest X-ray. We found that dynamic hyperinflation developed during HFOV may be detected and characterized noninvasively by EIT.
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Lee K, Jang GY, Kim Y, Woo EJ. Multi-channel Trans-impedance Leadforming for Cardiopulmonary Monitoring: Algorithm Development and Feasibility Assessment using In Vivo Animal Data. IEEE Trans Biomed Eng 2021; 69:1964-1974. [PMID: 34855581 DOI: 10.1109/tbme.2021.3132012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The objectives of this study were to (1) develop a multi-channel trans-impedance leadforming method for beat-to-beat stroke volume (SV) and breath-by-breath tidal volume (TV) measurements and (2) assess its feasibility on an existing in vivo animal dataset. METHODS A deterministic leadforming algorithm was developed to extract a cardiac volume signal (CVS) and a respiratory volume signal (RVS) from 208-channel trans-impedance data acquired every 20 ms by an electrical impedance tomography (EIT) device. SVEIT and TVEIT values were computed as a valley-to-peak value in the CVS and RVS, respectively. The method was applied to the existing dataset from five mechanically-ventilated pigs undergoing ten mini-fluid challenges. An invasive hemodynamic monitor was used in the arterial pressure-based cardiac output (APCO) mode to simultaneously measure SVAPCO values while a mechanical ventilator provided TVVent values. RESULTS The leadforming method could reliably extract the CVS and RVS from the 208-channel trans-impedance data measured with the EIT device, from which SV<sub>EIT</sub> and TV<sub>EIT</sub> were computed. The SV<sub>EIT</sub> and TV<sub>EIT</sub> values were comparable to those from the invasive hemodynamic monitor and mechanical ventilator. Using the data from 5 pigs and a simple calibration method to remove bias, the error in SV<sub>EIT<sub> and TV<sub>EIT<sub> was 9.5% and 5.4%, respectively. CONCLUSION We developed a new leadforming method for the EIT device to robustly extract both SV and TV values in a deterministic fashion. Future animal and clinical studies are needed to validate this leadforming method in various subject populations. SIGNIFICANCE The leadforming method could be an integral component for a new cardiopulmonary monitor in the future to simultaneously measure SV and TV noninvasively, which would be beneficial to patients.
Collapse
|
16
|
Chen R, Lovas A, Benyó B, Möller K. Detection of Different COVID-19 Pneumonia Phenotypes with Estimated Alveolar Collapse and Overdistention by Bedside Electrical Impedance Tomography. IFAC-PAPERSONLINE 2021; 54:269-274. [PMID: 38620949 PMCID: PMC8562158 DOI: 10.1016/j.ifacol.2021.10.267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
COVID-19 induced acute respiratory distress syndrome (ARDS) could have two different phenotypes, which was reported to have different response and outcome to the typical ARDS positive end-expiration pressure (PEEP) treatment. The identification of the different phenotypes in terms of the recruitability can help improve the patient outcome. In this contribution we conducted alveolar overdistention and collapse analysis with the long term electrical impedance tomography monitoring data on two severe COVID-19 pneumonia patients. The result showed different patient reactions to the PEEP trial, revealed the progressive change in the patient status, and indicted a possible phenotype transition in one patient. It might suggest that EIT can be a practical tool to identify phenotypes and to provide progressive information of COVID-19 pneumonia.
Collapse
Affiliation(s)
- Rongqing Chen
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Str. 17, VS-Schwenningen, Germany
| | - András Lovas
- Kiskunhalas Semmelweis Hospital, Department of Anaesthesiology and Intensive Therapy, H-6400, Dr. Monszpart L. u. 1, Hungary
| | - Balázs Benyó
- Department of Control Engineering and Information Technology, Budapest University of Technology and Economics, 1117 Budapest, Magyar tudósok krt. 2, Hungary
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Str. 17, VS-Schwenningen, Germany
| |
Collapse
|
17
|
Ko RE, Jang GY, Chung CR, Lee JY, Oh TI, Suh GY, Kim Y, Woo EJ. Noninvasive Beat-To-Beat Stroke Volume Measurements to Determine Preload Responsiveness During Mini-Fluid Challenge in a Swine Model: A Preliminary Study. Shock 2021; 56:850-856. [PMID: 33534400 DOI: 10.1097/shk.0000000000001739] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
ABSTRACT Cardiac output (CO) is an important parameter in fluid management decisions for treating hemodynamically unstable patients in intensive care unit. The gold standard for CO measurements is the thermodilution method, which is an invasive procedure with intermittent results. Recently, electrical impedance tomography (EIT) has emerged as a new method for noninvasive measurements of stroke volume (SV). The objectives of this paper are to compare EIT with an invasive pulse contour analysis (PCA) method in measuring SV during mini-fluid challenge in animals and determine preload responsiveness with EIT. Five pigs were anesthetized and mechanically ventilated. After removing 25% to 30% of the total blood from each animal, multiple fluid injections were conducted. The EIT device successfully tracked changes in SV beat-to-beat during varying volume states, i.e., from hypovolemia and preload responsiveness to target volume and volume overload. From a total of 50 100-mL fluid injections on five pigs (10 injections per pig), the preload responsiveness value was as large as 32.3% in the preload responsiveness state while in the volume overload state it was as low as -4.9%. The bias of the measured SV data using EIT and PCA was 0 mL, and the limits of agreement were ±3.6 mL in the range of 17.6 mL to 51.0 mL. The results of the animal experiments suggested that EIT is capable of measuring beat-to-beat SV changes during mini-fluid challenge and determine preload responsiveness. Further animal and clinical studies will be needed to demonstrate the feasibility of the EIT method as a new tool for fluid management.
Collapse
Affiliation(s)
- Ryoung Eun Ko
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Geuk Young Jang
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Korea
| | - Chi Ryang Chung
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jin Young Lee
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Tong In Oh
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Korea
| | - Gee Young Suh
- Department of Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yongmin Kim
- Department of Creative IT Engineering, POSTECH, Pohang, Korea
| | - Eung Je Woo
- Department of Biomedical Engineering, Kyung Hee University, Seoul, Korea
| |
Collapse
|
18
|
Eimer C, Freier K, Weiler N, Frerichs I, Becher T. The Effect of Physical Therapy on Regional Lung Function in Critically Ill Patients. Front Physiol 2021; 12:749542. [PMID: 34616313 PMCID: PMC8488288 DOI: 10.3389/fphys.2021.749542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 08/23/2021] [Indexed: 02/04/2023] Open
Abstract
Early mobilization has become an important aspect of treatment in intensive care medicine, especially in patients with acute pulmonary dysfunction. As its effects on regional lung physiology have not been fully explored, we conceived a prospective observational study (Registration number: DRKS00023076) investigating regional lung function during a 15-min session of early mobilization physiotherapy with a 30-min follow-up period. The study was conducted on 20 spontaneously breathing adult patients with impaired pulmonary gas exchange receiving routine physical therapy during their intensive care unit stay. Electrical impedance tomography (EIT) was applied to continuously monitor ventilation distribution and changes in lung aeration during mobilization and physical therapy. Baseline data was recorded in the supine position, the subjects were then transferred into the seated and partly standing position for physical therapy. Afterward, patients were transferred back into the initial position and followed up with EIT for 30 min. EIT data were analyzed to assess changes in dorsal fraction of ventilation (%dorsal), end-expiratory lung impedance normalized to tidal variation (ΔEELI), center of ventilation (CoV) and global inhomogeneity index (GI index).Follow-up was completed in 19 patients. During exercise, patients exhibited a significant change in ventilation distribution in favor of dorsal lung regions, which did not persist during follow-up. An identical effect was shown by CoV. ΔEELI increased significantly during follow-up. In conclusion, mobilization led to more dorsal ventilation distribution, but this effect subsided after returning to initial position. End-expiratory lung impedance increased during follow-up indicating a slow increase in end-expiratory lung volume following physical therapy.
Collapse
Affiliation(s)
- Christine Eimer
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Kiel, Germany
| | - Katharina Freier
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Kiel, Germany
| | - Norbert Weiler
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Kiel, Germany
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Kiel, Germany
| | - Tobias Becher
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Kiel, Germany
| |
Collapse
|
19
|
Shi Y, Yang Z, Xie F, Ren S, Xu S. The Research Progress of Electrical Impedance Tomography for Lung Monitoring. Front Bioeng Biotechnol 2021; 9:726652. [PMID: 34660553 PMCID: PMC8517404 DOI: 10.3389/fbioe.2021.726652] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 08/09/2021] [Indexed: 01/16/2023] Open
Abstract
Medical imaging can intuitively show people the internal structure, morphological information, and organ functions of the organism, which is one of the most important inspection methods in clinical medical diagnosis. Currently used medical imaging methods can only be applied to some diagnostic occasions after qualitative lesions have been generated, and the general imaging technology is usually accompanied by radiation and other conditions. However, electrical impedance tomography has the advantages of being noninvasive and non-radiative. EIT (Electrical Impedance Tomography) is also widely used in the early diagnosis and treatment of some diseases because of these advantages. At present, EIT is relatively mature and more and more image reconstruction algorithms are used to improve imaging resolution. Hardware technology is also developing rapidly, and the accuracy of data collection and processing is continuously improving. In terms of clinical application, EIT has also been used for pathological treatment of lungs, the brain, and the bladder. In the future, EIT has a good application prospect in the medical field, which can meet the needs of real-time, long-term monitoring and early diagnosis. Aiming at the application of EIT in the treatment of lung pathology, this article reviews the research progress of EIT, image reconstruction algorithms, hardware system design, and clinical applications used in the treatment of lung diseases. Through the research and introduction of several core components of EIT technology, it clarifies the characteristics of EIT system complexity and its solutions, provides research ideas for subsequent research, and once again verifies the broad development prospects of EIT technology in the future.
Collapse
Affiliation(s)
- Yan Shi
- The School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| | - ZhiGuo Yang
- The School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| | - Fei Xie
- Department of Pulmonary and Critical Care Medicine, Chinese PLA General Hospital, Beijing, China
| | - Shuai Ren
- The School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
- State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou, China
| | - ShaoFeng Xu
- The School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| |
Collapse
|
20
|
Hentze B, Muders T, Hoog Antink C, Putensen C, Larsson A, Hedenstierna G, Walter M, Leonhardt S. A model-based source separation algorithm for lung perfusion imaging using electrical impedance tomography. Physiol Meas 2021; 42. [PMID: 34167091 DOI: 10.1088/1361-6579/ac0e84] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/24/2021] [Indexed: 11/11/2022]
Abstract
Objective. Electrical impedance tomography (EIT) for lung perfusion imaging is attracting considerable interest in intensive care, as it might open up entirely new ways to adjust ventilation therapy. A promising technique is bolus injection of a conductive indicator to the central venous catheter, which yields the indicator-based signal (IBS). Lung perfusion images are then typically obtained from the IBS using the maximum slope technique. However, the low spatial resolution of EIT results in a partial volume effect (PVE), which requires further processing to avoid regional bias.Approach. In this work, we repose the extraction of lung perfusion images from the IBS as a source separation problem to account for the PVE. We then propose a model-based algorithm, called gamma decomposition (GD), to derive an efficient solution. The GD algorithm uses a signal model to transform the IBS into a parameter space where the source signals of heart and lung are separable by clustering in space and time. Subsequently, it reconstructs lung model signals from which lung perfusion images are unambiguously extracted.Main results. We evaluate the GD algorithm on EIT data of a prospective animal trial with eight pigs. The results show that it enables lung perfusion imaging using EIT at different stages of regional impairment. Furthermore, parameters of the source signals seem to represent physiological properties of the cardio-pulmonary system.Significance. This work represents an important advance in IBS processing that will likely reduce bias of EIT perfusion images and thus eventually enable imaging of regional ventilation/perfusion (V/Q) ratio.
Collapse
Affiliation(s)
- Benjamin Hentze
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany.,Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Thomas Muders
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Christoph Hoog Antink
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany.,Biomedical Engineering, TU Darmstadt, Darmstadt, Germany
| | - Christian Putensen
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Anders Larsson
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Marian Walter
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Steffen Leonhardt
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| |
Collapse
|
21
|
Menden T, Alcaín GB, Stevenson AT, Pollock RD, Tank H, Hodkinson P, Jolley C, Smith TG, Leonhardt S, Walter M. Dynamic lung behavior under high G acceleration monitored with electrical impedance tomography. Physiol Meas 2021; 42. [PMID: 34375953 DOI: 10.1088/1361-6579/ac1c63] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/10/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE During launch and atmospheric re-entry in suborbital space flights, astronauts are exposed to high G-acceleration. These acceleration levels influence gas exchange inside the lung and can potentially lead to hypoxaemia. The distribution of air inside the lung can be monitored by Electrical Impedance Tomography (EIT). This imaging technique might reveal how high gravitational forces affect the dynamic behavior of ventilation and impair gas exchange resulting in hypoxaemia. APPROACH We performed a trial in a long-arm centrifuge with ten participants lying supine while being exposed to +2, +4 and +6\,Gx(chest-to-back acceleration) to study the magnitude of accelerations experienced during suborbital spaceflight. MAIN RESULTS First, the tomographic images revealed that the dorsal region of the lung emptied faster than the ventral region. Second, the ventilated area shifted from dorsal to ventral. Consequently, alveolar pressure in the dorsal area reached the pressure of the upper airways before the ventral area emptied completely. Finally, the upper airways collapsed and the end-expiratory volume increased. This resulted in ventral gas trapping with restricted gas exchange. SIGNIFICANCE At +4xchanges in ventilation distribution varied considerably between subjects potentially due to variation in individual physical conditions. However, at +6\,Gxall participants were affected similarly and the influence of high gravitational conditions was pronounced.
Collapse
Affiliation(s)
- Tobias Menden
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Gema B Alcaín
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Alec T Stevenson
- QinetiQ EMEA, Farnborough, Hampshire, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Ross D Pollock
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Henry Tank
- QinetiQ EMEA, Farnborough, Hampshire, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Peter Hodkinson
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Caroline Jolley
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Thomas G Smith
- King's College London Centre of Human and Aerospace Physiological Sciences, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Steffen Leonhardt
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| | - Marian Walter
- Chair for Medical Information Technology, RWTH Aachen University, Aachen, Nordrhein-Westfalen, GERMANY
| |
Collapse
|
22
|
Omer N, Abboud S, Arad M. Diagnosing and monitoring pleural effusion using parametric electrical impedance tomography - a computational 3D model and preliminary experimental results. Med Eng Phys 2021; 92:45-53. [PMID: 34167711 DOI: 10.1016/j.medengphy.2021.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/21/2021] [Accepted: 04/30/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Diagnosing and monitoring pleural effusion (PE) is challenging due unsuitability of existing modalities. In the present study, a novel parametric electrical impedance tomography (pEIT) technique, tailored to a clinically feasible system to diagnose PE is presented. METHODS An electrical impedance tomography (EIT) numeric solver was applied to a 3D realistic normal model and five PE models to simulate sets of surface measurements. Simulations were triggered by a series of eight independent projections using five electrodes positioned around the thorax. The relative changes in the potential between the PE models and the normal model were assessed and the error in the estimated PE volume was examined at varying signal to noise ratio (SNR) levels. For experimental feasibility, measurements were performed in four healthy subjects and were correlated with the potentials that were calculated from the normal model. RESULTS Relative potential changes were notable (reached until ~55%) and increased with the increasing PE volumes. Maximal error of ± 20 [mL] was obtained for SNR levels >50 [dB]. The feasibility real measurements in healthy subjects showed a strong linear correlation (R2 > 0.85) and a successful diagnosis for all subjects. CONCLUSION The proposed technique can estimate PE volumes from a redundant set of measurements in a realistic 3D human model and may be utilized for monitoring PE patients.
Collapse
Affiliation(s)
- Noam Omer
- Department of Biomedical Engineering, Tel-Aviv University, Israel.
| | - Shimon Abboud
- Department of Biomedical Engineering, Tel-Aviv University, Israel
| | - Marina Arad
- Department of Geriatric Rehabilitation, Sheba Medical Center, Israel
| |
Collapse
|
23
|
Effects of pleural effusion drainage in the mechanically ventilated patient as monitored by electrical impedance tomography and end-expiratory lung volume: A pilot study. J Crit Care 2020; 59:76-80. [DOI: 10.1016/j.jcrc.2020.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/25/2020] [Accepted: 06/01/2020] [Indexed: 12/17/2022]
|
24
|
Noninvasive, simultaneous, and continuous measurements of stroke volume and tidal volume using EIT: feasibility study of animal experiments. Sci Rep 2020; 10:11242. [PMID: 32647206 PMCID: PMC7347894 DOI: 10.1038/s41598-020-68139-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 06/18/2020] [Indexed: 12/01/2022] Open
Abstract
Currently, there is no noninvasive method available for simultaneous measurements of tidal volume and stroke volume. Electrical impedance tomography (EIT) has been used for regional lung ventilation imaging. Cardiac EIT imaging, however, has not been successful due to the technical difficulty in extracting weak cardiogenic components. Instead of regional imaging, in this paper, we use the EIT technique to simultaneously measure two global variables of tidal volume and stroke volume. Time-varying patterns of boundary voltage data originating from lung ventilation and cardiac blood flow were extracted from measured boundary voltage data using the principal component analysis (PCA) and independent component analysis (ICA). The source consistency theory was adopted to separately synthesize time-series of boundary voltage data associated with lung ventilation and cardiac blood flow. The respiratory volume signal (RVS) and cardiac volume signal (CVS) were extracted from reconstructed time-difference EIT images of lung ventilation and cardiac blood flow, respectively. After calibrating the volume signals using the mechanical ventilator and the invasive transpulmonary thermodilution (TPTD) method, tidal volume and stroke volume were computed as valley-to-peak values of the RVS and CVS, respectively. The difference in the tidal volume data between EIT and mechanical ventilator was within ± 20 ml from six pigs. The difference in the stroke volume data between EIT and TPTD was within ± 4.7 ml from the same animals. The results show the feasibility of the proposed method as a new noninvasive cardiopulmonary monitoring tool for simultaneous continuous measurements of stroke volume and tidal volume that are two most important vital signs.
Collapse
|
25
|
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.
Collapse
|
26
|
Defining information needs in neonatal resuscitation with work domain analysis. J Clin Monit Comput 2020; 35:689-710. [PMID: 32458169 DOI: 10.1007/s10877-020-00526-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 05/07/2020] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To gain a deeper understanding of the information requirements of clinicians conducting neonatal resuscitation in the first 10 min after birth. BACKGROUND During the resuscitation of a newborn infant in the first minutes after birth, clinicians must monitor crucial physiological adjustments that are relatively unobservable, unpredictable, and highly variable. Clinicians' access to information regarding the physiological status of the infant is also crucial to determining which interventions are most appropriate. To design displays to support clinicians during newborn resuscitation, we must first carefully consider the information requirements. METHODS We conducted a work domain analysis (WDA) for the neonatal transition in the first 10 min after birth. We split the work domain into two 'subdomains'; the physiology of the neonatal transition, and the clinical resources supporting the neonatal transition. A WDA can reveal information requirements that are not yet supported by resources. RESULTS The physiological WDA acted as a conceptual tool to model the exact processes and functions that clinicians must monitor and potentially support during the neonatal transition. Importantly, the clinical resources WDA revealed several capabilities and limitations of the physical objects in the work domain-ultimately revealing which physiological functions currently have no existing sensor to provide clinicians with information regarding their status. CONCLUSION We propose two potential approaches to improving the clinician's information environment: (1) developing new sensors for the information we lack, and (2) employing principles of ecological interface design to present currently available information to the clinician in a more effective way.
Collapse
|
27
|
Lehmann M, Oehler B, Zuber J, Malzahn U, Walles T, Muellenbach RM, Roewer N, Kredel M. Redistribution of pulmonary ventilation after lung surgery detected with electrical impedance tomography. Acta Anaesthesiol Scand 2020; 64:517-525. [PMID: 31830306 DOI: 10.1111/aas.13525] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 10/09/2019] [Accepted: 11/04/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND Regional ventilation of the lung can be visualized by pulmonary electrical impedance tomography (EIT). The aim of this study was to examine the post-operative redistribution of regional ventilation after lung surgery dependent on the side of surgery and its association with forced vital capacity. METHODS In this prospective, observational cohort study 13 patients undergoing right and 13 patients undergoing left-sided open or video-thoracoscopic procedures have been investigated. Pre-operative measurements with EIT and spirometry were compared with data obtained 3 days post-operation. The center of ventilation (COV) within a 32 × 32 pixel matrix was calculated from EIT data. The transverse axis coordinate of COV, COVx (left/right), was modified to COVx' (ipsilateral/contralateral). Thus, COVx' shows a negative change if ventilation shifts contralateral independent of the side of surgery. This enabled testing with two-way ANOVA for repeated measurements (side, time). RESULTS The perioperative shift of COVx' was dependent on the side of surgery (P = .007). Ventilation shifted away from the side of surgery after the right-sided surgery (COVx'-1.97 pixel matrix points, P < .001), but not after the left-sided surgery (COVx'-0.61, P = .425). The forced vital capacity (%predicted) decreased from 94 (83-109)% (median [quartiles]; [left-sided]) and 89 (80-97)% (right-sided surgery) to 61 (59-66)% and 62 (40-72)% (P < .05), respectively. The perioperative changes in forced vital capacity (%predicted) were weakly associated with the shift of COVx'. CONCLUSION Only after right-sided lung surgery, EIT showed reduced ventilation on the side of surgery while vital capacity was markedly reduced in both groups.
Collapse
Affiliation(s)
- Martin Lehmann
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
| | - Beatrice Oehler
- Wolfson Centre for Age-Related Diseases King's College London London UK
| | - Jonas Zuber
- Department of Anesthesia, General Intensive Care and Pain Management Medical University of Vienna Vienna Austria
| | - Uwe Malzahn
- Clinical Trials Center Würzburg University Hospital of Würzburg Würzburg Germany
| | - Thorsten Walles
- Department of Thoracic Surgery Magdeburg University Medicine Magdeburg Germany
| | - Ralf M. Muellenbach
- Department of Anesthesiology, Critical Care Medicine, Emergency Medicine and Pain Therapy ECMO Center Campus Kassel of the University of Southampton Kassel Germany
| | - Norbert Roewer
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
| | - Markus Kredel
- Department of Anaesthesia and Critical Care University Hospital of Würzburg Würzburg Germany
| |
Collapse
|
28
|
King A, Blank D, Bhatia R, Marzbanrad F, Malhotra A. Tools to assess lung aeration in neonates with respiratory distress syndrome. Acta Paediatr 2020; 109:667-678. [PMID: 31536658 DOI: 10.1111/apa.15028] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/26/2019] [Accepted: 09/17/2019] [Indexed: 12/31/2022]
Abstract
AIM Respiratory distress syndrome is a common condition among preterm neonates, and assessing lung aeration assists in diagnosing the disease and helping to guide and monitor treatment. We aimed to identify and analyse the tools available to assess lung aeration in neonates with respiratory distress syndrome. METHODS A systematic review and narrative synthesis of studies published between January 1, 2004, and August 26, 2019, were performed using the OVID Medline, PubMed, Embase and Scopus databases. RESULTS A total of 53 relevant papers were retrieved for the narrative synthesis. The main tools used to assess lung aeration were respiratory function monitoring, capnography, chest X-rays, lung ultrasound, electrical impedance tomography and respiratory inductive plethysmography. This paper discusses the evidence to support the use of these tools, including their advantages and disadvantages, and explores the future of lung aeration assessments within neonatal intensive care units. CONCLUSION There are currently several promising tools available to assess lung aeration in neonates with respiratory distress syndrome, but they all have their limitations. These tools need to be refined to facilitate convenient and accurate assessments of lung aeration in neonates with respiratory distress syndrome.
Collapse
Affiliation(s)
- Arrabella King
- Department of Paediatrics Monash University Melbourne Vic. Australia
| | - Douglas Blank
- Monash Newborn Monash Children's Hospital Melbourne Vic. Australia
- The Ritchie Centre Hudson Institute of Medical Research Melbourne Vic. Australia
| | - Risha Bhatia
- Department of Paediatrics Monash University Melbourne Vic. Australia
- Monash Newborn Monash Children's Hospital Melbourne Vic. Australia
| | - Faezeh Marzbanrad
- Department of Electrical and Computer Systems Engineering Monash University Melbourne Vic. Australia
| | - Atul Malhotra
- Department of Paediatrics Monash University Melbourne Vic. Australia
- Monash Newborn Monash Children's Hospital Melbourne Vic. Australia
- The Ritchie Centre Hudson Institute of Medical Research Melbourne Vic. Australia
| |
Collapse
|
29
|
Abstract
Ventilation-induced lung injury results from mechanical stress and strain that occur during tidal ventilation in the susceptible lung. Classical descriptions of ventilation-induced lung injury have focused on harm from positive pressure ventilation. However, injurious forces also can be generated by patient effort and patient–ventilator interactions. While the role of global mechanics has long been recognized, regional mechanical heterogeneity within the lungs also appears to be an important factor propagating clinically significant lung injury. The resulting clinical phenotype includes worsening lung injury and a systemic inflammatory response that drives extrapulmonary organ failures. Bedside recognition of ventilation-induced lung injury requires a high degree of clinical acuity given its indistinct presentation and lack of definitive diagnostics. Yet the clinical importance of ventilation-induced lung injury is clear. Preventing such biophysical injury remains the most effective management strategy to decrease morbidity and mortality in patients with acute respiratory distress syndrome and likely benefits others at risk.
Collapse
Affiliation(s)
- Purnema Madahar
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
| | - Jeremy R Beitler
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
| |
Collapse
|
30
|
The dawn of physiological closed-loop ventilation-a review. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2020; 24:121. [PMID: 32223754 PMCID: PMC7104522 DOI: 10.1186/s13054-020-2810-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/25/2020] [Indexed: 01/06/2023]
Abstract
The level of automation in mechanical ventilation has been steadily increasing over the last few decades. There has recently been renewed interest in physiological closed-loop control of ventilation. The development of these systems has followed a similar path to that of manual clinical ventilation, starting with ensuring optimal gas exchange and shifting to the prevention of ventilator-induced lung injury. Systems currently aim to encompass both aspects, and early commercial systems are appearing. These developments remain unknown to many clinicians and, hence, limit their adoption into the clinical environment. This review shows the evolution of the physiological closed-loop control of mechanical ventilation.
Collapse
|
31
|
Bedside respiratory physiology to detect risk of lung injury in acute respiratory distress syndrome. Curr Opin Crit Care 2020; 25:3-11. [PMID: 30531534 DOI: 10.1097/mcc.0000000000000579] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW The most effective strategies for treating the patient with acute respiratory distress syndrome center on minimizing ventilation-induced lung injury (VILI). Yet, current standard-of-care does little to modify mechanical ventilation to patient-specific risk. This review focuses on evaluation of bedside respiratory mechanics, which when interpreted in patient-specific context, affords opportunity to individualize lung-protective ventilation in patients with acute respiratory distress syndrome. RECENT FINDINGS Four biophysical mechanisms of VILI are widely accepted: volutrauma, barotrauma, atelectrauma, and stress concentration. Resulting biotrauma, that is, local and systemic inflammation and endothelial activation, may be thought of as the final common pathway that propagates VILI-mediated multiorgan failure. Conventional, widely utilized techniques to assess VILI risk rely on airway pressure, flow, and volume changes, and remain essential tools for determining overdistension of aerated lung regions, particularly when interpreted cognizant of their limitations. Emerging bedside tools identify regional differences in mechanics, but further study is required to identify how they might best be incorporated into clinical practice. SUMMARY Quantifying patient-specific risk of VILI requires understanding each patient's pulmonary mechanics in context of biological predisposition. Tailoring support at bedside according to these factors affords the greatest opportunity to date for mitigating VILI and alleviating associated morbidity.
Collapse
|
32
|
Barrett NA, Hart N, Camporota L. Assessment of Work of Breathing in Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease. COPD 2019; 16:418-428. [PMID: 31694406 DOI: 10.1080/15412555.2019.1681390] [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
The assessment of the work of breathing (WOB) of patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) is difficult, particularly when the patient first presents with acute hypercapnia and respiratory acidosis. Acute exacerbations of COPD patients are in significant respiratory distress and noninvasive measurements of WOB are easier for the patient to tolerate. Given the interest in using alternative therapies to noninvasive ventilation, such as high flow nasal oxygen therapy or extracorporeal carbon dioxide removal, understanding the physiological changes are key and this includes assessment of WOB. This narrative review considers the role of three different methods of assessing WOB in patients with acute exacerbations of COPD. Esophageal pressure is a very well validated measure of WOB, however the ability of patients with acute exacerbations of COPD to tolerate esophageal tubes is poor. Noninvasive alternative measurements include parasternal electromyography (EMG) and electrical impedance tomography (EIT). EMG is easily applied and is a well validated measure of neural drive but is more likely to be degraded by the electrical environment in intensive care or high dependency. EIT is less well validated as a tool for WOB in COPD but extremely well tolerated by patients. Each of the different methods assess WOB in a different way and have different advantages and disadvantages. For research into therapies treating acute exacerbations of COPD, combinations of EIT, EMG and esophageal pressure are likely to be better than only one of these.
Collapse
Affiliation(s)
- N A Barrett
- Centre for Human & Applied Physiological Sciences (CHAPS), School of Basic & Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom.,Department of Critical Care, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - N Hart
- Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - L Camporota
- Centre for Human & Applied Physiological Sciences (CHAPS), School of Basic & Medical Biosciences, Faculty of Life Sciences & Medicine, King's College London, London, United Kingdom.,Department of Critical Care, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| |
Collapse
|
33
|
Electrical Impedance Tomography for Cardio-Pulmonary Monitoring. J Clin Med 2019; 8:jcm8081176. [PMID: 31394721 PMCID: PMC6722958 DOI: 10.3390/jcm8081176] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 12/14/2022] Open
Abstract
Electrical impedance tomography (EIT) is a bedside monitoring tool that noninvasively visualizes local ventilation and arguably lung perfusion distribution. This article reviews and discusses both methodological and clinical aspects of thoracic EIT. Initially, investigators addressed the validation of EIT to measure regional ventilation. Current studies focus mainly on its clinical applications to quantify lung collapse, tidal recruitment, and lung overdistension to titrate positive end-expiratory pressure (PEEP) and tidal volume. In addition, EIT may help to detect pneumothorax. Recent studies evaluated EIT as a tool to measure regional lung perfusion. Indicator-free EIT measurements might be sufficient to continuously measure cardiac stroke volume. The use of a contrast agent such as saline might be required to assess regional lung perfusion. As a result, EIT-based monitoring of regional ventilation and lung perfusion may visualize local ventilation and perfusion matching, which can be helpful in the treatment of patients with acute respiratory distress syndrome (ARDS).
Collapse
|
34
|
Stowe S, Boyle A, Sage M, See W, Praud JP, Fortin-Pellerin É, Adler A. Comparison of bolus- and filtering-based EIT measures of lung perfusion in an animal model. Physiol Meas 2019; 40:054002. [PMID: 30965314 DOI: 10.1088/1361-6579/ab1794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Two main functional imaging approaches have been used to measure regional lung perfusion using electrical impedance tomography (EIT): venous injection of a hypertonic saline contrast agent and imaging of its passage through the heart and lungs, and digital filtering of heart-frequency impedance changes over sequences of EIT images. This paper systematically compares filtering-based perfusion estimates and bolus injection methods to determine to which degree they are related. APPROACH EIT data was recorded on seven mechanically ventilated newborn lambs in which ventilation distribution was varied through changes in posture between prone, supine, left- and right-lateral positions. Perfusion images were calculated using frequency filtering and ensemble averaging during both ventilation and apnoea time segments for each posture to compare against contrast agent-based methods using Jaccard distance score. MAIN RESULTS Using bolus-based EIT measures of lung perfusion as the reference frequency filtering techniques performed better than ensemble averaging and both techniques performed equally well across apnoea and ventilation data segments. SIGNIFICANCE Our results indicate the potential for use of filtering-based EIT measures of heart-frequency activity as a non-invasive proxy for contrast agent injection-based measures of lung perfusion.
Collapse
Affiliation(s)
- Symon Stowe
- Systems and Computer Engineering, Carleton University, Ottawa, Canada. Author to whom any correspondence should be addressed
| | | | | | | | | | | | | |
Collapse
|
35
|
Vasques F, Sanderson B, Barrett NA, Camporota L. Monitoring of regional lung ventilation using electrical impedance tomography. Minerva Anestesiol 2019; 85:1231-1241. [PMID: 30945516 DOI: 10.23736/s0375-9393.19.13477-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among recent lung imaging techniques and devices, electrical impedance tomography (EIT) can provide dynamic information on the distribution regional lung ventilation. EIT images possess a high temporal and functional resolution allowing the visualization of dynamic physiological and pathological changes on a breath-by-breath basis. EIT detects changes in electric impedance (i.e., changes in gas/fluid ratio) and describes them in real time, both visually through images and waveforms, and numerically, allowing the clinician to monitor disease evolution and response to treatment. The use of EIT in clinical practice is supported by several studies demonstrating a good correlation between impedance tomography data and other validated methods of measuring lung volume. In this review, we will provide an overview on the rationale, basic functioning and most common applications of EIT in the management of mechanically ventilated patients.
Collapse
Affiliation(s)
- Francesco Vasques
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Barnaby Sanderson
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Nicholas A Barrett
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Luigi Camporota
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK - .,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| |
Collapse
|
36
|
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] [Received: 08/14/2018] [Revised: 01/25/2019] [Accepted: 01/28/2019] [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.
Collapse
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
| |
Collapse
|
37
|
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.
Collapse
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
| |
Collapse
|
38
|
Kusche R, Kaufmann S, Ryschka M. Dry electrodes for bioimpedance measurements—design, characterization and comparison. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaea59] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
39
|
Aguiar Santos S, Czaplik M, Orschulik J, Hochhausen N, Leonhardt S. Lung pathologies analyzed with multi-frequency electrical impedance tomography: Pilot animal study. Respir Physiol Neurobiol 2018; 254:1-9. [DOI: 10.1016/j.resp.2018.03.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/13/2018] [Accepted: 03/30/2018] [Indexed: 11/26/2022]
|
40
|
Hentze B, Muders T, Luepschen H, Maripuu E, Hedenstierna G, Putensen C, Walter M, Leonhardt S. Regional lung ventilation and perfusion by electrical impedance tomography compared to single-photon emission computed tomography. Physiol Meas 2018; 39:065004. [PMID: 29794336 DOI: 10.1088/1361-6579/aac7ae] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Electrical impedance tomography (EIT) is a noninvasive imaging modality that allows real-time monitoring of regional lung ventilation ([Formula: see text]) in intensive care patients at bedside. However, for improved guidance of ventilation therapy it would be beneficial to obtain regional ventilation-to-perfusion ratio ([Formula: see text]) by EIT. APPROACH In order to further explore the feasibility, we first evaluate a model-based approach, based on semi-negative matrix factorization and a gamma-variate model, to extract regional lung perfusion ([Formula: see text]) from EIT measurements. Subsequently, a combined validation of both [Formula: see text] and [Formula: see text] measured by EIT against single-photon emission computed tomography (SPECT) is performed on data acquired as part of a porcine animal trial. Four pigs were ventilated at two different levels of positive end-expiratory pressure (PEEP 0 and 15 cm H2O, respectively) in randomized order. Repeated injections of an EIT contrast agent (NaCl 10%) and simultaneous SPECT measurements of [Formula: see text] (81mKr gas) and [Formula: see text] (99mTc-labeled albumin) were performed. MAIN RESULTS Both [Formula: see text] and [Formula: see text] from EIT and SPECT were compared by correlation analysis. Very strong (r 2 = 0.94 to 0.95) correlations were found for [Formula: see text] and [Formula: see text] in the dorsal-ventral direction at both PEEP levels. Moderate (r 2 = 0.36 to 0.46) and moderate to strong (r 2 = 0.61 to 0.82) correlations resulted for [Formula: see text] and [Formula: see text] in the right-left direction, respectively. SIGNIFICANCE The results of combined validation indicate that monitoring of [Formula: see text] and [Formula: see text] by EIT is possible. However, care should be taken when trying to quantify [Formula: see text] by EIT, as imaging artefacts and model bias may void necessary spatial matching.
Collapse
Affiliation(s)
- Benjamin Hentze
- Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany. Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Mueller JL, Muller P, Mellenthin M, Murthy R, Capps M, Alsaker M, Deterding R, Sagel SD, DeBoer E. Estimating regions of air trapping from electrical impedance tomography data. Physiol Meas 2018; 39:05NT01. [PMID: 29726838 PMCID: PMC6015736 DOI: 10.1088/1361-6579/aac295] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrical impedance tomography (EIT) has been shown to be a viable non-invasive, bedside imaging modality to monitor lung function. This paper introduces a method for identifying regions of air trapping from EIT data collected during tidal breathing and breath-holding maneuvers. APPROACH Ventilation-perfusion index maps are computed from dynamic EIT images. These maps are then used to identify regions of air trapping in the area of the lung as regions that are poorly ventilated but well perfused throughout the breathing and cardiac cycles. These EIT-identified regions are then compared with independently identified regions of low attenuation, or air trapping, on chest CT. Results of this method are demonstrated in two children with cystic fibrosis and on a healthy control subject. MAIN RESULTS In both CF children, the EIT-identified regions of air trapping matched the regions indicated from the chest CT. The EIT-based method is only validated with CT scans within 4 cm of the chest cross-section defined by the electrode plane. SIGNIFICANCE The results indicate the potential use of EIT-derived ventilation-perfusion index maps as a non-invasive method for identifying regions of air trapping.
Collapse
Affiliation(s)
- Jennifer L Mueller
- Department of Mathematics, Colorado State University, Fort Collins, CO, United States of America. School of Biomedical Engineering, Colorado State University, Fort Collins, CO, United States of America
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
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.
Collapse
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
| |
Collapse
|
43
|
Meira C, Joerger FB, Kutter AP, Waldmann A, Ringer SK, Böehm SH, Iff S, Mosing M. Comparison of three continuous positive airway pressure (CPAP) interfaces in healthy Beagle dogs during medetomidine–propofol constant rate infusions. Vet Anaesth Analg 2018; 45:145-157. [DOI: 10.1016/j.vaa.2017.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 10/18/2022]
|
44
|
Reychler G, Uribe Rodriguez V, Hickmann CE, Tombal B, Laterre PF, Feyaerts A, Roeseler J. Incentive spirometry and positive expiratory pressure improve ventilation and recruitment in postoperative recovery: A randomized crossover study. Physiother Theory Pract 2018; 35:199-205. [PMID: 29485340 DOI: 10.1080/09593985.2018.1443185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Introduction: Impairment of global and regional pulmonary ventilations is a well-known consequence of general anesthesia. Positive expiratory pressure (PEP) or incentive spirometry (IS) is commonly prescribed, albeit their efficacy is poorly demonstrated. The aim of this study was to assess the effects of PEP and IS on lung ventilation and recruitment in patients after surgery involving anesthesia using electrical impedance tomography (EIT). Method: Ten male subjects (age = 61.2 ± 16.3 years; BMI = 25.3 ± 3.8 kg/m2), free of pulmonary disease before being anesthetized, were recruited. Two series of manoeuvers (PEP and volume-oriented IS) were randomly performed with quiet breathing interposed between these phases. Pulmonary ventilation (ΔEELVVT (i - e)) and recruitment (ΔEELI) were evaluated continuously in a semi-seated position during all phases by EIT. Comparisons between rest and treatment were performed by Wilcoxon signed rank test. Rest phases were compared by a mixed ANOVA. Bonferroni method was used for post-hoc comparisons. Results: ΔEELVVT (i - e) and ΔEELI were significantly increased by both techniques (+422% [p < 0.001]; +138% [p = 0.040] and +296% [p < 0.001]; +638% [p < 0.001] for PEP and IS, respectively). No difference was observed between both manoeuvers neither on ventilation nor on recruitment. This positive effect disappeared during the quiet breathing phases. Conclusion: IS and PEP improved ventilation and recruitment instantaneously without remnant effect after stopping the exercise.
Collapse
Affiliation(s)
- Gregory Reychler
- Institut de Recherche Expérimentale et Clinique (IREC), Pôle de Pneumologie, ORL & Dermatologie, Université Catholique de Louvain, Brussels, Belgium.,Service de Pneumologie, Cliniques universitaires Saint-Luc, Brussels, Belgium.,Service de Médecine Physique et Réadaptation, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Valeska Uribe Rodriguez
- Service de Soins Intensifs, Cliniques universitaires Saint-Luc, Brussels, Belgium.,Institut de Recherche Expérimentale et Clinique (IREC), Pôle de Médicine aigue, Université Catholique de Louvain, Brussels, Belgium
| | - Cheryl Elizabeth Hickmann
- Service de Soins Intensifs, Cliniques universitaires Saint-Luc, Brussels, Belgium.,Institut de Recherche Expérimentale et Clinique (IREC), Pôle de Médicine aigue, Université Catholique de Louvain, Brussels, Belgium
| | - Bertrand Tombal
- Service d'Urologie, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | | | - Axel Feyaerts
- Service d'Urologie, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Jean Roeseler
- Service de Soins Intensifs, Cliniques universitaires Saint-Luc, Brussels, Belgium.,Institut de Recherche Expérimentale et Clinique (IREC), Pôle de Médicine aigue, Université Catholique de Louvain, Brussels, Belgium
| |
Collapse
|
45
|
Orschulik J, Pokee D, Menden T, Leonhardt S, Walter M. Three-dimensional Pulmonary Monitoring Using Focused Electrical Impedance Measurements. JOURNAL OF ELECTRICAL BIOIMPEDANCE 2018; 9:84-95. [PMID: 33584924 PMCID: PMC7852007 DOI: 10.2478/joeb-2018-0013] [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: 12/17/2018] [Indexed: 06/12/2023]
Abstract
Lung pathologies such as edema, atelectasis or pneumonia are potentially life threatening conditions. Especially in critically ill and mechanically ventilated patients, an early diagnosis and treatment is crucial to prevent an Acute Respiratory Distress Syndrome [1]. Thus, continuous monitoring tool for the lung condition available at the bedside would be highly appreciated. One concept for this is Electrical Impedance Tomography (EIT). In EIT, an electrode belt of typically 16 or 32 electrodes is attached at the body surface and multiple impedance measurements are performed. From this, the conductivity change inside the body is reconstructed in a two-dimensional image. In various studies, EIT proved to be a useful tool for quantifying recruitment maneuvers, the assessment of the ventilation homogeneity, the detection of lung edema or perfusion monitoring [2, 3, 4, 5]. Nevertheless, the main problem of EIT is the low spatial resolution (compared to CT) and the limitation to two dimensional images. In this paper, we try to address the latter issue: Instead of projecting conductivity changes onto a two-dimensional image, we adjust electrode positions to focus single tetrapolar measurements to specific, three-dimensional regions of interest. In earlier work, we defined guidelines to achieve this focusing [6, 7]. In this paper, we demonstrate in simulations and in a water tank experiment that applying these guidelines can help to detect pathologies in specific lung regions.
Collapse
Affiliation(s)
- Jakob Orschulik
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Diana Pokee
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Tobias Menden
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Steffen Leonhardt
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Marian Walter
- Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| |
Collapse
|
46
|
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.
Collapse
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
| |
Collapse
|
47
|
Image Reconstruction for Electrical Impedance Tomography: Experimental Comparison of Radial Basis Neural Network and Gauss – Newton Method. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.ifacol.2018.07.114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
48
|
|
49
|
Ambrisko TD, Schramel JP, Auer U, Moens YPS. Impact of four different recumbencies on the distribution of ventilation in conscious or anaesthetized spontaneously breathing beagle dogs: An electrical impedance tomography study. PLoS One 2017; 12:e0183340. [PMID: 28922361 PMCID: PMC5603158 DOI: 10.1371/journal.pone.0183340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 08/02/2017] [Indexed: 11/18/2022] Open
Abstract
The aim was to examine the effects of recumbency and anaesthesia on distribution of ventilation in beagle dogs using Electrical Impedance Tomography (EIT). Nine healthy beagle dogs, aging 3.7±1.7 (mean±SD) years and weighing 16.3±1.6 kg, received a series of treatments in a fixed order on a single occasion. Conscious dogs were positioned in right lateral recumbency (RLR) and equipped with 32 EIT electrodes around the thorax. Following five minutes of equilibration, two minutes of EIT recordings were made in each recumbency in the following order: RLR, dorsal (DR), left (LLR) and sternal (SR). The dogs were then positioned in RLR, premedicated (medetomidine 0.01, midazolam 0.1, butorphanol 0.1 mg kg-1 iv) and pre-oxygenated. Fifteen minutes later anaesthesia was induced with 1 mg kg-1 propofol iv and maintained with propofol infusion (0.1–0.2 mg kg-1 minute-1 iv). After induction, the animals were intubated and allowed to breathe spontaneously (FIO2 = 1). Recordings of EIT were performed again in four recumbencies similarly to conscious state. Centre of ventilation (COV) and global inhomogeneity (GI) index were calculated from the functional EIT images. Repeated-measures ANOVA and Bonferroni tests were used for statistical analysis (p < 0.05). None of the variables changed in the conscious state. During anaesthesia left-to-right COV increased from 46.8±2.8% in DR to 49.8±2.9% in SR indicating a right shift, and ventral-to-dorsal COV increased from 49.8±1.7% in DR to 51.8±1.1% in LLR indicating a dorsal shift in distribution of ventilation. Recumbency affected distribution of ventilation in anaesthetized but not in conscious dogs. This can be related to loss of respiratory muscle tone (e.g. diaphragm) and changes in thoracic shape. Changing position of thoraco-abdominal organs under the EIT belt should be considered as alternative explanation of these findings.
Collapse
Affiliation(s)
- Tamas D Ambrisko
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Johannes P Schramel
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Ulrike Auer
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| | - Yves P S Moens
- Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
| |
Collapse
|
50
|
Martin S, Choi CTM. A Post-Processing Method for Three-Dimensional Electrical Impedance Tomography. Sci Rep 2017; 7:7212. [PMID: 28775284 PMCID: PMC5543057 DOI: 10.1038/s41598-017-07727-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 06/29/2017] [Indexed: 11/13/2022] Open
Abstract
Electrical impedance tomography is a modern biomedical imaging method. Its goal is to image the electrical properties of human tissues. This approach is safe for the patient's health, is non-invasive and has no known hazards. However, the approach suffers from low accuracy. Linear inverse solvers are commonly used in medical applications, as they are strongly robust to noise. However, linear methods can give only an approximation of the solution that corresponds to a linear perturbation from an initial estimate. This paper proposes a novel reconstruction process. After applying a linear solver, the conductivity distribution is post-processed with a nonlinear algorithm, with the aim of reproducing the abrupt change in conductivity at the boundaries between tissues or organs. The results are used to compare the proposed method with three other widely used methods. The proposed method offers higher quality images and a higher robustness to noise, and significantly reduces the error associated with image reconstruction.
Collapse
Affiliation(s)
- Sébastien Martin
- Department of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan
| | - Charles T M Choi
- Department of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan.
- Institute of Biomedical Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan.
| |
Collapse
|