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Yang L, Gao Z, Cao X, Sun S, Wang C, Wang H, Dai J, Liu Y, Qin Y, Dai M, Guo W, Zhang B, Zhao K, Zhao Z. Electrical impedance tomography as a bedside assessment tool for COPD treatment during hospitalization. Front Physiol 2024; 15:1352391. [PMID: 38562620 PMCID: PMC10982416 DOI: 10.3389/fphys.2024.1352391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 03/06/2024] [Indexed: 04/04/2024] Open
Abstract
For patients with chronic obstructive pulmonary disease (COPD), the assessment of the treatment efficacy during hospitalization is of importance to the optimization of clinical treatments. Conventional spirometry might not be sensitive enough to capture the regional lung function development. The study aimed to evaluate the feasibility of using electrical impedance tomography (EIT) as an objective bedside evaluation tool for the treatment of acute exacerbation of COPD (AECOPD). Consecutive patients who required hospitalization due to AECOPD were included prospectively. EIT measurements were conducted at the time of admission and before the discharge simultaneously when a forced vital capacity maneuver was conducted. EIT-based heterogeneity measures of regional lung function were calculated based on the impedance changes over time. Surveys for attending doctors and patients were designed to evaluate the ease of use, feasibility, and overall satisfaction level to understand the acceptability of EIT measurements. Patient-reported outcome assessments were conducted. User's acceptance of EIT technology was investigated with a five-dimension survey. A total of 32 patients were included, and 8 patients were excluded due to the FVC maneuver not meeting the ATS criteria. Spirometry-based lung function was improved during hospitalization but not significantly different (FEV1 %pred.: 35.8% ± 6.7% vs. 45.3% ± 8.8% at admission vs. discharge; p = 0.11. FVC %pred.: 67.8% ± 0.4% vs. 82.6% ± 5.0%; p = 0.15. FEV1/FVC: 0.41 ± 0.09 vs. 0.42 ± 0.07, p = 0.71). The symptoms of COPD were significantly improved, but the correlations between the improvement of symptoms and spirometry FEV1 and FEV1/FVC were low (R = 0.1 and -0.01, respectively). The differences in blood gasses and blood tests were insignificant. All but one EIT-based regional lung function parameter were significantly improved after hospitalization. The results highly correlated with the patient-reported outcome assessment (R > 0.6, p < 0.001). The overall acceptability score of EIT measurement for both attending physicians and patients was high (4.1 ± 0.8 for physicians, 4.5 ± 0.5 for patients out of 5). These results demonstrated that it was feasible and acceptable to use EIT as an objective bedside evaluation tool for COPD treatment efficacy.
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Affiliation(s)
- Lin Yang
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Zhijun Gao
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Xinsheng Cao
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Shuying Sun
- Department of Pulmonary and Critical Care Medicine, 986th Hospital of Air Force, Air Force Medical University, Xi’an, China
| | - Chunchen Wang
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Hang Wang
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Jing Dai
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Yang Liu
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Yilong Qin
- Department of Aerospace Medicine, Air Force Medical University, Xi’an, China
| | - Meng Dai
- Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
| | - Wei Guo
- Department of Pulmonary and Critical Care Medicine, 986th Hospital of Air Force, Air Force Medical University, Xi’an, China
| | - Binghua Zhang
- Department of Pulmonary and Critical Care Medicine, 986th Hospital of Air Force, Air Force Medical University, Xi’an, China
| | - Ke Zhao
- Department of Pulmonary and Critical Care Medicine, 986th Hospital of Air Force, Air Force Medical University, Xi’an, China
| | - Zhanqi Zhao
- School of Biomedical Engineering, Guangzhou Medical University, Guangzhou, China
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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Yang L, Gao Z, Wang C, Wang H, Dai J, Liu Y, Qin Y, Dai M, Cao X, Zhao Z. Evaluation of adjacent and opposite current injection patterns for a wearable chest electrical impedance tomography system. Physiol Meas 2024; 45:025004. [PMID: 38266301 DOI: 10.1088/1361-6579/ad2215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 01/24/2024] [Indexed: 01/26/2024]
Abstract
Objective.Wearable electrical impedance tomography (EIT) can be used to monitor regional lung ventilation and perfusion at the bedside. Due to its special system architecture, the amplitude of the injected current is usually limited compared to stationary EIT system. This study aims to evaluate the performance of current injection patterns with various low-amplitude currents in healthy volunteers.Approach.A total of 96 test sets of EIT measurement was recorded in 12 healthy subjects by employing adjacent and opposite current injection patterns with four amplitudes of small current (i.e. 1 mA, 500 uA, 250 uA and 125 uA). The performance of the two injection patterns with various currents was evaluated in terms of signal-to-noise ratio (SNR) of thorax impedance, EIT image metrics and EIT-based clinical parameters.Main results.Compared with adjacent injection, opposite injection had higher SNR (p< 0.01), less inverse artifacts (p< 0.01), and less boundary artifacts (p< 0.01) with the same current amplitude. In addition, opposite injection exhibited more stable EIT-based clinical parameters (p< 0.01) across the current range. For adjacent injection, significant differences were found for three EIT image metrics (p< 0.05) and four EIT-based clinical parameters (p< 0.01) between the group of 125 uA and the other groups.Significance.For better performance of wearable pulmonary EIT, currents greater than 250 uA should be used in opposite injection, 500 uA in adjacent one, to ensure a high level of SNR, a high quality of reconstructed image as well as a high reliability of clinical parameters.
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Affiliation(s)
- Lin Yang
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Zhijun Gao
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Chunchen Wang
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Hang Wang
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Jing Dai
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Yang Liu
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Yilong Qin
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Meng Dai
- Department of Biomedical Engineering, Air Force Medical University, Xi'an, People's Republic of China
| | - Xinsheng Cao
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Zhanqi Zhao
- School of Biomedical Engineering, Guangzhou Medical University, Guangzhou, People's Republic of China
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Beijing, People's Republic of China
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Xiao Z, Yang L, Dai M, Lu W, Liu F, Frerichs I, Gao C, Sun X, Zhao Z. Regional ventilation distribution before and after laparoscopic lung parenchymal resection. Physiol Meas 2024; 45:015004. [PMID: 38176102 DOI: 10.1088/1361-6579/ad1b3b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/04/2024] [Indexed: 01/06/2024]
Abstract
Objective.The aim of the present study was to evaluate the influence of one-sided pulmonary nodule and tumour on ventilation distribution pre- and post- partial lung resection.Approach.A total of 40 consecutive patients scheduled for laparoscopic lung parenchymal resection were included. Ventilation distribution was measured with electrical impedance tomography (EIT) in supine and surgery lateral positions 72 h before surgery (T1) and 48 h after extubation (T2). Left lung to global ventilation ratio (Fl), the global inhomogeneity index (GI), standard deviation of regional ventilation delay (RVDSD) and pendelluft amplitude (Apendelluft) were calculated to assess the spatial and temporal ventilation distribution.Main results.After surgery (T2), ventilation at the operated chest sides generally deteriorated compared to T1 as expected. For right-side resection, the differences were significant at both supine and left lateral positions (p< 0.001). The change of RVDSDwas in general more heterogeneous. For left-side resection, RVDSDwas worse at T2 compared to T1 at left lateral position (p= 0.002). The other EIT-based parameters showed no significant differences between the two time points. No significant differences were observed between supine and lateral positions for the same time points respectively.Significance.In the present study, we found that the surgery side influenced the ventilation distribution. When the resection was performed on the right lung, the postoperative ipsilateral ventilation was reduced and the right lung ratio fell significantly. When the resection was on the left lung, the ventilation delay was significantly increased.
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Affiliation(s)
- Zhibin Xiao
- Department of Anesthesiology, the 986th Air Force Hospital, Xijing hospital, the Air Force Medical University, Xi'an, Shaanxi 710032, People's Republic of China
| | - Lin Yang
- Department of Aerospace Medicine, Air Force Medical University, Xi'an, People's Republic of China
| | - Meng Dai
- Department of Biomedical Engineering, Air Force Medical University, Xi'an, People's Republic of China
| | - Wenjun Lu
- Department of Anesthesiology, The Second Affiliated Hospital of Air Force Medical University, Xi'an, Shaanxi 710032, People's Republic of China
| | - Feng Liu
- Department of Anesthesiology, The Second Affiliated Hospital of Air Force Medical University, Xi'an, Shaanxi 710032, People's Republic of China
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Germany
| | - Changjun Gao
- Department of Anesthesiology, The Second Affiliated Hospital of Air Force Medical University, Xi'an, Shaanxi 710032, People's Republic of China
| | - Xude Sun
- Department of Anesthesiology, The Second Affiliated Hospital of Air Force Medical University, Xi'an, Shaanxi 710032, People's Republic of China
| | - Zhanqi Zhao
- School of Biomedical Engineering, Guangzhou Medical University, Guangzhou, People's Republic of China
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, People's Republic of China
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Yang L, Fu F, Frerichs I, Moeller K, Dai M, Zhao Z. The calculation of electrical impedance tomography based silent spaces requires individual thorax and lung contours. Physiol Meas 2022; 43. [PMID: 35995039 DOI: 10.1088/1361-6579/ac8bc2] [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: 04/29/2022] [Accepted: 08/22/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The present study evaluates the influence of different thorax contours (generic vs individual) on the parameter "silent spaces" computed from electrical impedance tomography (EIT) measurements. APPROACH Six patients with acute respiratory distress syndrome were analyzed retrospectively. EIT measurements were performed and the silent spaces were calculated based on (1) patient-specific contours Sind, (2) generic adult male contours SEidorsA and (3) generic neonate contours SEidorsN. MAIN RESULTS The differences among all studied subjects were 5±6% and 8±7% for Sind vs. SEidorsA, Sind vs. SEidorsN, respectively (median ± interquartile range). Sind values were higher than the generic ones in two patients. SIGNIFICANCE In the present study, we demonstrated the differences in values when the silent spaces were calculated based on different body and organ contours. To our knowledge, this study was the first one showing explicitly that silent spaces calculated with generic thorax and lung contours might lead to results with different locations and values as compared to the calculation with subject-specific models. Interpretations of silent spaces should be proceeded with caution.
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Affiliation(s)
- Lin Yang
- Fourth Military Medical University, Xi'an, Xi'an, 710032, CHINA
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Xi'an, 710000, CHINA
| | - Inez Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein Campus Kiel, Kiel, Kiel, x, GERMANY
| | - Knut Moeller
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Strasse 17, Villingen-Schwenningen, D-78054, GERMANY
| | - Meng Dai
- Biomedical Engineering Department, Fourth Military Medical University, 17 Changlex West Road, Xian, Shaanxi 710033, PR CHINA, Xi'an, 710000, CHINA
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Xi'an, 710032, CHINA
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Zhao Z, Chen TF, Teng HC, Wang YC, Chang MY, Chang HT, Frerichs I, Fu F, Moeller K. Is there a need for individualized adjustment of electrode belt position during EIT-guided titration of positive end-expiratory pressure? Physiol Meas 2022; 43. [PMID: 35617942 DOI: 10.1088/1361-6579/ac73d6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/26/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The aim of the present study was to evaluate the variation of tidal volume-to-impedance ratio (VT/ZT) during positive end-expiratory pressure (PEEP) titration with electrical impedance tomography (EIT) measurement. APPROACH Forty-two patients with acute respiratory distress syndrome were retrospectively analyzed. An incremental and subsequently a decremental PEEP trial were performed with steps of 2 cmH2O and duration of 2 minutes per step during volume-controlled ventilation with decelerating flow. EIT measurement was conducted in the 5th intercostal space and VT was recorded simultaneously. The variation of VT/ZT (RatioV) was defined as the changes in percentage to average ratio per cmH2O PEEP change. A z-score>1 was considered as a significant variation and an implication that the measurement plane was inadequate. MAIN RESULTS The RatioV of 42 patients was 1.29±0.80 %∙cmH2O-1. A z-score of 1 corresponded to the variation of 2.09 %∙cmH2O-1. Seven patients (16.7%) had a z-score>1 and showed either positive or negative correlation between the volume-to-impedance ratio and PEEP. SIGNIFICANCE Electrode placement at 5th intercostal space might not be ideal for every individual during EIT measurement. Evaluation of volume-to-impedance ratio variation is necessary for patients undergoing maneuvers with wide alteration in absolute lung volume.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Changle Rd. 167, Xi'an, 710032, CHINA
| | - Tsai-Fen Chen
- Far Eastern Memorial Hospital, x, New Taipei City, New Taipei City, x, TAIWAN
| | - Hui-Chen Teng
- Far Eastern Memorial Hospital, x, New Taipei City, New Taipei City, x, TAIWAN
| | - Yi-Chun Wang
- Far Eastern Memorial Hospital, x, New Taipei City, New Taipei City, x, TAIWAN
| | - Mei-Yun Chang
- Far Eastern Memorial Hospital, x, New Taipei City, New Taipei City, x, TAIWAN
| | - Hou-Tai Chang
- Far Eastern Memorial Hospital, z, New Taipei City, New Taipei City, x, TAIWAN
| | - Inez Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein Campus Kiel, x, Kiel, x, GERMANY
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, x, Xi'an, x, CHINA
| | - Knut Moeller
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle-Strasse 17, Villingen-Schwenningen, D-78054, GERMANY
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Zhang C, Wang Y, Liu L, Li Q, Li Y, Li N, Xi J, Jiang H, Fu F, Frerichs I, Möller K, Zhao Z. Regional ventilation distribution in patients with scoliosis assessed by electrical impedance tomography: is individual thorax shape required? Respir Physiol Neurobiol 2022; 299:103854. [DOI: 10.1016/j.resp.2022.103854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/20/2022] [Accepted: 01/28/2022] [Indexed: 10/19/2022]
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Zhao Z, Yuan T, Chuang Y, Wang Y, Chang H, Bien M, Huang J, Lin N, Frerichs I, Möller K, Fu F, Yang Y. Lung ventilation distribution in patients after traditional full sternotomy and minimally invasive thoracotomy: An observational study. Acta Anaesthesiol Scand 2021; 65:877-885. [PMID: 33294975 DOI: 10.1111/aas.13759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/18/2020] [Accepted: 11/29/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND The aim of the study was to examine the post-operative ventilation distribution changes in cardiac surgical patients after traditional full sternotomy (FS) or minimally invasive thoracotomy (MIT). METHODS A total of 40 patients scheduled for FS with two-lung ventilation or MIT with one-lung ventilation were included. Ventilation distribution was measured with electrical impedance tomography (EIT) at T1, before surgery; T2, after surgery in ICU before weaning; T3, 24 hours after extubation. EIT-based parameters were calculated to assess the ventilation distribution, including the left-to-right lung ratio, ventral-to-dorsal ratio, and the global inhomogeneity index. RESULTS The global inhomogeneity index increased at T2 and T3 compared to T1 in all patients but only statistically significant in patients with MIT (FS, P = .06; MIT, P < .01). Notable decrease in the dorsal regions (FS) or in the non-ventilated side (MIT) was observed at T2. Ventilation distribution was partially improved at T3 but huge variations of recovery progresses were found in all patients regardless of the surgery types. Subgroup analysis indicated that operation duration was significantly lower in the MIT group (240 ± 40 in FS vs 205 ± 90 minutes in MIT, median ± interquartile range, P < .05) but the incidence of atrial fibrillation/flutter was significantly higher (5% in FS vs 50% in MIT, P < .01). Other exploratory outcomes showed no statistical differences. CONCLUSIONS Ventilation distribution was impaired after cardiac surgery. The recovery process of ventilation homogeneity was strongly depending on individuals so that MIT was not always superior in this aspect. EIT may help to identify the patients requiring further care after surgery.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering Fourth Military Medical University Xi'an China
- Institute of Technical Medicine Furtwangen University Villingen‐Schwenningen Germany
| | - Tsai‐Ming Yuan
- Department of Chest MedicineFar Eastern Memorial Hospital New Taipei City Taiwan
- School of Respiratory Therapy College of Medicine Taipei Medical University Taipei Taiwan
| | - Ya‐Hui Chuang
- Department of Chest MedicineFar Eastern Memorial Hospital New Taipei City Taiwan
| | - Yu‐Wen Wang
- Department of Chest MedicineFar Eastern Memorial Hospital New Taipei City Taiwan
| | - Hou‐Tai Chang
- Department of Critical CareFar Eastern Memorial Hospital New Taipei City Taiwan
| | - Mauo‐Ying Bien
- School of Respiratory Therapy College of Medicine Taipei Medical University Taipei Taiwan
- Division of Pulmonary Medicine Department of Internal Medicine Taipei Medical University Hospital Taipei Taiwan
| | - Jih‐Hsin Huang
- Department of Cardiac SurgeryFar Eastern Memorial Hospital New Taipei City Taiwan
| | - Nian‐Jhen Lin
- Department of Chest MedicineFar Eastern Memorial Hospital New Taipei City Taiwan
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine University Medical Centre of Schleswig‐Holstein Campus Kiel Germany
| | - Knut Möller
- Institute of Technical Medicine Furtwangen University Villingen‐Schwenningen Germany
| | - Feng Fu
- Department of Biomedical Engineering Fourth Military Medical University Xi'an China
| | - You‐Lan Yang
- School of Respiratory Therapy College of Medicine Taipei Medical University Taipei Taiwan
- Division of Pulmonary Medicine Department of Internal Medicine Wan Fang HospitalTaipei Medical University Taipei Taiwan
- Division of Pulmonary Medicine Department of Internal Medicine Landseed International Hospital Taoyuan City Taiwan
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Yang L, Dai M, Cao X, Möller K, Dargvainis M, Frerichs I, Becher T, Fu F, Zhao Z. Regional ventilation distribution in healthy lungs: can reference values be established for electrical impedance tomography parameters? ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:789. [PMID: 34268402 PMCID: PMC8246208 DOI: 10.21037/atm-20-7442] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/24/2021] [Indexed: 12/26/2022]
Abstract
Background Although electrical impedance tomography (EIT) is widely used for monitoring regional ventilation distribution, reference values have yet to be established for clinical use. The present study aimed to evaluate the feasibility of creating reference values for standard EIT parameters for potential clinical application. Methods A total of 75 participants with healthy lungs were included in this prospective study (male:female, 48:27; age, 34±14 years; height, 172±7 cm; weight, 73±12 kg). The subjects were examined during spontaneous breathing in the supine position. EIT measurements were performed at the level of the 4th intercostal space. Commonly used EIT-based parameters, including the center of ventilation (CoV), dorsal and most dorsal fractions of ventilation distribution (TVD and TVROI4 respectively), global inhomogeneity (GI) index, and standard deviation of regional ventilation delay index (RVDSD) were calculated. Results Following outlier detection, EIT data from 71 subjects were finally evaluated. The values of the evaluated parameters were: CoV, 48.7%±1.7%; TVD, 48.1%±5.4%; TVROI4, 7.1%±1.8%; GI, 0.49±0.04; and RVDSD, 7.0±2.0. The coefficients of variation for CoV and GI were low (0.03 and 0.07, respectively), but those for TVROI4 and RVDSD were comparatively high (0.26 and 0.28, respectively). None of the evaluated parameters showed a significant correlation with age. The GI index showed a weak but significant correlation with body mass index (R=0.29, P=0.01). The RVDSD was slightly higher in males than in females. Conclusions Our study indicated that CoV and GI were stable parameters with small coefficients of variation in participants with healthy lungs. The creation of EIT parameter reference values for setting treatment targets may be feasible.
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Affiliation(s)
- Lin Yang
- Department of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Meng Dai
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Xinsheng Cao
- Department of Aerospace Medicine, Fourth Military Medical University, Xi'an, China
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Mantas Dargvainis
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Tobias Becher
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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Sang L, Zhao Z, Lin Z, Liu X, Zhong N, Li Y. A narrative review of electrical impedance tomography in lung diseases with flow limitation and hyperinflation: methodologies and applications. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1688. [PMID: 33490200 PMCID: PMC7812189 DOI: 10.21037/atm-20-4984] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Electrical impedance tomography (EIT) is a functional radiation-free imaging technique that measures regional lung ventilation distribution by calculating the impedance changes in the corresponding regions. The aim of the present review was to summarize the current literature concerning the methodologies and applications of EIT in lung diseases with flow limitation and hyperinflation. PubMed was searched up to May 2020 to identify studies investigating the use of EIT in patients with asthma, bronchiectasis, bronchitis, bronchiolitis, chronic obstructive pulmonary disease, and cystic fibrosis. The extracted data included study design, EIT methodologies, interventions, validation and comparators, population characteristics, and key findings. Of the 44 included studies, seven were related to simulation, animal experimentation, or reconstruction algorithm development with evaluation on patients; 27 studies had the primary objective of validating EIT technique and measures including regional ventilation distribution, regional EIT-spirometry parameters, end-expiratory lung impedance, and regional time constants; and 10 studies had the primary objective of applying EIT to monitor the response to therapeutic interventions, including various ventilation supports, patient repositioning, and airway suctioning. In pediatric and adult patients, EIT has been successfully validated for assessing spatial and temporal ventilation distribution, measuring changes in lung volume and flow, and studying regional respiratory mechanics. EIT has also demonstrated potential as an alternative or supplement to well-established measurement modalities (e.g., conventional pulmonary function testing) to monitor the progression of obstructive lung diseases, although the existing literature lacks prediction values as references and lacks clinical outcome evidence.
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Affiliation(s)
- Ling Sang
- State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, the First Affiliated Hospital of Guangzhou Medical University, Department of Crit Care Med, Guangzhou, China
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Zhimin Lin
- State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, the First Affiliated Hospital of Guangzhou Medical University, Department of Crit Care Med, Guangzhou, China
| | - Xiaoqing Liu
- State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, the First Affiliated Hospital of Guangzhou Medical University, Department of Crit Care Med, Guangzhou, China
| | - Nanshan Zhong
- State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, the First Affiliated Hospital of Guangzhou Medical University, Department of Crit Care Med, Guangzhou, China
| | - Yimin Li
- State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, the First Affiliated Hospital of Guangzhou Medical University, Department of Crit Care Med, Guangzhou, China
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He H, Chi Y, Long Y, Yuan S, Zhang R, Frerichs I, Möller K, Fu F, Zhao Z. Bedside Evaluation of Pulmonary Embolism by Saline Contrast Electrical Impedance Tomography Method: A Prospective Observational Study. Am J Respir Crit Care Med 2020; 202:1464-1468. [PMID: 32585116 PMCID: PMC7667910 DOI: 10.1164/rccm.202005-1780le] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Huaiwu He
- Peking Union Medical College Hospital Beijing, China
| | - Yi Chi
- Peking Union Medical College Hospital Beijing, China
| | - Yun Long
- Peking Union Medical College Hospital Beijing, China
| | - Siyi Yuan
- Peking Union Medical College Hospital Beijing, China
| | - Rui Zhang
- Peking Union Medical College Hospital Beijing, China
| | - Inéz Frerichs
- University Medical Center of Schleswig-Holstein Campus Kiel Kiel, Germany
| | - Knut Möller
- Furtwangen University Villingen-Schwenningen, Germany and
| | - Feng Fu
- Fourth Military Medical University Xi'an, China
| | - Zhanqi Zhao
- Furtwangen University Villingen-Schwenningen, Germany and.,Fourth Military Medical University Xi'an, China
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Zhao Z, Fu F, Frerichs I. Thoracic electrical impedance tomography in Chinese hospitals: a review of clinical research and daily applications. Physiol Meas 2020; 41:04TR01. [PMID: 32197257 DOI: 10.1088/1361-6579/ab81df] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chinese scientists and researchers have a long history with electrical impedance tomography (EIT), which can be dated back to the 1980s. No commercial EIT devices for chest imaging were available until the year 2014 when the first device received its approval from the China Food and Drug Administration. Ever since then, clinical research and daily applications have taken place in Chinese hospitals. Up to this date (2019.11) 47 hospitals have been equipped with 50 EIT devices. Twenty-three SCI publications are recorded and a further 21 clinical trials are registered. Thoracic EIT is mainly used in patients before or after surgery, or in intensive care units (ICU). Application fields include the development of strategies for protective lung ventilation (e.g. tidal volume and positive end-expiratory pressure (PEEP) titration, recruitment, choice of ventilation mode and weaning from ventilator), regional lung perfusion monitoring, perioperative monitoring, and potential feedback for rehabilitation. The main challenges for promoting clinical use of EIT are the financial cost and the education of personnel. In this review, the past, present and future of EIT in China are introduced and discussed.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, No. 169 Changle West Road, Xincheng District, Xi'an 710005 People's Republic of China. Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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Zhao Z, Chang MY, Frerichs I, Zhang JH, Chang HT, Gow CH, Möller K. Regional air trapping in acute exacerbation of obstructive lung diseases measured with electrical impedance tomography: a feasibility study. Minerva Anestesiol 2019; 86:172-180. [PMID: 31808658 DOI: 10.23736/s0375-9393.19.13732-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Since bronchial abnormalities often exhibit spatial non-uniformity which may be not correctly assessed by conventional global lung function measures, regional information may help to characterize the disease progress. We hypothesized that regional air trapping during mechanical ventilation could be characterized by regional end-expiratory flow (EEF) derived from electrical impedance tomography (EIT). METHODS Twenty-five patients suffering from chronic obstructive pulmonary disease (COPD grade 3 or 4) or severe asthma with acute exacerbation were examined prospectively. Patients were ventilated under assist-control mode. EIT measurements were conducted before and one hour after inhaled combined corticosteroid and long-acting β2 agonist, on two consecutive days. Regional EEF was calculated as derivative of relative impedance for every image pixel in the lung regions. The results were normalized to global flow values measured by the ventilator. RESULTS Regional and global EEF were highly correlated (P<0.00001) and regional effects of medication and disease progression were visible in the regional EEF maps. The sums of regional EEF in lung regions were 3.8 [2.0, 5.1] and 3.6 [1.9, 4.5] L/min in COPD patients before and after medication (median [lower, upper quartiles]; P=0.37). The corresponding values in asthma patients were 3.0 [2.5, 4.2] and 2.2 [1.7, 3.2] L/min (P<0.05). Histograms of regional EEF showed high spatial heterogeneity of EEF before medication. After one day of treatment, the histograms exhibited less heterogeneous and a decrease in EEF level. CONCLUSIONS Regional EEF characterizes air trapping and intrinsic PEEP, which could provide diagnostic information for monitoring the disease progress during treatment.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Mei-Yun Chang
- Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center of Schleswig-Holstein Campus, Kiel, Germany
| | - Jia-Hao Zhang
- Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Hou-Tai Chang
- Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Chien-Hung Gow
- Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan - .,Department of Healthcare Information and Management, Ming-Chuan University, Taoyuan, Taiwan
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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Zhao Z, Lee LC, Chang MY, Frerichs I, Chang HT, Gow CH, Hsu YL, Möller K. The incidence and interpretation of large differences in EIT-based measures for PEEP titration in ARDS patients. J Clin Monit Comput 2019; 34:1005-1013. [PMID: 31587120 DOI: 10.1007/s10877-019-00396-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/26/2019] [Indexed: 12/18/2022]
Abstract
Positive end-expiratory pressure (PEEP) can be titrated by electrical impedance tomography (EIT). The aim of the present study was to examine the performance of different EIT measures during PEEP trials with the aim of identifying "optimum" PEEP and to provide possible interpretations of largely diverging results. After recruitment (maximum plateau pressure 35 cmH2O), decremental PEEP trial with steps of 2 cmH2O and duration of 2 min per step was performed. Ventilation gain and loss, the global inhomogeneity (GI) index, trend of end-expiratory lung impedance (EELI) and regional compliance (Creg) for estimation of overdistension and collapse were calculated. Largely diverging results of PEEP selection among the measures were defined as differences ≥ 4 PEEP steps (i.e. ≥ 8 cmH2O). In 30 ARDS patients we examined so far, 3 patients showed significant differences in PEEP selections. Overdistension and collapse estimation based on Creg tended to select lower PEEP while the GI index and EELI trend suggested higher PEEP settings. Regional inspiration times were heterogeneous indicating that the assumption of a uniform driving pressure in the calculation of Creg may not be valid. Judging by the predominant ventilation distribution in the most dependent regions, these patients were non-recruitable with the applied recruitment method or pressure levels. The existence of differences in the recommended PEEP among the analyzed EIT measures might be an indicator of non-recruitable lungs and heterogeneous airway resistances. In these extreme cases, the largely diverging results may prompt the attending clinician to develop individual ventilation strategies.Clinical Trial Registration Registration number NCT03112512, https://clinicaltrials.gov/ Registered 13 April 2017.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Li-Chung Lee
- Department of Internal Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City, Taiwan
| | - Mei-Yun Chang
- Department of Internal Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City, Taiwan
| | - Inez Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Hou-Tai Chang
- Department of Internal Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City, Taiwan.
| | - Chien-Hung Gow
- Department of Internal Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City, Taiwan
| | - Yeong-Long Hsu
- Department of Internal Medicine, Far Eastern Memorial Hospital, No. 21, Sec. 2, Nanya S. Rd., Banciao Dist., New Taipei City, Taiwan. .,Department of Healthcare Management, College of Medical Technology and Nursing, Yuanpei University of Medical Technology, No. 306 Yuanpei Street, Hsinchu, Taiwan.
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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de Castro Martins T, Sato AK, de Moura FS, de Camargo EDLB, Silva OL, Santos TBR, Zhao Z, Möeller K, Amato MBP, Mueller JL, Lima RG, de Sales Guerra Tsuzuki M. A Review of Electrical Impedance Tomography in Lung Applications: Theory and Algorithms for Absolute Images. ANNUAL REVIEWS IN CONTROL 2019; 48:442-471. [PMID: 31983885 PMCID: PMC6980523 DOI: 10.1016/j.arcontrol.2019.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Electrical Impedance Tomography (EIT) is under fast development, the present paper is a review of some procedures that are contributing to improve spatial resolution and material properties accuracy, admitivitty or impeditivity accuracy. A review of EIT medical applications is presented and they were classified into three broad categories: ARDS patients, obstructive lung diseases and perioperative patients. The use of absolute EIT image may enable the assessment of absolute lung volume, which may significantly improve the clinical acceptance of EIT. The Control Theory, the State Observers more specifically, have a developed theory that can be used for the design and operation of EIT devices. Electrode placement, current injection strategy and electrode electric potential measurements strategy should maximize the number of observable and controllable directions of the state vector space. A non-linear stochastic state observer, the Unscented Kalman Filter, is used directly for the reconstruction of absolute EIT images. Historically, difference images were explored first since they are more stable in the presence of modelling errors. Absolute images require more detailed models of contact impedance, stray capacitance and properly refined finite element mesh where the electric potential gradient is high. Parallelization of the forward program computation is necessary since the solution of the inverse problem often requires frequent solutions of the forward problem. Several reconstruction algorithms benefit by the Bayesian inverse problem approach and the concept of prior information. Anatomic and physiologic information are used to form the prior information. An already tested methodology is presented to build the prior probability density function using an ensemble of CT scans and in vivo impedance measurements. Eight absolute EIT image algorithms are presented.
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Affiliation(s)
| | - André Kubagawa Sato
- Computational Geometry Laboratory, Escola Politécnica da Universidade de São Paulo, Brazil
| | - Fernando Silva de Moura
- Universidade Federal do ABC, Center of Engineering, Modeling and Applied Social Sciences, Brazil
| | | | - Olavo Luppi Silva
- Universidade Federal do ABC, Center of Engineering, Modeling and Applied Social Sciences, Brazil
| | | | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Germany
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Knut Möeller
- Institute of Technical Medicine, Furtwangen University, Germany
| | - Marcelo Brito Passos Amato
- Respiratory Intensive Care Unit, Pulmonary Division, Hospital das Clínicas, Universidade de São Paulo, Brazil
| | - Jennifer L Mueller
- Department of Mathematics, and School of Biomedical Engineering, Colorado State University, United States of America
| | - Raul Gonzalez Lima
- Department of Mechanical Engineering, Escola Politécnica da Universidade de São Paulo, Brazil
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Morton SE, Knopp JL, Chase JG, Docherty P, Howe SL, Möller K, Shaw GM, Tawhai M. Optimising mechanical ventilation through model-based methods and automation. ANNUAL REVIEWS IN CONTROL 2019; 48:369-382. [PMID: 36911536 PMCID: PMC9985488 DOI: 10.1016/j.arcontrol.2019.05.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/09/2019] [Accepted: 05/01/2019] [Indexed: 06/11/2023]
Abstract
Mechanical ventilation (MV) is a core life-support therapy for patients suffering from respiratory failure or acute respiratory distress syndrome (ARDS). Respiratory failure is a secondary outcome of a range of injuries and diseases, and results in almost half of all intensive care unit (ICU) patients receiving some form of MV. Funding the increasing demand for ICU is a major issue and MV, in particular, can double the cost per day due to significant patient variability, over-sedation, and the large amount of clinician time required for patient management. Reducing cost in this area requires both a decrease in the average duration of MV by improving care, and a reduction in clinical workload. Both could be achieved by safely automating all or part of MV care via model-based dynamic systems modelling and control methods are ideally suited to address these problems. This paper presents common lung models, and provides a vision for a more automated future and explores predictive capacity of some current models. This vision includes the use of model-based methods to gain real-time insight to patient condition, improve safety through the forward prediction of outcomes to changes in MV, and develop virtual patients for in-silico design and testing of clinical protocols. Finally, the use of dynamic systems models and system identification to guide therapy for improved personalised control of oxygenation and MV therapy in the ICU will be considered. Such methods are a major part of the future of medicine, which includes greater personalisation and predictive capacity to both optimise care and reduce costs. This review thus presents the state of the art in how dynamic systems and control methods can be applied to transform this core area of ICU medicine.
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Affiliation(s)
- Sophie E Morton
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Jennifer L Knopp
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - J Geoffrey Chase
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Paul Docherty
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Sarah L Howe
- Department of Mechanical Engineering, University of Canterbury, New Zealand
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Geoffrey M Shaw
- Department of Intensive Care, Christchurch Hospital, Christchurch, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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