1
|
Cui Z, Liu X, Qu H, Wang H. Technical Principles and Clinical Applications of Electrical Impedance Tomography in Pulmonary Monitoring. SENSORS (BASEL, SWITZERLAND) 2024; 24:4539. [PMID: 39065936 PMCID: PMC11281055 DOI: 10.3390/s24144539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/11/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024]
Abstract
Pulmonary monitoring is crucial for the diagnosis and management of respiratory conditions, especially after the epidemic of coronavirus disease. Electrical impedance tomography (EIT) is an alternative non-radioactive tomographic imaging tool for monitoring pulmonary conditions. This review proffers the current EIT technical principles and applications on pulmonary monitoring, which gives a comprehensive summary of EIT applied on the chest and encourages its extensive usage to clinical physicians. The technical principles involving EIT instrumentations and image reconstruction algorithms are explained in detail, and the conditional selection is recommended based on clinical application scenarios. For applications, specifically, the monitoring of ventilation/perfusion (V/Q) is one of the most developed EIT applications. The matching correlation of V/Q could indicate many pulmonary diseases, e.g., the acute respiratory distress syndrome, pneumothorax, pulmonary embolism, and pulmonary edema. Several recently emerging applications like lung transplantation are also briefly introduced as supplementary applications that have potential and are about to be developed in the future. In addition, the limitations, disadvantages, and developing trends of EIT are discussed, indicating that EIT will still be in a long-term development stage before large-scale clinical applications.
Collapse
Affiliation(s)
- Ziqiang Cui
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China; (X.L.); (H.Q.); (H.W.)
| | | | | | | |
Collapse
|
2
|
Evaluation of atelectasis using electrical impedance tomography during procedural deep sedation for MRI in small children: A prospective observational trial. J Clin Anesth 2021; 77:110626. [PMID: 34902800 DOI: 10.1016/j.jclinane.2021.110626] [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: 09/22/2021] [Revised: 11/29/2021] [Accepted: 12/02/2021] [Indexed: 12/14/2022]
Abstract
STUDY OBJECTIVE To investigate the variation of poorly ventilated lung units (i.e., silent spaces) in children undergoing procedural sedation in a day-hospital setting, until discharge home from the Post-Anesthesia Care Unit (PACU). DESIGN Prospective, single-center, observational cohort trial. SETTING This study was conducted at the radiology department and in PACU at Bern University Hospital (Switzerland), a tertiary care hospital. PATIENTS We included 25 children (1-6 years, ASA I-III) scheduled for cerebral magnetic resonance imaging scan, spontaneously breathing under deep sedation. Children planned for tracheal intubation, supraglottic airway insertion, or with contraindication for propofol were excluded. INTERVENTION After intravenous or inhaled induction, deep sedation was performed with 10 mg/kg/h Propofol. All children received nasal oxygen 0.3 ml/kg/min. MEASUREMENTS The proportion of silent spaces and the global inhomogeneity index were determined at each of five procedural points, using electrical impedance tomography: before induction (T1); before (T2) and after (T3) magnetic resonance imaging; at the end of sedation before transport to the PACU (T4); and before hospital discharge (T5). MAIN RESULTS The median [interquartile range (IQR)] proportion of silent spaces at the five analysis points were: T1, 5% [2%-14%]; T2, 10% [7%-14%]; T3, 12% [5%-23%]; T4, 12% [7%-24%]; and T5, 3% [2%-11%]. These defined significant changes in silent spaces over the course of sedation (p = 0.009), but no differences in silent spaces from before induction to before discharge from the PACU (T1 vs. T5; p = 0.29). Median [IQR] global inhomogeneity indices were 0.57 [0.55-0.58], 0.56 [0.53-0.59], 0.56 [0.54-0.59], 0.57 [0.54-0.60] and 0.56 [0.54-0.57], respectively (p = 0.93). None of the children reported anesthesia-related complications. CONCLUSION Deep sedation results in significantly increased poorly ventilated lung units during sedation. However, this does not significantly affect ventilation homogeneity, which was fully resolved at discharge from the PACU. TRIAL REGISTRATION clinicaltrials.gov, identifier NCT04507581.
Collapse
|
3
|
Bleul U, Wey C, Meira C, Waldmann A, Mosing M. Assessment of Postnatal Pulmonary Adaption in Bovine Neonates Using Electric Impedance Tomography (EIT). Animals (Basel) 2021; 11:3216. [PMID: 34827949 PMCID: PMC8614262 DOI: 10.3390/ani11113216] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/04/2021] [Accepted: 11/08/2021] [Indexed: 01/06/2023] Open
Abstract
Several aspects of postnatal pulmonary adaption in the bovine neonate remain unclear, particularly the dynamics and regional ventilation of the lungs. We used electric impedance tomography (EIT) to measure changes in ventilation in the first 3 weeks of life in 20 non-sedated neonatal calves born without difficulty in sternal recumbency. Arterial blood gas variables were determined in the first 24 h after birth. Immediately after birth, dorsal parts of the lungs had 4.53% ± 2.82% nondependent silent spaces (NSS), and ventral parts had 5.23% ± 2.66% dependent silent spaces (DSS). The latter increased in the first hour, presumably because of gravity-driven ventral movement of residual amniotic fluid. The remaining lung regions had good ventilation immediately after birth, and the percentage of lung regions with high ventilation increased significantly during the study period. The centre of ventilation was always dorsal to and on the right of the theoretical centre of ventilation. The right lung was responsible for a significantly larger proportion of ventilation (63.84% ± 12.74%, p < 0.00001) compared with the left lung. In the right lung, the centrodorsal lung area was the most ventilated, whereas, in the left lung, it was the centroventral area. Tidal impedance changes, serving as a surrogate for tidal volume, increased in the first 3 weeks of life (p < 0.00001). This study shows the dynamic changes in lung ventilation in the bovine neonate according to EIT measurements. The findings form a basis for the recognition of structural and functional lung disorders in neonatal calves.
Collapse
Affiliation(s)
- Ulrich Bleul
- Department of Farm Animals, Clinic of Reproductive Medicine, Vetsuisse-Faculty University Zurich, 8057 Zurich, Switzerland;
| | - Corina Wey
- Department of Farm Animals, Clinic of Reproductive Medicine, Vetsuisse-Faculty University Zurich, 8057 Zurich, Switzerland;
| | - Carolina Meira
- Department of Clinical Diagnostics and Services, Section Anaesthesiology, Vetsuisse Faculty, University of Zurich, 8057 Zürich, Switzerland;
| | - Andreas Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, 39071 Rostock, Germany;
| | - Martina Mosing
- Department of Veterinary Anaesthesia and Analgesia, School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Murdoch 6150, Australia;
| |
Collapse
|
4
|
He H, Chi Y, Long Y, Yuan S, Zhang R, Yang Y, Frerichs I, Möller K, Fu F, Zhao Z. Three broad classifications of acute respiratory failure etiologies based on regional ventilation and perfusion by electrical impedance tomography: a hypothesis-generating study. Ann Intensive Care 2021; 11:134. [PMID: 34453622 PMCID: PMC8401348 DOI: 10.1186/s13613-021-00921-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 08/19/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND The aim of this study was to validate whether regional ventilation and perfusion data measured by electrical impedance tomography (EIT) with saline bolus could discriminate three broad acute respiratory failure (ARF) etiologies. METHODS Perfusion image was generated from EIT-based impedance-time curves caused by 10 ml 10% NaCl injection during a respiratory hold. Ventilation image was captured before the breath holding period under regular mechanical ventilation. DeadSpace%, Shunt% and VQMatch% were calculated based on lung perfusion and ventilation images. Ventilation and perfusion maps were divided into four cross-quadrants (lower left and right, upper left and right). Regional distribution defects of each quadrant were scored as 0 (distribution% ≥ 15%), 1 (15% > distribution% ≥ 10%) and 2 (distribution% < 10%). Data percentile distributions in the control group and clinical simplicity were taken into consideration when defining the scores. Overall defect scores (DefectV, DefectQ and DefectV+Q) were the sum of four cross-quadrants of the corresponding images. RESULTS A total of 108 ICU patients were prospectively included: 93 with ARF and 15 without as a control. PaO2/FiO2 was significantly correlated with VQMatch% (r = 0.324, P = 0.001). Three broad etiologies of ARF were identified based on clinical judgment: pulmonary embolism-related disease (PED, n = 14); diffuse lung involvement disease (DLD, n = 21) and focal lung involvement disease (FLD, n = 58). The PED group had a significantly higher DeadSpace% [40(24)% vs. 14(15)%, PED group vs. the rest of the subjects; median(interquartile range); P < 0.0001] and DefectQ score than the other groups [1(1) vs. 0(1), PED vs. the rest; P < 0.0001]. The DLD group had a significantly lower DefectV+Q score than the PED and FLD groups [0(1) vs. 2.5(2) vs. 3(3), DLD vs. PED vs. FLD; P < 0.0001]. The FLD group had a significantly higher DefectV score than the other groups [2(2) vs. 0(1), FLD vs. the rest; P < 0.0001]. The area under the receiver operating characteristic (AUC) for using DeadSpace% to identify PED was 0.894 in all ARF patients. The AUC for using the DefectV+Q score to identify DLD was 0.893. The AUC for using the DefectV score to identify FLD was 0.832. CONCLUSIONS Our study showed that it was feasible to characterize three broad etiologies of ARF with EIT-based regional ventilation and perfusion. Further study is required to validate clinical applicability of this method. Trial registration clinicaltrials, NCT04081142. Registered 9 September 2019-retrospectively registered, https://clinicaltrials.gov/show/NCT04081142 .
Collapse
Affiliation(s)
- Huaiwu He
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Chi
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yun Long
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
| | - Siyi Yuan
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Rui Zhang
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yingying Yang
- Department of Critical Care Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center of Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Knut Möller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, 169 Changle Xi Rd, Xi'an, China
| | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany.
- Department of Biomedical Engineering, Fourth Military Medical University, 169 Changle Xi Rd, Xi'an, China.
| |
Collapse
|
5
|
Sacks M, Byrne DP, Herteman N, Secombe C, Adler A, Hosgood G, Raisis AL, Mosing M. Electrical impedance tomography to measure lung ventilation distribution in healthy horses and horses with left-sided cardiac volume overload. J Vet Intern Med 2021; 35:2511-2523. [PMID: 34347908 PMCID: PMC8478054 DOI: 10.1111/jvim.16227] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 12/24/2022] Open
Abstract
Background Left‐sided cardiac volume overload (LCVO) can cause fluid accumulation in lung tissue changing the distribution of ventilation, which can be evaluated by electrical impedance tomography (EIT). Objectives To describe and compare EIT variables in horses with naturally occurring compensated and decompensated LCVO and compare them to a healthy cohort. Animals Fourteen adult horses, including university teaching horses and clinical cases (healthy: 8; LCVO: 4 compensated, 2 decompensated). Methods In this prospective cohort study, EIT was used in standing, unsedated horses and analyzed for conventional variables, ventilated right (VAR) and left (VAL) lung area, linear‐plane distribution variables (avg‐max VΔZLine, VΔZLine), global peak flows, inhomogeneity factor, and estimated tidal volume. Horses with decompensated LCVO were assessed before and after administration of furosemide. Variables for healthy and LCVO‐affected horses were compared using a Mann‐Whitney test or unpaired t‐test and observations from compensated and decompensated horses are reported. Results Compared to the healthy horses, the LCVO cohort had significantly less VAL (mean difference 3.02; 95% confidence interval .77‐5.2; P = .02), more VAR (−1.13; −2.18 to −.08; P = .04), smaller avg‐max VΔZLLine (2.54; 1.07‐4.00; P = .003) and VΔZLLine (median difference 5.40; 1.71‐9.09; P = .01). Observation of EIT alterations were reflected by clinical signs in horses with decompensated LCVO and after administration of furosemide. Conclusions and Clinical Importance EIT measurements of ventilation distribution showed less ventilation in the left lung of horses with LCVO and might be useful as an objective assessment of the ventilation effects of cardiogenic pulmonary disease in horses.
Collapse
Affiliation(s)
- Muriel Sacks
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - David P Byrne
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Nicolas Herteman
- Equine Clinic, Department for Equine Medicine, Vetsuisse Faculty, University of Zurich, Zürich, Switzerland
| | - Cristy Secombe
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - Giselle Hosgood
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Anthea L Raisis
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| | - Martina Mosing
- School of Veterinary Medicine, Murdoch University, Perth, Australia
| |
Collapse
|
6
|
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
|
7
|
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.
Collapse
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
| | | | | |
Collapse
|
8
|
Zhao Z, He H, Luo J, Adler A, Zhang X, Liu R, Lan Y, Lu S, Luo X, Lei Y, Frerichs I, Huang X, Möller K. Detection of pulmonary oedema by electrical impedance tomography: validation of previously proposed approaches in a clinical setting. Physiol Meas 2019; 40:054008. [DOI: 10.1088/1361-6579/ab1d90] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
9
|
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]
|
10
|
Santos SA, Wembers CC, Horst K, Pfeifer R, Simon TP, Pape HC, Hildebrand F, Czaplik M, Leonhardt S, Teichmann D. Monitoring lung contusion in a porcine polytrauma model using EIT: an application study. Physiol Meas 2017. [DOI: 10.1088/1361-6579/aa7985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
11
|
Frerichs I, Amato MBP, van Kaam AH, Tingay DG, Zhao Z, Grychtol B, Bodenstein M, Gagnon H, Böhm SH, Teschner E, Stenqvist O, Mauri T, Torsani V, Camporota L, Schibler A, Wolf GK, Gommers D, Leonhardt S, Adler A. Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: consensus statement of the TRanslational EIT developmeNt stuDy group. Thorax 2016; 72:83-93. [PMID: 27596161 PMCID: PMC5329047 DOI: 10.1136/thoraxjnl-2016-208357] [Citation(s) in RCA: 490] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/12/2016] [Accepted: 07/16/2016] [Indexed: 11/04/2022]
Abstract
Electrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function testing in patients with chronic lung diseases. As EIT becomes an established medical technology, it requires consensus examination, nomenclature, data analysis and interpretation schemes. Such consensus is needed to compare, understand and reproduce study findings from and among different research groups, to enable large clinical trials and, ultimately, routine clinical use. Recommendations of how EIT findings can be applied to generate diagnoses and impact clinical decision-making and therapy planning are required. This consensus paper was prepared by an international working group, collaborating on the clinical promotion of EIT called TRanslational EIT developmeNt stuDy group. It addresses the stated needs by providing (1) a new classification of core processes involved in chest EIT examinations and data analysis, (2) focus on clinical applications with structured reviews and outlooks (separately for adult and neonatal/paediatric patients), (3) a structured framework to categorise and understand the relationships among analysis approaches and their clinical roles, (4) consensus, unified terminology with clinical user-friendly definitions and explanations, (5) a review of all major work in thoracic EIT and (6) recommendations for future development (193 pages of online supplements systematically linked with the chief sections of the main document). We expect this information to be useful for clinicians and researchers working with EIT, as well as for industry producers of this technology.
Collapse
Affiliation(s)
- Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Marcelo B P Amato
- Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Anton H van Kaam
- Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Bartłomiej Grychtol
- Fraunhofer Project Group for Automation in Medicine and Biotechnology PAMB, Mannheim, Germany
| | - Marc Bodenstein
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Hervé Gagnon
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | | | | | - Ola Stenqvist
- Department of Anesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Vinicius Torsani
- Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Luigi Camporota
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Andreas Schibler
- Paediatric Critical Care Research Group, Mater Research University of Queensland, South Brisbane, Australia
| | - Gerhard K Wolf
- Children's Hospital Traunstein, Ludwig Maximilian's University, Munich, Germany
| | - Diederik Gommers
- Department of Adult Intensive Care, Erasmus MC, Rotterdam, The Netherlands
| | - Steffen Leonhardt
- Philips Chair for Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | | |
Collapse
|
12
|
Kobylianskii J, Murray A, Brace D, Goligher E, Fan E. Electrical impedance tomography in adult patients undergoing mechanical ventilation: A systematic review. J Crit Care 2016; 35:33-50. [PMID: 27481734 DOI: 10.1016/j.jcrc.2016.04.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 01/20/2023]
Abstract
PURPOSE The purpose of the study is to systematically review and summarize current literature concerning the validation and application of electrical impedance tomography (EIT) in mechanically ventilated adult patients. MATERIALS AND METHODS An electronic search of MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, and the Web of Science was performed up to June 2014. Studies investigating the use of EIT in an adult human patient population treated with mechanical ventilation (MV) were included. Data extracted included study objectives, EIT details, interventions, MV protocol, validation and comparators, population characteristics, and key findings. RESULTS Of the 67 included studies, 35 had the primary objective of validating EIT measures including regional ventilation distribution, lung volume, regional respiratory mechanics, and nonventilatory parameters. Thirty-two studies had the primary objective of applying EIT to monitor the response to therapeutic MV interventions including change in ventilation mode, patient repositioning, endotracheal suctioning, recruitment maneuvers, and change in positive end-expiratory pressure. CONCLUSIONS In adult patients, EIT has been successfully validated for assessing ventilation distribution, measuring changes in lung volume, studying regional respiratory mechanics, and investigating nonventilatory parameters. Electrical impedance tomography has also been demonstrated to be useful in monitoring regional respiratory system changes during MV interventions, although existing literature lacks clinical outcome evidence.
Collapse
Affiliation(s)
- Jane Kobylianskii
- School of Medicine, Queen's University, Kingston, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Alistair Murray
- Schulich School of Medicine & Dentistry, Western University, London, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Debbie Brace
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Ewan Goligher
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
| |
Collapse
|
13
|
Balleza-Ordaz M, Alday-Perez E, Vargas-Luna M, Kashina S, Huerta-Franco M, Torres-González L, Riu-Costa P. Tidal volume monitoring by a set of tetrapolar impedance measurements selected from the 16-electrodes arrangement used in electrical impedance tomography (EIT) technique. Calibration equations in a group of healthy males. Biomed Signal Process Control 2016. [DOI: 10.1016/j.bspc.2016.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
14
|
Trepte CJC, Phillips CR, Solà J, Adler A, Haas SA, Rapin M, Böhm SH, Reuter DA. Electrical impedance tomography (EIT) for quantification of pulmonary edema in acute lung injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:18. [PMID: 26796635 PMCID: PMC4722629 DOI: 10.1186/s13054-015-1173-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/13/2015] [Indexed: 01/19/2023]
Abstract
Background Assessment of pulmonary edema is a key factor in monitoring and guidance of therapy in critically ill patients. To date, methods available at the bedside for estimating the physiologic correlate of pulmonary edema, extravascular lung water, often are unreliable or require invasive measurements. The aim of the present study was to develop a novel approach to reliably assess extravascular lung water by making use of the functional imaging capabilities of electrical impedance tomography. Methods Thirty domestic pigs were anesthetized and randomized to three different groups. Group 1 was a sham group with no lung injury. Group 2 had acute lung injury induced by saline lavage. Group 3 had vascular lung injury induced by intravenous injection of oleic acid. A novel, noninvasive technique using changes in thoracic electrical impedance with lateral body rotation was used to measure a new metric, the lung water ratioEIT, which reflects total extravascular lung water. The lung water ratioEIT was compared with postmortem gravimetric lung water analysis and transcardiopulmonary thermodilution measurements. Results A significant correlation was found between extravascular lung water as measured by postmortem gravimetric analysis and electrical impedance tomography (r = 0.80; p < 0.05). Significant changes after lung injury were found in groups 2 and 3 in extravascular lung water derived from transcardiopulmonary thermodilution as well as in measurements derived by lung water ratioEIT. Conclusions Extravascular lung water could be determined noninvasively by assessing characteristic changes observed on electrical impedance tomograms during lateral body rotation. The novel lung water ratioEIT holds promise to become a noninvasive bedside measure of pulmonary edema.
Collapse
Affiliation(s)
- Constantin J C Trepte
- Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany.
| | - Charles R Phillips
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Intensive Care Research, Oregon Health & Science University, Portland, OR, USA.
| | - Josep Solà
- CSEM Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland.
| | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada.
| | - Sebastian A Haas
- Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany.
| | - Michael Rapin
- CSEM Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland.
| | | | - Daniel A Reuter
- Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany.
| |
Collapse
|
15
|
Jozwiak M, Teboul JL, Monnet X. Extravascular lung water in critical care: recent advances and clinical applications. Ann Intensive Care 2015; 5:38. [PMID: 26546321 PMCID: PMC4636545 DOI: 10.1186/s13613-015-0081-9] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 10/27/2015] [Indexed: 12/16/2022] Open
Abstract
Extravascular lung water (EVLW) is the amount of fluid that is accumulated in the interstitial and alveolar spaces. In lung oedema, EVLW increases either because of increased lung permeability or because of increased hydrostatic pressure in the pulmonary capillaries, or both. Increased EVLW is always potentially life-threatening, mainly because it impairs gas exchange and reduces lung compliance. The only technique that provides an easy measurement of EVLW at the bedside is transpulmonary thermodilution. The validation of EVLW measurements by thermodilution was based on studies showing reasonable correlations with gravimetry or thermo-dye dilution in experimental and clinical studies. EVLW should be indexed to predicted body weight. This indexation reduces the proportion of ARDS patients for whom EVLW is in the normal range. Compared to non-indexed EVLW, indexed EVLW (EVLWI) is better correlated with the lung injury score and the oxygenation and it is a better predictor of mortality of patients with acute lung injury or acute respiratory distress syndrome (ARDS). Transpulmonary thermodilution also provides the pulmonary vascular permeability index (PVPI), which is an indirect reflection of the integrity of the alveolocapillary barrier. As clinical applications, EVLWI and PVPI may be useful to guide fluid management of patients at risk of fluid overload, as during septic shock and ARDS. High EVLWI and PVPI values predict mortality in several categories of critically ill patients, especially during ARDS. Thus, fluid administration should be limited when EVLWI is already high. Whatever the value of EVLWI, PVPI may indicate that fluid administration is particularly at risk of aggravating lung oedema. In the acute phase of haemodynamic resuscitation during septic shock and ARDS, high EVLWI and PVPI values may warn of the risk of fluid overload and prevent excessive volume expansion. At the post-resuscitation phase, they may prompt initiation of fluid removal thereby achieving a negative fluid balance.
Collapse
Affiliation(s)
- Mathieu Jozwiak
- Faculté de Médecine, Université Paris-Sud, Université Paris-Saclay, Le Kremlin Bicêtre, France. .,AP-HP, Service de réanimation médicale, Hôpital de Bicêtre, 78, rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France. .,Inserm UMR_S 999, Hôpital Marie Lannelongue, Le Plessis-Robinson, France.
| | - Jean-Louis Teboul
- Faculté de Médecine, Université Paris-Sud, Université Paris-Saclay, Le Kremlin Bicêtre, France. .,AP-HP, Service de réanimation médicale, Hôpital de Bicêtre, 78, rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France. .,Inserm UMR_S 999, Hôpital Marie Lannelongue, Le Plessis-Robinson, France.
| | - Xavier Monnet
- Faculté de Médecine, Université Paris-Sud, Université Paris-Saclay, Le Kremlin Bicêtre, France. .,AP-HP, Service de réanimation médicale, Hôpital de Bicêtre, 78, rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France. .,Inserm UMR_S 999, Hôpital Marie Lannelongue, Le Plessis-Robinson, France.
| |
Collapse
|
16
|
Tidal volume monitoring by electrical impedance tomography (EIT) using different regions of interest (ROI): Calibration equations. Biomed Signal Process Control 2015. [DOI: 10.1016/j.bspc.2014.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
17
|
Dodd M, Mueller JL. A Real-time D-bar Algorithm for 2-D Electrical Impedance Tomography Data. INVERSE PROBLEMS AND IMAGING (SPRINGFIELD, MO.) 2014; 8:1013-1031. [PMID: 25937856 PMCID: PMC4414053 DOI: 10.3934/ipi.2014.8.1013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this paper is to show the feasibility of the D-bar method for real-time 2-D EIT reconstructions. A fast implementation of the D-bar method for reconstructing conductivity changes on a 2-D chest-shaped domain is described. Cross-sectional difference images from the chest of a healthy human subject are presented, demonstrating what can be achieved in real time. The images constitute the first D-bar images from EIT data on a human subject collected on a pairwise current injection system.
Collapse
Affiliation(s)
- Melody Dodd
- Department of Mathematics, Colorado State University, USA
| | - Jennifer L Mueller
- Department of Mathematics and School of Biomedical Engineering, Colorado State University, USA
| |
Collapse
|
18
|
Bodenstein M, Boehme S, Wang H, Duenges B, Markstaller K. Hints for cyclical recruitment of atelectasis during ongoing mechanical ventilation in lavage and oleic acid lung injury detected by SpO₂ oscillations and electrical impedance tomography. Exp Lung Res 2014; 40:427-38. [PMID: 25153803 DOI: 10.3109/01902148.2014.944719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE OF THE STUDY Detection of cyclical recruitment of atelectasis after induction of lavage (LAV) or oleic acid injury (OAI) in mechanically ventilated pigs. Primary hypothesis is that oxygen oscillations within the respiratory cycle can be detected by SpO₂ recordings (direct hint). SpO₂ oscillations reflect shunt oscillations that can only be explained by cyclical recruitment of atelectasis. Secondary hypothesis is that electrical impedance tomography (EIT) depicts specific regional changes of lung aeration and of pulmonary mechanical properties (indirect hint). MATERIALS AND METHODS Three groups (each n = 7) of mechanically ventilated pigs were investigated applying above mentioned methods before and repeatedly after induction of lung injury: (1) sham treated animals (SHAM), (2) LAV, and (3) OAI. RESULTS Early oxygen oscillations occurred in the LAV group (mean calculated amplitude: 73.8 mmHg reflecting shunt oscillation of 11.2% in mean). In the OAI group oxygen oscillations occurred hours after induction of lung injury (mean calculated amplitude: 57.1 mmHg reflecting shunt oscillations of 8.4% in mean). The SHAM group had no relevant oxygen oscillations (<30 mmHg, shunt oscillations < 1.5%). Synchronously to oxygen oscillations, EIT depicted (1) a decrease of ventilation in dorsal areas, (2) an increase in ventral areas, (3) a decrease of especially dependent expiratory impedance, 3) an increase in late inspiratory flow especially in the dependant areas, (4) an increase in the speed of peak expiratory flow (PEF), and (5) a decrease of dorsal late expiratory flow. CONCLUSIONS SpO2 and EIT recordings detect events that are interpreted as cyclical recruitment of atelectasis.
Collapse
Affiliation(s)
- Marc Bodenstein
- 1Department of Anaesthesiology, University Medical Center Mainz, Mainz, Germany
| | | | | | | | | |
Collapse
|
19
|
Crabb MG, Davidson JL, Little R, Wright P, Morgan AR, Miller CA, Naish JH, Parker GJM, Kikinis R, McCann H, Lionheart WRB. Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT. Physiol Meas 2014; 35:863-79. [PMID: 24710978 PMCID: PMC4059506 DOI: 10.1088/0967-3334/35/5/863] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction.
Collapse
Affiliation(s)
- M G Crabb
- School of Mathematics, University of Manchester, UK
| | - J L Davidson
- School of Electrical and Electronic Engineering, University of Manchester, UK
| | - R Little
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, UK
| | - P Wright
- School of Electrical and Electronic Engineering, University of Manchester, UK
| | - A R Morgan
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, UK
| | - C A Miller
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, UK
| | - J H Naish
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, UK
| | - G J M Parker
- Centre for Imaging Sciences, Biomedical Imaging Institute, University of Manchester, UK
| | - R Kikinis
- Surgical Planning Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA
| | - H McCann
- School of Electrical and Electronic Engineering, University of Manchester, UK
| | | |
Collapse
|
20
|
Hamilton SJ, Mueller JL. Direct EIT reconstructions of complex admittivities on a chest-shaped domain in 2-D. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:757-769. [PMID: 23314771 DOI: 10.1109/tmi.2012.2237389] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Electrical impedance tomography (EIT) is a medical imaging technique in which current is applied on electrodes on the surface of the body, the resulting voltage is measured, and an inverse problem is solved to recover the conductivity and/or permittivity in the interior. Images are then formed from the reconstructed conductivity and permittivity distributions. In the 2-D geometry, EIT is clinically useful for chest imaging. In this work, an implementation of a D-bar method for complex admittivities on a general 2-D domain is presented. In particular, reconstructions are computed on a chest-shaped domain for several realistic phantoms including a simulated pneumothorax, hyperinflation, and pleural effusion. The method demonstrates robustness in the presence of noise. Reconstructions from trigonometric and pairwise current injection patterns are included.
Collapse
Affiliation(s)
- Sarah J Hamilton
- Department of Mathematics, Colorado State University, Fort Collins, CO 80523, USA.
| | | |
Collapse
|
21
|
Burkhardt W, Kurth F, Pitterle M, Blassnig N, Wemhöner A, Rüdiger M. Continuous noninvasive monitoring of lung recruitment during high-frequency oscillatory ventilation by electrical impedance measurement: an animal study. Neonatology 2013; 103:218-23. [PMID: 23364000 DOI: 10.1159/000345612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 11/05/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Ventilatory pressures should target the range between the upper and lower inflection point of the pressure volume curve in order to avoid atelecto- and volutrauma. During high-frequency oscillatory ventilation (HFOV), this range is difficult to determine. Quadrant impedance measurement (QIM) has recently been shown to allow accurate and precise measurement of lung volume changes during conventional mechanical ventilation. OBJECTIVES To investigate if QIM can be used to determine a static pressure-residual impedance curve during a recruitment-derecruitment manoeuvre on HFOV and to monitor the time course of alveolar recruitment after changing mean airway pressure (MAP). METHODS An incremental and decremental MAP trial (6 cm H2O to 27 cm H2O) was conducted in five surfactant-depleted newborn piglets during HFOV. Ventilatory, gas exchange and haemodynamic parameters were recorded. Continuous measurement of thoracic impedance change was performed. RESULTS Mean residual impedance (RI) increased with each stepwise increase of MAP resulting in a total mean increase of +26.5% (±4.0) at the highest MAP (27 cm H2O) compared to baseline ventilation at 6 cm H2O. Upon decreasing MAP levels, RI fell more slowly compared to its ascent; 83.4% (±19.1) and 84.8% (±16.4) of impedance changes occurred in the first 5 min after an increase or decrease in airway pressure, respectively. CONCLUSIONS QIM could be used for continuous monitoring of thoracic impedance and determination of the pressure-RI curve during HFOV. The method could prove to be a promising bedside method for the monitoring of lung recruitment during HFOV in the future.
Collapse
Affiliation(s)
- Wolfram Burkhardt
- Department of Neonatology and Paediatric Intensive Care, University Hospital Carl Gustav Carus Dresden, Dresden, Germany
| | | | | | | | | | | |
Collapse
|
22
|
Electrical impedance tomography: the holy grail of ventilation and perfusion monitoring? Intensive Care Med 2012; 38:1917-29. [DOI: 10.1007/s00134-012-2684-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 08/08/2012] [Indexed: 01/08/2023]
|
23
|
Bodenstein M, Wang H, Boehme S, Vogt A, Kwiecien R, David M, Markstaller K. Influence of crystalloid and colloid fluid infusion and blood withdrawal on pulmonary bioimpedance in an animal model of mechanical ventilation. Physiol Meas 2012; 33:1225-36. [PMID: 22735353 DOI: 10.1088/0967-3334/33/7/1225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electrical impedance tomography (EIT) is considered useful for monitoring regional ventilation and aeration in intensive-care patients during mechanical ventilation. Changes in their body fluid state modify the electrical properties of lung tissue and may interfere with the EIT measurements of lung aeration. The aim of our study was to assess the effects of crystalloid and colloid infusion and blood withdrawal on bioimpedance determined by EIT in a chest cross-section. Fourteen anaesthetized mechanically ventilated pigs were subjected to interventions affecting the volume state (crystalloid and colloid infusion, blood withdrawal). Six animals received additional crystalloid fluids (fluid group) whereas eight did not (no-fluid group). Global and regional relative impedance changes (RIC, dimensionless unit) were determined by backprojection at end-expiration. Regional ventilation distribution was analyzed by calculating the tidal RIC in the same regions. Colloid infusion led to a significant fall in the global end-expiratory RIC (mean differences: fluid: -91.2, p < 0.001, no-fluid: -38.9, p < 0.001), which was partially reversed after blood withdrawal (mean differences, fluid: +45.1, p = 0.047 and no-fluid: +26.2, p = 0.009). The RIC was significantly lower in the animals with additional crystalloids (mean group difference: 45.5, p < 0.001). Global and regional tidal volumes were not significantly affected by the fluid and volume states.
Collapse
Affiliation(s)
- Marc Bodenstein
- Department of Anaesthesiology, University Medical Centre, 55101 Mainz, Germany.
| | | | | | | | | | | | | |
Collapse
|
24
|
Frerichs I, Achtzehn U, Pechmann A, Pulletz S, Schmidt EW, Quintel M, Weiler N. High-frequency oscillatory ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease. J Crit Care 2011; 27:172-81. [PMID: 21715133 DOI: 10.1016/j.jcrc.2011.04.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/11/2011] [Accepted: 04/29/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE High-frequency oscillatory ventilation (HFOV) is usually considered not indicated for treatment of patients with chronic obstructive pulmonary disease (COPD) because of the theoretical risk of air trapping and hyperinflation. The aim of our study was to establish whether HFOV can be safely applied in patients with acute exacerbation of COPD and hypercapnic respiratory failure. METHODS Ten patients (age, 63-83 years) requiring intensive care treatment who failed on noninvasive ventilation were studied. After initial conventional mechanical ventilation (CMV) of less than 72 hours, all patients were transferred to HFOV for 24 hours and then back to CMV. Arterial blood gases, spirometry, and hemodynamic parameters were repeatedly obtained in all phases of CMV and HFOV at different settings. Regional lung aeration and ventilation were assessed by electrical impedance tomography. RESULTS High-frequency oscillatory ventilation was tolerated well; no adverse effects or severe hyperinflation and hemodynamic compromise were observed. Effective CO(2) elimination and oxygenation were achieved. Ventilation was more homogeneously distributed during HFOV than during initial CMV. Higher respiratory system compliance and tidal volume were found during CMV after 24 hours of HFOV. CONCLUSIONS Our study indicates that short-term HFOV, using lower mean airway pressures than recommended for acute respiratory distress syndrome, appears safe in patients with COPD while securing adequate pulmonary gas exchange.
Collapse
Affiliation(s)
- Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, 24105 Kiel, Germany.
| | | | | | | | | | | | | |
Collapse
|
25
|
Arad M, Zlochiver S, Davidson T, Shovman O, Shoenfeld Y, Adunsky A, Abboud S. Estimating pulmonary congestion in elderly patients using bio-impedance technique: Correlation with clinical examination and X-ray results. Med Eng Phys 2009; 31:959-63. [DOI: 10.1016/j.medengphy.2009.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 03/12/2009] [Accepted: 05/19/2009] [Indexed: 11/27/2022]
|
26
|
Brown LM, Liu KD, Matthay MA. Measurement of extravascular lung water using the single indicator method in patients: research and potential clinical value. Am J Physiol Lung Cell Mol Physiol 2009; 297:L547-58. [PMID: 19617309 DOI: 10.1152/ajplung.00127.2009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Extravascular lung water includes all of the fluid within the lung but outside of the vasculature. Lung water increases as a result of increased hydrostatic vascular pressure or from an increase in lung endothelial and epithelial permeability or both. Experimentally, extravascular lung water has been measured gravimetrically. Clinically, the chest radiograph is used to determine whether extravascular lung water is present but is an insensitive instrument for determining the quantity of lung water. Bedside measurement of extravascular lung water in patients is now possible using a single indicator thermodilution method. This review critically evaluates the experimental and clinical evidence supporting the potential value of measuring extravascular lung water in patients using the single indicator method.
Collapse
Affiliation(s)
- Lisa M Brown
- Department of Surgery, Univ. of California-San Francisco, 505 Parnassus Ave., San Francisco, CA 94143, USA.
| | | | | |
Collapse
|
27
|
Arad M, Zlochiver S, Davidson T, Shoenfeld Y, Adunsky A, Abboud S. The detection of pleural effusion using a parametric EIT technique. Physiol Meas 2009; 30:421-8. [DOI: 10.1088/0967-3334/30/4/006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
28
|
|
29
|
Fagerberg A, Stenqvist O, Aneman A. Monitoring pulmonary perfusion by electrical impedance tomography: an evaluation in a pig model. Acta Anaesthesiol Scand 2009; 53:152-8. [PMID: 19175575 DOI: 10.1111/j.1399-6576.2008.01847.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Electrical impedance tomography (EIT) is a non-invasive technique that generates images of impedance distribution. Changes in the pulmonary content of air and blood are major determinants of thoracic impedance. This study was designed to evaluate EIT in monitoring pulmonary perfusion in a wide range of cardiac output. METHODS Eight anaesthetised, mechanically ventilated pigs were fitted with a 16-electrode belt at the mid-thoracic level to generate EIT images that were analysed to determine pulse-synchronous systolic changes in impedance (DeltaZ(sys)). Stroke volume (SV) was derived using a pulmonary artery catheter. Reductions in cardiac pre-load, and thus pulmonary perfusion, were induced either by inflating the balloon of a Fogarty catheter positioned in the inferior caval vein or by increasing the positive end-expiratory pressure (PEEP). All measurements were performed in a steady state during a short apnoea. RESULTS Pulse-synchronous changes in DeltaZ(sys) were easily discernable during apnoea. Balloon inflation reduced SV to 36% of the baseline, with a corresponding decrease in DeltaZ(sys) to 45% of baseline. PEEP reduced SV and DeltaZ(sys) to 52% and 44% of the baseline, respectively. Significant correlations between SV and DeltaZ(sys) were demonstrated during all measurements (rho=0.62) as well as during balloon inflation (rho=0.73) and increased PEEP (rho=0.40). A Bland-Altman comparison of relative changes in SV and DeltaZ(sys) demonstrated a bias of -7%, with 95% limits of agreement at -51% and 36%. CONCLUSIONS EIT provided beat-to-beat approximations of pulmonary perfusion that significantly correlated to a wide range of SV values achieved during both extra and intrapulmonary interventions to change cardiac output.
Collapse
Affiliation(s)
- A Fagerberg
- Department of Anaesthesiology and Intensive Care, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
| | | | | |
Collapse
|
30
|
Clinical Utility of Extravascular Lung Water Measurements. Intensive Care Med 2009. [DOI: 10.1007/978-0-387-92278-2_42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
31
|
Putensen C, Wrigge H, Zinserling J. Electrical impedance tomography guided ventilation therapy. Curr Opin Crit Care 2008; 13:344-50. [PMID: 17468569 DOI: 10.1097/mcc.0b013e328136c1e2] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Computed tomography (CT) in patients with acute respiratory distress syndrome has shown that intrapulmonary gas is not homogeneously distributed. Although regional ventilation can be studied by isotope and magnetic resonance techniques while aeration of the lungs can be imaged using CT, these techniques are not available at the bedside. Recently, electrical impedance tomography has been introduced as a true bedside technique which provides information on regional ventilation distribution. RECENT FINDINGS Electrical impedance tomography can reliably determine regional ventilation in healthy lungs and various models of induced lung injury when compared with CT, electron beam CT, and single photon emission CT. In healthy volunteers and patients with acute lung injury, relative impedance changes on the electrical impedance tomography image demonstrate an excellent correlation with regional changes in lung air content detected by CT. In a limited number of patients with respiratory dysfunction, gas exchange was found to improve when electrical impedance tomography was used to adjust ventilator settings, improving regional ventilation and avoiding tidal alveolar collapse. SUMMARY In view of recently published data, it can be concluded that, in critically ill patients, electrical impedance tomography determines reliable regional ventilation. Therefore, this technique has the potential to become a valuable bedside tool.
Collapse
Affiliation(s)
- Christian Putensen
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Germany.
| | | | | |
Collapse
|
32
|
Electrical Impedance Tomography and its Perspectives in Intensive Care Medicine. Intensive Care Med 2007. [DOI: 10.1007/0-387-35096-9_40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
33
|
Freimark D, Arad M, Sokolover R, Zlochiver S, Abboud S. Monitoring lung fluid content in CHF patients under intravenous diuretics treatment using bio-impedance measurements. Physiol Meas 2007; 28:S269-77. [PMID: 17664641 DOI: 10.1088/0967-3334/28/7/s20] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A pulmonary edema monitoring system (PulmoTrace, CardioInspect, Tel-Aviv University, Israel) was evaluated for tracking lung resistivity during diuretics treatment in congestive heart failure (CHF) patients. The system incorporates a bio-impedance measurement algorithm and enables, by employing an eight-electrode thoracic belt, the assessment of both the left- and right-lung resistivity values. A clinical study was conducted on a group of 13 CHF patients under intravenous diuretics treatment. The group was measured twice-before the beginning of treatment and following a period of a couple of hours. An increase of 8% of the mean lung resistivity (median value) was found between the two measuring sessions, which indicates a dehydration of the lungs, and a significant correlation (R=0.73, p=0.004) was found between the lung resistivity change and the urine output. In conjunction with previously reported results, which demonstrated the system's reproducibility and long-term monitoring capabilities, this study further supports the diagnostics value of the system.
Collapse
Affiliation(s)
- D Freimark
- Department of Cardiology, Sheba Medical Center, Ramat-Gan, Israel
| | | | | | | | | |
Collapse
|
34
|
Khan S, Trof RJ, Groeneveld ABJ. Transpulmonary dilution-derived extravascular lung water as a measure of lung edema. Curr Opin Crit Care 2007; 13:303-7. [PMID: 17468563 DOI: 10.1097/mcc.0b013e32811d6ccd] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW This review highlights current insights concerning the (measurement of) extravascular lung water as an index of pulmonary edema, by transpulmonary dilution techniques. The focus is on the applicability of the technique at the bedside in monitoring critically ill patients. RECENT FINDINGS Several (animal) studies have been performed to validate the technique by postmortem gravimetry in different conditions. Moreover, recent clinical data emphasize the utility of the thermodilution-derived extravascular lung water, its contribution to the clinical manifestations of acute lung injury/acute respiratory distress syndrome, its response to treatment aimed at edema prevention or resolution, and as a prognostic parameter. SUMMARY The thermodilution-derived extravascular lung water is a useful adjunct to assess lung vascular injury, cardiogenic edema and overhydration and to guide treatment in critically ill patients. The effects on morbidity and mortality of this approach need to be studied further.
Collapse
Affiliation(s)
- Saheed Khan
- Department of Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
| | | | | |
Collapse
|
35
|
Zlochiver S, Arad M, Radai MM, Barak-Shinar D, Krief H, Engelman T, Ben-Yehuda R, Adunsky A, Abboud S. A portable bio-impedance system for monitoring lung resistivity. Med Eng Phys 2006; 29:93-100. [PMID: 16546432 DOI: 10.1016/j.medengphy.2006.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Revised: 01/26/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
The principles of a hybrid bio-impedance technique are implemented in a novel, lung resistivity monitoring system ("CardioInspect" Tel-Aviv University, Israel). The system is to be utilized in the clinic or at home, for daily monitoring of patients suffering from pulmonary edema. The developed system consists of an eight-electrode belt worn around the thorax, an electronic unit containing analog and digital boards, and a stand-alone DSP based system with a designated software to analyze the data. A Newton-Raphson algorithm based on the finite-volume method is employed for the optimization of the left and right lung resistivity values, making use of the voltage measurements retrieved from opposite current injections. In this preliminary study, 33 healthy volunteers were measured with the system during tidal respiration, yielding symmetric mean left and right lung resistivity values of (1205+/-163, 1200+/-165) (Omega cm). The system reproducibility was better than 2% for both within and between tests measurements, and no dependency between the reconstructed values and various anthropometric parameters was found.
Collapse
Affiliation(s)
- S Zlochiver
- Department of Biomedical Engineering, Tel-Aviv University, Israel
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Frerichs I, Scholz J, Weiler N. Electrical Impedance Tomography and its Perspectives in Intensive Care Medicine. YEARBOOK OF INTENSIVE CARE AND EMERGENCY MEDICINE 2006. [DOI: 10.1007/3-540-33396-7_40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
37
|
Yamashiro T, Ando M, Okazaki Y, Sasaguri S. Dielectric behavior of pulmonary edema induced in the rat lung. Respir Physiol Neurobiol 2005; 145:91-100. [PMID: 15652791 DOI: 10.1016/j.resp.2004.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2004] [Indexed: 10/26/2022]
Abstract
The dielectric properties (conductivity, kappa and relative permittivity, epsilon) of excised rat lung are modified by lung air and water content. The measurements of these quantities were made over the frequency range of 10 kHz to 100 MHz with an open-ended coaxial probe. The following relationships were analyzed in an oleic acid-induced pulmonary edema model using 18 animals: the spectra of kappa, epsilon and the loss tangent as a function of lung air and water content. Secondly, an isolated-perfused lung system was produced to induce a gradual increase in lung water. The time course of kappa, epsilon and the loss tangent for one excised lung was analyzed. The principal findings were: (i) a decrease in kappa and epsilon with increasing air content, (ii) an increase in kappa and epsilon with increasing water content, and (iii) a good correlation between lung water content and maximum loss tangent that was insensitive to changes in air content. We conclude that this technique could provide a quantitative assessment of lung water during pulmonary edema formation.
Collapse
Affiliation(s)
- T Yamashiro
- Department of Thoracic and Cardiovascular Surgery and Regeneration Technology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan.
| | | | | | | |
Collapse
|
38
|
Mayer M, Brunner P, Merwa R, Scharfetter H. Monitoring of lung edema using focused impedance spectroscopy: a feasibility study. Physiol Meas 2005; 26:185-92. [PMID: 15798294 DOI: 10.1088/0967-3334/26/3/004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Currently only ionizing or invasive methods are used in clinical applications for the monitoring of extracellular lung water. Alternatively a method called focused conductivity spectroscopy (FCS) is suggested, which aims at reconstructing a pulmonary edema index (PEIX) by measuring the electrical conductivity of the region of interest (ROI) at several frequencies. In contrast to electrical impedance tomography (EIT) a minimum number of strategically placed electrodes is used. The goals of this study were the analysis of the sensitivity for the PEIX, an estimate of the optimal electrode configuration and the determination of the required frequencies. In order to calculate the solution of the FCS forward problem a realistic 3D model of a human torso was developed containing both lungs, the heart, the liver and the thorax musculature. The bioelectrical properties for each compartment were described with appropriate tissue models which relate the conductivity spectra to physiological parameters. The PEIX was defined as the interstitial volume fraction of the alveolar septa. Furthermore the model includes 48 electrodes subdivided into three layers. The optimal electrode configuration was selected by minimizing the number of electrodes, among certain subsets of these electrodes. The analysis shows that eight to ten electrodes and six frequencies are theoretically sufficient to obtain a coefficient of variation.
Collapse
Affiliation(s)
- Michael Mayer
- Institute for Medical Engineering, Graz University of Technology, Krenngasse 37, 8010 Graz, Austria.
| | | | | | | |
Collapse
|
39
|
Groeneveld ABJ, Plötz FB, van Genderingen HR. Monitoring the permeability edema of ventilator-associated lung injury. Crit Care Med 2005; 33:250-2. [PMID: 15644689 DOI: 10.1097/01.ccm.0000150756.05628.a5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
40
|
Mason NP, Petersen M, Melot C, Imanow B, Matveykine O, Gautier MT, Sarybaev A, Aldashev A, Mirrakhimov MM, Brown BH, Leathard AD, Naeije R. Serial changes in nasal potential difference and lung electrical impedance tomography at high altitude. J Appl Physiol (1985) 2003; 94:2043-50. [PMID: 12471048 DOI: 10.1152/japplphysiol.00777.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Recent work suggests that treatment with inhaled beta(2)-agonists reduces the incidence of high-altitude pulmonary edema in susceptible subjects by increasing respiratory epithelial sodium transport. We estimated respiratory epithelial ion transport by transepithelial nasal potential difference (NPD) measurements in 20 normal male subjects before, during, and after a stay at 3,800 m. NPD hyperpolarized on ascent to 3,800 m (P < 0.05), but the change in potential difference with superperfusion of amiloride or isoprenaline was unaffected. Vital capacity (VC) fell on ascent to 3,800 m (P < 0.05), as did the normalized change in electrical impedance (NCI) measured over the right lung parenchyma (P < 0.05) suggestive of an increase in extravascular lung water. Echo-Doppler-estimated pulmonary artery pressure increases were insufficient to cause clinical pulmonary edema. There was a positive correlation between VC and NCI (R(2) = 0.633) and between NPD and both VC and NCI (R(2) = 0.267 and 0.418). These changes suggest that altered respiratory epithelial ion transport might play a role in the development of subclinical pulmonary edema at high altitude in normal subjects.
Collapse
Affiliation(s)
- Nicholas P Mason
- Department of Physiology, Free University of Brussels, B1070 Brussels, Belgium.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Mason NP, Barry PW, Pollard AJ, Collier DJ, Taub NA, Miller MR, Milledge JS. Serial changes in spirometry during an ascent to 5,300 m in the Nepalese Himalayas. High Alt Med Biol 2001; 1:185-95. [PMID: 11254228 DOI: 10.1089/15270290050144181] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aims of the present study were to determine the changes in forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and peak expiratory flow (PEF), during an ascent to 5,300 m in the Nepalese Himalayas, and to correlate the changes with arterial oxygen saturation measured by pulse oximetry (SpO2) and symptoms of acute mountain sickness (AMS). Forty-six subjects were studied twice daily during an ascent from 2,800 m (mean barometric pressure 550.6 mmHg) to 5,300 m (mean barometric pressure 404.3 mmHg) during a period of between 10 and 16 days. Measurements of FVC, FEV1, PEF, SpO2, and AMS were recorded. AMS was assessed using a standardized scoring system. FVC fell with altitude, by a mean of 4% from sea level values [95% confidence intervals (CI) 0.9% to 7.4%] at 2,800 m, and 8.6% (95% CI 5.8 to 11.4%) at 5,300 m. FEV1 did not change with increasing altitude. PEF increased with altitude by a mean of 8.9% (95% CI 2.7 to 15.1%) at 2,800 m, and 16% (95% CI 9 to 23%) at 5,300 m. These changes were not significantly related to SpO2 or AMS scores. These results confirm a progressive fall in FVC and increase in PEF with increasing hypobaric hypoxia while FEV1 remains unchanged. The increase in PEF is less than would be predicted from the change in gas density. The fall in FVC may be due to reduced inspiratory force producing a reduction in total lung capacity; subclinical pulmonary edema; an increase in pulmonary blood volume, or changes in airway closure. The absence of a correlation between the spirometric changes and SpO2 or AMS may simply reflect that these measurements of pulmonary function are not sufficiently sensitive indicators of altitude-related disease. Further studies are required to clarify the effects of hypobaric hypoxia on lung volumes and flows in an attempt to obtain a unifying explanation for these changes.
Collapse
Affiliation(s)
- N P Mason
- Laboratoire de Physiologie et de Physiopathologie, Faculté de Médecine, Université Libre de Bruxelles, Belgium.
| | | | | | | | | | | | | |
Collapse
|