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Rosà T, Bongiovanni F, Michi T, Mastropietro C, Menga LS, DE Pascale G, Antonelli M, Grieco DL. Recruitment-to-inflation ratio for bedside PEEP selection in acute respiratory distress syndrome. Minerva Anestesiol 2024; 90:694-706. [PMID: 39021144 DOI: 10.23736/s0375-9393.24.17982-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
In acute respiratory distress syndrome, the role of positive end-expiratory pressure (PEEP) to prevent ventilator-induced lung injury is controversial. Randomized trials comparing higher versus lower PEEP strategies failed to demonstrate a clinical benefit. This may depend on the inter-individually variable potential for lung recruitment (i.e. recruitability), which would warrant PEEP individualization to balance alveolar recruitment and the unavoidable baby lung overinflation produced by high pressure. Many techniques have been used to assess recruitability, including lung imaging, multiple pressure-volume curves and lung volume measurement. The Recruitment-to-Inflation ratio (R/I) has been recently proposed to bedside assess recruitability without additional equipment. R/I assessment is a simplified technique based on the multiple pressure-volume curve concept: it is measured by monitoring respiratory mechanics and exhaled tidal volume during a 10-cmH2O one-breath derecruitment maneuver after a short high-PEEP test. R/I scales recruited volume to respiratory system compliance, and normalizes recruitment to a proxy of actual lung size. With modest R/I (<0.3-0.4), setting low PEEP (5-8 cmH2O) may be advisable; with R/I>0.6-0.7, high PEEP (≥15 cmH2O) can be considered, provided that airway and/or transpulmonary plateau pressure do not exceed safety limits. In case of intermediate R/I (≈0.5), a more granular assessment of recruitability may be needed. This could be accomplished with advanced monitoring tools, like sequential lung volume measurement with granular R/I assessment or electrical impedance tomography monitoring during a decremental PEEP trial. In this review, we discuss R/I rationale, applications and limits, providing insights on its clinical use for PEEP selection in moderate-to-severe acute respiratory distress syndrome.
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Affiliation(s)
- Tommaso Rosà
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Filippo Bongiovanni
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Teresa Michi
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Claudia Mastropietro
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Luca S Menga
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Gennaro DE Pascale
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Massimo Antonelli
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
| | - Domenico L Grieco
- Department of Emergency, Intensive Care Medicine and Anesthesia, IRCCS A. Gemelli University Polyclinic Foundation, Rome, Italy -
- Institute of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy
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Kuk WJ, Wright NR. Bedside Diagnosis of Pulmonary Embolism Using Electrical Impedance Tomography: A Case Report. A A Pract 2022; 16:e01606. [PMID: 35861569 DOI: 10.1213/xaa.0000000000001606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Electrical impedance tomography (EIT) is an emerging imaging modality that can be used to diagnose ventilatory and intrathoracic perfusion mismatches in unstable patients at the bedside. We present a case of a postoperative hypoxic patient in the intensive care unit (ICU) who was too unstable for transport for computed tomography (CT) imaging but was diagnosed and treated for a pulmonary embolism using EIT at the bedside. After the patient clinically improved, CT imaging confirmed the pulmonary embolism diagnosis. EIT is a promising diagnostic tool that may have great utility in ICUs, where it can be safely applied at the bedside.
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Affiliation(s)
| | - Nathan R Wright
- Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Li Z, Qin S, Chen C, Mei S, Yao Y, Zhao Z, Li W, Deng Y, Gao Y. Emerging Trends and Hot Spots of Electrical Impedance Tomography Applications in Clinical Lung Monitoring. Front Med (Lausanne) 2022; 8:813640. [PMID: 35174185 PMCID: PMC8841839 DOI: 10.3389/fmed.2021.813640] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/28/2021] [Indexed: 12/14/2022] Open
Abstract
Objective This study explores the emerging trends and hot topics concerning applications on electrical impedance tomography (EIT) in clinical lung monitoring. Methods Publications on EIT applications in clinical lung monitoring in 2001–2021 were extracted from the Web of Science Core Collection (WoSCC). The search strategy was “electrical impedance tomography” and “lung.” CiteSpace, a VOS viewer was used to study the citation characteristics, cooperation, and keyword co-occurrence. Moreover, co-cited reference clustering, structural variation analysis (SVA), and future research trends were presented. Results Six hundred and thirty-six publications were included for the final analysis. The global annual publications on clinical lung monitoring gradually increased in the last two decades. Germany contributes 32.2% of total global publications. University Medical Center Schleswig-Holstein (84 publications, cited frequency 2,205), Physiological Measurement (105 publications, cited frequency 2,056), and Inéz Frerichs (116 articles, cited frequency 3,609) were the institution, journal, and author with the largest number of article citations in the research field. “Electrical impedance tomography” (occurrences, 304), “mechanical ventilation” (occurrences, 99), and “acute respiratory distress syndrome” (occurrences, 67) were the top most three frequent keywords, “noninvasive monitoring” (Avg, pub, year: 2008.17), and “extracorporeal membrane oxygenation” (Avg, pub, year: 2019.60) were the earliest and latest keywords. The keywords “electrical impedance tomography” (strength 7.88) and co-cited reference “Frerichs I, 2017, THORAX” (strength 47.45) had the highest burst value. “Driving pressure,” “respiratory failure,” and “titration” are the three keywords still maintaining a high brush value until now. The largest and smallest cluster of the co-cited references are “obstructive lung diseases” (#0, size: 97) and “lung perfusion” (#20, size: 5). Co-cited reference “Frerichs I, 2017, THORAX” (modularity change rate: 98.49) has the highest structural variability. Categories with most and least interdisciplinary crossing are “ENGINEERING” and “CRITICAL CARE MEDICINE.” Conclusions EIT is a valuable technology for clinical lung monitoring, gradually converting from imaging techniques to the clinic. Research hot spots may continue monitoring techniques, the ventilation distribution of acute respiratory distress syndrome (ARDS), and respiratory therapy strategies. More diversified lung function monitoring studies, such as lung perfusion and interdisciplinary crossing, are potentially emerging research trends.
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Affiliation(s)
- Zhe Li
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shaojie Qin
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Chen
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shuya Mei
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yulong Yao
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Wen Li
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Wen Li
| | - Yuxiao Deng
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Yuxiao Deng
| | - Yuan Gao
- Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Yuan Gao
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Bronco A, Grassi A, Meroni V, Giovannoni C, Rabboni F, Rezoagli E, Teggia-Droghi M, Foti G, Bellani G. Clinical value of electrical impedance tomography (EIT) in the management of patients with acute respiratory failure: a single centre experience. Physiol Meas 2021; 42. [PMID: 34167097 DOI: 10.1088/1361-6579/ac0e85] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/24/2021] [Indexed: 12/22/2022]
Abstract
Objective.We will describe our clinical experience using electrical impedance tomography (EIT) in the management of mechanical ventilation in patients with acute respiratory failure and to determine to which extent EIT-guided positive end-expiratory pressure (PEEP) setting differed from clinically set values.Approach.We conducted a retrospective, observational cohort study performed in a hub centre for the treatment of acute respiratory failure and veno-venous extracorporeal membrane oxygenation (ECMO).Main results.Between January 2017 and December 2019, EIT was performed 54 times in 41 patients, not feasible only in one case because of signal instability. More than 50% was on veno-venous ECMO support. In 16 cases (30%), EIT was used for monitoring mechanical ventilation, i.e. to evaluate recruitability or sigh setting. In 37 cases (70%), EIT was used to set PEEP both with incremental (11 cases in nine patients) and decremental (26 cases, 18 patients) PEEP trial. Clinical PEEP before the decremental PEEP trial (PEEPPRE) was 14.1 ± 3.4 cmH2O and clinical PEEP set by clinicians after the PEEP trial (PEEPPOST) was 13.6 ± 3.1 (p = ns). EIT analyses demonstrated that more hypoxic patients were higher derecruited when compared to less hypoxic patients that were, on the contrary, more overdistended (p < 0.05). No acute effects of PEEP adjustment based on EIT on respiratory mechanics or regional EIT parameters modification were observed.Significance.The variability of EIT findings in our population confirmed the need to provide ventilation settings individually tailored and EIT was confirmed to be an optimal useful clinical bedside noninvasive tool to provide real-time monitoring of the PEEP effect and ventilation distribution.
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Affiliation(s)
- Alfio Bronco
- Department of Emergency and Intensive Care, ASST Monza, Monza, Italy
| | - Alice Grassi
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto (ON), Canada
| | - Valeria Meroni
- Department of Emergency and Intensive Care, ASST Monza, Monza, Italy
| | | | - Francesca Rabboni
- Department of Emergency and Intensive Care, ASST Monza, Monza, Italy
| | - Emanuele Rezoagli
- Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | | | - Giuseppe Foti
- Department of Emergency and Intensive Care, ASST Monza, Monza, Italy.,Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Giacomo Bellani
- Department of Emergency and Intensive Care, ASST Monza, Monza, Italy.,Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
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6
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Zhao Z, Sang L, Li Y, Frerichs I, Möller K, Fu F. Identification of lung overdistension caused by tidal volume and positive end-expiratory pressure increases based on electrical impedance tomography. Br J Anaesth 2021; 126:e167-e170. [PMID: 33640117 DOI: 10.1016/j.bja.2021.01.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 01/19/2021] [Accepted: 01/28/2021] [Indexed: 11/28/2022] Open
Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China; Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Ling Sang
- State Key Lab of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Department of Critical Care Medicine, Guangzhou, China.
| | - Yimin Li
- State Key Lab of Respiratory Diseases, Guangzhou Institute of Respiratory Health, Guangzhou Medical University, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Department of Critical Care Medicine, Guangzhou, China
| | - Inéz Frerichs
- Department of Anaesthesiology 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, Xi'an, China
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7
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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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Shono A, Kotani T. Clinical implication of monitoring regional ventilation using electrical impedance tomography. J Intensive Care 2019; 7:4. [PMID: 30680219 PMCID: PMC6339287 DOI: 10.1186/s40560-019-0358-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/09/2019] [Indexed: 11/10/2022] Open
Abstract
Mechanical ventilation can initiate ventilator-associated lung injury (VALI) and contribute to the development of multiple organ dysfunction. Although a lung protective strategy limiting both tidal volume and plateau pressure reduces VALI, uneven intrapulmonary gas distribution is still capable of increasing regional stress and strain, especially in non-homogeneous lungs, such as during acute respiratory distress syndrome. Real-time monitoring of regional ventilation may prevent inhomogeneous ventilation, leading to a reduction in VALI. Electrical impedance tomography (EIT) is a technique performed at the patient's bedside. It is noninvasive and radiation-free and provides dynamic tidal images of gas distribution. Studies have reported that EIT provides useful information both in animal and clinical studies during mechanical ventilation. EIT has been shown to be useful during lung recruitment, titration of positive end-expiratory pressure, lung volume estimation, and evaluation of homogeneity of gas distribution in a single EIT measure or in combination with multiple EIT measures. EIT-guided mechanical ventilation preserved the alveolar architecture and maintained oxygenation and lung mechanics better than low-tidal volume ventilation in animal models. However, careful assessment is required for data analysis owing to the limited understanding of the results of EIT interpretation. Previous studies indicate monitoring regional ventilation by EIT is feasible in the intensive care setting and has potential to lead to lung protective ventilation. Further clinical studies are warranted to evaluate whether monitoring of regional ventilation using EIT can shorten the duration of ventilation or improve mortality in patients with acute respiratory distress syndrome.
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Affiliation(s)
- Atsuko Shono
- 1Department of Anesthesiology, Shimane University, 89-1 Enya-cho, Izumo City, Shimane 693-8501 Japan
| | - Toru Kotani
- 2Department of Intensive Care Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8666 Japan
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Bachmann MC, Morais C, Bugedo G, Bruhn A, Morales A, Borges JB, Costa E, Retamal J. Electrical impedance tomography in acute respiratory distress syndrome. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2018; 22:263. [PMID: 30360753 PMCID: PMC6203288 DOI: 10.1186/s13054-018-2195-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/14/2018] [Indexed: 12/29/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is a clinical entity that acutely affects the lung parenchyma, and is characterized by diffuse alveolar damage and increased pulmonary vascular permeability. Currently, computed tomography (CT) is commonly used for classifying and prognosticating ARDS. However, performing this examination in critically ill patients is complex, due to the need to transfer these patients to the CT room. Fortunately, new technologies have been developed that allow the monitoring of patients at the bedside. Electrical impedance tomography (EIT) is a monitoring tool that allows one to evaluate at the bedside the distribution of pulmonary ventilation continuously, in real time, and which has proven to be useful in optimizing mechanical ventilation parameters in critically ill patients. Several clinical applications of EIT have been developed during the last years and the technique has been generating increasing interest among researchers. However, among clinicians, there is still a lack of knowledge regarding the technical principles of EIT and potential applications in ARDS patients. The aim of this review is to present the characteristics, technical concepts, and clinical applications of EIT, which may allow better monitoring of lung function during ARDS.
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Affiliation(s)
- M Consuelo Bachmann
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Caio Morais
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Guillermo Bugedo
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Alejandro Bruhn
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Arturo Morales
- Departamento Enfermedades Respiratorias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - João B Borges
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anaesthesiology and Critical Care, Uppsala University, Uppsala, Sweden
| | - Eduardo Costa
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Jaime Retamal
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile.
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10
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Lobo B, Hermosa C, Abella A, Gordo F. Electrical impedance tomography. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:26. [PMID: 29430443 PMCID: PMC5799136 DOI: 10.21037/atm.2017.12.06] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 11/30/2017] [Indexed: 11/06/2022]
Abstract
Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way.
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Affiliation(s)
- Beatriz Lobo
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Cecilia Hermosa
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Ana Abella
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
| | - Federico Gordo
- Intensive Care Unit, Henares University Hospital, Coslada-Madrid, Spain
- Grupo de Investigación en Patología Crítica, Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria, Pozuelo de Alarcón, Madrid, Spain
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11
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Bickenbach J, Czaplik M, Polier M, Marx G, Marx N, Dreher M. Electrical impedance tomography for predicting failure of spontaneous breathing trials in patients with prolonged weaning. Crit Care 2017; 21:177. [PMID: 28697778 PMCID: PMC5506613 DOI: 10.1186/s13054-017-1758-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 06/19/2017] [Indexed: 11/23/2022] Open
Abstract
Background Spontaneous breathing trials (SBTs) on a T-piece can be difficult in patients with prolonged weaning because of remaining de-recruitment phenomena and/or insufficient ventilation. There is no clinically established method existent other than experience for estimating whether an SBT is most probably beneficial. Electrical impedance tomography (EIT) is a clinical useful online monitoring technique during mechanical ventilation, particularly because it enables analysis of effects of regional ventilation distribution. The aim of our observational study was to examine if EIT can predict whether patients with prolonged weaning will benefit from a planned SBT. Methods Thirty-one patients were examined. Blood gas analysis, vital parameter measurements, and EIT recordings were performed at three time points: (1) baseline with pressure support ventilation (PSV) (t0), (2) during a T-piece trial (t1), and (3) after resumption of PSV (t2). Calculation of EIT parameters was performed, including the impedance ratio (IR), the tidal variation of impedance (TIV), the changes in end-expiratory lung impedance (ΔEELI), the global inhomogeneity index (GI), and the regional ventilation delay (RVD) index with use of different thresholds of the percentage inspiration time (RVD40, RVD60, RVD80). The predictive power of the baseline GI with regard to clinical impairment of an SBT was analyzed by means of ROC curves. Clinical deterioration was assumed when tidal volume was decreased by at least 20 ml after the T-piece trial, measured at t2. Results Partial pressure of arterial oxygen significantly decreased at t1 (71 ± 15 mmHg) compared with t0 (85 ± 17 mmHg, p < 0.05) and t2 (82 ± 18 mmHg, p < 0.05). The IR trended toward higher values during t1. At t1, TIV and ΔEELI significantly decreased. The GI was significantly increased at t1 (t0 59.3 ± 46.1 vs t1 81.5 ± 62.5, p = 0.001), as were all RVD indexes. Assuming a GI cutoff value of >40, sensitivity of 85% and specificity of 50% were reached for predicting an increased future tidal volume. Conclusions EIT enables monitoring of regional ventilation distribution during SBTs and is suitable to estimate whether an SBT probably will be beneficial for an individual patient. Therefore, the application of EIT can support clinical decisions regarding patients in the phase of prolonged weaning.
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Affiliation(s)
- Johannes Bickenbach
- Department of Intensive Care Medicine, University Hospital of the RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany.
| | - Michael Czaplik
- Department of Anesthesiology, University Hospital RWTH Aachen, Aachen, Germany
| | - Mareike Polier
- Department of Intensive Care Medicine, University Hospital of the RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Gernot Marx
- Department of Intensive Care Medicine, University Hospital of the RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Nikolaus Marx
- Department of Cardiology, Pneumology, Angiology and Intensive Care Medicine, University Hospital RWTH Aachen, Aachen, Germany
| | - Michael Dreher
- Department of Cardiology, Pneumology, Angiology and Intensive Care Medicine, University Hospital RWTH Aachen, Aachen, Germany
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12
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Rosa RG, Rutzen W, Madeira L, Ascoli AM, Dexheimer Neto FL, Maccari JG, Oliveira RPD, Teixeira C. Use of thoracic electrical impedance tomography as an auxiliary tool for alveolar recruitment maneuvers in acute respiratory distress syndrome: case report and brief literature review. Rev Bras Ter Intensiva 2016; 27:406-11. [PMID: 26761481 PMCID: PMC4738829 DOI: 10.5935/0103-507x.20150068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/22/2015] [Indexed: 12/17/2022] Open
Abstract
Thoracic electrical impedance tomography is a real-time, noninvasive monitoring tool
of the regional pulmonary ventilation distribution. Its bedside use in patients with
acute respiratory distress syndrome has the potential to aid in alveolar recruitment
maneuvers, which are often necessary in cases of refractory hypoxemia. In this case
report, we describe the monitoring results and interpretation of thoracic electrical
impedance tomography used during alveolar recruitment maneuvers in a patient with
acute respiratory distress syndrome, with transient application of high alveolar
pressures and optimal positive end-expiratory pressure titration. Furthermore, we
provide a brief literature review regarding the use of alveolar recruitment maneuvers
and monitoring using thoracic electrical impedance tomography in patients with acute
respiratory distress syndrome.
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Affiliation(s)
- Regis Goulart Rosa
- Departamento de Medicina Intensiva, Hospital Moinhos de Vento, Porto Alegre, RS, Brazil
| | - William Rutzen
- Departamento de Medicina Intensiva, Hospital Moinhos de Vento, Porto Alegre, RS, Brazil
| | - Laura Madeira
- Departamento de Medicina Intensiva, Hospital Moinhos de Vento, Porto Alegre, RS, Brazil
| | - Aline Maria Ascoli
- Departamento de Medicina Intensiva, Hospital Moinhos de Vento, Porto Alegre, RS, Brazil
| | | | | | | | - Cassiano Teixeira
- Departamento de Medicina Intensiva, Hospital Moinhos de Vento, Porto Alegre, RS, Brazil
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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.
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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.
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Yun L, He HW, Möller K, Frerichs I, Liu D, Zhao Z. Assessment of Lung Recruitment by Electrical Impedance Tomography and Oxygenation in ARDS Patients. Medicine (Baltimore) 2016; 95:e3820. [PMID: 27258527 PMCID: PMC4900735 DOI: 10.1097/md.0000000000003820] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We hypothesized that not all patients with appreciably recruited lung tissue during a recruitment maneuver (RM) show significant improvement of oxygenation. In the present study, we combined electrical impedance tomography (EIT) with oxygenation measurements to examine the discrepancies of lung ventilation and perfusion versus oxygenation after RM.A 2-minute RM (20 cm H2O positive end-expiratory pressure [PEEP] + 20 cm H2O pressure control) was prospectively conducted in 20 acute respiratory distress syndrome patients from January 2014 to December 2014. A decremental PEEP trial was performed to select the PEEP level after RM. A positive response to RM was identified as PaO2 + PaCO2 ≥400 mm Hg. Relative differences in the distribution of ventilation and perfusion in the most dependent region of interest (ROI4) were monitored with EIT and denoted as the ventilation-perfusion index.Ten patients were found to be responders and 10 patients to be nonresponders. No significant difference in baseline PaO2/FiO2 was observed between nonresponders and responders. A significantly higher PaO2/FiO2 ratio during RM and higher PEEP set after PEEP titration were recorded in responders. In both responders and nonresponders, the proportion of ventilation distributed in ROI4 compared with the global value was lower than the cardiac-related activity before RM, but this situation was reversed after RM (P < 0.01 in each group). Six out of 10 nonresponders exhibited a remarkable increase in ventilation in ROI4. A significant difference in the relative ventilation-perfusion index was found between the patients with remarkable and insufficient lung tissue reopening in the nonresponder group (P < 0.01).A discrepancy between lung tissue reopening and oxygenation improvement after RM was observed. EIT has the potential to evaluate the efficacy of RM by combining oxygenation measurements.
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Affiliation(s)
- Long Yun
- From the Department of Critical Care (YL, H-wH, DL), Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, China; Institute of Technical Medicine (KM, ZZ), Furtwangen University, Villingen-Schwenningen; and Department of Anesthesiology and Intensive Care Medicine (IF), University Medical Center of Schleswig-Holstein Campus, Kiel, Germany
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Wirth S, Baur M, Spaeth J, Guttmann J, Schumann S. Intraoperative positive end-expiratory pressure evaluation using the intratidal compliance-volume profile. Br J Anaesth 2014; 114:483-90. [PMID: 25416274 DOI: 10.1093/bja/aeu385] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Lung-protective mechanical ventilation during general surgery including the application of PEEP can reduce postoperative pulmonary complications. In a prospective clinical observation study, we evaluated volume-dependent respiratory system compliance in adult patients undergoing ear-nose-throat surgery with ventilation settings chosen empirically by the attending anaesthetist. METHODS In 40 patients, we measured the respiratory variables during intraoperative mechanical ventilation. All measurements were subdivided into 5 min intervals. Dynamic compliance (CRS) and the intratidal volume-dependent CRS curve was calculated for each interval and classified into one of the six specific compliance profiles indicating intratidal recruitment/derecruitment, overdistension or all. We retrospectively compared the occurrences of the respective compliance profiles at PEEP levels of 5 cm H2O and at higher levels. RESULTS The attending anaesthetists set the PEEP level initially to 5 cm H2O in 29 patients (83%), to 7 cm H2O in 5 patients (14%), and to 8 cm H2O in 2 patients (6%). Across all measurements the mean CRS was 61 (11) ml cm H2O(-1) (40-86 ml cm H2O(-1)) and decreased continuously during the procedure. At PEEP of 5 cm H2O the compliance profile indicating strong intratidal recruitment/derecruitment occurred more often (18.6%) compared with higher PEEP levels (5.5%, P<0.01). Overdistension was practically never observed. CONCLUSIONS In most patients, a PEEP of 5 cm H2O during intraoperative mechanical ventilation is too low to prevent intratidal recruitment/derecruitment. The analysis of the intratidal compliance profile provides the rationale to individually titrate a PEEP level that stabilizes the alveolar recruitment status of the lung during intraoperative mechanical ventilation. TRIAL REGISTRATION NUMBER DRKS00004286.
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Affiliation(s)
- S Wirth
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany
| | - M Baur
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany
| | - J Spaeth
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany
| | - J Guttmann
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany
| | - S Schumann
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany
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Guo R, Fan E. Beyond low tidal volumes: ventilating the patient with acute respiratory distress syndrome. Clin Chest Med 2014; 35:729-41. [PMID: 25453421 DOI: 10.1016/j.ccm.2014.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cornerstone of lung protective ventilation in patients with acute respiratory distress syndrome (ARDS) is a pressure- and volume-limited strategy. Other interventions have also been investigated. Although no method for positive end-expiratory pressure (PEEP) titration has proven most advantageous, experimental and clinical data support the use of higher PEEP in patients with moderate/severe ARDS. There is no benefit to the early use of high-frequency oscillatory ventilation (HFOV) in patients with moderate/severe ARDS, although it may be considered as rescue therapy. Further investigations of novel methods of bedside monitoring of mechanical ventilation may help identify the optimal ventilatory strategy.
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Affiliation(s)
- Ray Guo
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada.
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Zhao Z, Pulletz S, Frerichs I, Müller-Lisse U, Möller K. The EIT-based global inhomogeneity index is highly correlated with regional lung opening in patients with acute respiratory distress syndrome. BMC Res Notes 2014; 7:82. [PMID: 24502320 PMCID: PMC3922336 DOI: 10.1186/1756-0500-7-82] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 02/04/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The electrical impedance tomography (EIT)-based global inhomogeneity (GI) index was introduced to quantify tidal volume distribution within the lung. Up to now, the GI index was evaluated for plausibility but the analysis of how it is influenced by various physiological factors is still missing. The aim of our study was to evaluate the influence of proportion of open lung regions measured by EIT on the GI index. METHODS A constant low-flow inflation maneuver was performed in 18 acute respiratory distress syndrome (ARDS) patients (58 ± 14 years, mean age ± SD) and 8 lung-healthy patients (41 ± 12 years) under controlled mechanical ventilation. EIT raw data were acquired at 25 scans/s and reconstructed offline. Recruited lung regions were identified as those image pixels of the lung regions within the EIT scans where local impedance amplitudes exceeded 10% of the maximum amplitude during the maneuver. A series of GI indices was calculated during mechanical lung inflation, based on the differential images obtained between different time points. Respiratory system elastance (Ers) values were calculated at 10 lung volume levels during low-flow maneuver. RESULTS The GI index decreased during low-flow inflation, while the percentage of open lung regions increased. The values correlated highly in both ARDS (r2 = 0.88 ± 0.08, p < 0.01) and lung-healthy patients (r2 = 0.92 ± 0.05, p < 0.01). Ers and GI index were also significantly correlated in 16 out of 18 ARDS (r2 = 0.84 ± 0.13, p < 0.01) and in 6 out of 8 lung-healthy patients (r2 = 0.84 ± 0.07, p < 0.01). Significant differences were found in GI values between two groups (0.52 ± 0.21 for ARDS and 0.41 ± 0.04 for lung-healthy patients, p < 0.05) as well in Ers values (0.017 ± 0.008 cmH2O/ml for ARDS and 0.009 ± 0.001 cmH2O/ml for lung-healthy patients, p < 0.01). CONCLUSIONS We conclude that the GI index is a reliable measure of ventilation heterogeneity highly correlated with lung recruitability measured with EIT. The GI index may prove to be a useful EIT-based index to guide ventilation therapy.
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Affiliation(s)
- Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle Straße 17, D-78054 VS-Schwenningen, Germany.
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Chiumello D, Froio S, Bouhemad B, Camporota L, Coppola S. Clinical review: Lung imaging in acute respiratory distress syndrome patients--an update. Crit Care 2013; 17:243. [PMID: 24238477 PMCID: PMC4056355 DOI: 10.1186/cc13114] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Over the past 30 years lung imaging has greatly contributed to the current understanding of the pathophysiology and the management of acute respiratory distress syndrome (ARDS). In the past few years, in addition to chest X-ray and lung computed tomography, newer functional lung imaging techniques, such as lung ultrasound, positron emission tomography, electrical impedance tomography and magnetic resonance, have been gaining a role as diagnostic tools to optimize lung assessment and ventilator management in ARDS patients. Here we provide an updated clinical review of lung imaging in ARDS over the past few years to offer an overview of the literature on the available imaging techniques from a clinical perspective.
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Affiliation(s)
- Davide Chiumello
- Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, Milan, Italy
| | - Sara Froio
- Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, Milan, Italy
| | - Belaïd Bouhemad
- Multidisciplinary Critical Care Unit, La Pitié-Salpêtrière Hospital, University Pierre and Marie Curie Paris, Paris, France
| | - Luigi Camporota
- Guy’s and St Thomas’ NHS Foundation Trust, St Thomas’ Hospital, London, UK
| | - Silvia Coppola
- Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda - Ospedale Maggiore Policlinico, Via F. Sforza 35, Milan, Italy
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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]
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Vogt B, Pulletz S, Elke G, Zhao Z, Zabel P, Weiler N, Frerichs I. Spatial and temporal heterogeneity of regional lung ventilation determined by electrical impedance tomography during pulmonary function testing. J Appl Physiol (1985) 2012; 113:1154-61. [PMID: 22898553 DOI: 10.1152/japplphysiol.01630.2011] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical impedance tomography (EIT) is a functional imaging modality capable of tracing continuously regional pulmonary gas volume changes. The aim of our study was to determine if EIT was able to assess spatial and temporal heterogeneity of ventilation during pulmonary function testing in 14 young (37 ± 10 yr, mean age ± SD) and 12 elderly (71 ± 9 yr) subjects without lung disease and in 33 patients with chronic obstructive pulmonary disease (71 ± 9 yr). EIT and spirometry examinations were performed during tidal breathing and a forced vital capacity (FVC) maneuver preceded by full inspiration to total lung capacity. Regional inspiratory vital capacity (IVC); FVC; forced expiratory volume in 1 s (FEV(1)); FEV(1)/FVC; times required to expire 25%, 50%, 75%, and 90% of FVC (t(25), t(50), t(75), t(90)); and tidal volume (V(T)) were determined in 912 EIT image pixels in the chest cross section. Coefficients of variation (CV) were calculated from all pixel values of IVC, FVC, FEV(1), and V(T) to characterize the ventilation heterogeneity. The highest values were found in patients, and no differences existed between the healthy young and elderly subjects. Receiver-operating characteristics curves showed that CV of regional IVC, FVC, FEV(1), and V(T) discriminated the young and elderly subjects from the patients. Frequency distributions of pixel FEV(1)/FVC, t(25), t(50), t(75), and t(90) identified the highest ventilation heterogeneity in patients but distinguished also the healthy young from the elderly subjects. These results indicate that EIT may provide additional information during pulmonary function testing and identify pathologic and age-related spatial and temporal heterogeneity of regional lung function.
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Affiliation(s)
- Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, Kiel, Germany
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Abstract
PURPOSE OF REVIEW Computed tomography (CT) has fostered pivotal advancements in the understanding of acute lung injury/acute respiratory distress syndrome and ventilator-induced lung injury. Apart from CT-based studies, the past years have seen fascinating work using positron emission tomography, electrical impedance tomography and lung ultrasound as diagnostic tools to optimize mechanical ventilation. This review aims to present the major findings of recent studies on lung imaging. RECENT FINDINGS Patients presenting with a focal loss of aeration on CT may not be suitable candidates for recruitment maneuvers and high levels of positive end-expiratory pressure (PEEP) in supine position. PET/CT has provided valuable insights into the inflammatory response of the lung. Electrical impedance tomography has been used to assess lung recruitability and to titrate PEEP. Finally, lung ultrasound has proven to be reliable diagnostic tool for assessing PEEP-induced recruitment. SUMMARY Whereas quantitative CT remains the gold standard to assess lung morphology, recruitment and hyperinflation of lung tissue at different inflation pressures, EIT and LUS have emerged as valuable, radiation-free, noninvasive bedside lung imaging tools that should be used together with global parameters like lung mechanics and gas exchange to acquire additional information on recruitability and ventilation distribution.
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Adler A, Amato MB, Arnold JH, Bayford R, Bodenstein M, Böhm SH, Brown BH, Frerichs I, Stenqvist O, Weiler N, Wolf GK. Whither lung EIT: Where are we, where do we want to go and what do we need to get there? Physiol Meas 2012; 33:679-94. [DOI: 10.1088/0967-3334/33/5/679] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gómez-Laberge C, Arnold JH, Wolf GK. A unified approach for EIT imaging of regional overdistension and atelectasis in acute lung injury. IEEE TRANSACTIONS ON MEDICAL IMAGING 2012; 31:834-842. [PMID: 22249646 PMCID: PMC7176466 DOI: 10.1109/tmi.2012.2183641] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 12/27/2011] [Indexed: 05/31/2023]
Abstract
Patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) are vulnerable to ventilator-induced lung injury. Although this syndrome affects the lung heterogeneously, mechanical ventilation is not guided by regional indicators of potential lung injury. We used electrical impedance tomography (EIT) to estimate the extent of regional lung overdistension and atelectasis during mechanical ventilation. Techniques for tidal breath detection, lung identification, and regional compliance estimation were combined with the Graz consensus on EIT lung imaging (GREIT) algorithm. Nine ALI/ARDS patients were monitored during stepwise increases and decreases in airway pressure. Our method detected individual breaths with 96.0% sensitivity and 97.6% specificity. The duration and volume of tidal breaths erred on average by 0.2 s and 5%, respectively. Respiratory system compliance from EIT and ventilator measurements had a correlation coefficient of 0.80. Stepwise increases in pressure could reverse atelectasis in 17% of the lung. At the highest pressures, 73% of the lung became overdistended. During stepwise decreases in pressure, previously-atelectatic regions remained open at sub-baseline pressures. We recommend that the proposed approach be used in collaborative research of EIT-guided ventilation strategies for ALI/ARDS.
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Affiliation(s)
- Camille Gómez-Laberge
- Harvard Medical SchoolDepartment of AnesthesiologyPerioperative and Pain MedicineChildren’s Hospital BostonBostonMAUSA02115
| | - John H. Arnold
- Harvard Medical SchoolDepartment of AnesthesiologyPerioperative and Pain MedicineChildren’s Hospital BostonBostonMAUSA02115
| | - Gerhard K. Wolf
- Harvard Medical SchoolDepartment of AnesthesiologyPerioperative and Pain MedicineChildren’s Hospital BostonBostonMAUSA02115
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Bayford R, Tizzard A. Bioimpedance imaging: an overview of potential clinical applications. Analyst 2012; 137:4635-43. [DOI: 10.1039/c2an35874c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nouvelles perspectives dans le monitoring respiratoire. MEDECINE INTENSIVE REANIMATION 2012. [DOI: 10.1007/s13546-011-0323-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
PURPOSE OF REVIEW Electrical impedance tomography (EIT) is an attractive method of monitoring patients during mechanical ventilation because it can provide a noninvasive continuous image of pulmonary impedance, which indicates the distribution of ventilation. This article will discuss ongoing research on EIT, with a focus on methodological aspects and limitations and novel approaches in terms of pathophysiology, diagnosis and therapeutic advancements. RECENT FINDINGS EIT enables the detection of regional distribution of alveolar ventilation and, thus, the quantification of local inhomogeneities in lung mechanics. By detecting recruitment and derecruitment, a positive end-expiratory pressure level at which tidal ventilation is relatively homogeneous in all lung regions can be defined. Additionally, different approaches to characterize the temporal local behaviour of lung tissue during ventilation have been proposed, which adds important information. SUMMARY There is growing evidence that supports EIT usage as a bedside measure to individually optimize ventilator settings in critically ill patients in order to prevent ventilator-induced lung injury. A standardization of current approaches to analyse and interpret EIT data is required in order to facilitate the clinical implementation.
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Riera J, Riu PJ, Casan P, Masclans JR. [Electrical impedance tomography in acute lung injury]. Med Intensiva 2011; 35:509-17. [PMID: 21680060 DOI: 10.1016/j.medin.2011.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 05/01/2011] [Accepted: 05/03/2011] [Indexed: 01/18/2023]
Abstract
Electrical impedance tomography has been described as a new method of monitoring critically ill patients on mechanical ventilation. It has recently gained special interest because of its applicability for monitoring ventilation and pulmonary perfusion. Its bedside and continuous implementation, and the fact that it is a non-ionizing and non-invasive technique, makes it an extremely attractive measurement tool. Likewise, given its ability to assess the regional characteristics of lung structure, it could be considered an ideal monitoring tool in the heterogeneous lung with acute lung injury. This review explains the physical concept of bioimpedance and its clinical application, and summarizes the scientific evidence published to date with regard to the implementation of electrical impedance tomography as a method for monitoring ventilation and perfusion, mainly in the patient with acute lung injury, and other possible applications of the technique in the critically ill patient. The review also summarizes the limitations of the technique and its potential areas of future development.
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Affiliation(s)
- J Riera
- Servicio de Medicina Intensiva, Hospital Universitario Vall d'Hebron, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, España.
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