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Gaulton TG, Xin Y, Victor M, Nova A, Cereda M. Imaging the pulmonary vasculature in acute respiratory distress syndrome. Nitric Oxide 2024; 147:6-12. [PMID: 38588918 DOI: 10.1016/j.niox.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/21/2024] [Accepted: 04/03/2024] [Indexed: 04/10/2024]
Abstract
Acute respiratory distress syndrome (ARDS) is characterized by a redistribution of regional lung perfusion that impairs gas exchange. While speculative, experimental evidence suggests that perfusion redistribution may contribute to regional inflammation and modify disease progression. Unfortunately, tools to visualize and quantify lung perfusion in patients with ARDS are lacking. This review explores recent advances in perfusion imaging techniques that aim to understand the pulmonary circulation in ARDS. Dynamic contrast-enhanced computed tomography captures first-pass kinetics of intravenously injected dye during continuous scan acquisitions. Different contrast characteristics and kinetic modeling have improved its topographic measurement of pulmonary perfusion with high spatial and temporal resolution. Dual-energy computed tomography can map the pulmonary blood volume of the whole lung with limited radiation exposure, enabling its application in clinical research. Electrical impedance tomography can obtain serial topographic assessments of perfusion at the bedside in response to treatments such as inhaled nitric oxide and prone position. Ongoing technological improvements and emerging techniques will enhance lung perfusion imaging and aid its incorporation into the care of patients with ARDS.
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Affiliation(s)
- Timothy G Gaulton
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA.
| | - Yi Xin
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA
| | - Marcus Victor
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA; Electronics Engineering Division, Aeronautics Institute of Technology, Sao Paulo, Brazil
| | - Alice Nova
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA
| | - Maurizio Cereda
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Boston, MA, USA
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2
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Victor M, Xin Y, Alcala G, Gaulton T, Costa E, Winkler T, Berra L, Amato M, Cereda M. First-Pass Kinetics Model to Estimate Pulmonary Perfusion by Electrical Impedance Tomography During Uninterrupted Breathing. Am J Respir Crit Care Med 2024; 209:1263-1265. [PMID: 38412326 PMCID: PMC11146534 DOI: 10.1164/rccm.202310-1919le] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/27/2024] [Indexed: 02/29/2024] Open
Affiliation(s)
- Marcus Victor
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
- Electronics Engineering Division, Aeronautics Institute of Technology, Sao Paulo, Brazil; and
| | - Yi Xin
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
| | - Glasiele Alcala
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
| | - Timothy Gaulton
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
| | - Eduardo Costa
- Disciplina de Pneumologia, Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Sao Paulo, Brazil
| | - Tilo Winkler
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
| | - Marcelo Amato
- Disciplina de Pneumologia, Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Sao Paulo, Brazil
| | - Maurizio Cereda
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Boston, Massachusetts
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Ekkapat G, Ribeiro De Santis Santiago R, Victor M, Berra L. Electrical Impedance Tomography for Assessing the Impact of Inhaled Nitric Oxide on Pulmonary Artery Pressure. Anesthesiology 2024:141422. [PMID: 38743612 DOI: 10.1097/aln.0000000000004972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Affiliation(s)
- Gamonmas Ekkapat
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Department of Anesthesiology, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Roberta Ribeiro De Santis Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Marcus Victor
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Electronics Engineering, Aeronautics Institute of Technology, São José dos Campos, Brazil
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Hyun CM, Kim TG, Lee K. Unsupervised sequence-to-sequence learning for automatic signal quality assessment in multi-channel electrical impedance-based hemodynamic monitoring. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 247:108079. [PMID: 38394789 DOI: 10.1016/j.cmpb.2024.108079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 11/08/2023] [Accepted: 02/11/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND AND OBJECTIVE This study proposes an unsupervised sequence-to-sequence learning approach that automatically assesses the motion-induced reliability degradation of the cardiac volume signal (CVS) in multi-channel electrical impedance-based hemodynamic monitoring. The proposed method attempts to tackle shortcomings in existing learning-based assessment approaches, such as the requirement of manual annotation for motion influence and the lack of explicit mechanisms for realizing motion-induced abnormalities under contextual variations in CVS over time. METHOD By utilizing long-short term memory and variational auto-encoder structures, an encoder-decoder model is trained not only to self-reproduce an input sequence of the CVS but also to extrapolate the future in a parallel fashion. By doing so, the model can capture contextual knowledge lying in a temporal CVS sequence while being regularized to explore a general relationship over the entire time-series. A motion-influenced CVS of low-quality is detected, based on the residual between the input sequence and its neural representation with a cut-off value determined from the two-sigma rule of thumb over the training set. RESULT Our experimental observations validated two claims: (i) in the learning environment of label-absence, assessment performance is achievable at a competitive level to the supervised setting, and (ii) the contextual information across a time series of CVS is advantageous for effectively realizing motion-induced unrealistic distortions in signal amplitude and morphology. We also investigated the capability as a pseudo-labeling tool to minimize human-craft annotation by preemptively providing strong candidates for motion-induced anomalies. Empirical evidence has shown that machine-guided annotation can reduce inevitable human-errors during manual assessment while minimizing cumbersome and time-consuming processes. CONCLUSION The proposed method has a particular significance in the industrial field, where it is unavoidable to gather and utilize a large amount of CVS data to achieve high accuracy and robustness in real-world applications.
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Affiliation(s)
- Chang Min Hyun
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; School of Mathematics and Computing (Computational Science and Engineering), Yonsei University, Seoul, Republic of Korea.
| | - Tae-Geun Kim
- Department of Physics, Yonsei University, Seoul, Republic of Korea
| | - Kyounghun Lee
- Medical Science Research Institute, Kyung Hee University Medical Center, Seoul 02447, Republic of Korea.
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Gao Y, Zhang K, Li M, Yuan S, Wang Q, Chi Y, Long Y, Zhao Z, He H. Feasibility of 3D-EIT in identifying lung perfusion defect and V/Q mismatch in a patient with VA-ECMO. Crit Care 2024; 28:90. [PMID: 38509551 PMCID: PMC10956177 DOI: 10.1186/s13054-024-04865-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 03/08/2024] [Indexed: 03/22/2024] Open
Affiliation(s)
- Yelin Gao
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Ke Zhang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute of Precision Medicine, Tsinghua University, Beijing, 100084, China
| | - Maokun Li
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute of Precision Medicine, Tsinghua University, Beijing, 100084, China
| | - Siyi Yuan
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Qianlin Wang
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Chi
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yun Long
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Zhanqi Zhao
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- School of Biomedical Engineering, Guangzhou Medical University, Guangzhou, China
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Huaiwu He
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
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Santos A, Motta-Ribeiro GC, de Prost N, Tucci MR, Wellman TJ, Vidal Melo MF, Winkler T. Regional pulmonary perfusion, blood volume, and their relationship change in experimental early ARDS. Sci Rep 2024; 14:5832. [PMID: 38461172 PMCID: PMC10925058 DOI: 10.1038/s41598-024-56565-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 03/08/2024] [Indexed: 03/11/2024] Open
Abstract
Regional pulmonary perfusion (Q) has been investigated using blood volume (Fb) imaging as an easier-to-measure surrogate. However, it is unclear if changing pulmonary conditions could affect their relationship. We hypothesized that vascular changes in early acute respiratory distress syndrome (ARDS) affect Q and Fb differently. Five sheep were anesthetized and received lung protective mechanical ventilation for 20 h while endotoxin was continuously infused. Using dynamic 18F-FDG and 13NN Positron Emission Tomography (PET), regional Fb and Q were analysed in 30 regions of interest (ROIs) and normalized by tissue content (Fbn and Qn, respectively). After 20 h, the lung injury showed characteristics of early ARDS, including gas exchange and lung mechanics. PET images of Fbn and Qn showed substantial differences between baseline and lung injury. Lung injury caused a significant change in the Fbn-Qn relationship compared to baseline (p < 0.001). The best models at baseline and lung injury were Fbn = 0.32 + 0.690Qn and Fbn = 1.684Qn-0.538Qn2, respectively. Endotoxine-associated early ARDS changed the relationship between Fb and Q, shifting from linear to curvilinear. Effects of endotoxin exposure on the vasoactive blood flow regulation were most likely the key factor for this change limiting the quantitative accuracy of Fb imaging as a surrogate for regional Q.
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Affiliation(s)
- Arnoldo Santos
- Intensive Care Medicine Department, Hospital Universitario Fundación Jiménez Díaz, IIS-FJD, Madrid, Spain
- CIBER de enfermedades respiratorias CIBERES ISCIII, Madrid, Spain
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Gabriel C Motta-Ribeiro
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Biomedical Engineering Program, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nicolas de Prost
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Medical Intensive Care Unit, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France
| | - Mauro R Tucci
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Divisao de Pneumologia, Faculdade de Medicina, Instituto do Coracao, Hospital Das Clinicas HCFMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Tyler J Wellman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- GE Healthcare, Ultrasound Digital Solutions, San Mateo, CA, USA
| | - Marcos F Vidal Melo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Anesthesiology, Columbia University Irving Medical Center, 622 West 168th St., PH 5-505, New York, NY, 10032, USA
| | - Tilo Winkler
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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Frerichs I, Schädler D, Becher T. Setting positive end-expiratory pressure by using electrical impedance tomography. Curr Opin Crit Care 2024; 30:43-52. [PMID: 38085866 DOI: 10.1097/mcc.0000000000001117] [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: 01/03/2024]
Abstract
PURPOSE OF REVIEW This review presents the principles and possibilities of setting positive end-expiratory pressure (PEEP) using electrical impedance tomography (EIT). It summarizes the major findings of recent studies where EIT was applied to monitor the effects of PEEP on regional lung function and to guide the selection of individualized PEEP setting. RECENT FINDINGS The most frequent approach of utilizing EIT for the assessment of PEEP effects and the PEEP setting during the time period from January 2022 till June 2023 was based on the analysis of pixel tidal impedance variation, typically acquired during stepwise incremental and/or decremental PEEP variation. The most common EIT parameters were the fraction of ventilation in various regions of interest, global inhomogeneity index, center of ventilation, silent spaces, and regional compliance of the respiratory system. The studies focused mainly on the spatial and less on the temporal distribution of ventilation. Contrast-enhanced EIT was applied in a few studies for the estimation of ventilation/perfusion matching. SUMMARY The availability of commercial EIT devices resulted in an increase in clinical studies using this bedside imaging technology in neonatal, pediatric and adult critically ill patients. The clinical interest in EIT became evident but the potential of this method in clinical decision-making still needs to be fully exploited.
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Affiliation(s)
- Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
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Martin KT, Xin Y, Gaulton TG, Victor M, Santiago RR, Kim T, Morais CCA, Kazimi AA, Connell M, Gerard SE, Herrmann J, Mueller AL, Lenart A, Shen J, Khan SS, Petrov M, Reutlinger K, Rozenberg K, Amato M, Berra L, Cereda M. Electrical Impedance Tomography Identifies Evolution of Regional Perfusion in a Porcine Model of Acute Respiratory Distress Syndrome. Anesthesiology 2023; 139:815-826. [PMID: 37566686 PMCID: PMC10840641 DOI: 10.1097/aln.0000000000004731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
BACKGROUND Bedside electrical impedance tomography could be useful to visualize evolving pulmonary perfusion distributions when acute respiratory distress syndrome worsens or in response to ventilatory and positional therapies. In experimental acute respiratory distress syndrome, this study evaluated the agreement of electrical impedance tomography and dynamic contrast-enhanced computed tomography perfusion distributions at two injury time points and in response to increased positive end-expiratory pressure (PEEP) and prone position. METHODS Eleven mechanically ventilated (VT 8 ml · kg-1) Yorkshire pigs (five male, six female) received bronchial hydrochloric acid (3.5 ml · kg-1) to invoke lung injury. Electrical impedance tomography and computed tomography perfusion images were obtained at 2 h (early injury) and 24 h (late injury) after injury in supine position with PEEP 5 and 10 cm H2O. In eight animals, electrical impedance tomography and computed tomography perfusion imaging were also conducted in the prone position. Electrical impedance tomography perfusion (QEIT) and computed tomography perfusion (QCT) values (as percentages of image total) were compared in eight vertical regions across injury stages, levels of PEEP, and body positions using mixed-effects linear regression. The primary outcome was agreement between QEIT and QCT, defined using limits of agreement and Pearson correlation coefficient. RESULTS Pao2/Fio2 decreased over the course of the experiment (healthy to early injury, -253 [95% CI, -317 to -189]; early to late injury, -88 [95% CI, -151 to -24]). The limits of agreement between QEIT and QCT were -4.66% and 4.73% for the middle 50% quantile of average regional perfusion, and the correlation coefficient was 0.88 (95% CI, 0.86 to 0.90]; P < 0.001). Electrical impedance tomography and computed tomography showed similar perfusion redistributions over injury stages and in response to increased PEEP. QEIT redistributions after positional therapy underestimated QCT in ventral regions and overestimated QCT in dorsal regions. CONCLUSIONS Electrical impedance tomography closely approximated computed tomography perfusion measures in experimental acute respiratory distress syndrome, in the supine position, over injury progression and with increased PEEP. Further validation is needed to determine the accuracy of electrical impedance tomography in measuring perfusion redistributions after positional changes. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Kevin T Martin
- Department of Anesthesia and Perioperative Care, University of California San Francisco, CA, USA
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi Xin
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Timothy G Gaulton
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Marcus Victor
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Electronics Engineering Division, Aeronautics Institute of Technology, São Paulo, Brazil
| | - Roberta R Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Taehwan Kim
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Caio C A Morais
- Department of Physical Therapy, Federal University of Pernambuco, Recife, Brazil
| | - Aubrey A Kazimi
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc Connell
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
| | - Sarah E Gerard
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Jacob Herrmann
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Ariel L Mueller
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Austin Lenart
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Jiacheng Shen
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Sherbano S Khan
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Mihail Petrov
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristan Reutlinger
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Karina Rozenberg
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Marcelo Amato
- Department of Cardio-Pulmonary, University of São Paulo, São Paulo, Brazil
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
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Cenci S, Santiago RDS, Bittner EA, Berra L. Assessing Regional Lung Perfusion Changes to Inhaled Pulmonary Vasodilators by Electrical Impedance Tomography. Am J Respir Crit Care Med 2023; 208:e39-e40. [PMID: 37450762 DOI: 10.1164/rccm.202302-0247im] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 07/14/2023] [Indexed: 07/18/2023] Open
Affiliation(s)
- Stefano Cenci
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Harvard University, Boston, Massachusetts; and
| | - Roberta De Santis Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Harvard University, Boston, Massachusetts; and
| | - Edward A Bittner
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Harvard University, Boston, Massachusetts; and
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Harvard University, Boston, Massachusetts; and
- Respiratory Care Services, Massachusetts General Hospital, Boston, Massachusetts
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Larrabee S, Nugen S, Bruhn A, Porter I, Stowe S, Adler A, Martin-Flores M, Araos J. Three-dimensional electrical impedance tomography to study regional ventilation/perfusion ratios in anesthetized pigs. Am J Physiol Lung Cell Mol Physiol 2023; 325:L638-L646. [PMID: 37724348 DOI: 10.1152/ajplung.00180.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/08/2023] [Accepted: 09/13/2023] [Indexed: 09/20/2023] Open
Abstract
This study aimed to develop a three-dimensional (3-D) method for assessing ventilation/perfusion (V/Q̇) ratios in a pig model of hemodynamic perturbations using electrical impedance tomography (EIT). To evaluate the physiological coherence of changes in EIT-derived V/Q̇ ratios, global EIT-derived V/Q̇ mismatches were compared with global gold standards. The study found regional heterogeneity in the distribution of V/Q̇ ratios in both the ventrodorsal and craniocaudal directions. Although global EIT-derived indices of V/Q̇ mismatch consistently underestimated both low and high V/Q̇ mismatch compared with global gold standards, the direction of the change was similar. We made the software available at no cost for other researchers to use. Future studies should compare regional V/Q̇ ratios determined by our method against other regional, high-resolution methods.NEW & NOTEWORTHY In this study, we introduce a novel 3-D method for assessing ventilation-perfusion (V/Q̇) ratios using electrical impedance tomography (EIT). Heterogeneity in V/Q̇ distribution showcases the significant potential for enhanced understanding of pulmonary conditions. This work signifies a substantial step forward in the application of EIT for monitoring and managing lung diseases.
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Affiliation(s)
- Shannon Larrabee
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States
| | - Sarah Nugen
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States
| | - Alejandro Bruhn
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ian Porter
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States
| | - Symon Stowe
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | - Andy Adler
- Department of Systems and Computer Engineering, Carleton University, Ottawa, Ontario, Canada
| | - Manuel Martin-Flores
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States
| | - Joaquin Araos
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States
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11
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Gaulton TG, Martin K, Xin Y, Victor M, Ribeiro De Santis Santiago R, Britto Passos Amato M, Berra L, Cereda M. Regional lung perfusion using different indicators in electrical impedance tomography. J Appl Physiol (1985) 2023; 135:500-507. [PMID: 37439236 PMCID: PMC10538981 DOI: 10.1152/japplphysiol.00130.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/19/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023] Open
Abstract
Management of acute respiratory distress syndrome (ARDS) is classically guided by protecting the injured lung and mitigating damage from mechanical ventilation. Yet the natural history of ARDS is also dictated by disruption in lung perfusion. Unfortunately, diagnosis and treatment are hampered by the lack of bedside perfusion monitoring. Electrical impedance tomography is a portable imaging technique that can estimate regional lung perfusion in experimental settings from the kinetic analysis of a bolus of an indicator with high conductivity. Hypertonic sodium chloride has been the standard indicator. However, hypertonic sodium chloride is often inaccessible in the hospital, limiting practical adoption. We investigated whether regional lung perfusion measured using electrical impedance tomography is comparable between indicators. Using a swine lung injury model, we determined regional lung perfusion (% of total perfusion) in five pigs, comparing 12% sodium chloride to 8.4% sodium bicarbonate across stages of lung injury and experimental conditions (body position, positive end-expiratory pressure). Regional lung perfusion for four lung regions was determined from maximum slope analysis of the indicator-based impedance signal. Estimates of regional lung perfusion between indicators were compared in the lung overall and within four lung regions. Regional lung perfusion estimated with a sodium bicarbonate indicator agreed with a hypertonic sodium chloride indicator overall (mean bias 0%, limits of agreement -8.43%, 8.43%) and within lung quadrants. The difference in regional lung perfusion between indicators did not change across experimental conditions. Sodium bicarbonate may be a comparable indicator to estimate regional lung perfusion using electrical impedance tomography.NEW & NOTEWORTHY Electrical impedance tomography is an emerging tool to measure regional lung perfusion using kinetic analysis of a conductive indicator. Hypertonic sodium chloride is the standard agent used. We measured regional lung perfusion using another indicator, comparing hypertonic sodium chloride to sodium bicarbonate in an experimental swine lung injury model. We found strong agreement between the two indicators. Sodium bicarbonate may be a comparable indicator to measure regional lung perfusion with electrical impedance tomography.
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Affiliation(s)
- Timothy G Gaulton
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Kevin Martin
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Yi Xin
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Marcus Victor
- Pulmonary Division, Heart Institute (InCor), University of São Paulo, São Paulo, Brazil
- Medical Electrical Devices Laboratory (LabMed), Electronics Engineering, Aeronautics Institute of Technology, Sao Jose dos Campos, Brazil
| | - Roberta Ribeiro De Santis Santiago
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | | | - Lorenzo Berra
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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12
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Ribeiro De Santis Santiago R, Xin Y, Gaulton TG, Alcala G, León Bueno de Camargo ED, Cereda M, Britto Passos Amato M, Berra L. Lung Imaging Acquisition with Electrical Impedance Tomography: Tackling Common Pitfalls. Anesthesiology 2023; 139:329-341. [PMID: 37402247 DOI: 10.1097/aln.0000000000004613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2023]
Abstract
Electrical impedance tomography is a powerful tool for lung imaging that can be employed at the bedside in multiple clinical scenarios. Diagnosing and preventing interpretation pitfalls will ensure reliable data and allow for appropriate clinical decision-making.
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Affiliation(s)
- Roberta Ribeiro De Santis Santiago
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yi Xin
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Timothy G Gaulton
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Glasiele Alcala
- Pulmonary Division, Heart Institute (InCor), University of São Paulo, São Paulo, Brazil
| | - Erick Dario León Bueno de Camargo
- Federal University of ABC/Engineering, Modeling and Applied Social Sciences Centre, Biomedical Engineering, São Bernardo do Campo, Brazil
| | - Maurizio Cereda
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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13
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Spina S, Marrazzo F, Morais CA, Victor M, Forlini C, Guarnieri M, Bastia L, Giudici R, Bassi G, Xin Y, Cereda M, Amato M, Langer T, Berra L, Fumagalli R. Modulation of pulmonary blood flow in patients with acute respiratory failure. Nitric Oxide 2023; 136-137:1-7. [PMID: 37172929 DOI: 10.1016/j.niox.2023.05.001] [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: 03/07/2023] [Revised: 04/19/2023] [Accepted: 05/08/2023] [Indexed: 05/15/2023]
Abstract
BACKGROUND Impairment of ventilation and perfusion (V/Q) matching is a common mechanism leading to hypoxemia in patients with acute respiratory failure requiring intensive care unit (ICU) admission. While ventilation has been thoroughly investigated, little progress has been made to monitor pulmonary perfusion at the bedside and treat impaired blood distribution. The study aimed to assess real-time changes in regional pulmonary perfusion in response to a therapeutic intervention. METHODS Single-center prospective study that enrolled adult patients with ARDS caused by SARS-Cov-2 who were sedated, paralyzed, and mechanically ventilated. The distribution of pulmonary perfusion was assessed through electrical impedance tomography (EIT) after the injection of a 10-ml bolus of hypertonic saline. The therapeutic intervention consisted in the administration of inhaled nitric oxide (iNO), as rescue therapy for refractory hypoxemia. Each patient underwent two 15-minute steps at 0 and 20 ppm iNO, respectively. At each step, respiratory, gas exchange, and hemodynamic parameters were recorded, and V/Q distribution was measured, with unchanged ventilatory settings. RESULTS Ten 65 [56-75] years old patients with moderate (40%) and severe (60%) ARDS were studied 10 [4-20] days after intubation. Gas exchange improved at 20 ppm iNO (PaO2/FiO2 from 86 ± 16 to 110 ± 30 mmHg, p = 0.001; venous admixture from 51 ± 8 to 45 ± 7%, p = 0.0045; dead space from 29 ± 8 to 25 ± 6%, p = 0.008). The respiratory system's elastic properties and ventilation distribution were unaltered by iNO. Hemodynamics did not change after gas initiation (cardiac output 7.6 ± 1.9 vs. 7.7 ± 1.9 L/min, p = 0.66). The EIT pixel perfusion maps showed a variety of patterns of changes in pulmonary blood flow, whose increase positively correlated with PaO2/FiO2 increase (R2 = 0.50, p = 0.049). CONCLUSIONS The assessment of lung perfusion is feasible at the bedside and blood distribution can be modulated with effects that are visualized in vivo. These findings might lay the foundations for testing new therapies aimed at optimizing the regional perfusion in the lungs.
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Affiliation(s)
- Stefano Spina
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Francesco Marrazzo
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - CaioC A Morais
- Division of Pneumology (Laboratory of Medical Investigation 09), Faculty of Medicine, University of São Paulo, São Paulo, Brazil
| | - Marcus Victor
- Division of Pneumology (Laboratory of Medical Investigation 09), Faculty of Medicine, University of São Paulo, São Paulo, Brazil
| | - Clarissa Forlini
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Marcello Guarnieri
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Luca Bastia
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Riccardo Giudici
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Gabriele Bassi
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Yi Xin
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Maurizio Cereda
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Marcelo Amato
- Division of Pneumology (Laboratory of Medical Investigation 09), Faculty of Medicine, University of São Paulo, São Paulo, Brazil
| | - Thomas Langer
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy; School of Medicine and Surgery, University of Milano-Bicocca, Milano, Italy
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Roberto Fumagalli
- Department of Anaesthesia and Critical Care, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy; School of Medicine and Surgery, University of Milano-Bicocca, Milano, Italy
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Muders T, Hentze B, Leonhardt S, Putensen C. Evaluation of Different Contrast Agents for Regional Lung Perfusion Measurement Using Electrical Impedance Tomography: An Experimental Pilot Study. J Clin Med 2023; 12:jcm12082751. [PMID: 37109088 PMCID: PMC10143707 DOI: 10.3390/jcm12082751] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 03/22/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
Monitoring regional blood flow distribution in the lungs appears to be useful for individually optimizing ventilation therapy. Electrical impedance tomography (EIT) can be used at the bedside for indicator-based regional lung perfusion measurement. Hypertonic saline is widely used as a contrast agent but could be problematic for clinical use due to potential side effects. In five ventilated healthy pigs, we investigated the suitability of five different injectable and clinically approved solutions as contrast agents for EIT-based lung perfusion measurement. Signal extraction success rate, signal strength, and image quality were analyzed after repeated 10 mL bolus injections during temporary apnea. The best results were obtained using NaCl 5.85% and sodium-bicarbonate 8.4% with optimal success rates (100%, each), the highest signal strengths (100 ± 25% and 64 ± 17%), and image qualities (r = 0.98 ± 0.02 and 0.95 ± 0.07). Iomeprol 400 mg/mL (non-ionic iodinated X-ray contrast medium) and Glucose 5% (non-ionic glucose solution) resulted in mostly well usable signals with above average success rates (87% and 89%), acceptable signal strength (32 ± 8% and 16 + 3%), and sufficient image qualities (r = 0.80 ± 0.19 and 0.72 ± 0.21). Isotonic balanced crystalloid solution failed due to a poor success rate (42%), low signal strength (10 ± 4%), and image quality (r = 0.43 ± 0.28). While Iomeprol might enable simultaneous EIT and X-ray measurements, glucose might help to avoid sodium and chloride overload. Further research should address optimal doses to balance reliability and potential side effects.
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Affiliation(s)
- Thomas Muders
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, 53127 Bonn, Germany
| | - Benjamin Hentze
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, 53127 Bonn, Germany
- Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany
| | - Steffen Leonhardt
- Chair for Medical Information Technology, RWTH Aachen University, 52074 Aachen, Germany
| | - Christian Putensen
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, 53127 Bonn, Germany
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Mlček M, Borges JB, Otáhal M, Alcala GC, Hladík D, Kuriščák E, Tejkl L, Amato M, Kittnar O. Real-time effects of lateral positioning on regional ventilation and perfusion in an experimental model of acute respiratory distress syndrome. Front Physiol 2023; 14:1113568. [PMID: 37020459 PMCID: PMC10067565 DOI: 10.3389/fphys.2023.1113568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/01/2023] [Indexed: 03/22/2023] Open
Abstract
Low-volume lung injury encompasses local concentration of stresses in the vicinity of collapsed regions in heterogeneously ventilated lungs. We aimed to study the effects on ventilation and perfusion distributions of a sequential lateral positioning (30°) strategy using electrical impedance tomography imaging in a porcine experimental model of early acute respiratory distress syndrome (ARDS). We hypothesized that such strategy, including a real-time individualization of positive end-expiratory pressure (PEEP) whenever in lateral positioning, would provide attenuation of collapse in the dependent lung regions. A two-hit injury acute respiratory distress syndrome experimental model was established by lung lavages followed by injurious mechanical ventilation. Then, all animals were studied in five body positions in a sequential order, 15 min each: Supine 1; Lateral Left; Supine 2; Lateral Right; Supine 3. The following functional images were analyzed by electrical impedance tomography: ventilation distributions and regional lung volumes, and perfusion distributions. The induction of the acute respiratory distress syndrome model resulted in a marked fall in oxygenation along with low regional ventilation and compliance of the dorsal half of the lung (gravitational-dependent in supine position). Both the regional ventilation and compliance of the dorsal half of the lung greatly increased along of the sequential lateral positioning strategy, and maximally at its end. In addition, a corresponding improvement of oxygenation occurred. In conclusion, our sequential lateral positioning strategy, with sufficient positive end-expiratory pressure to prevent collapse of the dependent lung units during lateral positioning, provided a relevant diminution of collapse in the dorsal lung in a porcine experimental model of early acute respiratory distress syndrome.
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Affiliation(s)
- Mikuláš Mlček
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
| | - João Batista Borges
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
- *Correspondence: João Batista Borges,
| | - Michal Otáhal
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
- Department of Anaesthesiology, Resuscitation and Intensive Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czechia
| | - Glasiele Cristina Alcala
- Pulmonology Division, Cardiopulmonary Department, Heart Institute, University of Sao Paulo, São Paulo, Brazil
| | - Dominik Hladík
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
- Department of Anaesthesiology, Resuscitation and Intensive Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czechia
| | - Eduard Kuriščák
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
| | - Leoš Tejkl
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
| | - Marcelo Amato
- Pulmonology Division, Cardiopulmonary Department, Heart Institute, University of Sao Paulo, São Paulo, Brazil
| | - Otomar Kittnar
- First Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czechia
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Min Hyun C, Jun Jang T, Nam J, Kwon H, Jeon K, Lee K. Machine learning-based signal quality assessment for cardiac volume monitoring in electrical impedance tomography. MACHINE LEARNING: SCIENCE AND TECHNOLOGY 2023. [DOI: 10.1088/2632-2153/acc637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023] Open
Abstract
Abstract
Owing to recent advances in thoracic electrical impedance tomography (EIT), a patient’s hemodynamic function can be noninvasively and continuously estimated in real-time by surveilling a cardiac volume signal (CVS) associated with stroke volume and cardiac output. In clinical applications, however, a CVS is often of low quality, mainly because of the patient’s deliberate movements or inevitable motions during clinical interventions. This study aims to develop a signal quality indexing method that assesses the influence of motion artifacts on transient CVSs. The assessment is performed on each cardiac cycle to take advantage of the periodicity and regularity in cardiac volume changes. Time intervals are identified using the synchronized electrocardiography system. We apply divergent machine-learning methods, which can be sorted into discriminative-model and manifold-learning approaches. The use of machine-learning could be suitable for our real-time monitoring application that requires fast inference and automation as well as high accuracy. In the clinical environment, the proposed method can be utilized to provide immediate warnings so that clinicians can minimize confusion regarding patients’ conditions, reduce clinical resource utilization, and improve the confidence level of the monitoring system. Numerous experiments using actual EIT data validate the capability of CVSs degraded by motion artifacts to be accurately and automatically assessed in real-time by machine learning. The best model achieved an accuracy of 0.95, positive and negative predictive values of 0.96 and 0.86, sensitivity of 0.98, specificity of 0.77, and AUC of 0.96.
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17
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Slobod D, Damia A, Leali M, Spinelli E, Mauri T. Pathophysiology and Clinical Meaning of Ventilation-Perfusion Mismatch in the Acute Respiratory Distress Syndrome. BIOLOGY 2022; 12:biology12010067. [PMID: 36671759 PMCID: PMC9855693 DOI: 10.3390/biology12010067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/20/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023]
Abstract
Acute respiratory distress syndrome (ARDS) remains an important clinical challenge with a mortality rate of 35-45%. It is being increasingly demonstrated that the improvement of outcomes requires a tailored, individualized approach to therapy, guided by a detailed understanding of each patient's pathophysiology. In patients with ARDS, disturbances in the physiological matching of alveolar ventilation (V) and pulmonary perfusion (Q) (V/Q mismatch) are a hallmark derangement. The perfusion of collapsed or consolidated lung units gives rise to intrapulmonary shunting and arterial hypoxemia, whereas the ventilation of non-perfused lung zones increases physiological dead-space, which potentially necessitates increased ventilation to avoid hypercapnia. Beyond its impact on gas exchange, V/Q mismatch is a predictor of adverse outcomes in patients with ARDS; more recently, its role in ventilation-induced lung injury and worsening lung edema has been described. Innovations in bedside imaging technologies such as electrical impedance tomography readily allow clinicians to determine the regional distributions of V and Q, as well as the adequacy of their matching, providing new insights into the phenotyping, prognostication, and clinical management of patients with ARDS. The purpose of this review is to discuss the pathophysiology, identification, consequences, and treatment of V/Q mismatch in the setting of ARDS, employing experimental data from clinical and preclinical studies as support.
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Affiliation(s)
- Douglas Slobod
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Department of Critical Care Medicine, McGill University, Montreal, QC H3A 3R1, Canada
| | - Anna Damia
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Marco Leali
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
- Correspondence:
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Zhang K, Li M, Liang H, Wang J, Yang F, Xu S, Abubakar A. Deep feature-domain matching for cardiac-related component separation from a chest electrical impedance tomography image series: proof-of-concept study. Physiol Meas 2022; 43. [PMID: 36265475 DOI: 10.1088/1361-6579/ac9c44] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 10/20/2022] [Indexed: 02/07/2023]
Abstract
Objectives.The cardiac-related component in chest electrical impedance tomography (EIT) measurement is of potential value to pulmonary perfusion monitoring and cardiac function measurement. In a spontaneous breathing case, cardiac-related signals experience serious interference from ventilation-related signals. Traditional cardiac-related signal-separation methods are usually based on certain features of signals. To further improve the separation accuracy, more comprehensive features of the signals should be exploited.Approach.We propose an unsupervised deep-learning method called deep feature-domain matching (DFDM), which exploits the feature-domain similarity of the desired signals and the breath-holding signals. This method is characterized by two sub-steps. In the first step, a novel Siamese network is designed and trained to learn common features of breath-holding signals; in the second step, the Siamese network is used as a feature-matching constraint between the separated signals and the breath-holding signals.Main results.The method is first tested using synthetic data, and the results show satisfactory separation accuracy. The method is then tested using the data of three patients with pulmonary embolism, and the consistency between the separated images and the radionuclide perfusion scanning images is checked qualitatively.Significance.The method uses a lightweight convolutional neural network for fast network training and inference. It is a potential method for dynamic cardiac-related signal separation in clinical settings.
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Affiliation(s)
- Ke Zhang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Maokun Li
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Haiqing Liang
- TEDA International Cardiovascular Hospital, Tianjin 300457, People's Republic of China
| | - Juan Wang
- National Laboratory of Pattern Recognition (NLPR), Institute of Automation, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fan Yang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shenheng Xu
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology (BNRist), Institute for Precision Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Aria Abubakar
- Schlumberger, Houston, TX 77056, United States of America
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Wang L, Zhu W, Wang R, Li W, Liang G, Ji Z, Dong X, Shi X. Suppressing interferences of EIT on synchronous recording EEG based on comb filter for seizure detection. Front Neurol 2022; 13:1070124. [DOI: 10.3389/fneur.2022.1070124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/18/2022] [Indexed: 12/03/2022] Open
Abstract
Background and objectiveThe purpose of this study was to eliminate the interferences of electrical impedance tomography (EIT) on synchronous recording electroencephalography (EEG) for seizure detection.MethodsThe simulated EIT signal generated by COMSOL Multiphysics was superimposed on the clinical EEG signal obtained from the CHB-MIT Scalp EEG Database, and then the spectrum features of superimposed mixed signals were analyzed. According to the spectrum analysis, in addition to high-frequency interference at 51.2 kHz related to the drive current, there was also low-frequency interference caused by switching of electrode pairs, which were used to inject drive current. A low pass filter and a comb filter were used to suppress the high-frequency interference and low-frequency interference, respectively. Simulation results suggested the low-pass filter and comb filter working together effectively filtered out the interference of EIT on EEG in the process of synchronous monitoring.ResultsAs a result, the normal EEG and epileptic EEG could be recognized effectively. Pearson correlation analysis further confirmed the interference of EIT on EEG was effectively suppressed.ConclusionsThis study provides a simple and effective interference suppression method for the synchronous monitoring of EIT and EEG, which could be served as a reference for the synchronous monitoring of EEG and other medical electromagnetic devices.
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Pavlovsky B, Pesenti A, Spinelli E, Scaramuzzo G, Marongiu I, Tagliabue P, Spadaro S, Grasselli G, Mercat A, Mauri T. Effects of PEEP on regional ventilation-perfusion mismatch in the acute respiratory distress syndrome. Crit Care 2022; 26:211. [PMID: 35818077 PMCID: PMC9272883 DOI: 10.1186/s13054-022-04085-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 07/05/2022] [Indexed: 11/10/2022] Open
Abstract
Purpose In the acute respiratory distress syndrome (ARDS), decreasing Ventilation-Perfusion \documentclass[12pt]{minimal}
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\begin{document}$$\left( {{{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}} \right)$$\end{document}V˙/Q˙ mismatch might enhance lung protection. We investigated the regional effects of higher Positive End Expiratory Pressure (PEEP) on \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch and their correlation with recruitability. We aimed to verify whether PEEP improves regional \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch, and to study the underlying mechanisms. Methods In fifteen patients with moderate and severe ARDS, two PEEP levels (5 and 15 cmH2O) were applied in random order. \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch was assessed by Electrical Impedance Tomography at each PEEP. Percentage of ventilation and perfusion reaching different ranges of \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ ratios were analyzed in 3 gravitational lung regions, leading to precise assessment of their distribution throughout different \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch compartments. Recruitability between the two PEEP levels was measured by the recruitment-to-inflation ratio method. Results In the non-dependent region, at higher PEEP, ventilation reaching the normal \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ compartment (p = 0.018) increased, while it decreased in the high \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ one (p = 0.023). In the middle region, at PEEP 15 cmH2O, ventilation and perfusion to the low \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ compartment decreased (p = 0.006 and p = 0.011) and perfusion to normal \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ increased (p = 0.003). In the dependent lung, the percentage of blood flowing through the non-ventilated compartment decreased (p = 0.041). Regional \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch improvement was correlated to lung recruitability and changes in regional tidal volume. Conclusions In patients with ARDS, higher PEEP optimizes the distribution of both ventilation (in the non-dependent areas) and perfusion (in the middle and dependent lung). Bedside measure of recruitability is associated with improved \documentclass[12pt]{minimal}
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\begin{document}$${{\dot{V}} \mathord{\left/ {\vphantom {{\dot{V}} {\dot{Q}}}} \right. \kern-\nulldelimiterspace} {\dot{Q}}}$$\end{document}V˙/Q˙ mismatch. Supplementary Information The online version contains supplementary material available at 10.1186/s13054-022-04085-y.
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Jiang H, Han Y, Zheng X, Fang Q. Roles of electrical impedance tomography in lung transplantation. Front Physiol 2022; 13:986422. [PMID: 36407002 PMCID: PMC9669435 DOI: 10.3389/fphys.2022.986422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
Lung transplantation is the preferred treatment method for patients with end-stage pulmonary disease. However, several factors hinder the progress of lung transplantation, including donor shortages, candidate selection, and various postoperative complications. Electrical impedance tomography (EIT) is a functional imaging tool that can be used to evaluate pulmonary ventilation and perfusion at the bedside. Among patients after lung transplantation, monitoring the graft’s pulmonary function is one of the most concerning issues. The feasible application of EIT in lung transplantation has been reported over the past few years, and this technique has gained increasing interest from multidisciplinary researchers. Nevertheless, physicians still lack knowledge concerning the potential applications of EIT in lung transplantation. We present an updated review of EIT in lung transplantation donors and recipients over the past few years, and discuss the potential use of ventilation- and perfusion-monitoring-based EIT in lung transplantation.
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Affiliation(s)
| | | | - Xia Zheng
- *Correspondence: Xia Zheng, ; Qiang Fang,
| | - Qiang Fang
- *Correspondence: Xia Zheng, ; Qiang Fang,
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Santos TBR, Nakanishi RM, de Camargo EDLB, Amato MBP, Kaipio JP, Lima RG, Mueller JL. Improved resolution of D-bar images of ventilation using a Schur complement property and an anatomical atlas. Med Phys 2022; 49:4653-4670. [PMID: 35411573 PMCID: PMC9544658 DOI: 10.1002/mp.15669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/31/2022] [Accepted: 03/31/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Electrical impedance tomography (EIT) is a nonionizing imaging technique for real-time imaging of ventilation of patients with respiratory distress. Cross-sectional dynamic images are formed by reconstructing the conductivity distribution from measured voltage data arising from applied alternating currents on electrodes placed circumferentially around the chest. Since the conductivity of lung tissue depends on air content, blood flow, and the presence of pathology, the dynamic images provide regional information about ventilation, pulsatile perfusion, and abnormalities. However, due to the ill-posedness of the inverse conductivity problem, EIT images have a coarse spatial resolution. One method of improving the resolution is to include prior information in the reconstruction. PURPOSE In this work, we propose a technique in which a statistical prior built from an anatomical atlas is used to postprocess EIT reconstructions of human chest data. The effectiveness of the method is demonstrated on data from two patients with cystic fibrosis. METHODS A direct reconstruction algorithm known as the D-bar method was used to compute a two-dimensional reconstruction of the conductivity distribution in the plane of the electrodes. Reconstructions using one step in an iterative (regularized) Newton's method were also computed for comparison. An anatomical atlas consisting of 1589 synthetic EIT images computed from X-ray computed tomography (CT) scans of 74 adult male subjects was computed for use as a statistical prior. The resolution of the D-bar images was then improved by maximizing the conditional probability density function of an image that is consistent with the a priori information and the statistical model. A new method to evaluate the accuracy of the EIT images using CT scans of the imaged patient as ground truth is presented. The novel approach is tested on data from two patients with cystic fibrosis. RESULTS AND CONCLUSIONS The D-bar images resulted in better structural similarity index measures (SSIM) and multiscale (MS) SSIM measures for both subjects using the mask or amplitude evaluation approach than the one-step (regularized) Newton's method. Further improvement was achieved using the Schur complement (SC) approach, with MS-SSIM values of 0.718 and 0.682 using SC evaluated with the mask and amplitude approach, respectively, for Patient 1, and MS-SSIM values of 0.726 and 0.692 using SC evaluated with the mask and amplitude approach, respectively, for Patient 2. The results from applying an anatomical atlas and statistical prior to EIT data from two patients with cystic fibrosis suggest that the spatial resolution of the EIT image can be improved to reveal pathology that may be difficult to discern in the original EIT image. The novel metric of evaluation is consistent with the appearance of improved spatial resolution and provides a new way to evaluate the accuracy of EIT reconstructions when a CT scan is available.
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Affiliation(s)
| | - Rafael Mikio Nakanishi
- Mechanical Engineering DepartmentPolytechnic School of the University of São PauloSão PauloSPBrazil
| | | | | | - Jari P. Kaipio
- Department of MathematicsUniversity of AucklandNew Zealand
- Department of Applied PhysicsUniversity of Eastern FinlandKuopioFinland
| | - Raul Gonzalez Lima
- Mechanical Engineering DepartmentPolytechnic School of the University of São PauloSão PauloSPBrazil
| | - Jennifer L. Mueller
- Department of Mathematics and School of Biomedical Engineering and the Department of Electrical and Computer EngineeringColorado State UniversityColoradoUSA
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Rauseo M, Spinelli E, Sella N, Slobod D, Spadaro S, Longhini F, Giarratano A, Gilda C, Mauri T, Navalesi P. Expert opinion document: "Electrical impedance tomography: applications from the intensive care unit and beyond". JOURNAL OF ANESTHESIA, ANALGESIA AND CRITICAL CARE (ONLINE) 2022; 2:28. [PMID: 37386674 DOI: 10.1186/s44158-022-00055-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/01/2022] [Indexed: 07/01/2023]
Abstract
Mechanical ventilation is a life-saving technology, but it can also inadvertently induce lung injury and increase morbidity and mortality. Currently, there is no easy method of assessing the impact that ventilator settings have on the degree of lung inssflation. Computed tomography (CT), the gold standard for visually monitoring lung function, can provide detailed regional information of the lung. Unfortunately, it necessitates moving critically ill patients to a special diagnostic room and involves exposure to radiation. A technique introduced in the 1980s, electrical impedance tomography (EIT) can non-invasively provide similar monitoring of lung function. However, while CT provides information on the air content, EIT monitors ventilation-related changes of lung volume and changes of end expiratory lung volume (EELV). Over the past several decades, EIT has moved from the research lab to commercially available devices that are used at the bedside. Being complementary to well-established radiological techniques and conventional pulmonary monitoring, EIT can be used to continuously visualize the lung function at the bedside and to instantly assess the effects of therapeutic maneuvers on regional ventilation distribution. EIT provides a means of visualizing the regional distribution of ventilation and changes of lung volume. This ability is particularly useful when therapy changes are intended to achieve a more homogenous gas distribution in mechanically ventilated patients. Besides the unique information provided by EIT, its convenience and safety contribute to the increasing perception expressed by various authors that EIT has the potential to be used as a valuable tool for optimizing PEEP and other ventilator settings, either in the operative room and in the intensive care unit. The effects of various therapeutic interventions and applications on ventilation distribution have already been assessed with the help of EIT, and this document gives an overview of the literature that has been published in this context.
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Affiliation(s)
- Michela Rauseo
- Department of Anesthesia and Intensive Care Medicine, University of Foggia, Policlinico Riuniti di Foggia, Foggia, Italy.
| | - Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico Milan, Milano, Italy
| | - Nicolò Sella
- Instiute of Anesthesia and Intensive Care, Padua University Hospital, Padova, Italy
| | - Douglas Slobod
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico Milan, Milano, Italy
- Department of Critical Care Medicine, McGill University, Montreal, Quebec, Canada
| | - Savino Spadaro
- Anesthesia and Intensive Care Unit, Department of Translational Medicine, University of Ferrara, Ferrara, Italy
| | - Federico Longhini
- Anesthesia and Intensive Care Unit, Department of Medical and Surgical Sciences, "Magna Graecia" University, "Mater Domini" University Hospital, Catanzaro, Italy
| | - Antonino Giarratano
- Department of Surgical, Oncological and Oral Science (Di.Chir.On.S.), Section of Anaesthesia, Analgesia, Intensive Care and Emergency, Policlinico Paolo Giaccone, University of Palermo, Palermo, Italy
| | - Cinnella Gilda
- Department of Anesthesia and Intensive Care Medicine, University of Foggia, Policlinico Riuniti di Foggia, Foggia, Italy
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico Milan, Milano, Italy
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Paolo Navalesi
- Instiute of Anesthesia and Intensive Care, Padua University Hospital, Padova, Italy
- Department of Medicine - DIMED, University of Padua, Padova, Italy
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Early physiological effects of prone positioning in COVID-19 Acute Respiratory Distress Syndrome. Anesthesiology 2022; 137:327-339. [PMID: 35708999 DOI: 10.1097/aln.0000000000004296] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND. The mechanisms underlying oxygenation improvement after prone positioning in COVID-19 ARDS have not been fully elucidated yet. We hypothesized that the oxygenation increase with prone positioning is secondary to the improvement of ventilation-perfusion matching. METHODS. In a series of consecutive intubated COVID-19 ARDS patients receiving volume-controlled ventilation, we prospectively assessed the percent variation of ventilation-perfusion matching by electrical impedance tomography (EIT) before and 90 minutes after the first cycle of prone positioning (primary endpoint). We also assessed changes in the distribution and homogeneity of lung ventilation and perfusion, lung overdistention and collapse, respiratory system compliance, driving pressure, optimal positive end-expiratory pressure (PEEP), as assessed by EIT, and the ratio of partial pressure to fractional inspired oxygen (PaO2/FiO2) (secondary endpoints). Data are reported as medians [25th - 75th] or percentages. RESULTS. We enrolled 30 consecutive patients, all analyzed without missing data. Compared to supine position, prone positioning overall improved ventilation-perfusion matching from 58 [43-69] % to 68 [56-75] % (p=0.042), with a median difference of 8.0% (95% Confidence Interval 0.1 to 16.0%) . Dorsal ventilation increased from 39 [31-43] % to 52 [44-62] % (p<0.001), while dorsal perfusion did not significantly vary. Prone positioning also reduced lung overdistension from 9 [4-11] % to 4 [2-6] % (p=0.025), while it did not significantly affect ventilation and perfusion homogeneity, lung collapse, static respiratory system compliance, driving pressure, and optimal PEEP. PaO2/FiO2 overall improved from 141 [104-182] mmHg to 235 [164-267] mmHg (p=0.019). However, 9 (30%) patients were non-responders, experiencing an increase in PaO2/FiO2 <20% with respect to baseline. CONCLUSIONS. In COVID-19 ARDS patients, prone positioning overall produced an early increase in ventilation-perfusion matching and dorsal ventilation. These effects were, however, heterogeneous among patients.
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Wang YX, Zhong M, Dong MH, Song JQ, Zheng YJ, Wu W, Tao JL, Zhu L, Zheng X. Prone positioning improves ventilation-perfusion matching assessed by electrical impedance tomography in patients with ARDS: a prospective physiological study. Crit Care 2022; 26:154. [PMID: 35624489 PMCID: PMC9137443 DOI: 10.1186/s13054-022-04021-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The physiological effects of prone ventilation in ARDS patients have been discussed for a long time but have not been fully elucidated. Electrical impedance tomography (EIT) has emerged as a tool for bedside monitoring of pulmonary ventilation and perfusion, allowing the opportunity to obtain data. This study aimed to investigate the effect of prone positioning (PP) on ventilation-perfusion matching by contrast-enhanced EIT in patients with ARDS. DESIGN Monocenter prospective physiologic study. SETTING University medical ICU. PATIENTS Ten mechanically ventilated ARDS patients who underwent PP. INTERVENTIONS We performed EIT evaluation at the initiation of PP, 3 h after PP initiation and the end of PP during the first PP session. MEASUREMENTS AND MAIN RESULTS The regional distribution of ventilation and perfusion was analyzed based on EIT images and compared to the clinical variables regarding respiratory and hemodynamic status. Prolonged prone ventilation improved oxygenation in the ARDS patients. Based on EIT measurements, the distribution of ventilation was homogenized and dorsal lung ventilation was significantly improved by PP administration, while the effect of PP on lung perfusion was relatively mild, with increased dorsal lung perfusion observed. The ventilation-perfusion matched region was found to increase and correlate with the increased PaO2/FiO2 by PP, which was attributed mainly to reduced shunt in the lung. CONCLUSIONS Prolonged prone ventilation increased dorsal ventilation and perfusion, which resulted in improved ventilation-perfusion matching and oxygenation. TRIAL REGISTRATION ClinicalTrials.gov, NCT04725227. Registered on 25 January 2021.
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Affiliation(s)
- Yu-Xian Wang
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Ming Zhong
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China. .,Shanghai Institute of Infectious Disease and Biosecurity, School of Public Health, Fudan University, Shanghai, China. .,Shanghai Committee of Science and Technology (21MC1930400), Shanghai, China.
| | - Min-Hui Dong
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Jie-Qiong Song
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Yi-Jun Zheng
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Wei Wu
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Jia-le Tao
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Ling Zhu
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Xin Zheng
- Department of Critical Care Medicine, Zhongshan Hospital of Fudan University, Shanghai, China
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Mendes PV, Park M, de Azevedo LCP, Morais CCA, Amato MBP, Costa ELV. Lung perfusion during veno-venous extracorporeal membrane oxygenation in a model of hypoxemic respiratory failure. Intensive Care Med Exp 2022; 10:15. [PMID: 35467225 PMCID: PMC9038965 DOI: 10.1186/s40635-022-00442-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 04/09/2022] [Indexed: 11/10/2022] Open
Abstract
Background Veno-venous extracorporeal membrane oxygenation (ECMO) provides blood oxygenation and carbon dioxide removal in acute respiratory distress syndrome. However, during ECMO support, the native lungs still play an important role in gas exchange, functioning as a second oxygenator in series with ECMO. The hypoxic vasoconstriction mechanism diverts regional blood flow within the lungs away from regions with low oxygen levels, optimizing ventilation/perfusion matching. ECMO support has the potential to reduce this adaptive pulmonary response and worsen the ventilation/perfusion mismatch by raising venous oxygen partial pressure. Thus, the objective of this study was to evaluate the effect of ECMO on regional pulmonary perfusion and pulmonary hemodynamics during unilateral ventilation and posterior lung collapse. Methods Five Agroceres pigs were instrumented, monitored and submitted to ECMO. We used the Electrical Impedance Tomography (EIT) to evaluate lung ventilation and perfusion in all protocol steps. Effects of ECMO support on pulmonary hemodynamics and perfusion involving two different scenarios of ventilation/perfusion mismatch: (1) right-lung selective intubation inducing collapse of the normal left lung and (2) dorsal lung collapse after repeated lung lavage. Data including hemodynamics, respiratory, lung perfusion/ventilation, and laboratory data over time were analyzed with a mixed generalized model using the subjects as a random factor. Results The initiation of ECMO support provided a significant reduction in Mean Pulmonary Artery Pressure (PAPm) in both situations of ventilation/perfusion mismatch. However, distribution of lung perfusion did not change with the use of ECMO support. Conclusions We found that the use of ECMO support with consequent increase in venous oxygen pressure induced a significant drop in PAPm with no detectable effect on regional lung perfusion in different scenarios of ventilation/perfusion mismatch. Supplementary Information The online version contains supplementary material available at 10.1186/s40635-022-00442-x.
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Affiliation(s)
- Pedro Vitale Mendes
- Medical Intensive Care Unit, Hospital das Clinicas HCFMUSP, University of São Paulo School of Medicine, São Paulo, SP, Brazil.
| | - Marcelo Park
- Medical Intensive Care Unit, Hospital das Clinicas HCFMUSP, University of São Paulo School of Medicine, São Paulo, SP, Brazil
| | - Luciano Cesar Pontes de Azevedo
- Medical Intensive Care Unit, Hospital das Clinicas HCFMUSP, University of São Paulo School of Medicine, São Paulo, SP, Brazil
| | | | - Marcelo Brito Passos Amato
- Pulmonary Division, Instituto do Coracao (Incor), University of São Paulo School of Medicine, São Paulo, SP, Brazil
| | - Eduardo Leite Vieira Costa
- Pulmonary Division, Instituto do Coracao (Incor), University of São Paulo School of Medicine, São Paulo, SP, Brazil.,Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil
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Electrical impedance tomography in the adult intensive care unit. Curr Opin Crit Care 2022; 28:292-301. [DOI: 10.1097/mcc.0000000000000936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tipre DN, Cidon M, Moats RA. Imaging Pulmonary Blood Vessels and Ventilation-Perfusion Mismatch in COVID-19. Mol Imaging Biol 2022; 24:526-536. [PMID: 35041149 PMCID: PMC8764889 DOI: 10.1007/s11307-021-01700-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 12/16/2022]
Abstract
COVID-19 hypoxemic patients although sharing a same etiology (SARS-CoV-2 infection) present themselves quite differently from one another. Patients also respond differently to prescribed medicine and to prone Vs supine bed positions. A severe pulmonary ventilation-perfusion mismatch usually triggers moderate to severe COVID-19 cases. Imaging can aid the physician in assessing severity of COVID-19. Although useful for their portability X-ray and ultrasound serving on the frontline to evaluate lung parenchymal abnormalities are unable to provide information about pulmonary vasculature and blood flow redistribution which is a consequence of hypoxemia in COVID-19. Advanced imaging modalities such as computed tomography, single-photon emission tomography, and electrical impedance tomography use a sharp algorithm visualizing pulmonary ventilation-perfusion mismatch in the abnormal and in the apparently normal parenchyma. Imaging helps to access the severity of infection, lung performance, ventilation-perfusion mismatch, and informs strategies for medical treatment. This review summarizes the capacity of these imaging modalities to assess ventilation-perfusion mismatch in COVID-19. Despite having limitations, these modalities provide vital information on blood volume distribution, pulmonary embolism, pulmonary vasculature and are useful to assess severity of lung disease and effectiveness of treatment in COVID-19 patients.
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Affiliation(s)
- Dnyanesh N Tipre
- Translational Biomedical Imaging Laboratory, Department of Radiology, Children's Hospital Los Angeles, The Saban Research Institute, 4650 Sunset Blvd Rm 305, Los Angeles, CA, USA.
| | - Michal Cidon
- Department of Rheumatology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Rex A Moats
- Translational Biomedical Imaging Laboratory, Department of Radiology, Children's Hospital Los Angeles, The Saban Research Institute, 4650 Sunset Blvd Rm 305, Los Angeles, CA, USA
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Nguyen DM, Duong Trong L, McEwan AL. An efficient and fast multi-band focused bioimpedance solution with EIT-based reconstruction for pulmonary embolism assessment: a simulation study from massive to segmental blockage. Physiol Meas 2022; 43. [PMID: 34986471 DOI: 10.1088/1361-6579/ac4830] [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: 10/09/2021] [Accepted: 01/05/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Pulmonary embolism (PE) is an acute condition that blocks the perfusion to the lungs and is a common complication of Covid-19. However, PE is often not diagnosed in time, especially in the pandemic time due to complicated diagnosis protocol. In this study, a non-invasive, fast and efficient bioimpedance method with the EIT-based reconstruction approach is proposed to assess the lung perfusion reliably. APPROACH Some proposals are presented to improve the sensitivity and accuracy for the bioimpedance method: (1) a new electrode configuration and focused pattern to help study deep changes caused by PE within each lung field separately, (2) a measurement strategy to compensate the effect of different boundary shapes and varied respiratory conditions on the perfusion signals and (3) an estimator to predict the lung perfusion capacity, from which the severity of PE can be assessed. The proposals were tested on the first-time simulation of PE events at different locations and degrees from segmental blockages to massive blockages. Different object boundary shapes and varied respiratory conditions were included in the simulation to represent for different populations in real measurements. RESULTS The correlation between the estimator and the perfusion was very promising (R = 0.91, errors < 6%). The measurement strategy with the proposed configuration and pattern has helped stabilize the estimator to non-perfusion factors such as the boundary shapes and varied respiration conditions (3-5% errors). SIGNIFICANCE This promising preliminary result has demonstrated the proposed bioimpedance method's capability and feasibility, and might start a new direction for this application.
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Affiliation(s)
- Duc Minh Nguyen
- School of Biomedical Engineering, University of Sydney - Camperdown and Darlington Campus SciTech Library, Room 415, Level 4, Link Building Faculty of Engineering and IT, The University of Sydney, Darlington, Hanoi, New South Wales, 100000, AUSTRALIA
| | - Luong Duong Trong
- School of Electronics and Telecommunication, Hanoi University of Science and Technology, No. 1, Dai Co Viet Street, Hai Ba Trung District, Hanoi, 100000, VIET NAM
| | - Alistair L McEwan
- School of Biomedical Engineering, The University of Sydney, Room 415, Level 4, Link Building Faculty of Engineering and IT, The University of Sydney, Darlington NSW 2006, Australia, Sydney, New South Wales, 2006, AUSTRALIA
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Lee K, Jang GY, Kim Y, Woo EJ. Multi-channel Trans-impedance Leadforming for Cardiopulmonary Monitoring: Algorithm Development and Feasibility Assessment using In Vivo Animal Data. IEEE Trans Biomed Eng 2021; 69:1964-1974. [PMID: 34855581 DOI: 10.1109/tbme.2021.3132012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The objectives of this study were to (1) develop a multi-channel trans-impedance leadforming method for beat-to-beat stroke volume (SV) and breath-by-breath tidal volume (TV) measurements and (2) assess its feasibility on an existing in vivo animal dataset. METHODS A deterministic leadforming algorithm was developed to extract a cardiac volume signal (CVS) and a respiratory volume signal (RVS) from 208-channel trans-impedance data acquired every 20 ms by an electrical impedance tomography (EIT) device. SVEIT and TVEIT values were computed as a valley-to-peak value in the CVS and RVS, respectively. The method was applied to the existing dataset from five mechanically-ventilated pigs undergoing ten mini-fluid challenges. An invasive hemodynamic monitor was used in the arterial pressure-based cardiac output (APCO) mode to simultaneously measure SVAPCO values while a mechanical ventilator provided TVVent values. RESULTS The leadforming method could reliably extract the CVS and RVS from the 208-channel trans-impedance data measured with the EIT device, from which SV<sub>EIT</sub> and TV<sub>EIT</sub> were computed. The SV<sub>EIT</sub> and TV<sub>EIT</sub> values were comparable to those from the invasive hemodynamic monitor and mechanical ventilator. Using the data from 5 pigs and a simple calibration method to remove bias, the error in SV<sub>EIT<sub> and TV<sub>EIT<sub> was 9.5% and 5.4%, respectively. CONCLUSION We developed a new leadforming method for the EIT device to robustly extract both SV and TV values in a deterministic fashion. Future animal and clinical studies are needed to validate this leadforming method in various subject populations. SIGNIFICANCE The leadforming method could be an integral component for a new cardiopulmonary monitor in the future to simultaneously measure SV and TV noninvasively, which would be beneficial to patients.
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Xu M, He H, Long Y. Lung Perfusion Assessment by Bedside Electrical Impedance Tomography in Critically Ill Patients. Front Physiol 2021; 12:748724. [PMID: 34721072 PMCID: PMC8548642 DOI: 10.3389/fphys.2021.748724] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/13/2021] [Indexed: 12/02/2022] Open
Abstract
As a portable, radiation-free imaging modality, electrical impedance tomography (EIT) technology has shown promise in the bedside visual assessment of lung perfusion distribution in critically ill patients. The two main methods of EIT for assessing lung perfusion are the pulsatility and conductivity contrast (saline) bolus method. Increasing attention is being paid to the saline bolus EIT method in the evaluation of regional pulmonary perfusion in clinical practice. This study seeks to provide an overview of experimental and clinical studies with the aim of clarifying the progress made in the use of the saline bolus EIT method. Animal studies revealed that the saline bolus EIT method presented good consistency with single-photon emission CT (SPECT) in the evaluation of lung regional perfusion changes in various pathological conditions. Moreover, the saline bolus EIT method has been applied to assess the lung perfusion in a pulmonary embolism and the effect of positive end-expiratory pressure (PEEP) on regional ventilation/perfusion ratio (V/Q) and acute respiratory distress syndrome (ARDS) in several clinical studies. The implementation of saline boluses, data analyses, precision, and cutoff values varied among different studies, and a consensus must be reached regarding the clinical application of the saline bolus EIT method. Further study is required to validate the impact of the described saline bolus EIT method on decision-making, therapeutic management, and outcomes in critically ill patients.
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Affiliation(s)
- Mengru Xu
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Huaiwu He
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Yun Long
- State Key Laboratory of Complex Severe and Rare Diseases, Department of Critical Care Medicine, Peking Union Medical College, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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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] [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 .
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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.
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Hentze B, Muders T, Hoog Antink C, Putensen C, Larsson A, Hedenstierna G, Walter M, Leonhardt S. A model-based source separation algorithm for lung perfusion imaging using electrical impedance tomography. Physiol Meas 2021; 42. [PMID: 34167091 DOI: 10.1088/1361-6579/ac0e84] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/24/2021] [Indexed: 11/11/2022]
Abstract
Objective. Electrical impedance tomography (EIT) for lung perfusion imaging is attracting considerable interest in intensive care, as it might open up entirely new ways to adjust ventilation therapy. A promising technique is bolus injection of a conductive indicator to the central venous catheter, which yields the indicator-based signal (IBS). Lung perfusion images are then typically obtained from the IBS using the maximum slope technique. However, the low spatial resolution of EIT results in a partial volume effect (PVE), which requires further processing to avoid regional bias.Approach. In this work, we repose the extraction of lung perfusion images from the IBS as a source separation problem to account for the PVE. We then propose a model-based algorithm, called gamma decomposition (GD), to derive an efficient solution. The GD algorithm uses a signal model to transform the IBS into a parameter space where the source signals of heart and lung are separable by clustering in space and time. Subsequently, it reconstructs lung model signals from which lung perfusion images are unambiguously extracted.Main results. We evaluate the GD algorithm on EIT data of a prospective animal trial with eight pigs. The results show that it enables lung perfusion imaging using EIT at different stages of regional impairment. Furthermore, parameters of the source signals seem to represent physiological properties of the cardio-pulmonary system.Significance. This work represents an important advance in IBS processing that will likely reduce bias of EIT perfusion images and thus eventually enable imaging of regional ventilation/perfusion (V/Q) ratio.
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Affiliation(s)
- Benjamin Hentze
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany.,Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Thomas Muders
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Christoph Hoog Antink
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany.,Biomedical Engineering, TU Darmstadt, Darmstadt, Germany
| | - Christian Putensen
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Anders Larsson
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Marian Walter
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Steffen Leonhardt
- Medical Information Technology, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
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Pan Q, Jia M, Ge H, Zhao Z. Electrical impedance tomography captures heterogeneous lung ventilation that may be associated with ineffective inspiratory efforts. Crit Care 2021; 25:303. [PMID: 34419115 PMCID: PMC8379879 DOI: 10.1186/s13054-021-03732-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/09/2021] [Indexed: 12/04/2022] Open
Affiliation(s)
- Qing Pan
- College of Information Engineering, Zhejiang University of Technology, Hangzhou, China
| | - Mengzhe Jia
- College of Information Engineering, Zhejiang University of Technology, Hangzhou, China
| | - Huiqing Ge
- Department of Respiratory Care, Regional Medical Center for National Institute of Respiratory Diseases, School of Medicine, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, China.
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, 169 Changle Xi Rd, Xi'an, China. .,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany.
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35
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Pelosi P, Ball L, Barbas CSV, Bellomo R, Burns KEA, Einav S, Gattinoni L, Laffey JG, Marini JJ, Myatra SN, Schultz MJ, Teboul JL, Rocco PRM. Personalized mechanical ventilation in acute respiratory distress syndrome. Crit Care 2021; 25:250. [PMID: 34271958 PMCID: PMC8284184 DOI: 10.1186/s13054-021-03686-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 07/08/2021] [Indexed: 01/22/2023] Open
Abstract
A personalized mechanical ventilation approach for patients with adult respiratory distress syndrome (ARDS) based on lung physiology and morphology, ARDS etiology, lung imaging, and biological phenotypes may improve ventilation practice and outcome. However, additional research is warranted before personalized mechanical ventilation strategies can be applied at the bedside. Ventilatory parameters should be titrated based on close monitoring of targeted physiologic variables and individualized goals. Although low tidal volume (VT) is a standard of care, further individualization of VT may necessitate the evaluation of lung volume reserve (e.g., inspiratory capacity). Low driving pressures provide a target for clinicians to adjust VT and possibly to optimize positive end-expiratory pressure (PEEP), while maintaining plateau pressures below safety thresholds. Esophageal pressure monitoring allows estimation of transpulmonary pressure, but its use requires technical skill and correct physiologic interpretation for clinical application at the bedside. Mechanical power considers ventilatory parameters as a whole in the optimization of ventilation setting, but further studies are necessary to assess its clinical relevance. The identification of recruitability in patients with ARDS is essential to titrate and individualize PEEP. To define gas-exchange targets for individual patients, clinicians should consider issues related to oxygen transport and dead space. In this review, we discuss the rationale for personalized approaches to mechanical ventilation for patients with ARDS, the role of lung imaging, phenotype identification, physiologically based individualized approaches to ventilation, and a future research agenda.
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Affiliation(s)
- Paolo Pelosi
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neuroscience, Genoa, Italy.
- Department of Surgical Sciences and Integrated Diagnostic (DISC), University of Genoa, Viale Benedetto XV 16, Genoa, Italy.
| | - Lorenzo Ball
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neuroscience, Genoa, Italy
- Department of Surgical Sciences and Integrated Diagnostic (DISC), University of Genoa, Viale Benedetto XV 16, Genoa, Italy
| | - Carmen S V Barbas
- Pneumology and Intensive Care Medicine, University of São Paulo, São Paulo, Brazil
- Adult Intensive Care Unit, Albert Einstein Hospital, São Paulo, Brazil
| | - Rinaldo Bellomo
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Department of Epidemiology and Preventive Medicine, Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, VIC, Australia
- Data Analytics Research and Evaluation Centre, The University of Melbourne and Austin Hospital, Melbourne, Australia
- Department of Intensive Care, Royal Melbourne Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, Australia
| | - Karen E A Burns
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Unity Health Toronto-St. Michael's Hospital, Li Ka Shing Knowledge Institute, Toronto, ON, Canada
| | - Sharon Einav
- Intensive Care Unit of the Shaare Zedek Medical Medical Centre, Hebrew University Faculty of Medicine, Jerusalem, Israel
| | - Luciano Gattinoni
- Department of Anaesthesiology, Emergency, and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - John G Laffey
- Anaesthesia and Intensive Care Medicine, University Hospital Galway, and School of Medicine, National University of Ireland, Galway, Ireland
| | - John J Marini
- University of Minnesota and Regions Hospital, St. Paul, MN, USA
| | - Sheila N Myatra
- Department of Anaesthesiology, Critical Care and Pain, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, India
| | - Marcus J Schultz
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand
- Department of Intensive Care, Amsterdam University Medical Centers, Amsterdam, The Netherlands
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Jean Louis Teboul
- Service de Médecine Intensive-Réanimation, Hôpital Bicêtre, Inserm UMR S_999, AP-HP Université Paris-Saclay, Le Kremlin-Bicêtre, France
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Spinelli E, Kircher M, Stender B, Ottaviani I, Basile MC, Marongiu I, Colussi G, Grasselli G, Pesenti A, Mauri T. Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2021; 25:192. [PMID: 34082795 PMCID: PMC8173510 DOI: 10.1186/s13054-021-03615-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 05/21/2021] [Indexed: 12/30/2022]
Abstract
Background In acute respiratory distress syndrome (ARDS), non-ventilated perfused regions coexist with non-perfused ventilated regions within lungs. The number of unmatched regions might reflect ARDS severity and affect the risk of ventilation-induced lung injury. Despite pathophysiological relevance, unmatched ventilation and perfusion are not routinely assessed at the bedside. The aims of this study were to quantify unmatched ventilation and perfusion at the bedside by electrical impedance tomography (EIT) investigating their association with mortality in patients with ARDS and to explore the effects of positive end-expiratory pressure (PEEP) on unmatched ventilation and perfusion in subgroups of patients with different ARDS severity based on PaO2/FiO2 and compliance. Methods Prospective observational study in 50 patients with mild (36%), moderate (46%), and severe (18%) ARDS under clinical ventilation settings. EIT was applied to measure the regional distribution of ventilation and perfusion using central venous bolus of saline 5% during end-inspiratory pause. We defined unmatched units as the percentage of only ventilated units plus the percentage of only perfused units. Results Percentage of unmatched units was significantly higher in non-survivors compared to survivors (32[27–47]% vs. 21[17–27]%, p < 0.001). Percentage of unmatched units was an independent predictor of mortality (OR 1.22, 95% CI 1.07–1.39, p = 0.004) with an area under the ROC curve of 0.88 (95% CI 0.79–0.97, p < 0.001). The percentage of ventilation to the ventral region of the lung was higher than the percentage of ventilation to the dorsal region (32 [27–38]% vs. 18 [13–21]%, p < 0.001), while the opposite was true for perfusion (28 [22–38]% vs. 36 [32–44]%, p < 0.001). Higher percentage of only perfused units was correlated with lower dorsal ventilation (r = − 0.486, p < 0.001) and with lower PaO2/FiO2 ratio (r = − 0.293, p = 0.039). Conclusions EIT allows bedside assessment of unmatched ventilation and perfusion in mechanically ventilated patients with ARDS. Measurement of unmatched units could identify patients at higher risk of death and could guide personalized treatment.
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Affiliation(s)
- Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Michael Kircher
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | | | - Irene Ottaviani
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Maria C Basile
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Ines Marongiu
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Giulia Colussi
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Giacomo Grasselli
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Antonio Pesenti
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122, Milan, Italy. .,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
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37
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Naber A, Reiß M, Nahm W. Transit Time Measurement in Indicator Dilution Curves: Overcoming the Missing Ground Truth and Quantifying the Error. Front Physiol 2021; 12:588120. [PMID: 34122123 PMCID: PMC8194354 DOI: 10.3389/fphys.2021.588120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
The vascular function of a vessel can be qualitatively and intraoperatively checked by recording the blood dynamics inside the vessel via fluorescence angiography (FA). Although FA is the state of the art in proving the existence of blood flow during interventions such as bypass surgery, it still lacks a quantitative blood flow measurement that could decrease the recurrence rate and postsurgical mortality. Previous approaches show that the measured flow has a significant deviation compared to the gold standard reference (ultrasonic flow meter). In order to systematically address the possible sources of error, we investigated the error in transit time measurement of an indicator. Obtaining in vivo indicator dilution curves with a known ground truth is complex and often not possible. Further, the error in transit time measurement should be quantified and reduced. To tackle both issues, we first computed many diverse indicator dilution curves using an in silico simulation of the indicator's flow. Second, we post-processed these curves to mimic measured signals. Finally, we fitted mathematical models (parabola, gamma variate, local density random walk, and mono-exponential model) to re-continualize the obtained discrete indicator dilution curves and calculate the time delay of two analytical functions. This re-continualization showed an increase in the temporal accuracy up to a sub-sample accuracy. Thereby, the Local Density Random Walk (LDRW) model performed best using the cross-correlation of the first derivative of both indicator curves with a cutting of the data at 40% of the peak intensity. The error in frames depends on the noise level and is for a signal-to-noise ratio (SNR) of 20 dB and a sampling rate of fs = 60 Hz at fs-1·0.25(±0.18), so this error is smaller than the distance between two consecutive samples. The accurate determination of the transit time and the quantification of the error allow the calculation of the error propagation onto the flow measurement. Both can assist surgeons as an intraoperative quality check and thereby reduce the recurrence rate and post-surgical mortality.
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Affiliation(s)
- Ady Naber
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Michael Reiß
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Werner Nahm
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany
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38
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Raisis AL, Mosing M, Hosgood GL, Secombe CJ, Adler A, Waldmann AD. The use of electrical impedance tomography (EIT) to evaluate pulse rate in anaesthetised horses. Vet J 2021; 273:105694. [PMID: 34148609 DOI: 10.1016/j.tvjl.2021.105694] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 05/04/2021] [Accepted: 05/12/2021] [Indexed: 10/21/2022]
Abstract
Electrical impedance tomography (EIT) provides clinically useful lung images; however, it would be an advantage to extract additional cardiovascular information from the data. The aim of this study was to evaluate if cardiac-related changes measured by EIT can be used to measure pulse rate (PR) under physiological as well as high and low blood pressure states in anaesthetised horses. Electrical impedance tomography data and PR from seven horses anaesthetised in dorsal recumbency were recorded over 1 min during mechanical ventilation and 1 min of apnoea. Data were collected at four measurement time points; before and during intravenous administration of nitroprusside and phenylephrine, respectively. Nine pixels, estimated to represent the heart, were chosen from the EIT image. A novel algorithm detected peaks of impedance change for these pixels over 10 s intervals. Concurrent PR measured using an invasive blood pressure trace, was recorded every 10 s. EIT- and pulse-rate data were compared using Bland-Altman assessment for multiple measurements on each horse. Overall, 288 paired datasets from six of seven horses were available for analysis. There was excellent agreement for baseline measurements, as well as during hypertension and hypotension, with a bias of -0.26 and lower and upper limit of agreement at -2.22 (95% confidence intervals [CI], -2.89 to -1.86) and 1.69 (95% CI, 1.34-2.36) beats per min, respectively. EIT can be used to evaluate PR using cardiac-related impedance changes. More work is required to determine bias that might occur in anaesthetised horses in other recumbencies or clinical situations.
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Affiliation(s)
- A L Raisis
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - M Mosing
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia.
| | - G L Hosgood
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - C J Secombe
- School of Veterinary Medicine, College of SHEE, Murdoch University, South Street, Perth, WA, Australia
| | - A Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - A D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
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Abstract
PURPOSE OF REVIEW Among noninvasive lung imaging techniques that can be employed at the bedside electrical impedance tomography (EIT) and lung ultrasound (LUS) can provide dynamic, repeatable data on the distribution regional lung ventilation and response to therapeutic manoeuvres.In this review, we will provide an overview on the rationale, basic functioning and most common applications of EIT and Point of Care Ultrasound (PoCUS, mainly but not limited to LUS) in the management of mechanically ventilated patients. RECENT FINDINGS The use of EIT in clinical practice is supported by several studies demonstrating good correlation between impedance tomography data and other validated methods of assessing lung aeration during mechanical ventilation. Similarly, LUS also correlates with chest computed tomography in assessing lung aeration, its changes and several pathological conditions, with superiority over other techniques. Other PoCUS applications have shown to effectively complement the LUS ultrasound assessment of the mechanically ventilated patient. SUMMARY Bedside techniques - such as EIT and PoCUS - are becoming standards of the care for mechanically ventilated patients to monitor the changes in lung aeration, ventilation and perfusion in response to treatment and to assess weaning from mechanical ventilation.
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40
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Hovnanian ALD, Costa ELV, Hoette S, Fernandes CJCS, Jardim CVP, Dias BA, Morinaga LTK, Amato MBP, Souza R. Electrical impedance tomography in pulmonary arterial hypertension. PLoS One 2021; 16:e0248214. [PMID: 33730110 PMCID: PMC7968654 DOI: 10.1371/journal.pone.0248214] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 02/22/2021] [Indexed: 02/06/2023] Open
Abstract
The characterization of pulmonary arterial hypertension (PAH) relies mainly on right heart catheterization (RHC). Electrical impedance tomography (EIT) provides a non-invasive estimation of lung perfusion that could complement the hemodynamic information from RHC. To assess the association between impedance variation of lung perfusion (ΔZQ) and hemodynamic profile, severity, and prognosis, suspected of PAH or worsening PAH patients were submitted simultaneously to RHC and EIT. Measurements of ΔZQ were obtained. Based on the results of the RHC, 35 patients composed the PAH group, and eight patients, the normopressoric (NP) group. PAH patients showed a significantly reduced ΔZQ compared to the NP group. There was a significant correlation between ΔZQ and hemodynamic parameters, particularly with stroke volume (SV) (r = 0.76; P < 0.001). At 60 months, 15 patients died (43%) and 1 received lung transplantation; at baseline they had worse hemodynamics, and reduced ΔZQ when compared to survivors. Patients with low ΔZQ (≤154.6%.Kg) presented significantly worse survival (P = 0.033). ΔZQ is associated with hemodynamic status of PAH patients, with disease severity and survival, demonstrating EIT as a promising tool for monitoring patients with pulmonary vascular disease.
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Affiliation(s)
- André L. D. Hovnanian
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
- * E-mail:
| | - Eduardo L. V. Costa
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Susana Hoette
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Caio J. C. S. Fernandes
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Carlos V. P. Jardim
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Bruno A. Dias
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Luciana T. K. Morinaga
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Marcelo B. P. Amato
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Rogério Souza
- Pulmonary Divison, Heart Institute, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
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41
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Yuan S, He H, Long Y, Chi Y, Frerichs I, Zhao Z. Rapid dynamic bedside assessment of pulmonary perfusion defect by electrical impedance tomography in a patient with acute massive pulmonary embolism. Pulm Circ 2021; 11:2045894020984043. [PMID: 33532059 PMCID: PMC7829466 DOI: 10.1177/2045894020984043] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 06/07/2020] [Indexed: 12/21/2022] Open
Abstract
Several animal studies have shown that regional lung perfusion could be
effectively estimated by the hypertonic saline contrast electrical impedance
tomography method. Here, we reported an application of this method to
dynamically assess regional pulmonary perfusion defect in a patient with acute
massive pulmonary embolism. A 68-year-old man experienced sudden dyspnea and
cardiac arrest during out-of-bed physical activity on the first day after
partial mediastinal tumor resection. Acute pulmonary embolism was suspected due
to acute enlargement of right heart and fixed inferior venous cava measured with
bedside ultrasound. The computed tomography pulmonary angiography further
confirmed large embolism in both left and right main pulmonary arteries and
branches. The regional time impedance curves, which were obtained by a bolus of
10 ml 10% NaCl through the central venous catheter, were then analyzed to
quantitatively assess regional perfusion. Normal ventilation distribution with
massive defects in regional perfusion in both lungs was observed, leading to a
ventilation–perfusion mismatch and low oxygenation index
(PaO2/FiO2 = 86 mmHg) at the first day of pulmonary embolism. The
anticoagulation was performed with heparin, and the patient’s condition (such as
shock, dyspnea, hypoxemia, etc.), regional lung perfusion defect, and
ventilation–perfusion mismatch continuously improved in the following days. In
conclusion, this case implies that electrical impedance tomography might have
the potential to assess and monitor regional perfusion for rapid diagnosis of
fatal pulmonary embolism in clinical practice.
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Affiliation(s)
- 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 Science, Beijing, China
| | - 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 Science, 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 Science, 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 Science, Beijing, China
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center of Schleswig-Holstein, Kiel, Germany
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.,Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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42
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Morais CCA, Safaee Fakhr B, De Santis Santiago RR, Di Fenza R, Marutani E, Gianni S, Pinciroli R, Kacmarek RM, Berra L. Bedside Electrical Impedance Tomography Unveils Respiratory "Chimera" in COVID-19. Am J Respir Crit Care Med 2021; 203:120-121. [PMID: 33196303 PMCID: PMC7781126 DOI: 10.1164/rccm.202005-1801im] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Caio C A Morais
- Department of Anesthesia, Critical Care and Pain Medicine and
| | | | | | | | - Eizo Marutani
- Department of Anesthesia, Critical Care and Pain Medicine and
| | - Stefano Gianni
- Department of Anesthesia, Critical Care and Pain Medicine and
| | | | - Robert M Kacmarek
- Department of Anesthesia, Critical Care and Pain Medicine and.,Respiratory Care Department, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Lorenzo Berra
- Department of Anesthesia, Critical Care and Pain Medicine and.,Respiratory Care Department, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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43
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Kircher M, Elke G, Stender B, Hernandez Mesa M, Schuderer F, Dossel O, Fuld MK, Halaweish AF, Hoffman EA, Weiler N, Frerichs I. Regional Lung Perfusion Analysis in Experimental ARDS by Electrical Impedance and Computed Tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:251-261. [PMID: 32956046 DOI: 10.1109/tmi.2020.3025080] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electrical impedance tomography is clinically used to trace ventilation related changes in electrical conductivity of lung tissue. Estimating regional pulmonary perfusion using electrical impedance tomography is still a matter of research. To support clinical decision making, reliable bedside information of pulmonary perfusion is needed. We introduce a method to robustly detect pulmonary perfusion based on indicator-enhanced electrical impedance tomography and validate it by dynamic multidetector computed tomography in two experimental models of acute respiratory distress syndrome. The acute injury was induced in a sublobar segment of the right lung by saline lavage or endotoxin instillation in eight anesthetized mechanically ventilated pigs. For electrical impedance tomography measurements, a conductive bolus (10% saline solution) was injected into the right ventricle during breath hold. Electrical impedance tomography perfusion images were reconstructed by linear and normalized Gauss-Newton reconstruction on a finite element mesh with subsequent element-wise signal and feature analysis. An iodinated contrast agent was used to compute pulmonary blood flow via dynamic multidetector computed tomography. Spatial perfusion was estimated based on first-pass indicator dilution for both electrical impedance and multidetector computed tomography and compared by Pearson correlation and Bland-Altman analysis. Strong correlation was found in dorsoventral (r = 0.92) and in right-to-left directions (r = 0.85) with good limits of agreement of 8.74% in eight lung segments. With a robust electrical impedance tomography perfusion estimation method, we found strong agreement between multidetector computed and electrical impedance tomography perfusion in healthy and regionally injured lungs and demonstrated feasibility of electrical impedance tomography perfusion imaging.
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44
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Proença M, Braun F, Lemay M, Solà J, Adler A, Riedel T, Messerli FH, Thiran JP, Rimoldi SF, Rexhaj E. Non-invasive pulmonary artery pressure estimation by electrical impedance tomography in a controlled hypoxemia study in healthy subjects. Sci Rep 2020; 10:21462. [PMID: 33293566 PMCID: PMC7722929 DOI: 10.1038/s41598-020-78535-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/25/2020] [Indexed: 11/09/2022] Open
Abstract
Pulmonary hypertension is a hemodynamic disorder defined by an abnormal elevation of pulmonary artery pressure (PAP). Current options for measuring PAP are limited in clinical practice. The aim of this study was to evaluate if electrical impedance tomography (EIT), a radiation-free and non-invasive monitoring technique, can be used for the continuous, unsupervised and safe monitoring of PAP. In 30 healthy volunteers we induced gradual increases in systolic PAP (SPAP) by exposure to normobaric hypoxemia. At various stages of the protocol, the SPAP of the subjects was estimated by transthoracic echocardiography. In parallel, in the pulmonary vasculature, pulse wave velocity was estimated by EIT and calibrated to pressure units. Within-cohort agreement between both methods on SPAP estimation was assessed through Bland-Altman analysis and at subject level, with Pearson's correlation coefficient. There was good agreement between the two methods (inter-method difference not significant (P > 0.05), bias ± standard deviation of - 0.1 ± 4.5 mmHg) independently of the degree of PAP, from baseline oxygen saturation levels to profound hypoxemia. At subject level, the median per-subject agreement was 0.7 ± 3.8 mmHg and Pearson's correlation coefficient 0.87 (P < 0.05). Our results demonstrate the feasibility of accurately assessing changes in SPAP by EIT in healthy volunteers. If confirmed in a patient population, the non-invasive and unsupervised day-to-day monitoring of SPAP could facilitate the clinical management of patients with pulmonary hypertension.
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Affiliation(s)
- Martin Proença
- Systems Division, Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland. .,Signal Processing Laboratory (LTS5), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Fabian Braun
- Systems Division, Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland.,Signal Processing Laboratory (LTS5), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Mathieu Lemay
- Systems Division, Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland
| | - Josep Solà
- Systems Division, Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland
| | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - Thomas Riedel
- Department of Paediatrics, Cantonal Hospital Graubuenden, Chur, Switzerland.,Department of Paediatrics, Inselspital Bern, University Children's Hospital, Bern, Switzerland
| | - Franz H Messerli
- Department of Cardiology and Clinical Research, Inselspital Bern, University Hospital, Bern, Switzerland
| | - Jean-Philippe Thiran
- Signal Processing Laboratory (LTS5), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Department of Radiology, University Hospital Center (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Stefano F Rimoldi
- Department of Cardiology and Clinical Research, Inselspital Bern, University Hospital, Bern, Switzerland
| | - Emrush Rexhaj
- Department of Cardiology and Clinical Research, Inselspital Bern, University Hospital, Bern, Switzerland
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45
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He H, Chi Y, Long Y, Yuan S, Zhang R, Frerichs I, Möller K, Fu F, Zhao Z. Bedside Evaluation of Pulmonary Embolism by Saline Contrast Electrical Impedance Tomography Method: A Prospective Observational Study. Am J Respir Crit Care Med 2020; 202:1464-1468. [PMID: 32585116 PMCID: PMC7667910 DOI: 10.1164/rccm.202005-1780le] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Huaiwu He
- Peking Union Medical College Hospital Beijing, China
| | - Yi Chi
- Peking Union Medical College Hospital Beijing, China
| | - Yun Long
- Peking Union Medical College Hospital Beijing, China
| | - Siyi Yuan
- Peking Union Medical College Hospital Beijing, China
| | - Rui Zhang
- Peking Union Medical College Hospital Beijing, China
| | - Inéz Frerichs
- University Medical Center of Schleswig-Holstein Campus Kiel Kiel, Germany
| | - Knut Möller
- Furtwangen University Villingen-Schwenningen, Germany and
| | - Feng Fu
- Fourth Military Medical University Xi'an, China
| | - Zhanqi Zhao
- Furtwangen University Villingen-Schwenningen, Germany and.,Fourth Military Medical University Xi'an, China
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46
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Borges JB, Alcala GC, Mlček M. A Step Forward toward a Bedside and Timely Monitoring of Regional [Formula: see text]/[Formula: see text] Matching. Am J Respir Crit Care Med 2020; 202:1342-1344. [PMID: 32833499 PMCID: PMC7667916 DOI: 10.1164/rccm.202007-2896ed] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
| | | | - Mikuláš Mlček
- Institute of PhysiologyCharles UniversityPrague, Czech Republicand
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47
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Mosing M, Waldmann AD, Sacks M, Buss P, Boesch JM, Zeiler GE, Hosgood G, Gleed RD, Miller M, Meyer LCR, Böhm SH. What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses ( Ceratotherium simum) in lateral recumbency? J Appl Physiol (1985) 2020; 129:1140-1149. [PMID: 33054661 DOI: 10.1152/japplphysiol.00359.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
This study used electrical impedance tomography (EIT) measurements of regional ventilation and perfusion to elucidate the reasons for severe gas exchange impairment reported in rhinoceroses during opioid-induced immobilization. EIT values were compared with standard monitoring parameters to establish a new monitoring tool for conservational immobilization and future treatment options. Six male white rhinoceroses were immobilized using etorphine, and EIT ventilation variables, venous admixture, and dead space were measured 30, 40, and 50 min after becoming recumbent in lateral position. Pulmonary perfusion mapping using impedance-enhanced EIT was performed at the end of the study period. The measured impedance (∆Z) by EIT was compared between pulmonary regions using mixed linear models. Measurements of regional ventilation and perfusion revealed a pronounced disproportional shift of ventilation and perfusion toward the nondependent lung. Overall, the dependent lung was minimally ventilated and perfused, but remained aerated with minimal detectable lung collapse. Perfusion was found primarily around the hilum of the nondependent lung and was minimal in the periphery of the nondependent and the entire dependent lung. These shifts can explain the high amount of venous admixture and physiological dead space found in this study. Breath holding redistributed ventilation toward dependent and ventral lung areas. The findings of this study reveal important pathophysiological insights into the changes in lung ventilation and perfusion during immobilization of white rhinoceroses. These novel insights might induce a search for better therapeutic options and is establishing EIT as a promising monitoring tool for large animals in the field.NEW & NOTEWORTHY Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.
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Affiliation(s)
- Martina Mosing
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Andreas D Waldmann
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
| | - Muriel Sacks
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Peter Buss
- Veterinary Wildlife Services, South African National Parks, Kruger National Park, Skukuza, South Africa
| | - Jordyn M Boesch
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Gareth E Zeiler
- Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.,Centre for Veterinary Wildlife Studies and Department of Paraclinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Giselle Hosgood
- School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia
| | - Robin D Gleed
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Michele Miller
- Department of Science and Technology-National Research Foundation Centre of Excellence for Biomedical TB Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Leith C R Meyer
- Centre for Veterinary Wildlife Studies and Department of Paraclinical Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Stephan H Böhm
- Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
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48
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He H, Chi Y, Long Y, Yuan S, Frerichs I, Möller K, Fu F, Zhao Z. Influence of overdistension/recruitment induced by high positive end-expiratory pressure on ventilation-perfusion matching assessed by electrical impedance tomography with saline bolus. Crit Care 2020; 24:586. [PMID: 32993811 PMCID: PMC7523261 DOI: 10.1186/s13054-020-03301-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/21/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND High positive end-expiratory pressures (PEEP) may induce overdistension/recruitment and affect ventilation-perfusion matching (VQMatch) in mechanically ventilated patients. This study aimed to investigate the association between PEEP-induced lung overdistension/recruitment and VQMatch by electrical impedance tomography (EIT). METHODS The study was conducted prospectively on 30 adult mechanically ventilated patients: 18/30 with ARDS and 12/30 with high risk for ARDS. EIT measurements were performed at zero end-expiratory pressures (ZEEP) and subsequently at high (12-15 cmH2O) PEEP. The number of overdistended pixels over the number of recruited pixels (O/R ratio) was calculated, and the patients were divided into low O/R (O/R ratio < 15%) and high O/R groups (O/R ratio ≥ 15%). The global inhomogeneity (GI) index was calculated to evaluate the ventilation distribution. Lung perfusion image was calculated from the EIT impedance-time curves caused by 10 ml 10% NaCl injection during a respiratory pause (> 8 s). DeadSpace%, Shunt%, and VQMatch% were calculated based on lung EIT perfusion and ventilation images. RESULTS Increasing PEEP resulted in recruitment mainly in dorsal regions and overdistension mainly in ventral regions. ΔVQMatch% (VQMatch% at high PEEP minus that at ZEEP) was significantly correlated with recruited pixels (r = 0.468, P = 0.009), overdistended pixels (r = - 0.666, P < 0.001), O/R ratio (r = - 0.686, P < 0.001), and ΔSpO2 (r = 0.440, P = 0.015). Patients in the low O/R ratio group (14/30) had significantly higher Shunt% and lower VQMatch% than those in the high O/R ratio group (16/30) at ZEEP but not at high PEEP. Comparable DeadSpace% was found in both groups. A high PEEP caused a significant improvement of VQMatch%, DeadSpace%, Shunt%, and GI in the low O/R ratio group, but not in the high O/R ratio group. Using O/R ratio of 15% resulted in a sensitivity of 81% and a specificity of 100% for an increase of VQMatch% > 20% in response to high PEEP. CONCLUSIONS Change of ventilation-perfusion matching was associated with regional overdistention and recruitment induced by PEEP. A low O/R ratio induced by high PEEP might indicate a more homogeneous ventilation and improvement of VQMatch. TRIAL REGISTRATION ClinicalTrials.gov, NCT04081155 . Registered on 9 September 2019-retrospectively registered.
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Affiliation(s)
- Huaiwu He
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Chi
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yun Long
- Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
| | - Siyi Yuan
- Department of Critical Care Medicine, 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 24105, 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.
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49
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De Santis Santiago R, Teggia Droghi M, Fumagalli J, Marrazzo F, Florio G, Grassi LG, Gomes S, Morais CCA, Ramos OPS, Bottiroli M, Pinciroli R, Imber DA, Bagchi A, Shelton K, Sonny A, Bittner EA, Amato MBP, Kacmarek RM, Berra L. High Pleural Pressure Prevents Alveolar Overdistension and Hemodynamic Collapse in ARDS with Class III Obesity. Am J Respir Crit Care Med 2020; 203:575-584. [PMID: 32876469 PMCID: PMC7924574 DOI: 10.1164/rccm.201909-1687oc] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rationale: Obesity is characterized by elevated pleural pressure (Ppl) and worsening atelectasis during mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Objectives: To determine the effects of a lung recruitment maneuver (LRM) in the presence of elevated Ppl on hemodynamics, left and right ventricular pressure, and pulmonary vascular resistance. We hypothesized that elevated Ppl protects the cardiovascular system against high airway pressure and prevents lung overdistension. Methods: First, an interventional crossover trial in adult subjects with ARDS and a body mass index ≥ 35 kg/m2 (n = 21) was performed to explore the hemodynamic consequences of the LRM. Second, cardiovascular function was studied during low and high positive end-expiratory pressure (PEEP) in a model of swine with ARDS and high Ppl (n = 9) versus healthy swine with normal Ppl (n = 6). Measurements and Main Results: Subjects with ARDS and obesity (body mass index = 57 ± 12 kg/m2) after LRM required an increase in PEEP of 8 (95% confidence interval [95% CI], 7–10) cm H2O above traditional ARDS Network settings to improve lung function, oxygenation and V./Q. matching, without impairment of hemodynamics or right heart function. ARDS swine with high Ppl demonstrated unchanged transmural left ventricular pressure and systemic blood pressure after the LRM protocol. Pulmonary arterial hypertension decreased (8 [95% CI, 13–4] mm Hg), as did vascular resistance (1.5 [95% CI, 2.2–0.9] Wood units) and transmural right ventricular pressure (10 [95% CI, 15–6] mm Hg) during exhalation. LRM and PEEP decreased pulmonary vascular resistance and normalized the V./Q. ratio. Conclusions: High airway pressure is required to recruit lung atelectasis in patients with ARDS and class III obesity but causes minimal overdistension. In addition, patients with ARDS and class III obesity hemodynamically tolerate LRM with high airway pressure. Clinical trial registered with www.clinicaltrials.gov (NCT 02503241).
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Affiliation(s)
- Roberta De Santis Santiago
- Massachusetts General Hospital, 2348, Department of Anesthesia, Critical Care and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Maddalena Teggia Droghi
- Massachusetts General Hospital, 2348, Department of Anesthesia, Critical Care and Pain Medicine, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Jacopo Fumagalli
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Francesco Marrazzo
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Gaetano Florio
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Luigi G Grassi
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Susimeire Gomes
- Universidade de Sao Paulo Hospital das Clinicas, 117265, São Paulo, Brazil
| | - Caio C A Morais
- Universidade de Sao Paulo Hospital das Clinicas, 117265, São Paulo, Brazil
| | - Ozires P S Ramos
- Universidade de Sao Paulo Hospital das Clinicas, 117265, São Paulo, Brazil
| | | | | | - David A Imber
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Aranya Bagchi
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Kenneth Shelton
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Abraham Sonny
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Edward A Bittner
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States
| | - Marcelo B P Amato
- Universidade de São Paulo Instituto do Coração, 42523, Cardio-Pulmonary Department, Pulmonary Division, Heart Institute, São Paulo, Brazil
| | - Robert M Kacmarek
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States
| | - Lorenzo Berra
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States.,Harvard Medical School, 1811, Boston, Massachusetts, United States;
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50
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Noninvasive, simultaneous, and continuous measurements of stroke volume and tidal volume using EIT: feasibility study of animal experiments. Sci Rep 2020; 10:11242. [PMID: 32647206 PMCID: PMC7347894 DOI: 10.1038/s41598-020-68139-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 06/18/2020] [Indexed: 12/01/2022] Open
Abstract
Currently, there is no noninvasive method available for simultaneous measurements of tidal volume and stroke volume. Electrical impedance tomography (EIT) has been used for regional lung ventilation imaging. Cardiac EIT imaging, however, has not been successful due to the technical difficulty in extracting weak cardiogenic components. Instead of regional imaging, in this paper, we use the EIT technique to simultaneously measure two global variables of tidal volume and stroke volume. Time-varying patterns of boundary voltage data originating from lung ventilation and cardiac blood flow were extracted from measured boundary voltage data using the principal component analysis (PCA) and independent component analysis (ICA). The source consistency theory was adopted to separately synthesize time-series of boundary voltage data associated with lung ventilation and cardiac blood flow. The respiratory volume signal (RVS) and cardiac volume signal (CVS) were extracted from reconstructed time-difference EIT images of lung ventilation and cardiac blood flow, respectively. After calibrating the volume signals using the mechanical ventilator and the invasive transpulmonary thermodilution (TPTD) method, tidal volume and stroke volume were computed as valley-to-peak values of the RVS and CVS, respectively. The difference in the tidal volume data between EIT and mechanical ventilator was within ± 20 ml from six pigs. The difference in the stroke volume data between EIT and TPTD was within ± 4.7 ml from the same animals. The results show the feasibility of the proposed method as a new noninvasive cardiopulmonary monitoring tool for simultaneous continuous measurements of stroke volume and tidal volume that are two most important vital signs.
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