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Franchineau G, Jonkman AH, Piquilloud L, Yoshida T, Costa E, Rozé H, Camporota L, Piraino T, Spinelli E, Combes A, Alcala GC, Amato M, Mauri T, Frerichs I, Brochard LJ, Schmidt M. Electrical Impedance Tomography to Monitor Hypoxemic Respiratory Failure. Am J Respir Crit Care Med 2024; 209:670-682. [PMID: 38127779 DOI: 10.1164/rccm.202306-1118ci] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023] Open
Abstract
Hypoxemic respiratory failure is one of the leading causes of mortality in intensive care. Frequent assessment of individual physiological characteristics and delivery of personalized mechanical ventilation (MV) settings is a constant challenge for clinicians caring for these patients. Electrical impedance tomography (EIT) is a radiation-free bedside monitoring device that is able to assess regional lung ventilation and changes in aeration. With real-time tomographic functional images of the lungs obtained through a thoracic belt, clinicians can visualize and estimate the distribution of ventilation at different ventilation settings or following procedures such as prone positioning. Several studies have evaluated the performance of EIT to monitor the effects of different MV settings in patients with acute respiratory distress syndrome, allowing more personalized MV. For instance, EIT could help clinicians find the positive end-expiratory pressure that represents a compromise between recruitment and overdistension and assess the effect of prone positioning on ventilation distribution. The clinical impact of the personalization of MV remains to be explored. Despite inherent limitations such as limited spatial resolution, EIT also offers a unique noninvasive bedside assessment of regional ventilation changes in the ICU. This technology offers the possibility of a continuous, operator-free diagnosis and real-time detection of common problems during MV. This review provides an overview of the functioning of EIT, its main indices, and its performance in monitoring patients with acute respiratory failure. Future perspectives for use in intensive care are also addressed.
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Affiliation(s)
- Guillaume Franchineau
- Service de Medecine Intensive Reanimation, Centre Hospitalier Intercommunal de Poissy-Saint-Germain-en-Laye, Poissy, France
| | - Annemijn H Jonkman
- Department of Intensive Care Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Lise Piquilloud
- Adult Intensive Care Unit, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Takeshi Yoshida
- Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Eduardo Costa
- Pulmonary Division, Cardiopulmonary Department, Heart Institute, University of São Paulo, São Paulo, Brazil
| | - Hadrien Rozé
- Department of Thoraco-Abdominal Anesthesiology and Intensive Care, Bordeaux University Hospital, University of Bordeaux, Bordeaux, France
- Réanimation Polyvalente, Centre Hospitalier Côte Basque, Bayonne, France
| | - Luigi Camporota
- Health Centre for Human and Applied Physiological Sciences, Department of Adult Critical Care, Guy's and St Thomas' National Health Service Foundation Trust, London, United Kingdom
| | - Thomas Piraino
- Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, Ontario, Canada
- Division of Critical Care, Department of Anesthesia, McMaster University, Hamilton, Ontario, Canada
| | - Elena Spinelli
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alain Combes
- Sorbonne Université, Groupe de Recherche Clinique 30, Réanimation et Soins Intensifs du Patient en Insuffisance Respiratoire Aigüe, UMRS_1166-ICAN, Institute of Cardiometabolism and Nutrition, Service de Médecine Intensive - Réanimation, Assistance Publique-Hôpitaux de Paris (APHP) Hôpital Pitié-Salpêtrière, Paris, France
| | - Glasiele C Alcala
- Pulmonary Division, Cardiopulmonary Department, Heart Institute, University of São Paulo, São Paulo, Brazil
| | - Marcelo Amato
- Pulmonary Division, Cardiopulmonary Department, Heart Institute, University of São Paulo, São Paulo, Brazil
| | - Tommaso Mauri
- Department of Anesthesia, Critical Care and Emergency, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Pathophysiology and Transplants, University of Milan, Milan, Italy
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Centre of Schleswig-Holstein Campus Kiel, Kiel, Germany; and
| | - Laurent J Brochard
- Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, Ontario, Canada
- Interdepartmental Division of Critical Care, University of Toronto, Toronto, Ontario, Canada
| | - Matthieu Schmidt
- Sorbonne Université, Groupe de Recherche Clinique 30, Réanimation et Soins Intensifs du Patient en Insuffisance Respiratoire Aigüe, UMRS_1166-ICAN, Institute of Cardiometabolism and Nutrition, Service de Médecine Intensive - Réanimation, Assistance Publique-Hôpitaux de Paris (APHP) Hôpital Pitié-Salpêtrière, Paris, France
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Haudebourg AF, Moncomble E, Lesimple A, Delamaire F, Louis B, Mekontso Dessap A, Mercat A, Richard JC, Beloncle F, Carteaux G. A novel method for assessment of airway opening pressure without the need for low-flow insufflation. Crit Care 2023; 27:273. [PMID: 37420282 PMCID: PMC10329375 DOI: 10.1186/s13054-023-04560-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 07/04/2023] [Indexed: 07/09/2023] Open
Abstract
BACKGROUND Airway opening pressure (AOP) detection and measurement are essential for assessing respiratory mechanics and adapting ventilation. We propose a novel approach for AOP assessment during volume assist control ventilation at a usual constant-flow rate of 60 L/min. OBJECTIVES To validate the conductive pressure (Pcond) method, which compare the Pcond-defined on the airway pressure waveform as the difference between the airway pressure level at which an abrupt change in slope occurs at the beginning of insufflation and PEEP-to resistive pressure for AOP detection and measurement, and to compare its respiratory and hemodynamic tolerance to the standard low-flow insufflation method. METHODS The proof-of-concept of the Pcond method was assessed on mechanical (lung simulator) and physiological (cadavers) bench models. Its diagnostic performance was evaluated in 213 patients, using the standard low-flow insufflation method as a reference. In 45 patients, the respiratory and hemodynamic tolerance of the Pcond method was compared with the standard low-flow method. MEASUREMENTS AND MAIN RESULTS Bench assessments validated the Pcond method proof-of-concept. Sensitivity and specificity of the Pcond method for AOP detection were 93% and 91%, respectively. AOP obtained by Pcond and standard low-flow methods strongly correlated (r = 0.84, p < 0.001). Changes in SpO2 were significantly lower during Pcond than during standard method (p < 0.001). CONCLUSION Determination of Pcond during constant-flow assist control ventilation may permit to easily and safely detect and measure AOP.
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Affiliation(s)
- Anne-Fleur Haudebourg
- Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor-Albert Chenevier, Service de Médecine Intensive Réanimation, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Groupe de Recherche Clinique CARMAS, Faculté de Santé, Université Paris Est-Créteil, 94010, Créteil, France
| | - Elsa Moncomble
- Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor-Albert Chenevier, Service de Médecine Intensive Réanimation, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Groupe de Recherche Clinique CARMAS, Faculté de Santé, Université Paris Est-Créteil, 94010, Créteil, France
| | - Arnaud Lesimple
- CNRS, INSERM 1083, MITOVASC, Université d'Angers, Angers, France
- Laboratoire Med2Lab ALMS, Antony, France
| | - Flora Delamaire
- Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor-Albert Chenevier, Service de Médecine Intensive Réanimation, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Groupe de Recherche Clinique CARMAS, Faculté de Santé, Université Paris Est-Créteil, 94010, Créteil, France
| | - Bruno Louis
- INSERM U955, Institut Mondor de Recherche Biomédicale, 94010, Créteil, France
| | - Armand Mekontso Dessap
- Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor-Albert Chenevier, Service de Médecine Intensive Réanimation, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France
- Groupe de Recherche Clinique CARMAS, Faculté de Santé, Université Paris Est-Créteil, 94010, Créteil, France
- INSERM U955, Institut Mondor de Recherche Biomédicale, 94010, Créteil, France
| | - Alain Mercat
- CNRS, INSERM 1083, MITOVASC, Université d'Angers, Angers, France
- Département de Médecine Intensive-Réanimation et Médecine Hyperbare, Centre Hospitalier Universitaire d'Angers, Vent' Lab, Faculté de Santé, Université d'Angers, Angers, France
| | - Jean-Christophe Richard
- Département de Médecine Intensive-Réanimation et Médecine Hyperbare, Centre Hospitalier Universitaire d'Angers, Vent' Lab, Faculté de Santé, Université d'Angers, Angers, France
- UMR 1066, INSERM, Créteil, France
| | - François Beloncle
- CNRS, INSERM 1083, MITOVASC, Université d'Angers, Angers, France
- Département de Médecine Intensive-Réanimation et Médecine Hyperbare, Centre Hospitalier Universitaire d'Angers, Vent' Lab, Faculté de Santé, Université d'Angers, Angers, France
| | - Guillaume Carteaux
- Assistance Publique-Hôpitaux de Paris, CHU Henri Mondor-Albert Chenevier, Service de Médecine Intensive Réanimation, 51, Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil Cedex, France.
- Groupe de Recherche Clinique CARMAS, Faculté de Santé, Université Paris Est-Créteil, 94010, Créteil, France.
- INSERM U955, Institut Mondor de Recherche Biomédicale, 94010, Créteil, France.
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Bastia L, Rozé H, Brochard L. Asymmetrical Lung Injury: Management and Outcome. Semin Respir Crit Care Med 2022; 43:369-378. [PMID: 35785812 DOI: 10.1055/s-0042-1744303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Among mechanically ventilated patients, asymmetrical lung injury is probably extremely frequent in the intensive care unit but the lack of standardized measurements does not allow to describe any prevalence among mechanically ventilated patients. Many past studies have focused only on unilateral injury and have mostly described the effect of lateral positioning. The good lung put downward might receive more perfusion while the sick lung placed upward receive more ventilation than supine. This usually results in better oxygenation but can also promote atelectasis in the healthy lung and no consensus has emerged on the clinical indication of this posture. Recently, electrical impedance tomography (EIT) has allowed for the first time to precisely describe the distribution of ventilation in each lung and to better study asymmetrical lung injury. At low positive-end-expiratory pressure (PEEP), a very heterogeneous ventilation exists between the two lungs and the initial increase in PEEP first helps to recruit the sick lung and protect the healthier lung. However, further increasing PEEP distends the less injured lung and must be avoided. The right level can be found using EIT and transpulmonary pressure. In addition, EIT can show that in the two lungs, airway closure is present but with very different airway opening pressures (AOPs) which cannot be identified on a global assessment. This may suggest a very different PEEP level than on a global assessment. Lastly, epidemiological studies suggest that in hypoxemic patients, the number of quadrants involved has a strong prognostic value. The number of quadrants is more important than the location of the unilateral or bilateral nature of the involvement for the prognosis, and hypoxemic patients with unilateral lung injury should probably be considered as requiring lung protective ventilation as classical acute respiratory distress syndrome.
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Affiliation(s)
- Luca Bastia
- Neurointensive Care Unit, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy.,Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Hadrien Rozé
- Thoracic Surgery and Lung Transplant Unit, Department of Anesthesiology and Critical Care, Bordeaux University Hospital, Haut Leveque Hospital, Pessac, France.,Centre de Recherche Cardio Thoracique INSERM 1045, Pessac, France
| | - Laurent Brochard
- Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada.,Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.,Keenan Research Centre, Li Ka Shing Knowledge Institute, St Michael's Hospital, Unity Health Toronto, Toronto, Canada
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4
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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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Chen Z, Hu Z, Zhong M, Deng L, Tao J, Song Y. Potential effect of pulmonary fluid viscosity on positive end-expiratory pressure and regional distribution of lung ventilation in acute respiratory distress syndrome. Clin Biomech (Bristol, Avon) 2021; 87:105407. [PMID: 34214731 PMCID: PMC9756214 DOI: 10.1016/j.clinbiomech.2021.105407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/03/2021] [Accepted: 06/03/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Computational fluid dynamic simulations have showed that the elevated viscosity of pulmonary fluids may increase the likelihood of airway closure, thus exacerbating inhomogeneity of regional lung ventilation. Unfortunately, there have been few studies directed toward measurements of viscosity of pulmonary fluids and its effect on airway opening pressure and regional distribution of lung ventilation in acute respiratory distress syndrome. METHODS In this study, pulmonary fluids from 8 ARDS patients were measured using a cone and plate rheometer on days 1, 3, 7 and 14 in the treatment of the disorder. Ventilator settings were simultaneously recorded, including tidal volume, positive end-expiratory pressure, fraction of inspired oxygen (FiO2), and so on. The regional distribution of lung ventilation was monitored by a bedside electrical impedance tomography system. FINDINGS The results showed that rheological properties of pulmonary fluids behaved as either Newtonian or non-Newtonian across all patients studied. Significant intersubject and intrasubject variations in measured viscosities were observed, spanning ranges from approximately 1 cP to 7 × 104 cP at shear rates between 0.075-750 s-1. The product of the positive end-expiratory airway pressure and fraction of inspired oxygen was well correlated with fluid viscosity in patients with high viscosity pulmonary fluids. Furthermore, lung ventilation in these patients was highly inhomogeneous and influenced by rheology of pulmonary fluids. INTERPRETATION The current findings provided the direct clinical data for theoretical models of airway reopening and may have important clinical implications in explaining inhomogeneity of lung ventilation and selecting initial levels of positive end-expiratory pressure in mechanically ventilated patients.
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Affiliation(s)
- Zhenglong Chen
- School of Medical Instrumentation, Shanghai University of Medicine & Health Sciences, Shanghai, China,NMPA Key Laboratory for Respiratory and Anaesthetic Equipment, Shanghai, China
| | - Zhaoyan Hu
- School of Medical Instrumentation, Shanghai University of Medicine & Health Sciences, Shanghai, China,NMPA Key Laboratory for Respiratory and Anaesthetic Equipment, Shanghai, China
| | - Ming Zhong
- Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,Corresponding author at: Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District 200032, Shanghai, China
| | - Linhong Deng
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, China
| | - Jiale Tao
- Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yuanlin Song
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China,Corresponding author
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6
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Sun XM, Chen GQ, Wang YM, Zhou YM, Chen JR, Cheng KM, Yang YL, Zhang LL, Li HL, Zhou JX. Derecruitment volume assessment derived from pressure-impedance curves with electrical impedance tomography in experimental acute lung injury. J Int Med Res 2021; 48:300060520949037. [PMID: 32816562 PMCID: PMC7444134 DOI: 10.1177/0300060520949037] [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] [Indexed: 12/16/2022] Open
Abstract
Objective To investigate the accuracy of derecruitment volume (VDER) assessed by pressure–impedance (P-I) curves derived from electrical impedance tomography (EIT). Methods Six pigs with acute lung injury received decremental positive end-expiratory pressure (PEEP) from 15 to 0 in steps of 5 cmH2O. At the end of each PEEP level, the pressure–volume (P-V) curves were plotted using the low constant flow method and release maneuvers to calculate the VDER between the PEEP of setting levels and 0 cmH2O (VDER-PV). The VDER derived from P-I curves that were recorded simultaneously using EIT was the difference in impedance at the same pressure multiplied by the ratio of tidal volume and corresponding tidal impedance (VDER-PI). The regional P-I curves obtained by EIT were used to estimate VDER in the dependent and nondependent lung. Results The global lung VDER-PV and VDER-PI showed close correlations (r = 0.948, P<0.001); the mean difference was 48 mL with limits of agreement of −133 to 229 mL. Lung derecruitment extended into the whole process of decremental PEEP levels but was unevenly distributed in different lung regions. Conclusions P-I curves derived from EIT can assess VDER and provide a promising method to estimate regional lung derecruitment at the bedside.
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Affiliation(s)
- Xiu-Mei Sun
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Guang-Qiang Chen
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yu-Mei Wang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yi-Min Zhou
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jing-Ran Chen
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Kun-Ming Cheng
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yan-Lin Yang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Lin-Lin Zhang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Hong-Liang Li
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jian-Xin Zhou
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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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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Rozé H, Boisselier C, Bonnardel E, Perrier V, Repusseau B, Brochard L, Ouattara A. Electrical Impedance Tomography to Detect Airway Closure Heterogeneity in Asymmetrical Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 2021; 203:511-515. [PMID: 33030960 DOI: 10.1164/rccm.202007-2937le] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Hadrien Rozé
- Bordeaux University Hospital Bordeaux, France.,University Bordeaux Pessac, France
| | | | | | | | | | - Laurent Brochard
- St. Michael's Hospital Toronto, Ontario, Canada and.,University of Toronto Toronto, Ontario, Canada
| | - Alexandre Ouattara
- Bordeaux University Hospital Bordeaux, France.,University Bordeaux Pessac, France
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Hedenstierna G, Chen L, Brochard L. Airway closure, more harmful than atelectasis in intensive care? Intensive Care Med 2020; 46:2373-2376. [PMID: 32500181 PMCID: PMC7271133 DOI: 10.1007/s00134-020-06144-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 05/26/2020] [Indexed: 01/23/2023]
Affiliation(s)
- Göran Hedenstierna
- Hedenstierna Laboratory, Department of Medical Sciences, University Hospital, Uppsala University, Entr 40:2, 75185, Uppsala, Sweden.
| | - Lu Chen
- Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Laurent Brochard
- Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
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Prevalence of Complete Airway Closure According to Body Mass Index in Acute Respiratory Distress Syndrome. Anesthesiology 2020; 133:867-878. [PMID: 32701573 DOI: 10.1097/aln.0000000000003444] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Complete airway closure during expiration may underestimate alveolar pressure. It has been reported in cases of acute respiratory distress syndrome (ARDS), as well as in morbidly obese patients with healthy lungs. The authors hypothesized that complete airway closure was highly prevalent in obese ARDS and influenced the calculation of respiratory mechanics. METHODS In a post hoc pooled analysis of two cohorts, ARDS patients were classified according to body mass index (BMI) terciles. Low-flow inflation pressure-volume curve and partitioned respiratory mechanics using esophageal manometry were recorded. The authors' primary aim was to compare the prevalence of complete airway closure according to BMI terciles. Secondary aims were to compare (1) respiratory system mechanics considering or not considering complete airway closure in their calculation, and (2) and partitioned respiratory mechanics according to BMI. RESULTS Among the 51 patients analyzed, BMI was less than 30 kg/m2 in 18, from 30 to less than 40 in 16, and greater than or equal to 40 in 17. Prevalence of complete airway closure was 41% overall (95% CI, 28 to 55; 21 of 51 patients), and was lower in the lowest (22% [3 to 41]; 4 of 18 patients) than in the highest BMI tercile (65% [42 to 87]; 11 of 17 patients). Driving pressure and elastances of the respiratory system and of the lung were higher when complete airway closure was not taken into account in their calculation. End-expiratory esophageal pressure (ρ = 0.69 [95% CI, 0.48 to 0.82]; P < 0.001), but not chest wall elastance, was associated with BMI, whereas elastance of the lung was negatively correlated with BMI (ρ = -0.27 [95% CI, -0.56 to -0.10]; P = 0.014). CONCLUSIONS Prevalence of complete airway closure was high in ARDS and should be taken into account when calculating respiratory mechanics, especially in the most morbidly obese patients. EDITOR’S PERSPECTIVE
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12
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Zhao Z, Fu F, Frerichs I. Thoracic electrical impedance tomography in Chinese hospitals: a review of clinical research and daily applications. Physiol Meas 2020; 41:04TR01. [PMID: 32197257 DOI: 10.1088/1361-6579/ab81df] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chinese scientists and researchers have a long history with electrical impedance tomography (EIT), which can be dated back to the 1980s. No commercial EIT devices for chest imaging were available until the year 2014 when the first device received its approval from the China Food and Drug Administration. Ever since then, clinical research and daily applications have taken place in Chinese hospitals. Up to this date (2019.11) 47 hospitals have been equipped with 50 EIT devices. Twenty-three SCI publications are recorded and a further 21 clinical trials are registered. Thoracic EIT is mainly used in patients before or after surgery, or in intensive care units (ICU). Application fields include the development of strategies for protective lung ventilation (e.g. tidal volume and positive end-expiratory pressure (PEEP) titration, recruitment, choice of ventilation mode and weaning from ventilator), regional lung perfusion monitoring, perioperative monitoring, and potential feedback for rehabilitation. The main challenges for promoting clinical use of EIT are the financial cost and the education of personnel. In this review, the past, present and future of EIT in China are introduced and discussed.
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Affiliation(s)
- Zhanqi Zhao
- Department of Biomedical Engineering, Fourth Military Medical University, No. 169 Changle West Road, Xincheng District, Xi'an 710005 People's Republic of China. Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
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13
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Wang YM, Sun XM, Zhou YM, Chen JR, Cheng KM, Li HL, Yang YL, Zhang L, Zhou JX. Use of Electrical Impedance Tomography (EIT) to Estimate Global and Regional Lung Recruitment Volume (VREC) Induced by Positive End-Expiratory Pressure (PEEP): An Experiment in Pigs with Lung Injury. Med Sci Monit 2020; 26:e922609. [PMID: 32172276 PMCID: PMC7094060 DOI: 10.12659/msm.922609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Background Electrical impedance tomography (EIT) is a real-time tool used to monitor lung volume change at the bedside, which could be used to measure lung recruitment volume (VREC) for setting positive end-expiratory pressure (PEEP). We assessed and compared the agreement in VREC measurement with the EIT method versus the flow-derived method. Material/Methods In 12 Bama pigs, lung injury was induced by tracheal instillation of hydrochloric acid and verified by an arterial partial pressure of oxygen to inspired oxygen fraction ratio below 200 mmHg. During the end-expiratory occlusion, an airway release maneuver was conduct at 5 and 15 cmH2O of PEEP. VREC was measured by flow-integrated PEEP-induced lung volume change (flow-derived method) and end-expiratory lung impedance change (EIT-derived method). Linear regression and Bland-Altman analysis were used to test the correlation and agreement between these 2 measures. Results Lung injury was successfully induced in all the animals. EIT-derived VREC was significantly correlated with flow-derived VREC (R2=0.650, p=0.002). The bias (the lower and upper limits of agreement) was −19 (−182 to 144) ml. The median (interquartile range) of EIT-derived VREC was 322 (218–469) ml, with 110 (59–142) ml and 194 (157–307) ml in dependent and nondependent lung regions, respectively. Global and regional respiratory system compliance increased significantly at high PEEP compared to those at low PEEP. Conclusions Close correlation and agreement were found between EIT-derived and flow-derived VREC measurements. The advantages of EIT-derived recruitability assessment included the avoidance of ventilation interruption and the ability to provide regional recruitment information.
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Affiliation(s)
- Yu-Mei Wang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Xiu-Mei Sun
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Yi-Min Zhou
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Jing-Ran Chen
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Kun-Ming Cheng
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Hong-Liang Li
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Yan-Lin Yang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Linlin Zhang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
| | - Jian-Xin Zhou
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (mainland)
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14
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Abstract
BACKGROUND Airway closure causes lack of communication between proximal airways and alveoli, making tidal inflation start only after a critical airway opening pressure is overcome. The authors conducted a matched cohort study to report the existence of this phenomenon among obese patients undergoing general anesthesia. METHODS Within the procedures of a clinical trial during gynecological surgery, obese patients underwent respiratory/lung mechanics and lung volume assessment both before and after pneumoperitoneum, in the supine and Trendelenburg positions, respectively. Among patients included in this study, those exhibiting airway closure were compared to a control group of subjects enrolled in the same trial and matched in 1:1 ratio according to body mass index. RESULTS Eleven of 50 patients (22%) showed airway closure after intubation, with a median (interquartile range) airway opening pressure of 9 cm H2O (6 to 12). With pneumoperitoneum, airway opening pressure increased up to 21 cm H2O (19 to 28) and end-expiratory lung volume remained unchanged (1,294 ml [1,154 to 1,363] vs. 1,160 ml [1,118 to 1,256], P = 0.155), because end-expiratory alveolar pressure increased consistently with airway opening pressure and counterbalanced pneumoperitoneum-induced increases in end-expiratory esophageal pressure (16 cm H2O [15 to 19] vs. 27 cm H2O [23 to 30], P = 0.005). Conversely, matched control subjects experienced a statistically significant greater reduction in end-expiratory lung volume due to pneumoperitoneum (1,113 ml [1,040 to 1,577] vs. 1,000 ml [821 to 1,061], P = 0.006). With airway closure, static/dynamic mechanics failed to measure actual lung/respiratory mechanics. When patients with airway closure underwent pressure-controlled ventilation, no tidal volume was inflated until inspiratory pressure overcame airway opening pressure. CONCLUSIONS In obese patients, complete airway closure is frequent during anesthesia and is worsened by Trendelenburg pneumoperitoneum, which increases airway opening pressure and alveolar pressure: besides preventing alveolar derecruitment, this yields misinterpretation of respiratory mechanics and generates a pressure threshold to inflate the lung that can reach high values, spreading concerns on the safety of pressure-controlled modes in this setting.
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15
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Airway closure and fiberoptic evidence of bronchial collapse during the acute respiratory distress syndrome. Intensive Care Med 2019; 45:1838-1839. [DOI: 10.1007/s00134-019-05800-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2019] [Indexed: 11/27/2022]
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16
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Vasques F, Sanderson B, Barrett NA, Camporota L. Monitoring of regional lung ventilation using electrical impedance tomography. Minerva Anestesiol 2019; 85:1231-1241. [PMID: 30945516 DOI: 10.23736/s0375-9393.19.13477-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among recent lung imaging techniques and devices, electrical impedance tomography (EIT) can provide dynamic information on the distribution regional lung ventilation. EIT images possess a high temporal and functional resolution allowing the visualization of dynamic physiological and pathological changes on a breath-by-breath basis. EIT detects changes in electric impedance (i.e., changes in gas/fluid ratio) and describes them in real time, both visually through images and waveforms, and numerically, allowing the clinician to monitor disease evolution and response to treatment. The use of EIT in clinical practice is supported by several studies demonstrating a good correlation between impedance tomography data and other validated methods of measuring lung volume. In this review, we will provide an overview on the rationale, basic functioning and most common applications of EIT in the management of mechanically ventilated patients.
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Affiliation(s)
- Francesco Vasques
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Barnaby Sanderson
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Nicholas A Barrett
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
| | - Luigi Camporota
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK - .,Division of Centre of Human Applied Physiological Sciences, King's College London, London, UK
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17
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Bachmann MC, Morais C, Bugedo G, Bruhn A, Morales A, Borges JB, Costa E, Retamal J. Electrical impedance tomography in acute respiratory distress syndrome. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2018; 22:263. [PMID: 30360753 PMCID: PMC6203288 DOI: 10.1186/s13054-018-2195-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/14/2018] [Indexed: 12/29/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is a clinical entity that acutely affects the lung parenchyma, and is characterized by diffuse alveolar damage and increased pulmonary vascular permeability. Currently, computed tomography (CT) is commonly used for classifying and prognosticating ARDS. However, performing this examination in critically ill patients is complex, due to the need to transfer these patients to the CT room. Fortunately, new technologies have been developed that allow the monitoring of patients at the bedside. Electrical impedance tomography (EIT) is a monitoring tool that allows one to evaluate at the bedside the distribution of pulmonary ventilation continuously, in real time, and which has proven to be useful in optimizing mechanical ventilation parameters in critically ill patients. Several clinical applications of EIT have been developed during the last years and the technique has been generating increasing interest among researchers. However, among clinicians, there is still a lack of knowledge regarding the technical principles of EIT and potential applications in ARDS patients. The aim of this review is to present the characteristics, technical concepts, and clinical applications of EIT, which may allow better monitoring of lung function during ARDS.
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Affiliation(s)
- M Consuelo Bachmann
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Caio Morais
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Guillermo Bugedo
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Alejandro Bruhn
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile
| | - Arturo Morales
- Departamento Enfermedades Respiratorias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - João B Borges
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.,Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anaesthesiology and Critical Care, Uppsala University, Uppsala, Sweden
| | - Eduardo Costa
- Divisao de Pneumologia, Instituto do Coracao (Incor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil
| | - Jaime Retamal
- Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Acute Respiratory and Critical Illness Center (ARCI), Santiago, Chile.
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