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Sun N, Brault C, Rodrigues A, Ko M, Vieira F, Phoophiboon V, Slama M, Chen L, Brochard L. Distribution of airway pressure opening in the lungs measured with electrical impedance tomography (POET): a prospective physiological study. Crit Care 2025; 29:28. [PMID: 39819779 PMCID: PMC11740639 DOI: 10.1186/s13054-025-05264-3] [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: 10/18/2024] [Accepted: 01/07/2025] [Indexed: 01/19/2025] Open
Abstract
BACKGROUND In patients with acute hypoxemic respiratory failure (AHRF) under mechanical ventilation, the change in pressure slope during a low-flow insufflation indicates a global airway opening pressure (AOP) needed to reopen closed airways and may be used for titration of positive end-expiratory pressure. OBJECTIVES To understand 1) if airways open homogeneously inside the lungs or significant regional AOP variations exist; 2) whether the pattern of the pressure slope change during low-flow insufflation can indicate the presence of regional AOP variations. METHODS Using electrical impedance tomography, we recorded low-flow insufflation maneuvers (< 10 L/min) starting from end-expiratory positive pressure 0-5 cmH2O. We measured global (AOPglobal) and regional AOPs from pressure-impedance curves in the four different lung quadrants, and compared AOPglobal with the highest quadrantal AOP (AOPhighest). We categorized the slope change of the low-flow inflation pressure-time curve into three patterns: no change, progressive change, abrupt change. RESULTS Among the 36 patients analyzed, 9 (25%) had AOPglobal ≥ 5 cmH2O whereas 19 (53%) exhibited regional AOPhighest ≥ 5 cmH2O. AOPglobal was on average similar to AOP of the upper right quadrant (P = 0.182) but was lower than AOPs of the other three quadrants (P < 0.01 of each). AOPglobal was significantly lower than AOPhighest: 3.0 [2.0-4.3] vs. 5.0 [2.8-8.3] cmH2O, P < 0.001. AOP was higher in the dependent than the non-dependent ventilated lung (4.0 [2.0-6.3] vs. 3.0 [2.0-5.0] cmH2O, P < 0.001). Seventeen (47%) patients exhibited a 'progressive change' pattern in the pressure-time curve. These patients had a larger difference between AOPhighest and AOPglobal (3.0 [2.0-4.0] cmH2O with a maximum of 8 cmH2O) compared to the other two patterns: 1.0 [0-1.0] cmH2O in 'no change' , P < 0.001 and 1.0 [0-2.0] cmH2O in 'abrupt change' , P = 0.003. CONCLUSION AOPglobal mostly reflects the lowest opening pressure in the lung and frequently underestimates the highest regional AOP in mechanically ventilated patients with AHRF. A progressive slope change during the low-flow pressure-time curve indicates the presence of several and higher regional AOPs. TRIAL REGISTRATION Clinicaltrials.gov, NCT05825534 (registered, April 24th, 2023), retrospectively registered.
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Affiliation(s)
- Nannan Sun
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Department of Critical Care Medicine and Anesthesia Intensive Care Unit, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Institute of Anesthesia and Respiratory Critical Medicine, Shandong Provincial Clinical Research Center for Anesthesiology, Jinan, Shandong, China
| | - Clement Brault
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Intensive Care Department, Amiens-Picardie University Hospital, Amiens, France
| | - Antenor Rodrigues
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Matthew Ko
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Fernando Vieira
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Vorakamol Phoophiboon
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Michel Slama
- Intensive Care Department, Amiens-Picardie University Hospital, Amiens, France
| | - Lu Chen
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Laurent Brochard
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, Unity Health Toronto, Toronto, ON, Canada.
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.
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Giani M, Restivo A, Raimondi Cominesi D, Fracchia R, Pozzi M, Del Sorbo L, Foti G, Brochard L, Rezoagli E. Prone-position decreases airway closure in a patient with ARDS undergoing venovenous extracorporeal membrane oxygenation. J Clin Monit Comput 2024; 38:1425-1429. [PMID: 39066871 DOI: 10.1007/s10877-024-01182-x] [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: 02/18/2024] [Accepted: 05/27/2024] [Indexed: 07/30/2024]
Abstract
PURPOSE Airway closure is a interruption of communication between larger and smaller airways. The presence of airway closure during mechanical ventilation may lead to the overestimation of driving pressure (DP), introducing errors in the assessment of respiratory mechanics and in positive end-expiratory pressure (PEEP) setting on the ventilator. Patients with severe acute respiratory distress syndrome (ARDS) may exhibit the airway closure phenomenon, which can be easily diagnosed with a low-flow inflation. Prone positioning is a therapeutic manoeuver proven to reduce mortality in ARDS patients, and has been widely implemented also in patients requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). To date, the impact of prone positioning on changes in airway closure has not been described. METHODS We present an image analysis of the pressure waveform during volume-controlled ventilation and low-flow inflations before and after prone positioning in an ARDS patient on VV ECMO. RESULTS A high airway opening pressure level (23 cmH2O) was detected in the supine position during tidal ventilation. Airway closure was confirmed by using a low-flow inflation. Prone positioning significantly attenuated airway closure, with the airway opening pressure decreasing to 13 cmH2O. After re-supination, airway closure was lower as compared with supine position at baseline (17 cmH2O). CONCLUSION Prone positioning reduced airway closure in an ARDS patient on VV ECMO support.
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Affiliation(s)
- Marco Giani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Department of Emergency and Intensive Care, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Andrea Restivo
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | | | - Rosa Fracchia
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Department of Emergency and Intensive Care, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Matteo Pozzi
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Department of Emergency and Intensive Care, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Lorenzo Del Sorbo
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Department of Medicine, Division of Respirology, University Health Network/Sinai Health System, University of Toronto, Toronto, Canada
- Toronto General Hospital, Toronto, Canada
| | - Giuseppe Foti
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- Department of Emergency and Intensive Care, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Laurent Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St Michael's Hospital, Unity Health Toronto, Toronto, Canada
| | - Emanuele Rezoagli
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
- Department of Emergency and Intensive Care, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy.
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Rodriguez Guerineau L, Vieira F, Rodrigues A, Reise K, Todd M, Guerguerian AM, Brochard L. Airway opening pressure maneuver to detect airway closure in mechanically ventilated pediatric patients. Front Pediatr 2024; 12:1310494. [PMID: 38379913 PMCID: PMC10877025 DOI: 10.3389/fped.2024.1310494] [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: 10/09/2023] [Accepted: 01/12/2024] [Indexed: 02/22/2024] Open
Abstract
Background Airway closure, which refers to the complete collapse of the airway, has been described under mechanical ventilation during anesthesia and more recently in adult patients with acute respiratory distress syndrome (ARDS). A ventilator maneuver can be used to identify airway closure and measure the pressure required for the airway to reopen, known as the airway opening pressure (AOP). Without that maneuver, AOP is unknown to clinicians. Objective This study aims to demonstrate the technical adaptation of the adult maneuver for children and illustrate its application in two cases of pediatric ARDS (p-ARDS). Methods A bench study was performed to adapt the maneuver for 3-50 kg patients. Four maneuvers were performed for each simulated patient, with 1, 2, 3, and 4 s of insufflation time to deliver a tidal volume (Vt) of 6 ml/kg by a continuous flow. Results Airway closure was simulated, and AOP was visible at 15 cmH2O with a clear inflection point, except for the 3 kg simulated patient. Regarding insufflation time, a 4 s maneuver exhibited a better performance in 30 and 50 kg simulated patients since shorter insufflation times had excessive flowrates (>10 L/min). Below 20 kg, the difference in resistive pressure between a 3 s and a 4 sec maneuver was negligible; therefore, prolonging the maneuver beyond 3 s was not useful. Airway closure was identified in two p-ARDS patients, with the pediatric maneuver being employed in the 28 kg patient. Conclusions We propose a pediatric AOP maneuver delivering 6 ml/kg of Vt at a continuous low-flow inflation for 3 s for patients weighing up to 20 kg and for 4 s for patients weighing beyond 20 kg.
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Affiliation(s)
- Luciana Rodriguez Guerineau
- Department of Critical Care Medicine, Hospital for Sick Children, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Fernando Vieira
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Antenor Rodrigues
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Katherine Reise
- Department of Respiratory Therapy and Critical Care Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Mark Todd
- Department of Respiratory Therapy and Critical Care Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Anne-Marie Guerguerian
- Department of Critical Care Medicine, Hospital for Sick Children, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Laurent Brochard
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
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Viola HL, Vasani V, Washington K, Lee JH, Selva C, Li A, Llorente CJ, Murayama Y, Grotberg JB, Romanò F, Takayama S. Liquid plug propagation in computer-controlled microfluidic airway-on-a-chip with semi-circular microchannels. LAB ON A CHIP 2024; 24:197-209. [PMID: 38093669 PMCID: PMC10842925 DOI: 10.1039/d3lc00957b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
This paper introduces a two-inlet, one-outlet lung-on-a-chip device with semi-circular cross-section microchannels and computer-controlled fluidic switching that enables a broader systematic investigation of liquid plug dynamics in a manner relevant to the distal airways. A leak-proof bonding protocol for micro-milled devices facilitates channel bonding and culture of confluent primary small airway epithelial cells. Production of liquid plugs with computer-controlled inlet channel valving and just one outlet allows more stable long-term plug generation and propagation compared to previous designs. The system also captures both plug speed and length as well as pressure drop concurrently. In one demonstration, the system reproducibly generates surfactant-containing liquid plugs, a challenging process due to lower surface tension that makes the plug formation less stable. The addition of surfactant decreases the pressure required to initiate plug propagation, a potentially significant effect in diseases where surfactant in the airways is absent or dysfunctional. Next, the device recapitulates the effect of increasing fluid viscosity, a challenging analysis due to higher resistance of viscous fluids that makes plug formation and propagation more difficult particularly in airway-relevant length scales. Experimental results show that increased fluid viscosity decreases plug propagation speed for a given air flow rate. These findings are supplemented by computational modeling of viscous plug propagation that demonstrates increased plug propagation time, increased maximum wall shear stress, and greater pressure differentials in more viscous conditions of plug propagation. These results match physiology as mucus viscosity is increased in various obstructive lung diseases where it is known that respiratory mechanics can be compromised due to mucus plugging of the distal airways. Finally, experiments evaluate the effect of channel geometry on primary human small airway epithelial cell injury in this lung-on-a-chip. There is more injury in the middle of the channel relative to the edges highlighting the role of channel shape, a physiologically relevant parameter as airway cross-sectional geometry can also be non-circular. In sum, this paper describes a system that pushes the device limits with regards to the types of liquid plugs that can be stably generated for studies of distal airway fluid mechanical injury.
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Affiliation(s)
- Hannah L Viola
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
| | - Vishwa Vasani
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Kendra Washington
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, 30332, USA
| | - Ji-Hoon Lee
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Cauviya Selva
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, 30332, USA
| | - Andrea Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, 30332, USA
| | - Carlos J Llorente
- Department of Physics & Astronomy, Michigan State University, Lansing, MI, 48824, USA
| | - Yoshinobu Murayama
- Department of Electrical and Electronics Engineering, College of Engineering, Nihon University, Fukushima, Japan
| | - James B Grotberg
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Francesco Romanò
- Univ. Lille, CNRS, ONERA, Arts et Métiers Institute of Technology, Centrale Lille, FRE 2017-LMFL-Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet, F-59000, Lille, France
| | - Shuichi Takayama
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, 30332, USA
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5
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Katsamenis OL, Basford PJ, Robinson SK, Boardman RP, Konstantinopoulou E, Lackie PM, Page A, Ratnayaka JA, Goggin PM, Thomas GJ, Cox SJ, Sinclair I, Schneider P. A high-throughput 3D X-ray histology facility for biomedical research and preclinical applications. Wellcome Open Res 2023; 8:366. [PMID: 37928208 PMCID: PMC10620852 DOI: 10.12688/wellcomeopenres.19666.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2023] [Indexed: 11/07/2023] Open
Abstract
Background The University of Southampton, in collaboration with the University Hospital Southampton (UHS) NHS Foundation Trust and industrial partners, has been at the forefront of developing three-dimensional (3D) imaging workflows using X-ray microfocus computed tomography (μCT) -based technology. This article presents the outcomes of these endeavours and highlights the distinctive characteristics of a μCT facility tailored explicitly for 3D X-ray Histology, with a primary focus on applications in biomedical research and preclinical and clinical studies. Methods The UHS houses a unique 3D X-ray Histology (XRH) facility, offering a range of services to national and international clients. The facility employs specialised μCT equipment explicitly designed for histology applications, allowing whole-block XRH imaging of formalin-fixed and paraffin-embedded tissue specimens. It also enables correlative imaging by combining μCT imaging with other microscopy techniques, such as immunohistochemistry (IHC) and serial block-face scanning electron microscopy, as well as data visualisation, image quantification, and bespoke analysis. Results Over the past seven years, the XRH facility has successfully completed over 120 projects in collaboration with researchers from 60 affiliations, resulting in numerous published manuscripts and conference proceedings. The facility has streamlined the μCT imaging process, improving productivity and enabling efficient acquisition of 3D datasets. Discussion & Conclusions The 3D X-ray Histology (XRH) facility at UHS is a pioneering platform in the field of histology and biomedical imaging. To the best of our knowledge, it stands out as the world's first dedicated XRH facility, encompassing every aspect of the imaging process, from user support to data generation, analysis, training, archiving, and metadata generation. This article serves as a comprehensive guide for establishing similar XRH facilities, covering key aspects of facility setup and operation. Researchers and institutions interested in developing state-of-the-art histology and imaging facilities can utilise this resource to explore new frontiers in their research and discoveries.
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Affiliation(s)
- Orestis L. Katsamenis
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Philip J. Basford
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton, UK
- Computational Engineering and Design, Faculty of Engineering and Physical Sciences,, University of Southampton, Southampton, England, SO17 1BJ, UK
| | - Stephanie K. Robinson
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
| | - Richard P. Boardman
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
| | - Elena Konstantinopoulou
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
| | - Peter M. Lackie
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
- Biomedical Imaging Unit, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
| | - Anton Page
- University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - J. Arjuna Ratnayaka
- Institute for Life Sciences, University of Southampton, Southampton, UK
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
- Biomedical Imaging Unit, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Patricia M. Goggin
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
- Biomedical Imaging Unit, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Gareth J. Thomas
- Institute for Life Sciences, University of Southampton, Southampton, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- School of Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, England, SO16 6YD, UK
| | - Simon J. Cox
- Institute for Life Sciences, University of Southampton, Southampton, UK
- Computational Engineering and Design, Faculty of Engineering and Physical Sciences,, University of Southampton, Southampton, England, SO17 1BJ, UK
| | - Ian Sinclair
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Philipp Schneider
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, England, SO17 1BJ, UK
- High-Performance Vision Systems, Center for Vision, Automation & Control, AIT Austrian Institute of Technology, Vienna, Austria
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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: 8] [Impact Index Per Article: 4.0] [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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Viola HL, Vasani V, Washington K, Lee JH, Selva C, Li A, Llorente CJ, Murayama Y, Grotberg JB, Romanò F, Takayama S. Liquid plug propagation in computer-controlled microfluidic airway-on-a-chip with semi-circular microchannels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.24.542177. [PMID: 37292706 PMCID: PMC10245866 DOI: 10.1101/2023.05.24.542177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This paper introduces a two-inlet, one-outlet lung-on-a-chip device with semi-circular cross-section microchannels and computer-controlled fluidic switching that enables a broader systematic investigation of liquid plug dynamics in a manner relevant to the distal airways. A leak-proof bonding protocol for micro-milled devices facilitates channel bonding and culture of confluent primary small airway epithelial cells. Production of liquid plugs with computer-controlled inlet channel valving and just one outlet allows more stable long-term plug generation and propagation compared to previous designs. The system also captures both plug speed and length as well as pressure drop concurrently. In one demonstration, the system reproducibly generates surfactant-containing liquid plugs, a challenging process due to lower surface tension that makes the plug formation less stable. The addition of surfactant decreases the pressure required to initiate plug propagation, a potentially significant effect in diseases where surfactant in the airways is absent or dysfunctional. Next, the device recapitulates the effect of increasing fluid viscosity, a challenging analysis due to higher resistance of viscous fluids that makes plug formation and propagation more difficult particularly in airway-relevant length scales. Experimental results show that increased fluid viscosity decreases plug propagation speed for a given air flow rate. These findings are supplemented by computational modeling of viscous plug propagation that demonstrate increased plug propagation time, increased maximum wall shear stress, and greater pressure differentials in more viscous conditions of plug propagation. These results match physiology as mucus viscosity is increased in various obstructive lung diseases where it is known that respiratory mechanics can be compromised due to mucus plugging of the distal airways. Finally, experiments evaluate the effect of channel geometry on primary human small airway epithelial cell injury in this lung-on-a-chip. There is more injury in the middle of the channel relative to the edges highlighting the role of channel shape, a physiologically relevant parameter as airway cross-sectional geometry can also be non-circular. In sum, this paper describes a system that pushes the device limits with regards to the types of liquid plugs that can be stably generated for studies of distal airway fluid mechanical injury.
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Affiliation(s)
- Hannah L Viola
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 30332
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA, 30332
| | - Vishwa Vasani
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA, 30332
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 30332
| | - Kendra Washington
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, USA, 30332
| | - Ji-Hoon Lee
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA, 30332
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 30332
| | - Cauviya Selva
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, USA, 30332
| | - Andrea Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, USA, 30332
| | - Carlos J Llorente
- Department of Physics & Astronomy, Michigan State University, Lansing, MI, USA, 48824
| | - Yoshinobu Murayama
- Department of Electrical and Electronics Engineering, College of Engineering, Nihon University, Fukushima, Japan
| | - James B Grotberg
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA, 48109
| | - Francesco Romanò
- Univ. Lille, CNRS, ONERA, Arts et Métiers Institute of Technology, Centrale Lille, FRE 2017 -LMFL-Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet, F-59000, Lille, France
| | - Shuichi Takayama
- The Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA, 30332
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, GA, USA, 30332
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8
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Brunet J, Walsh CL, Wagner WL, Bellier A, Werlein C, Marussi S, Jonigk DD, Verleden SE, Ackermann M, Lee PD, Tafforeau P. Preparation of large biological samples for high-resolution, hierarchical, synchrotron phase-contrast tomography with multimodal imaging compatibility. Nat Protoc 2023; 18:1441-1461. [PMID: 36859614 DOI: 10.1038/s41596-023-00804-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 12/12/2022] [Indexed: 03/03/2023]
Abstract
Imaging across different scales is essential for understanding healthy organ morphology and pathophysiological changes. The macro- and microscale three-dimensional morphology of large samples, including intact human organs, is possible with X-ray microtomography (using laboratory or synchrotron sources). Preparation of large samples for high-resolution imaging, however, is challenging due to limitations such as sample shrinkage, insufficient contrast, movement of the sample and bubble formation during mounting or scanning. Here, we describe the preparation, stabilization, dehydration and mounting of large soft-tissue samples for X-ray microtomography. We detail the protocol applied to whole human organs and hierarchical phase-contrast tomography at the European Synchrotron Radiation Facility, yet it is applicable to a range of biological samples, including complete organisms. The protocol enhances the contrast when using X-ray imaging, while preventing sample motion during the scan, even with different sample orientations. Bubbles trapped during mounting and those formed during scanning (in the case of synchrotron X-ray imaging) are mitigated by multiple degassing steps. The sample preparation is also compatible with magnetic resonance imaging, computed tomography and histological observation. The sample preparation and mounting require 24-36 d for a large organ such as a whole human brain or heart. The preparation time varies depending on the composition, size and fragility of the tissue. Use of the protocol enables scanning of intact organs with a diameter of 150 mm with a local voxel size of 1 μm. The protocol requires users with expertise in handling human or animal organs, laboratory operation and X-ray imaging.
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Affiliation(s)
- J Brunet
- Department of Mechanical Engineering, University College London, London, UK.
- European Synchrotron Radiation Facility, Grenoble, France.
| | - C L Walsh
- Department of Mechanical Engineering, University College London, London, UK.
| | - W L Wagner
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany
- Translational Lung Research Centre Heidelberg (TLRC), German Lung Research Centre (DZL), Heidelberg, Germany
| | - A Bellier
- Laboratoire d'Anatomie des Alpes Françaises (LADAF), Université Grenoble Alpes, Grenoble, France
| | - C Werlein
- Institute of Pathology, Hannover Medical School, Hannover, Germany
| | - S Marussi
- Department of Mechanical Engineering, University College London, London, UK
| | - D D Jonigk
- Institute of Pathology, Hannover Medical School, Hannover, Germany
- Biomedical Research in End-stage and Obstructive Lung Disease Hannover (BREATH), German Lung Research Centre (DZL), Hannover, Germany
| | - S E Verleden
- Antwerp Surgical Training, Anatomy and Research Centre (ASTARC), University of Antwerp, Antwerp, Belgium
| | - M Ackermann
- Institute of Pathology and Molecular Pathology, Helios University Clinic Wuppertal, University of Witten/Herdecke, Wuppertal, Germany
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Peter D Lee
- Department of Mechanical Engineering, University College London, London, UK.
- Research Complex at Harwell, Didcot, UK.
| | - Paul Tafforeau
- European Synchrotron Radiation Facility, Grenoble, France.
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9
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Fardin L, Giaccaglia C, Busca P, Bravin A. Characterization of a CdTe single-photon-counting detector for biomedical imaging applications. Phys Med 2023; 108:102571. [PMID: 36989977 DOI: 10.1016/j.ejmp.2023.102571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 03/12/2023] [Accepted: 03/18/2023] [Indexed: 03/29/2023] Open
Abstract
PURPOSE The Eiger 2X CdTe 1 M-W (Dectris ltd, Baden, Switzerland) single photon counting detector was characterized for imaging applications at the biomedical beamline ID17 of the European Synchrotron Radiation Facility. METHODS Linearity, Modulation Transfer Function, Noise Power Spectrum and Detective Quantum Efficiency were measured as a function of photon energy and flux in the range 26-80 keV. RESULTS The linearity was confirmed in the flux range specified by Dectris and a detection efficiency higher than 60 % was measured for energies up to 80 keV. The spatial resolution was inferred from the Modulation Transfer Function and was found to be compatible with the pixel size of the detector (75 μm), except at energies just above the K-edge of Cd and Te where it reached 150 μm. The study of the Noise Power Spectrum showed a time-dependency in the response of the sensor, which is mitigated at low photon fluxes (<2⨯108 ph mm-2 s-1). CONCLUSIONS This work was the first characterization of the Eiger 2X CdTe 1 M-W for imaging applications with monochromatic synchrotron radiation. The spatial resolution and the quantum efficiency are compatible with low-dose imaging applications.
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10
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Hudock MR, Pinezich MR, Mir M, Chen J, Bacchetta M, Vunjak-Novakovic G, Kim J. Emerging Imaging Modalities for Functional Assessment of Donor Lungs Ex Vivo. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2023; 25:100432. [PMID: 36778755 PMCID: PMC9913406 DOI: 10.1016/j.cobme.2022.100432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The severe shortage of functional donor lungs that can be offered to recipients has been a major challenge in lung transplantation. Innovative ex vivo lung perfusion (EVLP) and tissue engineering methodologies are now being developed to repair damaged donor lungs that are deemed unsuitable for transplantation. To assess the efficacy of donor lung reconditioning methods intended to rehabilitate rejected donor lungs, monitoring of lung function with improved spatiotemporal resolution is needed. Recent developments in live imaging are enabling non-destructive, direct, and longitudinal modalities for assessing local tissue and whole lung functions. In this review, we describe how emerging live imaging modalities can be coupled with lung tissue engineering approaches to promote functional recovery of ex vivo donor lungs.
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Affiliation(s)
- Maria R. Hudock
- Department of Biomedical Engineering, Columbia University,
New York, NY, USA
| | - Meghan R. Pinezich
- Department of Biomedical Engineering, Columbia University,
New York, NY, USA
| | - Mohammad Mir
- Department of Biomedical Engineering, Stevens Institute of
Technology, Hoboken, NJ, USA
| | - Jiawen Chen
- Department of Biomedical Engineering, Stevens Institute of
Technology, Hoboken, NJ, USA
| | - Matthew Bacchetta
- Department of Cardiac Surgery, Vanderbilt University,
Nashville, TN, USA
- Department of Biomedical Engineering, Vanderbilt
University, Nashville, TN, USA
| | - Gordana Vunjak-Novakovic
- Department of Biomedical Engineering, Columbia University,
New York, NY, USA
- Department of Medicine, Columbia University, New York, NY,
USA
| | - Jinho Kim
- Department of Biomedical Engineering, Stevens Institute of
Technology, Hoboken, NJ, USA
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11
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Nieman G, Kollisch-Singule M, Ramcharran H, Satalin J, Blair S, Gatto LA, Andrews P, Ghosh A, Kaczka DW, Gaver D, Bates J, Habashi NM. Unshrinking the baby lung to calm the VILI vortex. Crit Care 2022; 26:242. [PMID: 35934707 PMCID: PMC9357329 DOI: 10.1186/s13054-022-04105-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/12/2022] [Indexed: 02/07/2023] Open
Abstract
A hallmark of ARDS is progressive shrinking of the ‘baby lung,’ now referred to as the ventilator-induced lung injury (VILI) ‘vortex.’ Reducing the risk of the VILI vortex is the goal of current ventilation strategies; unfortunately, this goal has not been achieved nor has mortality been reduced. However, the temporal aspects of a mechanical breath have not been considered. A brief expiration prevents alveolar collapse, and an extended inspiration can recruit the atelectatic lung over hours. Time-controlled adaptive ventilation (TCAV) is a novel ventilator approach to achieve these goals, since it considers many of the temporal aspects of dynamic lung mechanics.
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Affiliation(s)
- Gary Nieman
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Michaela Kollisch-Singule
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Harry Ramcharran
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA.
| | - Sarah Blair
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - Penny Andrews
- Department of Medicine, University of Maryland, Baltimore, MD, USA
| | - Auyon Ghosh
- Department of Surgery, SUNY Upstate Medical Center, SUNY Upstate, 750 East Adams St., Syracuse, NY, 13210, USA
| | - David W Kaczka
- Departments of Anesthesia, Biomedical Engineering, and Radiology, University of Iowa, Iowa City, IA, USA
| | - Donald Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Jason Bates
- Department of Medicine, University of Vermont, Burlington, VT, USA
| | - Nader M Habashi
- Department of Medicine, University of Maryland, Baltimore, MD, USA
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12
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Andrews P, Shiber J, Madden M, Nieman GF, Camporota L, Habashi NM. Myths and Misconceptions of Airway Pressure Release Ventilation: Getting Past the Noise and on to the Signal. Front Physiol 2022; 13:928562. [PMID: 35957991 PMCID: PMC9358044 DOI: 10.3389/fphys.2022.928562] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/21/2022] [Indexed: 12/16/2022] Open
Abstract
In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): "Scientific orthodoxy kills truth". In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of "lung protective" ventilation. Unfortunately, inadequacies of the current conceptual model-that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the "baby lung" - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV's clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.
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Affiliation(s)
- Penny Andrews
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Joseph Shiber
- University of Florida College of Medicine, Jacksonville, FL, United States
| | - Maria Madden
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Luigi Camporota
- Department of Adult Critical Care, Guy’s and St Thomas’ NHS Foundation Trust, Health Centre for Human and Applied Physiological Sciences, London, United Kingdom
| | - Nader M. Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
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13
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SCARAMUZZO G, OTTAVIANI I, VOLTA CA, SPADARO S. Mechanical ventilation and COPD: from pathophysiology to ventilatory management. Minerva Med 2022; 113:460-470. [DOI: 10.23736/s0026-4806.22.07974-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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14
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Guérin C, Cour M, Argaud L. Airway Closure and Expiratory Flow Limitation in Acute Respiratory Distress Syndrome. Front Physiol 2022; 12:815601. [PMID: 35111078 PMCID: PMC8801584 DOI: 10.3389/fphys.2021.815601] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/09/2021] [Indexed: 12/12/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is mostly characterized by the loss of aerated lung volume associated with an increase in lung tissue and intense and complex lung inflammation. ARDS has long been associated with the histological pattern of diffuse alveolar damage (DAD). However, DAD is not the unique pathological figure in ARDS and it can also be observed in settings other than ARDS. In the coronavirus disease 2019 (COVID-19) related ARDS, the impairment of lung microvasculature has been pointed out. The airways, and of notice the small peripheral airways, may contribute to the loss of aeration observed in ARDS. High-resolution lung imaging techniques found that in specific experimental conditions small airway closure was a reality. Furthermore, low-volume ventilator-induced lung injury, also called as atelectrauma, should involve the airways. Atelectrauma is one of the basic tenet subtending the use of positive end-expiratory pressure (PEEP) set at the ventilator in ARDS. Recent data revisited the role of airways in humans with ARDS and provided findings consistent with the expiratory flow limitation and airway closure in a substantial number of patients with ARDS. We discussed the pattern of airway opening pressure disclosed in the inspiratory volume-pressure curves in COVID-19 and in non-COVID-19 related ARDS. In addition, we discussed the functional interplay between airway opening pressure and expiratory flow limitation displayed in the flow-volume curves. We discussed the individualization of the PEEP setting based on these findings.
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Affiliation(s)
- Claude Guérin
- Médecine Intensive - Réanimation Hôpital Edouard Herriot Lyon, Lyon, France
- Faculté de Médecine Lyon-Est, Université de Lyon, Lyon, France
- Institut Mondor de Recherches Biomédicales, INSERM-UPEC UMR 955 Team 13 - CNRS ERL 7000, Créteil, France
| | - Martin Cour
- Médecine Intensive - Réanimation Hôpital Edouard Herriot Lyon, Lyon, France
- Faculté de Médecine Lyon-Est, Université de Lyon, Lyon, France
| | - Laurent Argaud
- Médecine Intensive - Réanimation Hôpital Edouard Herriot Lyon, Lyon, France
- Faculté de Médecine Lyon-Est, Université de Lyon, Lyon, France
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15
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Zeng C, Lagier D, Lee JW, Melo MFV. Perioperative Pulmonary Atelectasis: Part I. Biology and Mechanisms. Anesthesiology 2022; 136:181-205. [PMID: 34499087 PMCID: PMC9869183 DOI: 10.1097/aln.0000000000003943] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.
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Affiliation(s)
- Congli Zeng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - David Lagier
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jae-Woo Lee
- Department of Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Marcos F. Vidal Melo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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16
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Romano M, Bravin DA, Wright DMD, Jacques L, Miettinen DA, Hlushchuk DR, Dinkel J, Bartzsch DS, Laissue JA, Djonov V, Coan DP. X-ray Phase Contrast 3D virtual histology: evaluation of lung alterations after micro-beam irradiation. Int J Radiat Oncol Biol Phys 2021; 112:818-830. [PMID: 34678432 DOI: 10.1016/j.ijrobp.2021.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/20/2021] [Accepted: 10/05/2021] [Indexed: 12/24/2022]
Abstract
PURPOSE This study provides the first experimental application of multiscale three-dimensional (3D) X-ray Phase Contrast Imaging Computed Tomography (XPCI-CT) virtual histology for the inspection and quantitative assessment of the late stage effects of radio-induced lesions on lungs in a small animal model. METHODS AND MATERIALS Healthy male Fischer rats were irradiated with X-ray standard broad beams and Microbeam Radiation Therapy (MRT), a high dose rate (14 kGy/s), FLASH spatially-fractionated X-ray therapy to avoid the beamlets smearing due to cardiosynchronous movements of the organs during the irradiation. After organ dissection, ex-vivo XPCI-CT was applied to all the samples and the results were quantitatively analysed and correlated to histologic data. RESULTS XPCI-CT enables the 3D visualization of lung tissues with unprecedented contrast and sensitivity allowing alveoli, vessels and bronchi hierarchical visualization. XPCI-CT discriminates in 3D radio-induced lesions such as fibrotic scars, Ca/Fe deposits and, in addition, allows a full-organ accurate quantification of the fibrotic tissue within the irradiated organs. The radiation-induced fibrotic tissue content is less than 10% of the analyzed volume for all the MRT treated organs while it reaches the 34% in the case of irradiations with 50 Gy using a broad beam. CONCLUSIONS XPCI-CT is an effective imaging technique able to provide detailed 3D information for the assessment of lung pathology and treatment efficacy in a small animal model.
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Affiliation(s)
- Mariele Romano
- Faculty of Physics, Ludwig Maximilian University, Am Coulombwall 1, München, Garching, Germany
| | - Dr Alberto Bravin
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, Grenoble, France, 38000
| | | | - Laurent Jacques
- Faculty of Physics, Ludwig Maximilian University, Am Coulombwall 1, München, Garching, Germany
| | - Dr Arttu Miettinen
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Dr Ruslan Hlushchuk
- Institute of Anatomy, University of Bern, 2 Baltzerstrasse, Bern, Switzerland Department
| | - Julien Dinkel
- Department of Clinical Radiology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dr Stefan Bartzsch
- Department of Radiation Oncology, School of Medicine, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany; Helmholtz Centre Munich, Institute for Radiation Medicine, Munich, Germany
| | - Jean Albert Laissue
- Institute of Anatomy, University of Bern, 2 Baltzerstrasse, Bern, Switzerland Department
| | - Valentin Djonov
- Institute of Anatomy, University of Bern, 2 Baltzerstrasse, Bern, Switzerland Department
| | - Dr Paola Coan
- Faculty of Physics, Ludwig Maximilian University, Am Coulombwall 1, München, Garching, Germany; Department of Clinical Radiology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
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17
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Herrmann J, Gerard SE, Shao W, Xin Y, Cereda M, Reinhardt JM, Christensen GE, Hoffman EA, Kaczka DW. Effects of Lung Injury on Regional Aeration and Expiratory Time Constants: Insights From Four-Dimensional Computed Tomography Image Registration. Front Physiol 2021; 12:707119. [PMID: 34393824 PMCID: PMC8355819 DOI: 10.3389/fphys.2021.707119] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Rationale: Intratidal changes in regional lung aeration, as assessed with dynamic four-dimensional computed tomography (CT; 4DCT), may indicate the processes of recruitment and derecruitment, thus portending atelectrauma during mechanical ventilation. In this study, we characterized the time constants associated with deaeration during the expiratory phase of pressure-controlled ventilation in pigs before and after acute lung injury using respiratory-gated 4DCT and image registration. Methods: Eleven pigs were mechanically ventilated in pressure-controlled mode under baseline conditions and following an oleic acid model of acute lung injury. Dynamic 4DCT scans were acquired without interrupting ventilation. Automated segmentation of lung parenchyma was obtained by a convolutional neural network. Respiratory structures were aligned using 4D image registration. Exponential regression was performed on the time-varying CT density in each aligned voxel during exhalation, resulting in regional estimates of intratidal aeration change and deaeration time constants. Regressions were also performed for regional and total exhaled gas volume changes. Results: Normally and poorly aerated lung regions demonstrated the largest median intratidal aeration changes during exhalation, compared to minimal changes within hyper- and non-aerated regions. Following lung injury, median time constants throughout normally aerated regions within each subject were greater than respective values for poorly aerated regions. However, parametric response mapping revealed an association between larger intratidal aeration changes and slower time constants. Lower aeration and faster time constants were observed for the dependent lung regions in the supine position. Regional gas volume changes exhibited faster time constants compared to regional density time constants, as well as better correspondence to total exhaled volume time constants. Conclusion: Mechanical time constants based on exhaled gas volume underestimate regional aeration time constants. After lung injury, poorly aerated regions experience larger intratidal changes in aeration over shorter time scales compared to normally aerated regions. However, the largest intratidal aeration changes occur over the longest time scales within poorly aerated regions. These dynamic 4DCT imaging data provide supporting evidence for the susceptibility of poorly aerated regions to ventilator-induced lung injury, and for the functional benefits of short exhalation times during mechanical ventilation of injured lungs.
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Affiliation(s)
- Jacob Herrmann
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
| | - Sarah E. Gerard
- Department of Radiology, University of Iowa, Iowa City, IA, United States
| | - Wei Shao
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, United States
| | - Joseph M. Reinhardt
- Department of Radiology, University of Iowa, Iowa City, IA, United States
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - Gary E. Christensen
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA, United States
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, United States
| | - Eric A. Hoffman
- Department of Radiology, University of Iowa, Iowa City, IA, United States
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
- Department of Internal Medicine, University of Iowa, Iowa City, IA, United States
| | - David W. Kaczka
- Department of Radiology, University of Iowa, Iowa City, IA, United States
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
- Department of Anesthesia, University of Iowa, Iowa City, IA, United States
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18
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Olivo A. Edge-illumination x-ray phase-contrast imaging. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:363002. [PMID: 34167096 PMCID: PMC8276004 DOI: 10.1088/1361-648x/ac0e6e] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 06/07/2021] [Accepted: 06/24/2021] [Indexed: 05/08/2023]
Abstract
Although early demonstration dates back to the mid-sixties, x-ray phase-contrast imaging (XPCI) became hugely popular in the mid-90s, thanks to the advent of 3rd generation synchrotron facilities. Its ability to reveal object features that had so far been considered invisible to x-rays immediately suggested great potential for applications across the life and the physical sciences, and an increasing number of groups worldwide started experimenting with it. At that time, it looked like a synchrotron facility was strictly necessary to perform XPCI with some degree of efficiency-the only alternative being micro-focal sources, the limited flux of which imposed excessively long exposure times. However, new approaches emerged in the mid-00s that overcame this limitation, and allowed XPCI implementations with conventional, non-micro-focal x-ray sources. One of these approaches showing particular promise for 'real-world' applications is edge-illumination XPCI: this article describes the key steps in its evolution in the context of contemporary developments in XPCI research, and presents its current state-of-the-art, especially in terms of transition towards practical applications.
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Affiliation(s)
- Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, UCL, London, United Kingdom
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19
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Solé Cruz E, Mercier A, Suuronen JP, Chaffanjon P, Brun E, Bellier A. Synchrotron phase-contrast imaging applied to the anatomical study of the hand and its vascularization. J Anat 2021; 239:536-543. [PMID: 33686643 PMCID: PMC8273599 DOI: 10.1111/joa.13427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 10/05/2020] [Accepted: 02/24/2021] [Indexed: 11/27/2022] Open
Abstract
Microscopic anatomical study of the hand requires difficult or destructive dissection techniques for each anatomical structure. Synchrotron phase-contrast imaging (sPCI) allows us to study precisely, at a microscopic resolution and in a nondestructive approach, the soft tissues and bone structures within a single 3D image. Therefore, we aimed to assess the capacity of sPCI to study the arterial anatomy of the hand and digits in human cadavers for anatomical purposes. A non-injected hand from an embalmed body was imaged using sPCI at 21-µm pixel size. The vascularization and innervation of the hands were virtually reconstructed at 84-µm resolution, and the medial neurovascular bundle of the third digit at 21 µm. The thinner-most distal structures were observed and reported. The diameter and thickness of the vascular and neural structures were defined on 2D computed tomographic axial projections, and using a granulometry method coupled to the 3D reconstructions. The vascularization of the hand was visible from the radial and ulnar arteries to the distal digital transverse anastomoses. The thinnest structure observed was the anastomotic arterial network around the proper palmar digital nerve. The latter emerged from the proper palmar digital artery and vascularized the nerve around its whole length and circumference. The perineural arterioles individualizable at this resolution had a diameter of 66-309 µm. In conclusion, sPCI allows both the arterial and neural anatomy of the hand to be studied at the same time, as well as the anatomical interactions between both networks. It facilitates the study of structures that have different sizes, diameters, thickness, and histological origin with great precision, in a noninvasive way, and using a single technique.
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Affiliation(s)
- Eva Solé Cruz
- French Alpes Laboratory of Anatomy, Grenoble Alpes University, Grenoble, France.,Inserm UA7 Strobe, Grenoble Alpes University, Grenoble, France.,ID17 Biomedical Beamline, European Synchrotron Radiation Facility, Grenoble, France
| | - Alexis Mercier
- French Alpes Laboratory of Anatomy, Grenoble Alpes University, Grenoble, France
| | - Jussi-Petteri Suuronen
- Inserm UA7 Strobe, Grenoble Alpes University, Grenoble, France.,ID17 Biomedical Beamline, European Synchrotron Radiation Facility, Grenoble, France
| | - Philippe Chaffanjon
- French Alpes Laboratory of Anatomy, Grenoble Alpes University, Grenoble, France
| | - Emmanuel Brun
- Inserm UA7 Strobe, Grenoble Alpes University, Grenoble, France
| | - Alexandre Bellier
- French Alpes Laboratory of Anatomy, Grenoble Alpes University, Grenoble, France.,Computational Biology and Mathematics, TIMC Laboratory, UMR 5525 CNRS, Grenoble, France
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20
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Arora H, Mitchell RL, Johnston R, Manolesos M, Howells D, Sherwood JM, Bodey AJ, Wanelik K. Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements. MATERIALS (BASEL, SWITZERLAND) 2021; 14:439. [PMID: 33477444 PMCID: PMC7829924 DOI: 10.3390/ma14020439] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/16/2020] [Accepted: 01/13/2021] [Indexed: 12/30/2022]
Abstract
The mechanics of breathing is a fascinating and vital process. The lung has complexities and subtle heterogeneities in structure across length scales that influence mechanics and function. This study establishes an experimental pipeline for capturing alveolar deformations during a respiratory cycle using synchrotron radiation micro-computed tomography (SR-micro-CT). Rodent lungs were mechanically ventilated and imaged at various time points during the respiratory cycle. Pressure-Volume (P-V) characteristics were recorded to capture any changes in overall lung mechanical behaviour during the experiment. A sequence of tomograms was collected from the lungs within the intact thoracic cavity. Digital volume correlation (DVC) was used to compute the three-dimensional strain field at the alveolar level from the time sequence of reconstructed tomograms. Regional differences in ventilation were highlighted during the respiratory cycle, relating the local strains within the lung tissue to the global ventilation measurements. Strains locally reached approximately 150% compared to the averaged regional deformations of approximately 80-100%. Redistribution of air within the lungs was observed during cycling. Regions which were relatively poorly ventilated (low deformations compared to its neighbouring region) were deforming more uniformly at later stages of the experiment (consistent with its neighbouring region). Such heterogenous phenomena are common in everyday breathing. In pathological lungs, some of these non-uniformities in deformation behaviour can become exaggerated, leading to poor function or further damage. The technique presented can help characterize the multiscale biomechanical nature of a given pathology to improve patient management strategies, considering both the local and global lung mechanics.
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Affiliation(s)
- Hari Arora
- Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK; (R.J.); (M.M.); (D.H.)
| | - Ria L. Mitchell
- Faculty of Engineering, The University of Sheffield, Sheffield S10 2TN, UK;
| | - Richard Johnston
- Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK; (R.J.); (M.M.); (D.H.)
| | - Marinos Manolesos
- Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK; (R.J.); (M.M.); (D.H.)
| | - David Howells
- Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK; (R.J.); (M.M.); (D.H.)
| | - Joseph M. Sherwood
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK;
| | - Andrew J. Bodey
- Diamond Light Source Ltd., Didcot OX11 0DE, Oxfordshire, UK; (A.J.B.); (K.W.)
| | - Kaz Wanelik
- Diamond Light Source Ltd., Didcot OX11 0DE, Oxfordshire, UK; (A.J.B.); (K.W.)
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21
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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: 16] [Impact Index Per Article: 3.2] [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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22
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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: 33] [Impact Index Per Article: 6.6] [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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23
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Gaver DP, Nieman GF, Gatto LA, Cereda M, Habashi NM, Bates JHT. The POOR Get POORer: A Hypothesis for the Pathogenesis of Ventilator-induced Lung Injury. Am J Respir Crit Care Med 2020; 202:1081-1087. [PMID: 33054329 DOI: 10.1164/rccm.202002-0453cp] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Protective ventilation strategies for the injured lung currently revolve around the use of low Vt, ostensibly to avoid volutrauma, together with positive end-expiratory pressure to increase the fraction of open lung and reduce atelectrauma. Protective ventilation is currently applied in a one-size-fits-all manner, and although this practical approach has reduced acute respiratory distress syndrome deaths, mortality is still high and improvements are at a standstill. Furthermore, how to minimize ventilator-induced lung injury (VILI) for any given lung remains controversial and poorly understood. Here we present a hypothesis of VILI pathogenesis that potentially serves as a basis upon which minimally injurious ventilation strategies might be developed. This hypothesis is based on evidence demonstrating that VILI begins in isolated lung regions manifesting a Permeability-Originated Obstruction Response (POOR) in which alveolar leak leads to surfactant dysfunction and increases local tissue stresses. VILI progresses topographically outward from these regions in a POOR-get-POORer fashion unless steps are taken to interrupt it. We propose that interrupting the POOR-get-POORer progression of lung injury relies on two principles: 1) open the lung to minimize the presence of heterogeneity-induced stress concentrators that are focused around the regions of atelectasis, and 2) ventilate in a patient-dependent manner that minimizes the number of lung units that close during each expiration so that they are not forced to rerecruit during the subsequent inspiration. These principles appear to be borne out in both patient and animal studies in which expiration is terminated before derecruitment of lung units has enough time to occur.
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Affiliation(s)
- Donald P Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care and.,Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nader M Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland, Baltimore, Maryland; and
| | - Jason H T Bates
- Department of Medicine, University of Vermont, Burlington, Vermont
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24
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Functional lung imaging with synchrotron radiation: Methods and preclinical applications. Phys Med 2020; 79:22-35. [PMID: 33070047 DOI: 10.1016/j.ejmp.2020.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/30/2020] [Accepted: 10/03/2020] [Indexed: 01/05/2023] Open
Abstract
Many lung disease processes are characterized by structural and functional heterogeneity that is not directly appreciable with traditional physiological measurements. Experimental methods and lung function modeling to study regional lung function are crucial for better understanding of disease mechanisms and for targeting treatment. Synchrotron radiation offers useful properties to this end: coherence, utilized in phase-contrast imaging, and high flux and a wide energy spectrum which allow the selection of very narrow energy bands of radiation, thus allowing imaging at very specific energies. K-edge subtraction imaging (KES) has thus been developed at synchrotrons for both human and small animal imaging. The unique properties of synchrotron radiation extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and also to map regional lung ventilation, perfusion, inflammation and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. This review summarizes synchrotron radiation imaging methods and overviews examples of its application in the study of disease mechanisms in preclinical animal models, as well as the potential for clinical translation both through the knowledge gained using these techniques and transfer of imaging technology to laboratory X-ray sources.
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25
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26
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Gama de Abreu M, Schultz MJ, Pelosi P. Atelectasis during general anaesthesia for surgery: should we treat atelectasis or the patient? Br J Anaesth 2020; 124:662-664. [DOI: 10.1016/j.bja.2020.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/02/2020] [Accepted: 03/05/2020] [Indexed: 10/24/2022] Open
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27
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Guérin C, Terzi N, Galerneau LM, Mezidi M, Yonis H, Baboi L, Kreitmann L, Turbil E, Cour M, Argaud L, Louis B. Lung and chest wall mechanics in patients with acute respiratory distress syndrome, expiratory flow limitation, and airway closure. J Appl Physiol (1985) 2020; 128:1594-1603. [PMID: 32352339 DOI: 10.1152/japplphysiol.00059.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Tidal expiratory flow limitation (EFL), which may herald airway closure (AC), is a mechanism of loss of aeration in ARDS. In this prospective, short-term, two-center study, we measured static and dynamic chest wall (Est,cw and Edyn,cw) and lung (Est,L and Edyn,L) elastance with esophageal pressure, EFL, and AC at 5 cmH2O positive end-expiratory pressure (PEEP) in intubated, sedated, and paralyzed ARDS patients. For EFL determination, we used the atmospheric method and a new device allowing comparison of tidal flow during expiration to PEEP and to atmosphere. AC was validated when airway opening pressure (AOP) assessed from volume-pressure curve was found greater than PEEP by at least 1 cmH2O. EFL was defined whenever flow did not increase between exhalation to PEEP and to atmosphere over all or part of expiration. Elastance values were expressed as percentage of normal predicted values (%N). Among the 25 patients included, eight had EFL (32%) and 13 AOP (52%). Between patients with and without EFL Edyn,cw [median (1st to 3rd quartiles)] was 70 (16-127) and 102 (70-142) %N (P = 0.32) and Edyn,L338 (332-763) and 224 (160-275) %N (P < 0.001). The corresponding values for Est,cw and Est,L were 70 (56-88) and 85 (64-103) %N (P = 0.35) and 248 (206-348) and 170 (144-195) (P = 0.02), respectively. Dynamic EL had an area receiver operating characteristic curve of 0.88 [95% confidence intervals 0.83-0.92] for EFL and 0.74[0.68-0.79] for AOP. Higher Edyn,L was accurate to predict EFL in ARDS patients; AC can occur independently of EFL, and both should be assessed concurrently in ARDS patients.NEW & NOTEWORTHY Expiratory flow limitation (EFL) and airway closure (AC) were observed in 32% and 52%, respectively, of 25 patients with ARDS investigated during mechanical ventilation in supine position with a positive end-expiratory pressure of 5 cmH2O. The performance of dynamic lung elastance to detect expiratory flow limitation was good and better than that to detect airway closure. The vast majority of patients with EFL also had AC; however, AC can occur in the absence of EFL.
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Affiliation(s)
- Claude Guérin
- Medecine Intensive-Réanimation, Groupement Hospitalier Centre, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France.,Université de Lyon, Lyon, France.,Institut Mondor de Recherches Biomédicales INSERM 955 CNRS ERL 7000, Créteil, France
| | - Nicolas Terzi
- Medecine Intensive-Réanimation, CHU Grenoble-Alpes, Grenoble, France.,Université de Grenoble-Alpes, Grenoble, France
| | - Louis-Marie Galerneau
- Medecine Intensive-Réanimation, CHU Grenoble-Alpes, Grenoble, France.,Université de Grenoble-Alpes, Grenoble, France
| | - Mehdi Mezidi
- Université de Lyon, Lyon, France.,Médecine Intensive-Réanimation, Groupement Hospitalier Nord, Hospices Civils de Lyon, Lyon, France
| | - Hodane Yonis
- Médecine Intensive-Réanimation, Groupement Hospitalier Nord, Hospices Civils de Lyon, Lyon, France
| | - Loredana Baboi
- Médecine Intensive-Réanimation, Groupement Hospitalier Nord, Hospices Civils de Lyon, Lyon, France
| | - Louis Kreitmann
- Medecine Intensive-Réanimation, Groupement Hospitalier Centre, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France.,Université de Lyon, Lyon, France
| | - Emanuele Turbil
- Department of Anesthesia and Critical Care, University of Sassari, Sassari, Italy
| | - Martin Cour
- Medecine Intensive-Réanimation, Groupement Hospitalier Centre, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France.,Université de Lyon, Lyon, France
| | - Laurent Argaud
- Medecine Intensive-Réanimation, Groupement Hospitalier Centre, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France.,Université de Lyon, Lyon, France
| | - Bruno Louis
- Institut Mondor de Recherches Biomédicales INSERM 955 CNRS ERL 7000, Créteil, France
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28
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Hedenstierna G, Tokics L, Reinius H, Rothen HU, Östberg E, Öhrvik J. Higher age and obesity limit atelectasis formation during anaesthesia: an analysis of computed tomography data in 243 subjects. Br J Anaesth 2020; 124:336-344. [DOI: 10.1016/j.bja.2019.11.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/29/2019] [Accepted: 11/23/2019] [Indexed: 11/30/2022] Open
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29
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Nieman GF, Gatto LA, Andrews P, Satalin J, Camporota L, Daxon B, Blair SJ, Al-Khalisy H, Madden M, Kollisch-Singule M, Aiash H, Habashi NM. Prevention and treatment of acute lung injury with time-controlled adaptive ventilation: physiologically informed modification of airway pressure release ventilation. Ann Intensive Care 2020; 10:3. [PMID: 31907704 PMCID: PMC6944723 DOI: 10.1186/s13613-019-0619-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/23/2019] [Indexed: 12/16/2022] Open
Abstract
Mortality in acute respiratory distress syndrome (ARDS) remains unacceptably high at approximately 39%. One of the only treatments is supportive: mechanical ventilation. However, improperly set mechanical ventilation can further increase the risk of death in patients with ARDS. Recent studies suggest that ventilation-induced lung injury (VILI) is caused by exaggerated regional lung strain, particularly in areas of alveolar instability subject to tidal recruitment/derecruitment and stress-multiplication. Thus, it is reasonable to expect that if a ventilation strategy can maintain stable lung inflation and homogeneity, regional dynamic strain would be reduced and VILI attenuated. A time-controlled adaptive ventilation (TCAV) method was developed to minimize dynamic alveolar strain by adjusting the delivered breath according to the mechanical characteristics of the lung. The goal of this review is to describe how the TCAV method impacts pathophysiology and protects lungs with, or at high risk of, acute lung injury. We present work from our group and others that identifies novel mechanisms of VILI in the alveolar microenvironment and demonstrates that the TCAV method can reduce VILI in translational animal ARDS models and mortality in surgical/trauma patients. Our TCAV method utilizes the airway pressure release ventilation (APRV) mode and is based on opening and collapsing time constants, which reflect the viscoelastic properties of the terminal airspaces. Time-controlled adaptive ventilation uses inspiratory and expiratory time to (1) gradually “nudge” alveoli and alveolar ducts open with an extended inspiratory duration and (2) prevent alveolar collapse using a brief (sub-second) expiratory duration that does not allow time for alveolar collapse. The new paradigm in TCAV is configuring each breath guided by the previous one, which achieves real-time titration of ventilator settings and minimizes instability induced tissue damage. This novel methodology changes the current approach to mechanical ventilation, from arbitrary to personalized and adaptive. The outcome of this approach is an open and stable lung with reduced regional strain and greater lung protection.
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Affiliation(s)
- Gary F Nieman
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Louis A Gatto
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Penny Andrews
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
| | - Joshua Satalin
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA.
| | - Luigi Camporota
- Department of Critical Care, Guy's and St, Thomas' NHS Foundation Trust, Westminster Bridge Rd, London, SE1 7EH, UK
| | - Benjamin Daxon
- Dept of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 1st St SW, Rochester, MN, 55905, USA
| | - Sarah J Blair
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Hassan Al-Khalisy
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Maria Madden
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
| | | | - Hani Aiash
- Dept of Surgery, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA.,Department of Clinical Perfusion, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY, 13210, USA
| | - Nader M Habashi
- Multi-trauma Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD, USA
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30
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31
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Scaramuzzo G, Broche L, Pellegrini M, Porra L, Derosa S, Tannoia AP, Marzullo A, Borges JB, Bayat S, Bravin A, Larsson A, Perchiazzi G. The Effect of Positive End-Expiratory Pressure on Lung Micromechanics Assessed by Synchrotron Radiation Computed Tomography in an Animal Model of ARDS. J Clin Med 2019; 8:E1117. [PMID: 31357677 PMCID: PMC6723999 DOI: 10.3390/jcm8081117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/17/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023] Open
Abstract
Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH2O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 ± 2.0 at PEEP 12 to 7.6 ± 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 ± 52 at PEEP 12 to 146.4 ± 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.
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Affiliation(s)
- Gaetano Scaramuzzo
- Department of Morphology, Surgery and Experimental Medicine, Ferrara University, 44121 Ferrara, Italy
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Ludovic Broche
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Mariangela Pellegrini
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden
| | - Liisa Porra
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
- Helsinki University Hospital, FI-00029 Helsinki, Finland
| | - Savino Derosa
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | | | - Andrea Marzullo
- Department of Emergency and Organ Transplant, Bari University, 70124 Bari, Italy
| | - João Batista Borges
- Centre for Human and Applied Physiological Sciences, Faculty of Sciences and Medicine, King's College, London WC2R 2LS, UK
| | - Sam Bayat
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
- INSERM UA7, Synchrotron Radiation for Biomedicine (STROBE) Laboratory, University of Grenoble Alpes, 38043 Grenoble, France
| | - Alberto Bravin
- The European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden
| | - Gaetano Perchiazzi
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, 75185 Uppsala, Sweden.
- Department of Anesthesia and Intensive Care, Uppsala University Hospital, 75185 Uppsala, Sweden.
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