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Yue H, Yong T. Progress in the relationship between mechanical ventilation parameters and ventilator-related complications during perioperative anesthesia. Postgrad Med J 2024; 100:619-625. [PMID: 38507221 DOI: 10.1093/postmj/qgae035] [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: 10/12/2023] [Revised: 01/27/2024] [Accepted: 02/13/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND Mechanical ventilation, as an important respiratory support, plays an important role in general anesthesia and it is the cornerstone of intraoperative management of surgical patients. Different from spontaneous respiration, intraoperative mechanical ventilation can lead to postoperative lung injury, and its impact on surgical mortality cannot be ignored. Postoperative lung injury increases hospital stay and is related to preoperative conditions, anesthesia time, and intraoperative ventilation settings. METHOD Through reading literature and research reports, the relationship between perioperative input parameters and output parameters related to mechanical ventilation and ventilator-related complications was reviewed, providing reference for the subsequent setting of input parameters of mechanical ventilation and new ventilation strategies. RESULTS The parameters of inspiratory pressure rise time and inspiratory time can change the gas distribution, gas flow rate and airway pressure into the lungs, but there are few clinical studies on them. It can be used as a prospective intervention to study the effect of specific protective ventilation strategies on pulmonary complications after perioperative anesthesia. CONCLUSION There are many factors affecting lung function after perioperative mechanical ventilation. Due to the difference of human body, the ventilation parameters suitable for each patient are different, and the deviation of each ventilation parameter can lead to postoperative pulmonary complications. Inspiratory pressure rise time and inspiratory time will be used as the new ventilation strategy.
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Affiliation(s)
- Hu Yue
- Department of Anesthesia Operation, The First People's Hospital of Shuangliu District, Chengdu (West China Airport Hospital of Sichuan University), Chengdu 610200, China
| | - Tao Yong
- Department of Anesthesia Operation, The First People's Hospital of Shuangliu District, Chengdu (West China Airport Hospital of Sichuan University), Chengdu 610200, China
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2
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Abbott M, Pereira SM, Sanders N, Girard M, Sankar A, Sklar MC. Weaning from mechanical ventilation in the operating room: a systematic review. Br J Anaesth 2024; 133:424-436. [PMID: 38816331 PMCID: PMC11282496 DOI: 10.1016/j.bja.2024.03.043] [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: 11/09/2023] [Revised: 02/27/2024] [Accepted: 03/22/2024] [Indexed: 06/01/2024] Open
Abstract
BACKGROUND Postoperative pulmonary complications (PPCs) are associated with postoperative mortality and prolonged hospital stay. Although intraoperative mechanical ventilation (MV) is a risk factor for PPCs, strategies addressing weaning from MV are understudied. In this systematic review, we evaluated weaning strategies and their effects on postoperative pulmonary outcomes. METHODS Our protocol was registered on PROSPERO (CRD42022379145). Eligible studies included randomised controlled trials and observational studies of adults weaned from MV in the operating room. Primary outcomes included atelectasis and oxygenation; secondary outcomes included lung volume changes and PPCs. Risk of bias was assessed using the Cochrane Risk of Bias (RoB2) tool, and quality of evidence with the GRADE framework. RESULTS Screening identified 14 randomised controlled trials including 1719 patients; seven studies were limited to the weaning phase and seven included interventions not restricted to the weaning phase. Strategies combining pressure support ventilation (PSV) with positive end-expiratory pressure (PEEP) and low fraction of inspired oxygen (FiO2) improved atelectasis, oxygenation, and lung volumes. Low FiO2 improved atelectasis and oxygenation but might not improve lung volumes. A fixed-PEEP strategy led to no improvement in oxygenation or atelectasis; however, individualised PEEP with low FiO2 improved oxygenation and might be associated with reduced PPCs. Half of included studies are of moderate or high risk of bias; the overall quality of evidence is low. CONCLUSIONS There is limited research evaluating weaning from intraoperative MV. Based on low-quality evidence, PSV, individualised PEEP, and low FiO2 may be associated with reduced postoperative pulmonary outcomes. SYSTEMATIC REVIEW PROTOCOL PROSPERO (CRD42022379145).
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Affiliation(s)
- Megan Abbott
- Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada; Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada
| | - Sergio M Pereira
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada
| | - Noah Sanders
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada
| | - Martin Girard
- Department of Anesthesiology, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada; Division of Critical Care, Department of Medicine, Centre Hospitalier de l'Université de Montréal, Montreal, QC, Canada; Department of Anesthesiology, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC, Canada
| | - Ashwin Sankar
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada; Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada
| | - Michael C Sklar
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada; Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.
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3
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Gao W, Kanagarajah KR, Graham E, Soon K, Veres T, Moraes TJ, Bear CE, Veldhuizen RA, Wong AP, Günther A. Collagen Tubular Airway-on-Chip for Extended Epithelial Culture and Investigation of Ventilation Dynamics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2309270. [PMID: 38431940 DOI: 10.1002/smll.202309270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 02/07/2024] [Indexed: 03/05/2024]
Abstract
The lower respiratory tract is a hierarchical network of compliant tubular structures that are made from extracellular matrix proteins with a wall lined by an epithelium. While microfluidic airway-on-a-chip models incorporate the effects of shear and stretch on the epithelium, week-long air-liquid-interface culture at physiological shear stresses, the circular cross-section, and compliance of native airway walls have yet to be recapitulated. To overcome these limitations, a collagen tube-based airway model is presented. The lumen is lined with a confluent epithelium during two-week continuous perfusion with warm, humid air while presenting culture medium from the outside and compensating for evaporation. The model recapitulates human small airways in extracellular matrix composition and mechanical microenvironment, allowing for the first time dynamic studies of elastocapillary phenomena associated with regular breathing and mechanical ventilation, as well as their impacts on the epithelium. A case study reveales increasing damage to the epithelium during repetitive collapse and reopening cycles as opposed to overdistension, suggesting expiratory flow resistance to reduce atelectasis. The model is expected to promote systematic comparisons between different clinically used ventilation strategies and, more broadly, to enhance human organ-on-a-chip platforms for a variety of tubular tissues.
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Affiliation(s)
- Wuyang Gao
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8, Canada
| | - Kayshani R Kanagarajah
- Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, PGCRL Research Tower, Toronto, Ontario, M5G 0A4, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Emma Graham
- Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
- Lawson Health Research Institute, London Health Sciences Centre, 750 Base Line Rd E, London, Ontario, N6C 2R5, Canada
| | - Kayla Soon
- National Research Council Canada, 75 Bd de Mortagne, Boucherville, Quebec, J4B 6Y4, Canada
| | - Teodor Veres
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8, Canada
- National Research Council Canada, 75 Bd de Mortagne, Boucherville, Quebec, J4B 6Y4, Canada
| | - Theo J Moraes
- Department of Paediatrics, University of Toronto, 555 University Avenue, Toronto, Ontario, M5G 1×8, Canada
| | - Christine E Bear
- Program in Molecular Medicine, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1 × 8, Canada
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Ruud A Veldhuizen
- Department of Physiology and Pharmacology, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
- Lawson Health Research Institute, London Health Sciences Centre, 750 Base Line Rd E, London, Ontario, N6C 2R5, Canada
- Department of Medicine, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5C1, Canada
| | - Amy P Wong
- Program in Developmental & Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, PGCRL Research Tower, Toronto, Ontario, M5G 0A4, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Axel Günther
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8, Canada
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada
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4
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Zimmermann R, Roeder F, Ruppert C, Smith BJ, Knudsen L. Low-volume ventilation of preinjured lungs degrades lung function via stress concentration and progressive alveolar collapse. Am J Physiol Lung Cell Mol Physiol 2024; 327:L19-L39. [PMID: 38712429 DOI: 10.1152/ajplung.00323.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 03/27/2024] [Accepted: 04/22/2024] [Indexed: 05/08/2024] Open
Abstract
Mechanical ventilation can cause ventilation-induced lung injury (VILI). The concept of stress concentrations suggests that surfactant dysfunction-induced microatelectases might impose injurious stresses on adjacent, open alveoli and function as germinal centers for injury propagation. The aim of the present study was to quantify the histopathological pattern of VILI progression and to test the hypothesis that injury progresses at the interface between microatelectases and ventilated lung parenchyma during low-positive end-expiratory pressure (PEEP) ventilation. Bleomycin was used to induce lung injury with microatelectases in rats. Lungs were then mechanically ventilated for up to 6 h at PEEP = 1 cmH2O and compared with bleomycin-treated group ventilated protectively with PEEP = 5 cmH2O to minimize microatelectases. Lung mechanics were measured during ventilation. Afterward, lungs were fixed at end-inspiration or end-expiration for design-based stereology. Before VILI, bleomycin challenge reduced the number of open alveoli [N(alvair,par)] by 29%. No differences between end-inspiration and end-expiration were observed. Collapsed alveoli clustered in areas with a radius of up to 56 µm. After PEEP = 5 cmH2O ventilation for 6 h, N(alvair,par) remained stable while PEEP = 1 cmH2O ventilation led to an additional loss of aerated alveoli by 26%, mainly due to collapse, with a small fraction partly edema filled. Alveolar loss strongly correlated to worsening of tissue elastance, quasistatic compliance, and inspiratory capacity. The radius of areas of collapsed alveoli increased to 94 µm, suggesting growth of the microatelectases. These data provide evidence that alveoli become unstable in neighborhood of microatelectases, which most likely occurs due to stress concentration-induced local vascular leak and surfactant dysfunction.NEW & NOTEWORTHY Low-volume mechanical ventilation in the presence of high surface tension-induced microatelectases leads to the degradation of lung mechanical function via the progressive loss of alveoli. Microatelectases grow at the interfaces of collapsed and open alveoli. Here, stress concentrations might cause injury and alveolar instability. Accumulation of small amounts of alveolar edema can be found in a fraction of partly collapsed alveoli but, in this model, alveolar flooding is not a major driver for degradation of lung mechanics.
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Affiliation(s)
- Richard Zimmermann
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Franziska Roeder
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Clemens Ruppert
- Department of Internal Medicine, Justus-Liebig-University Giessen, Giessen, Germany
- University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Bradford J Smith
- Department of Bioengineering, College of Engineering, Design & Computing, University of Colorado Denver | Anschutz Medical Campus, Aurora, Colorado, United States
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, United States
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover Medical School, Hannover, Germany
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Al-Khalisy H, Nieman GF, Kollisch-Singule M, Andrews P, Camporota L, Shiber J, Manougian T, Satalin J, Blair S, Ghosh A, Herrmann J, Kaczka DW, Gaver DP, Bates JHT, Habashi NM. Time-Controlled Adaptive Ventilation (TCAV): a personalized strategy for lung protection. Respir Res 2024; 25:37. [PMID: 38238778 PMCID: PMC10797864 DOI: 10.1186/s12931-023-02615-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 11/25/2023] [Indexed: 01/22/2024] Open
Abstract
Acute respiratory distress syndrome (ARDS) alters the dynamics of lung inflation during mechanical ventilation. Repetitive alveolar collapse and expansion (RACE) predisposes the lung to ventilator-induced lung injury (VILI). Two broad approaches are currently used to minimize VILI: (1) low tidal volume (LVT) with low-moderate positive end-expiratory pressure (PEEP); and (2) open lung approach (OLA). The LVT approach attempts to protect already open lung tissue from overdistension, while simultaneously resting collapsed tissue by excluding it from the cycle of mechanical ventilation. By contrast, the OLA attempts to reinflate potentially recruitable lung, usually over a period of seconds to minutes using higher PEEP used to prevent progressive loss of end-expiratory lung volume (EELV) and RACE. However, even with these protective strategies, clinical studies have shown that ARDS-related mortality remains unacceptably high with a scarcity of effective interventions over the last two decades. One of the main limitations these varied interventions demonstrate to benefit is the observed clinical and pathologic heterogeneity in ARDS. We have developed an alternative ventilation strategy known as the Time Controlled Adaptive Ventilation (TCAV) method of applying the Airway Pressure Release Ventilation (APRV) mode, which takes advantage of the heterogeneous time- and pressure-dependent collapse and reopening of lung units. The TCAV method is a closed-loop system where the expiratory duration personalizes VT and EELV. Personalization of TCAV is informed and tuned with changes in respiratory system compliance (CRS) measured by the slope of the expiratory flow curve during passive exhalation. Two potentially beneficial features of TCAV are: (i) the expiratory duration is personalized to a given patient's lung physiology, which promotes alveolar stabilization by halting the progressive collapse of alveoli, thereby minimizing the time for the reopened lung to collapse again in the next expiration, and (ii) an extended inspiratory phase at a fixed inflation pressure after alveolar stabilization gradually reopens a small amount of tissue with each breath. Subsequently, densely collapsed regions are slowly ratcheted open over a period of hours, or even days. Thus, TCAV has the potential to minimize VILI, reducing ARDS-related morbidity and mortality.
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Affiliation(s)
| | - Gary F Nieman
- SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY, 13210, USA
| | | | - Penny Andrews
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, USA
| | - Luigi Camporota
- Health Centre for Human and Applied Physiological Sciences, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Joseph Shiber
- University of Florida College of Medicine, Jacksonville, FL, USA
| | | | - Joshua Satalin
- SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY, 13210, USA.
| | - Sarah Blair
- SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY, 13210, USA
| | - Auyon Ghosh
- SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY, 13210, USA
| | | | | | | | | | - Nader M Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, USA
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6
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Sibley D, Chen M, West MA, Matthew AG, Santa Mina D, Randall I. Potential mechanisms of multimodal prehabilitation effects on surgical complications: a narrative review. Appl Physiol Nutr Metab 2023; 48:639-656. [PMID: 37224570 DOI: 10.1139/apnm-2022-0272] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Continuous advances in prehabilitation research over the past several decades have clarified its role in improving preoperative risk factors, yet the evidence demonstrating reduced surgical complications remains uncertain. Describing the potential mechanisms underlying prehabilitation and surgical complications represents an important opportunity to establish biological plausibility, develop targeted therapies, generate hypotheses for future research, and contribute to the rationale for implementation into the standard of care. In this narrative review, we discuss and synthesize the current evidence base for the biological plausibility of multimodal prehabilitation to reduce surgical complications. The goal of this review is to improve prehabilitation interventions and measurement by outlining biologically plausible mechanisms of benefit and generating hypotheses for future research. This is accomplished by synthesizing the available evidence for the mechanistic benefit of exercise, nutrition, and psychological interventions for reducing the incidence and severity of surgical complications reported by the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). This review was conducted and reported in accordance with a quality assessment scale for narrative reviews. Findings indicate that prehabilitation has biological plausibility to reduce all complications outlined by NSQIP. Mechanisms for prehabilitation to reduce surgical complications include anti-inflammation, enhanced innate immunity, and attenuation of sympathovagal imbalance. Mechanisms vary depending on the intervention protocol and baseline characteristics of the sample. This review highlights the need for more research in this space while proposing potential mechanisms to be included in future investigations.
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Affiliation(s)
- Daniel Sibley
- Faculty of Kinesiology, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Maggie Chen
- Faculty of Kinesiology, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Malcolm A West
- Faculty of Medicine, Cancer Sciences, University of Southampton, UK
- NIHR Southampton Biomedical Research Centre, Perioperative and Critical Care, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Andrew G Matthew
- Department of Surgical Oncology, Princess Margaret Cancer Centre, Toronto, ON, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Daniel Santa Mina
- Faculty of Kinesiology, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Ian Randall
- Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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7
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Nieman GF, Kaczka DW, Andrews PL, Ghosh A, Al-Khalisy H, Camporota L, Satalin J, Herrmann J, Habashi NM. First Stabilize and then Gradually Recruit: A Paradigm Shift in Protective Mechanical Ventilation for Acute Lung Injury. J Clin Med 2023; 12:4633. [PMID: 37510748 PMCID: PMC10380509 DOI: 10.3390/jcm12144633] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/15/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) is associated with a heterogeneous pattern of injury throughout the lung parenchyma that alters regional alveolar opening and collapse time constants. Such heterogeneity leads to atelectasis and repetitive alveolar collapse and expansion (RACE). The net effect is a progressive loss of lung volume with secondary ventilator-induced lung injury (VILI). Previous concepts of ARDS pathophysiology envisioned a two-compartment system: a small amount of normally aerated lung tissue in the non-dependent regions (termed "baby lung"); and a collapsed and edematous tissue in dependent regions. Based on such compartmentalization, two protective ventilation strategies have been developed: (1) a "protective lung approach" (PLA), designed to reduce overdistension in the remaining aerated compartment using a low tidal volume; and (2) an "open lung approach" (OLA), which first attempts to open the collapsed lung tissue over a short time frame (seconds or minutes) with an initial recruitment maneuver, and then stabilize newly recruited tissue using titrated positive end-expiratory pressure (PEEP). A more recent understanding of ARDS pathophysiology identifies regional alveolar instability and collapse (i.e., hidden micro-atelectasis) in both lung compartments as a primary VILI mechanism. Based on this understanding, we propose an alternative strategy to ventilating the injured lung, which we term a "stabilize lung approach" (SLA). The SLA is designed to immediately stabilize the lung and reduce RACE while gradually reopening collapsed tissue over hours or days. At the core of SLA is time-controlled adaptive ventilation (TCAV), a method to adjust the parameters of the airway pressure release ventilation (APRV) modality. Since the acutely injured lung at any given airway pressure requires more time for alveolar recruitment and less time for alveolar collapse, SLA adjusts inspiratory and expiratory durations and inflation pressure levels. The TCAV method SLA reverses the open first and stabilize second OLA method by: (i) immediately stabilizing lung tissue using a very brief exhalation time (≤0.5 s), so that alveoli simply do not have sufficient time to collapse. The exhalation duration is personalized and adaptive to individual respiratory mechanical properties (i.e., elastic recoil); and (ii) gradually recruiting collapsed lung tissue using an inflate and brake ratchet combined with an extended inspiratory duration (4-6 s) method. Translational animal studies, clinical statistical analysis, and case reports support the use of TCAV as an efficacious lung protective strategy.
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Affiliation(s)
- Gary F. Nieman
- Department of Surgery, Upstate Medical University, Syracuse, NY 13210, USA;
| | - David W. Kaczka
- Departments of Anesthesia, Radiology and Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Penny L. Andrews
- Department of Medicine, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD 21201, USA
| | - Auyon Ghosh
- Department of Medicine, Upstate Medical University, Syracuse, NY 13210, USA
| | - Hassan Al-Khalisy
- Brody School of Medicine, Department of Internal Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Luigi Camporota
- Department of Adult Critical Care, Guy’s and St Thomas’ NHS Foundation Trust, King’s Partners, St Thomas’ Hospital, London SE1 7EH, UK
| | - Joshua Satalin
- Department of Surgery, Upstate Medical University, Syracuse, NY 13210, USA;
| | - Jacob Herrmann
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Nader M. Habashi
- Department of Medicine, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD 21201, USA
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Bates JHT, Nieman GF, Kollisch-Singule M, Gaver DP. Ventilator-Induced Lung Injury as a Dynamic Balance Between Epithelial Cell Damage and Recovery. Ann Biomed Eng 2023; 51:1052-1062. [PMID: 37000319 DOI: 10.1007/s10439-023-03186-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/15/2023] [Indexed: 04/01/2023]
Abstract
Acute respiratory distress syndrome (ARDS) has a high mortality rate that is due in part to ventilator-induced lung injury (VILI). Nevertheless, the majority of patients eventually recover, which means that their innate reparative capacities eventually prevail. Since there are currently no medical therapies for ARDS, minimizing its mortality thus amounts to achieving an optimal balance between spontaneous tissue repair versus the generation of VILI. In order to understand this balance better, we developed a mathematical model of the onset and recovery of VILI that incorporates two hypotheses: (1) a novel multi-hit hypothesis of epithelial barrier failure, and (2) a previously articulated rich-get-richer hypothesis of the interaction between atelectrauma and volutrauma. Together, these concepts explain why VILI appears in a normal lung only after an initial latent period of injurious mechanical ventilation. In addition, they provide a mechanistic explanation for the observed synergy between atelectrauma and volutrauma. The model recapitulates the key features of previously published in vitro measurements of barrier function in an epithelial monolayer and in vivo measurements of lung function in mice subjected to injurious mechanical ventilation. This provides a framework for understanding the dynamic balance between factors responsible for the generation of and recovery from VILI.
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Affiliation(s)
- Jason H T Bates
- Department of Medicine, University of Vermont, Burlington, VT, 05405, USA.
- Department of Medicine, Larner College of Medicine, 149 Beaumont Avenue, Burlington, 05405-0075, USA.
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, USA
| | | | - Donald P Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
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Hennessey E, Bittner E, White P, Kovar A, Meuchel L. Intraoperative Ventilator Management of the Critically Ill Patient. Anesthesiol Clin 2023; 41:121-140. [PMID: 36871995 PMCID: PMC9985493 DOI: 10.1016/j.anclin.2022.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Strategies for the intraoperative ventilator management of the critically ill patient focus on parameters used for lung protective ventilation with acute respiratory distress syndrome, preventing or limiting the deleterious effects of mechanical ventilation, and optimizing anesthetic and surgical conditions to limit postoperative pulmonary complications for patients at risk. Patient conditions such as obesity, sepsis, the need for laparoscopic surgery, or one-lung ventilation may benefit from intraoperative lung protective ventilation strategies. Anesthesiologists can use risk evaluation and prediction tools, monitor advanced physiologic targets, and incorporate new innovative monitoring techniques to develop an individualized approach for patients.
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Affiliation(s)
- Erin Hennessey
- Stanford University - School of Medicine Department of Anesthesiology, Perioperative and Pain Medicine, 300 Pasteur Drive, Room H3580, Stanford, CA 94305, USA.
| | - Edward Bittner
- Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Peggy White
- University of Florida College of Medicine, Department of Anesthesiology, 1500 SW Archer Road, PO Box 100254, Gainesville, FL 32610, USA
| | - Alan Kovar
- Oregon Health and Science University, 3161 SW Pavilion Loop, Portland, OR 97239, USA
| | - Lucas Meuchel
- Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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10
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Complications Associated With Venovenous Extracorporeal Membrane Oxygenation-What Can Go Wrong? Crit Care Med 2022; 50:1809-1818. [PMID: 36094523 DOI: 10.1097/ccm.0000000000005673] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVES Despite increasing use and promising outcomes, venovenous extracorporeal membrane oxygenation (V-V ECMO) introduces the risk of a number of complications across the spectrum of ECMO care. This narrative review describes the variety of short- and long-term complications that can occur during treatment with ECMO and how patient selection and management decisions may influence the risk of these complications. DATA SOURCES English language articles were identified in PubMed using phrases related to V-V ECMO, acute respiratory distress syndrome, severe respiratory failure, and complications. STUDY SELECTION Original research, review articles, commentaries, and published guidelines from the Extracorporeal Life support Organization were considered. DATA EXTRACTION Data from relevant literature were identified, reviewed, and integrated into a concise narrative review. DATA SYNTHESIS Selecting patients for V-V ECMO exposes the patient to a number of complications. Adequate knowledge of these risks is needed to weigh them against the anticipated benefit of treatment. Timing of ECMO initiation and transfer to centers capable of providing ECMO affect patient outcomes. Choosing a configuration that insufficiently addresses the patient's physiologic deficit leads to consequences of inadequate physiologic support. Suboptimal mechanical ventilator management during ECMO may lead to worsening lung injury, delayed lung recovery, or ventilator-associated pneumonia. Premature decannulation from ECMO as lungs recover can lead to clinical worsening, and delayed decannulation can prolong exposure to complications unnecessarily. Short-term complications include bleeding, thrombosis, and hemolysis, renal and neurologic injury, concomitant infections, and technical and mechanical problems. Long-term complications reflect the physical, functional, and neurologic sequelae of critical illness. ECMO can introduce ethical and emotional challenges, particularly when bridging strategies fail. CONCLUSIONS V-V ECMO is associated with a number of complications. ECMO selection, timing of initiation, and management decisions impact the presence and severity of these potential harms.
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11
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Ogawa F, Oi Y, Honzawa H, Misawa N, Takeda T, Kikuchi Y, Fukui R, Tanaka K, Kano D, Kato H, Abe T, Takeuchi I. Severity predictors of COVID-19 in SARS-CoV-2 variant, delta and omicron period; single center study. PLoS One 2022; 17:e0273134. [PMID: 36282812 PMCID: PMC9595523 DOI: 10.1371/journal.pone.0273134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/09/2022] [Indexed: 11/05/2022] Open
Abstract
Background The outcomes of coronavirus disease 2019 (COVID-19) treatment have improved due to vaccination and the establishment of better treatment regimens. However, the emergence of variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, and the corresponding changes in the characteristics of the disease present new challenges in patient management. This study aimed to analyze predictors of COVID-19 severity caused by the delta and omicron variants of SARS-CoV-2. Methods We retrospectively analyzed the data of patients who were admitted for COVID-19 at Yokohama City University Hospital from August 2021 to March 2022. Results A total of 141 patients were included in this study. Of these, 91 had moderate COVID-19, whereas 50 had severe COVID-19. There were significant differences in sex, vaccination status, dyspnea, sore throat symptoms, and body mass index (BMI) (p <0.0001, p <0.001, p <0.001, p = 0.02, p< 0.0001, respectively) between the moderate and severe COVID-19 groups. Regarding comorbidities, smoking habit and renal dysfunction were significantly different between the two groups (p = 0.007 and p = 0.01, respectively). Regarding laboratory data, only LDH level on the first day of hospitalization was significantly different between the two groups (p<0.001). Multiple logistic regression analysis revealed that time from the onset of COVID-19 to hospitalization, BMI, smoking habit, and LDH level were significantly different between the two groups (p<0.03, p = 0.039, p = 0.008, p<0.001, respectively). The cut-off value for the time from onset of COVID-19 to hospitalization was four days (sensitivity, 0.73; specificity, 0.70). Conclusions Time from the onset of COVID-19 to hospitalization is the most important factor in the prevention of the aggravation of COVID-19 caused by the delta and omicron SARS-CoV-2 variants. Appropriate medical management within four days after the onset of COVID-19 is essential for preventing the progression of COVID-19, especially in patients with smoking habits.
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Affiliation(s)
- Fumihiro Ogawa
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
- * E-mail:
| | - Yasufumi Oi
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Hiroshi Honzawa
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Naho Misawa
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Tomoaki Takeda
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Yushi Kikuchi
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Ryosuke Fukui
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Katsushi Tanaka
- Infection Prevention and Control Department, Yokohama City University Hospital, Yokohama, Kanagawa, Japan
| | - Daiki Kano
- Infection Prevention and Control Department, Yokohama City University Hospital, Yokohama, Kanagawa, Japan
| | - Hideaki Kato
- Infection Prevention and Control Department, Yokohama City University Hospital, Yokohama, Kanagawa, Japan
| | - Takeru Abe
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
| | - Ichiro Takeuchi
- Department of Emergency Medicine, Yokohama City University, School of Medicine, Yokohama, Kanagawa, Japan
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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: 3.5] [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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Cheng J, Yang J, Ma A, Dong M, Yang J, Wang P, Xue Y, Zhou Y, Kang Y. The Effects of Airway Pressure Release Ventilation on Pulmonary Permeability in Severe Acute Respiratory Distress Syndrome Pig Models. Front Physiol 2022; 13:927507. [PMID: 35936889 PMCID: PMC9354663 DOI: 10.3389/fphys.2022.927507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Objective: The aim of the study was to compare the effects of APRV and LTV ventilation on pulmonary permeability in severe ARDS.Methods: Mini Bama adult pigs were randomized into the APRV group (n = 5) and LTV group (n = 5). A severe ARDS animal model was induced by the whole lung saline lavage. Pigs were ventilated and monitored continuously for 48 h.Results: Compared with the LTV group, CStat was significantly better (p < 0.05), and the PaO2/FiO2 ratio showed a trend to be higher throughout the period of the experiment in the APRV group. The extravascular lung water index and pulmonary vascular permeability index showed a trend to be lower in the APRV group. APRV also significantly mitigates lung histopathologic injury determined by the lung histopathological injury score (p < 0.05) and gross pathological changes of lung tissues. The protein contents of occludin (p < 0.05), claudin-5 (p < 0.05), E-cadherin (p < 0.05), and VE-cadherin (p < 0.05) in the middle lobe of the right lung were higher in the APRV group than in the LTV group; among them, the contents of occludin (p < 0.05) and E-cadherin (p < 0.05) of the whole lung were higher in the APRV group. Transmission electron microscopy showed that alveolar–capillary barrier damage was more severe in the middle lobe of lungs in the LTV group.Conclusion: In comparison with LTV, APRV could preserve the alveolar–capillary barrier architecture, mitigate lung histopathologic injury, increase the expression of cell junction protein, improve respiratory system compliance, and showed a trend to reduce extravascular lung water and improve oxygenation. These findings indicated that APRV might lead to more profound beneficial effects on the integrity of the alveolar–capillary barrier architecture and on the expression of biomarkers related to pulmonary permeability.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Yan Kang
- *Correspondence: Yongfang Zhou, ; Yan Kang,
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14
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Neelakantan S, Xin Y, Gaver DP, Cereda M, Rizi R, Smith BJ, Avazmohammadi R. Computational lung modelling in respiratory medicine. J R Soc Interface 2022; 19:20220062. [PMID: 35673857 PMCID: PMC9174712 DOI: 10.1098/rsif.2022.0062] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/03/2022] [Indexed: 11/12/2022] Open
Abstract
Computational modelling of the lungs is an active field of study that integrates computational advances with lung biophysics, biomechanics, physiology and medical imaging to promote individualized diagnosis, prognosis and therapy evaluation in lung diseases. The complex and hierarchical architecture of the lung offers a rich, but also challenging, research area demanding a cross-scale understanding of lung mechanics and advanced computational tools to effectively model lung biomechanics in both health and disease. Various approaches have been proposed to study different aspects of respiration, ranging from compartmental to discrete micromechanical and continuum representations of the lungs. This article reviews several developments in computational lung modelling and how they are integrated with preclinical and clinical data. We begin with a description of lung anatomy and how different tissue components across multiple length scales affect lung mechanics at the organ level. We then review common physiological and imaging data acquisition methods used to inform modelling efforts. Building on these reviews, we next present a selection of model-based paradigms that integrate data acquisitions with modelling to understand, simulate and predict lung dynamics in health and disease. Finally, we highlight possible future directions where computational modelling can improve our understanding of the structure-function relationship in the lung.
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Affiliation(s)
- Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Yi Xin
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim Rizi
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
- Department of Pediatric Pulmonary and Sleep Medicine, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA
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15
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Elfsmark L, Ågren L, Akfur C, Jonasson S. Ammonia exposure by intratracheal instillation causes severe and deteriorating lung injury and vascular effects in mice. Inhal Toxicol 2022; 34:145-158. [PMID: 35452355 DOI: 10.1080/08958378.2022.2064566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Ammonia (NH3) is a corrosive alkaline gas that can cause life-threatening injuries by inhalation. The aim was to establish a disease model for NH3-induced injuries similar to acute lung injury (ALI) described in exposed humans and investigate the progression of lung damage, respiratory dysfunction and evaluate biomarkers for ALI and inflammation over time. METHODS Female BALB/c mice were exposed to an NH3 dose of 91.0 mg/kg·bw using intratracheal instillation and the pathological changes were followed for up to 7 days. RESULTS NH3 instillation resulted in the loss of body weight along with a significant increase in pro-inflammatory mediators in both bronchoalveolar lavage fluid (e.g. IL-1β, IL-6, KC, MMP-9, SP-D) and blood (e.g. IL-6, Fibrinogen, PAI-1, PF4/CXCL4, SP-D), neutrophilic lung inflammation, alveolar damage, increased peripheral airway resistance and methacholine-induced airway hyperresponsiveness compared to controls at 20 h. On day 7 after exposure, deteriorating pathological changes such as increased macrophage lung infiltration, heart weights, lung hemorrhages and coagulation abnormalities (elevated plasma levels of PAI-1, fibrinogen, endothelin and thrombomodulin) were observed but no increase in lung collagen. Some of the analyzed blood biomarkers (e.g. RAGE, IL-1β) were unaffected despite severe ALI and may not be significant for NH3-induced damages. CONCLUSIONS NH3 induces severe acute lung injuries that deteriorate over time and biomarkers in lungs and blood that are similar to those found in humans. Therefore, this model has potential use for developing diagnostic tools for NH3-induced ALI and for finding new therapeutic treatments, since no specific antidote has been identified yet.
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Affiliation(s)
- Linda Elfsmark
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - Lina Ågren
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - Christine Akfur
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - Sofia Jonasson
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
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16
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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: 3.5] [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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17
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Terzi N, Guérin C. Optimizing Mechanical Ventilation in Refractory ARDS. ENCYCLOPEDIA OF RESPIRATORY MEDICINE 2022. [PMCID: PMC8740657 DOI: 10.1016/b978-0-12-801238-3.11480-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mechanical ventilation in patients with refractory acute respiratory distress syndrome (ARDS) must provide lung protection. This is achieved by limiting tidal volume (VT) and plateau pressure (Pplat). With the current evidence available VT should be initially set around 6 mL per kg predicted body weight and PPlat maintained below 30 cmH2O and monitored. Positive end-expiratory pressure (PEEP), which also contributes to lung protection, should be set > 12 cmH2O, provided oxygenation gets improved, with same Pplat target. Recruitment maneuvers should be used with caution avoiding higher PEEP. Neuromuscular blockade should be started and prone position performed for sessions longer than 16 h. High frequency oscillation ventilation should be used in expert centers only if previous management failed to improve oxygenation.
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18
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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: 50] [Impact Index Per Article: 25.0] [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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19
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Albert RK. Constant Tidal Volume Ventilation and Surfactant Dysfunction: An Overlooked Cause of Ventilator-Induced Lung Injury. Am J Respir Crit Care Med 2021; 205:152-160. [PMID: 34699343 DOI: 10.1164/rccm.202107-1690cp] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Ventilator-induced lung injury (VILI) is currently ascribed to volutrauma and/or atelectrauma but the effect of constant tidal volume ventilation (CVTV) has received little attention. This Perspective summarizes the literature documenting that CVTV causes VILI and reviews the mechanisms by which it occurs. Surfactant is continuously inactivated, depleted, displaced or desorbed as a function of the duration of ventilation, the tidal volume, the level of PEEP and possibly the respiratory rate. Accordingly, surfactant must be continuously replenished and secretion primarily depends on intermittent delivery of large ventilatory excursions. The surfactant abnormalities resulting from CVTV result in atelectasis and VILI. While surfactant secretion is reduced by the absence of intermittent deep breaths continuous administration of large tidal volumes depletes surfactant and impairs subsequent secretion. Low or normal lung volumes result in desorption of surfactant. PEEP can be protective by reducing surface film collapse and subsequent film rupture on re-expansion, and/or by reducing surfactant displacement into the airways, but PEEP can also down-regulate surfactant release. Conclusions: The effect of CVTV on surfactant is complex. If attention is not paid to facilitating surfactant secretion and limiting its inactivation, depletion, desorption or displacement surface tension will increase and atelectasis and VILI will occur.
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Affiliation(s)
- Richard K Albert
- University of Colorado Denver School of Medicine, 12225, Aurora, Colorado, United States;
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20
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Surfactant protein disorders in childhood interstitial lung disease. Eur J Pediatr 2021; 180:2711-2721. [PMID: 33839914 DOI: 10.1007/s00431-021-04066-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/26/2021] [Accepted: 04/04/2021] [Indexed: 10/24/2022]
Abstract
Surfactant, which was first identified in the 1920s, is pivotal to lower the surface tension in alveoli of the lungs and helps to lower the work of breathing and prevents atelectasis. Surfactant proteins, such as surfactant protein B and surfactant protein C, contribute to function and stability of surfactant film. Additionally, adenosine triphosphate binding cassette 3 and thyroid transcription factor-1 are also integral for the normal structure and functioning of pulmonary surfactant. Through the study and improved understanding of surfactant over the decades, there is increasing interest into the study of childhood interstitial lung diseases (chILD) in the context of surfactant protein disorders. Surfactant protein deficiency syndrome (SPDS) is a group of rare diseases within the chILD group that is caused by genetic mutations of SFTPB, SFTPC, ABCA3 and TTF1 genes.Conclusion: This review article seeks to provide an overview of surfactant protein disorders in the context of chILD. What is Known: • Surfactant protein disorders are an extremely rare group of disorders caused by genetic mutations of SFTPB, SPTPC, ABCA3 and TTF1 genes. • Given its rarity, research is only beginning to unmask the pathophysiology, inheritance, spectrum of disease and its manifestations. What is New: • Diagnostic and treatment options continue to be explored and evolve in these conditions. • It is, therefore, imperative that we as paediatricians are abreast with current development in this field.
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21
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Ai Q, Lin X, Xie H, Li B, Liao M, Fan H. Proteome Analysis in PAM Cells Reveals That African Swine Fever Virus Can Regulate the Level of Intracellular Polyamines to Facilitate Its Own Replication through ARG1. Viruses 2021; 13:v13071236. [PMID: 34206713 PMCID: PMC8310191 DOI: 10.3390/v13071236] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/22/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022] Open
Abstract
In 2018, African swine fever broke out in China, and the death rate after infection was close to 100%. There is no effective and safe vaccine in the world. In order to better characterize and understand the virus–host-cell interaction, quantitative proteomics was performed on porcine alveolar macrophages (PAM) infected with ASFV through tandem mass spectrometry (TMT) technology, high-performance liquid chromatography (HPLC), and mass spectrometry (MS). The proteome difference between the simulated group and the ASFV-infected group was found at 24 h. A total of 4218 proteins were identified, including 306 up-regulated differentially expressed proteins and 238 down-regulated differentially expressed proteins. Western blot analysis confirmed changes in the expression level of the selected protein. Pathway analysis is used to reveal the regulation of protein and interaction pathways after ASFV infection. Functional network and pathway analysis can provide an insight into the complexity and dynamics of virus–host cell interactions. Further study combined with proteomics data found that ARG1 has a very important effect on ASFV replication. It should be noted that the host metabolic pathway of ARG1-polyamine is important for virus replication, revealing that the virus may facilitate its own replication by regulating the level of small molecules in the host cell.
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Affiliation(s)
- Qiangyun Ai
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (Q.A.); (X.L.); (H.X.)
- Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Key Laboratory of Animal Vaccine Development, Ministry of Agriculture, Guangzhou 510642, China
| | - Xiwei Lin
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (Q.A.); (X.L.); (H.X.)
- Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Key Laboratory of Animal Vaccine Development, Ministry of Agriculture, Guangzhou 510642, China
| | - Hangao Xie
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (Q.A.); (X.L.); (H.X.)
- Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Key Laboratory of Animal Vaccine Development, Ministry of Agriculture, Guangzhou 510642, China
| | - Bin Li
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Nanjing 210014, China;
| | - Ming Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (Q.A.); (X.L.); (H.X.)
- Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Key Laboratory of Animal Vaccine Development, Ministry of Agriculture, Guangzhou 510642, China
- Correspondence: (M.L.); (H.F.); Tel.: +86-20-85280240 (M.L.); +86-20-85283309 (H.F.)
| | - Huiying Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (Q.A.); (X.L.); (H.X.)
- Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Key Laboratory of Animal Vaccine Development, Ministry of Agriculture, Guangzhou 510642, China
- Correspondence: (M.L.); (H.F.); Tel.: +86-20-85280240 (M.L.); +86-20-85283309 (H.F.)
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22
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Janssen M, Meeder JHJ, Seghers L, den Uil CA. Time controlled adaptive ventilation™ as conservative treatment of destroyed lung: an alternative to lung transplantation. BMC Pulm Med 2021; 21:176. [PMID: 34022829 PMCID: PMC8140588 DOI: 10.1186/s12890-021-01545-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/16/2021] [Indexed: 02/06/2023] Open
Abstract
Background Acute respiratory distress syndrome (ARDS) often requires controlled ventilation, yielding high mechanical power and possibly further injury. Veno-venous extracorporeal membrane oxygenation (VV-ECMO) can be used as a bridge to recovery, however, if this fails the end result is destroyed lung parenchyma. This condition is fatal and the only remaining alternative is lung transplantation. In the case study presented in this paper, lung transplantation was not an option given the critically ill state and the presence of HLA antibodies. Airway pressure release ventilation (APRV) may be valuable in ARDS, but APRV settings recommended in various patient and clinical studies are inconsistent. The Time Controlled Adaptive Ventilation (TCAV™) method is the most studied technique to set and adjust the APRV mode and uses an extended continuous positive airway pressure (CPAP) Phase in combination with a very brief Release Phase. In addition, the TCAV™ method settings are personalized and adaptive based on changes in lung pathophysiology. We used the TCAV™ method in a case of severe ARDS, which enabled us to open, stabilize and slowly heal the severely damaged lung parenchyma. Case presentation A 43-year-old woman presented with Staphylococcus Aureus necrotizing pneumonia. Progressive respiratory failure necessitated invasive mechanical ventilation and VV-ECMO. Mechanical ventilation (MV) was ultimately discontinued because lung protective settings resulted in trivial tidal volumes. She was referred to our academic transplant center for bilateral lung transplantation after the remaining infection had been cleared. We initiated the TCAV™ method in order to stabilize the lung parenchyma and to promote tissue recovery. This strategy was challenged by the presence of a large bronchopleural fistula, however, APRV enabled weaning from VV-ECMO and mechanical ventilation. After two months, following nearly complete surgical closure of the remaining bronchopleural fistulas, the patient was readmitted to ICU where she had early postoperative complications. Since other ventilation modes resulted in significant atelectasis and hypercapnia, APRV was restarted. The patient was then again weaned from MV. Conclusions The TCAV™ method can be useful to wean challenging patients with severe ARDS and might contribute to lung recovery. In this particular case, a lung transplantation was circumvented.
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Affiliation(s)
- Malou Janssen
- Department of Intensive Care Medicine, Erasmus MC, University Medical Center, Dr Molewaterplein 40, Room Rg 626, 3015 GD, Rotterdam, The Netherlands.
| | - J Han J Meeder
- Department of Intensive Care Medicine, Erasmus MC, University Medical Center, Dr Molewaterplein 40, Room Rg 626, 3015 GD, Rotterdam, The Netherlands
| | - Leonard Seghers
- Department of Pulmonary Medicine, Transplant Center, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Corstiaan A den Uil
- Department of Intensive Care Medicine, Erasmus MC, University Medical Center, Dr Molewaterplein 40, Room Rg 626, 3015 GD, Rotterdam, The Netherlands.,Department of Cardiology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.,Department of Intensive Care Medicine, Maasstad Hospital, Rotterdam, The Netherlands
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23
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Ochs M, Timm S, Elezkurtaj S, Horst D, Meinhardt J, Heppner FL, Weber-Carstens S, Hocke AC, Witzenrath M. Collapse induration of alveoli is an ultrastructural finding in a COVID-19 patient. Eur Respir J 2021; 57:13993003.04165-2020. [PMID: 33446606 PMCID: PMC7815985 DOI: 10.1183/13993003.04165-2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/23/2020] [Indexed: 01/09/2023]
Abstract
The delicate alveolar blood–air barrier is a primary target in coronavirus disease 2019 (COVID-19). Its micro-architecture consists of an alveolar epithelium composed of type I and type II cells and covered with surfactant, a thin interstitium and a capillary endothelium. Of particular relevance for the pathogenesis of severe COVID-19 is the infection of type II alveolar epithelial cells [1]. Based on their dual function as producers of surfactant and as precursors for both epithelial cell types, surfactant alterations and aberrant epithelial regeneration can be expected. Electron microscopy reveals collapse induration with alveolar epithelial cell death, basal lamina denudation, collapse and sealing of alveoli in a COVID-19 patient, implicating surfactant dysfunction and alveolar instability in fibrosis initiationhttps://bit.ly/38yEX2g
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Affiliation(s)
- Matthias Ochs
- Institute of Functional Anatomy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.,German Center for Lung Research (DZL), Berlin, Germany.,Core Facility Electron Microscopy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sara Timm
- Core Facility Electron Microscopy, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sefer Elezkurtaj
- Dept of Pathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - David Horst
- Dept of Pathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jenny Meinhardt
- Dept of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Frank L Heppner
- Dept of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Cluster of Excellence, NeuroCure, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany
| | - Steffen Weber-Carstens
- Dept of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Andreas C Hocke
- German Center for Lung Research (DZL), Berlin, Germany.,Dept of Infectious Diseases and Respiratory Medicine, Division of Pulmonary Inflammation, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Martin Witzenrath
- German Center for Lung Research (DZL), Berlin, Germany.,Dept of Infectious Diseases and Respiratory Medicine, Division of Pulmonary Inflammation, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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24
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Hol L, Nijbroek SGLH, Schultz MJ. Perioperative Lung Protection: Clinical Implications. Anesth Analg 2020; 131:1721-1729. [PMID: 33186160 DOI: 10.1213/ane.0000000000005187] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the past, it was common practice to use a high tidal volume (VT) during intraoperative ventilation, because this reduced the need for high oxygen fractions to compensate for the ventilation-perfusion mismatches due to atelectasis in a time when it was uncommon to use positive end-expiratory pressure (PEEP) in the operating room. Convincing and increasing evidence for harm induced by ventilation with a high VT has emerged over recent decades, also in the operating room, and by now intraoperative ventilation with a low VT is a well-adopted approach. There is less certainty about the level of PEEP during intraoperative ventilation. Evidence for benefit and harm of higher PEEP during intraoperative ventilation is at least contradicting. While some PEEP may prevent lung injury through reduction of atelectasis, higher PEEP is undeniably associated with an increased risk of intraoperative hypotension that frequently requires administration of vasoactive drugs. The optimal level of inspired oxygen fraction (FIO2) during surgery is even more uncertain. The suggestion that hyperoxemia prevents against surgical site infections has not been confirmed in recent research. In addition, gas absorption-induced atelectasis and its association with adverse outcomes like postoperative pulmonary complications actually makes use of a high FIO2 less attractive. Based on the available evidence, we recommend the use of a low VT of 6-8 mL/kg predicted body weight in all surgery patients, and to restrict use of a high PEEP and high FIO2 during intraoperative ventilation to cases in which hypoxemia develops. Here, we prefer to first increase FIO2 before using high PEEP.
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Affiliation(s)
| | | | - Marcus J Schultz
- Department of Intensive Care.,Department of Intensive Care and Anesthesiology, Laboratory of Experimental Intensive Care and Anesthesiology (L·E·I·C·A), Amsterdam University Medical Centers, Location 'Amsterdam Medical Center', Amsterdam, the Netherlands.,Department of Intensive Care, Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Bangkok, Thailand.,Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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25
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Abstract
PURPOSE OF REVIEW Most clinical trials of lung-protective ventilation have tested one-size-fits-all strategies with mixed results. Data are lacking on how best to tailor mechanical ventilation to patient-specific risk of lung injury. RECENT FINDINGS Risk of ventilation-induced lung injury is determined by biological predisposition to biophysical lung injury and physical mechanical perturbations that concentrate stress and strain regionally within the lung. Recent investigations have identified molecular subphenotypes classified as hyperinflammatory and hypoinflammatory acute respiratory distress syndrome (ARDS), which may have dissimilar risk for ventilation-induced lung injury. Mechanically, gravity-dependent atelectasis has long been recognized to decrease total aerated lung volume available for tidal ventilation, a concept termed the 'ARDS baby lung'. Recent studies have demonstrated that the aerated baby lung also has nonuniform stress/strain distribution, with potentially injurious forces concentrated in zones of heterogeneity where aerated alveoli are adjacent to flooded or atelectatic alveoli. The preponderance of evidence also indicates that current standard-of-care tidal volume management is not universally protective in ARDS. When considering escalation of lung-protective interventions, potential benefits of the intervention should be weighed against tradeoffs of accompanying cointerventions required, for example, deeper sedation or neuromuscular blockade. A precision medicine approach to lung-protection would weigh. SUMMARY A precision medicine approach to lung-protective ventilation requires weighing four key factors in each patient: biological predisposition to biophysical lung injury, mechanical predisposition to biophysical injury accounting for spatial mechanical heterogeneity within the lung, anticipated benefits of escalating lung-protective interventions, and potential unintended adverse effects of mandatory cointerventions.
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26
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Mechanical ventilation-induced alterations of intracellular surfactant pool and blood-gas barrier in healthy and pre-injured lungs. Histochem Cell Biol 2020; 155:183-202. [PMID: 33188462 PMCID: PMC7910377 DOI: 10.1007/s00418-020-01938-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2020] [Indexed: 12/18/2022]
Abstract
Mechanical ventilation triggers the manifestation of lung injury and pre-injured lungs are more susceptible. Ventilation-induced abnormalities of alveolar surfactant are involved in injury progression. The effects of mechanical ventilation on the surfactant system might be different in healthy compared to pre-injured lungs. In the present study, we investigated the effects of different positive end-expiratory pressure (PEEP) ventilations on the structure of the blood–gas barrier, the ultrastructure of alveolar epithelial type II (AE2) cells and the intracellular surfactant pool (= lamellar bodies, LB). Rats were randomized into bleomycin-pre-injured or healthy control groups. One day later, rats were either not ventilated, or ventilated with PEEP = 1 or 5 cmH2O and a tidal volume of 10 ml/kg bodyweight for 3 h. Left lungs were subjected to design-based stereology, right lungs to measurements of surfactant proteins (SP−) B and C expression. In pre-injured lungs without ventilation, the expression of SP-C was reduced by bleomycin; while, there were fewer and larger LB compared to healthy lungs. PEEP = 1 cmH2O ventilation of bleomycin-injured lungs was linked with the thickest blood–gas barrier due to increased septal interstitial volumes. In healthy lungs, increasing PEEP levels reduced mean AE2 cell size and volume of LB per AE2 cell; while in pre-injured lungs, volumes of AE2 cells and LB per cell remained stable across PEEPs. Instead, in pre-injured lungs, increasing PEEP levels increased the number and decreased the mean size of LB. In conclusion, mechanical ventilation-induced alterations in LB ultrastructure differ between healthy and pre-injured lungs. PEEP = 1 cmH2O but not PEEP = 5 cmH2O ventilation aggravated septal interstitial abnormalities after bleomycin challenge.
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27
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Nguyen TL, Perlman CE. Sulforhodamine B and exogenous surfactant effects on alveolar surface tension under acute respiratory distress syndrome conditions. J Appl Physiol (1985) 2020; 129:1505-1513. [PMID: 32969780 DOI: 10.1152/japplphysiol.00422.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In the acute respiratory distress syndrome (ARDS), alveolar surface tension, T, may be elevated. Elevated T should increase ventilation-induced lung injury. Exogenous surfactant therapy, intended to lower T, has not reduced mortality. Sulforhodamine B (SRB) might, alternatively, be used to lower T. We test whether substances suspected of elevating T in ARDS raise T in the lungs and test the abilities of exogenous surfactant and SRB to reduce T. In isolated rat lungs, we micropuncture a surface alveolus and instill a solution of a purported T-raising substance: control saline, cell debris, secretory phospholipase A2 (sPLA2), acid, or mucins. We test each substance alone; with albumin, to model proteinaceous edema liquid; with albumin and exogenous surfactant; and with albumin and SRB. We determine T in situ in the lungs by combining servo-nulling pressure measurement with confocal microscopy and applying the Laplace relation. With control saline, albumin does not alter T, additional surfactant raises T, and additional SRB lowers T. The experimental substances, without or with albumin, raise T. Excepting under aspiration conditions, addition of surfactant or SRB lowers T. Exogenous surfactant activity is concentration and ventilation dependent. Sulforhodamine B, which could be delivered intravascularly, holds promise as an alternative therapeutic.NEW & NOTEWORTHY In the acute respiratory distress syndrome (ARDS), lowering surface tension, T, should reduce ventilation injury yet exogenous surfactant has not reduced mortality. We show with direct T determination in isolated lungs that substances suggested to elevate T in ARDS indeed raise T, and exogenous surfactant reduces T. Further, we extend our previous finding that sulforhodamine B (SRB) reduces T below normal in healthy lungs and show that SRB, too, reduces T under ARDS conditions.
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Affiliation(s)
- Tam L Nguyen
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - Carrie E Perlman
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
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28
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Albert K, Krischer JM, Pfaffenroth A, Wilde S, Lopez-Rodriguez E, Braun A, Smith BJ, Knudsen L. Hidden Microatelectases Increase Vulnerability to Ventilation-Induced Lung Injury. Front Physiol 2020; 11:530485. [PMID: 33071807 PMCID: PMC7530907 DOI: 10.3389/fphys.2020.530485] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/28/2020] [Indexed: 11/13/2022] Open
Abstract
Mechanical ventilation of lungs suffering from microatelectases may trigger the development of acute lung injury (ALI). Direct lung injury by bleomycin results in surfactant dysfunction and microatelectases at day 1 while tissue elastance and oxygenation remain normal. Computational simulations of alveolar micromechanics 1-day post-bleomycin predict persisting microatelectases throughout the respiratory cycle and increased alveolar strain during low positive end-expiratory pressure (PEEP) ventilation. As such, we hypothesize that mechanical ventilation in presence of microatelectases, which occur at low but not at higher PEEP, aggravates and unmasks ALI in the bleomycin injury model. Rats were randomized and challenged with bleomycin (B) or not (H = healthy). One day after bleomycin instillation the animals were ventilated for 3 h with PEEP 1 (PEEP1) or 5 cmH2O (PEEP5) and a tidal volume of 10 ml/kg bodyweight. Tissue elastance was repetitively measured after a recruitment maneuver to investigate the degree of distal airspace instability. The right lung was subjected to bronchoalveolar lavage (BAL), the left lung was fixed for design-based stereology at light- and electron microscopic level. Prior to mechanical ventilation, lung tissue elastance did not differ. During mechanical ventilation tissue elastance increased in bleomycin-injured lungs ventilated with PEEP = 1 cmH2O but remained stable in all other groups. Measurements at the conclusion of ventilation showed the largest time-dependent increase in tissue elastance after recruitment in B/PEEP1, indicating increased instability of distal airspaces. These lung mechanical findings correlated with BAL measurements including elevated BAL neutrophilic granulocytes as well as BAL protein and albumin in B/PEEP1. Moreover, the increased septal wall thickness and volume of peri-bronchiolar-vascular connective tissue in B/PEEP1 suggested aggravation of interstitial edema by ventilation in presence of microatelectases. At the electron microscopic level, the largest surface area of injured alveolar epithelial was observed in bleomycin-challenged lungs after PEEP = 1 cmH2O ventilation. After bleomycin treatment cellular markers of endoplasmic reticulum stress (p-Perk and p-EIF-2α) were positive within the septal wall and ventilation with PEEP = 1 cmH2O ventilation increased the surface area stained positively for p-EIF-2α. In conclusion, hidden microatelectases are linked with an increased pulmonary vulnerability for mechanical ventilation characterized by an aggravation of epithelial injury.
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Affiliation(s)
- Karolin Albert
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany
| | - Jeanne-Marie Krischer
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany
| | - Alexander Pfaffenroth
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany
| | - Sabrina Wilde
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hanover, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hanover, Germany.,Institute for Functional Anatomy, Charité, Berlin, Germany
| | - Armin Braun
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hanover, Germany
| | - Bradford J Smith
- Department of Bioengineering, College of Engineering, Design and Computing, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, United States
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hanover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hanover, Germany
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29
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Bollag WB, Gonzales JN. Phosphatidylglycerol and surfactant: A potential treatment for COVID-19? Med Hypotheses 2020; 144:110277. [PMID: 33254581 PMCID: PMC7493731 DOI: 10.1016/j.mehy.2020.110277] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/11/2020] [Accepted: 09/12/2020] [Indexed: 01/08/2023]
Abstract
A hypothesis concerning the potential utility of surfactant supplementation for the treatment of critically ill patients with COVID-19 is proposed, along with a brief summary of the data in the literature supporting this idea. It is thought that surfactant, which is already approved by the Food and Drug Administration for intratracheal administration to treat neonatal respiratory distress syndrome in pre-term infants, could benefit COVID-19-infected individuals by: (1) restoring surfactant damaged by lung infection and/or decreased due to the virus-induced death of the type II pneumocytes that produce it and (2) reducing surface tension to decrease the work of breathing and limit pulmonary edema. In addition, a constituent of surfactant, phosphatidylglycerol, could mitigate COVID-19-induced lung pathology by: (3) decreasing excessive innate immune system stimulation via its inhibition of toll-like receptor-2 and -4 activation by microbial components and cellular proteins released by damaged cells, thereby limiting inflammation and the resultant pulmonary edema, and (4) possibly blocking spread of the viral infection to non-infected cells in the lung. Therefore, it is suggested that surfactant preparations containing phosphatidylglycerol be tested for their ability to improve lung function in critically ill patients with COVID-19.
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Affiliation(s)
- Wendy B Bollag
- Charlie Norwood VA Medical Center, Augusta, GA 30904, United States; Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States; Department of Dermatology, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States; Department of Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States.
| | - Joyce N Gonzales
- Department of Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, United States
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Abstract
OBJECTIVES To examine the potentially modifiable drivers that injure and heal the "baby lung" of acute respiratory distress syndrome and describe a rational clinical approach to favor benefit. DATA SOURCES Published experimental studies and clinical papers that address varied aspects of ventilator-induced lung injury pathogenesis and its consequences. STUDY SELECTION Published information relevant to the novel hypothesis of progressive lung vulnerability and to the biophysical responses of lung injury and repair. DATA EXTRACTION None. DATA SYNTHESIS In acute respiratory distress syndrome, the reduced size and capacity for gas exchange of the functioning "baby lung" imply loss of ventilatory capability that dwindles in proportion to severity of lung injury. Concentrating the entire ventilation workload and increasing perfusion to these already overtaxed units accentuates their potential for progressive injury. Unlike static airspace pressures, which, in theory, apply universally to aerated structures of all dimensions, the components of tidal inflation that relate to power (which include frequency and flow) progressively intensify their tissue-stressing effects on parenchyma and microvasculature as the ventilated compartment shrinks further, especially during the first phase of the evolving injury. This "ventilator-induced lung injury vortex" of the shrinking baby lung is opposed by reactive, adaptive, and reparative processes. In this context, relatively little attention has been paid to the evolving interactions between lung injury and response and to the timing of interventions that worsen, limit or reverse a potentially accelerating ventilator-induced lung injury process. Although universal and modifiable drivers hold the potential to progressively injure the functional lung units of acute respiratory distress syndrome in a positive feedback cycle, measures can be taken to interrupt that process and encourage growth and healing of the "baby lung" of severe acute respiratory distress syndrome.
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Affiliation(s)
- John J Marini
- University of Minnesota and Regions Hospital, Minneapolis/St. Paul, MN
| | - Luciano Gattinoni
- Department of Anesthesiology, Intensive Care and Emergency Medicine, Medical University of Göttingen, Göttingen, Germany
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31
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Resolving the Ionotropic P2X4 Receptor Mystery Points Towards a New Therapeutic Target for Cardiovascular Diseases. Int J Mol Sci 2020; 21:ijms21145005. [PMID: 32679900 PMCID: PMC7404342 DOI: 10.3390/ijms21145005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/09/2020] [Accepted: 07/13/2020] [Indexed: 12/18/2022] Open
Abstract
Adenosine triphosphate (ATP) is a primordial versatile autacoid that changes its role from an intracellular energy saver to a signaling molecule once released to the extracellular milieu. Extracellular ATP and its adenosine metabolite are the main activators of the P2 and P1 purinoceptor families, respectively. Mounting evidence suggests that the ionotropic P2X4 receptor (P2X4R) plays pivotal roles in the regulation of the cardiovascular system, yet further therapeutic advances have been hampered by the lack of selective P2X4R agonists. In this review, we provide the state of the art of the P2X4R activity in the cardiovascular system. We also discuss the role of P2X4R activation in kidney and lungs vis a vis their interplay to control cardiovascular functions and dysfunctions, including putative adverse effects emerging from P2X4R activation. Gathering this information may prompt further development of selective P2X4R agonists and its translation to the clinical practice.
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32
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Wei W, Fan Y, Liu W, Zhao T, Tian H, Xu Y, Tan Y, Song X, Ma D. Combined non-intubated anaesthesia and paravertebral nerve block in comparison with intubated anaesthesia in children undergoing video-assisted thoracic surgery. Acta Anaesthesiol Scand 2020; 64:810-818. [PMID: 32145713 DOI: 10.1111/aas.13572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/27/2020] [Accepted: 02/20/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND This study is to investigate if non-intubated anaesthesia combined with paravertebral nerve block (PVNB) can enhance recovery in children undergoing video-assisted thoracic surgery (VATS). METHODS A randomized controlled trial including 60 patients aged 3 to 8 years old who underwent elective VATS was performed. They were randomly assigned to receive non-intubated anaesthesia combined with PVNB or general anaesthesia with tracheal intubation (1:1 ratio). The primary outcome was the length of postoperative in-hospital stay. The secondary outcomes included emergence time, the incidence of emergence delirium, time to first feeding, time to first out-of-bed activity, pain score and in-hospital complications. RESULTS The non-intubated group had shorter postoperative in-hospital stay than the control group (4 days [IQR, 4-6] vs 5 days [IQR, 5-8], 95% CI 0-2; P = .013). When compared to the control group, the incidence of emergence delirium (odds ratio [OR] 3.39, 95% CI 1.01-11.41; P = .043), emergence time, duration in the PACU, time to first eating food, first out-of-bed activity, pain score and consumption of sufentanil (at 6 and 12 hours after surgery) were decreased in the intervention group. In contrast, the incidence of airway complications was higher in the control than the intervention group (27.6% vs 6.9%, P = .037). There was no statistical significance in the occurrence of PONV, pneumothorax and other complications between the two groups. CONCLUSIONS Non-intubated anaesthesia combined with PVNB enhances recovery in paediatric patients for video-assisted thoracic surgery although further multi-centre study is needed.
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Affiliation(s)
- Wei Wei
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Yanting Fan
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Wei Liu
- Department of Thoracic Surgery Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Tianyun Zhao
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Hang Tian
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Yingyi Xu
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Yonghong Tan
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Xingrong Song
- Department of Anaesthesiology Guangzhou Women and Children’s Medical Center Guangzhou Medical University Guangzhou China
| | - Daqing Ma
- Anaethetics, Pain Medicine and Intensive Care Department of Surgery and Cancer Faculty of Medicine Imperial College London Chelsea and Westminster Hospital London UK
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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: 2.8] [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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Daniher D, McCaig L, Ye Y, Veldhuizen R, Lewis J, Ma Y, Zhu J. Protective effects of aerosolized pulmonary surfactant powder in a model of ventilator-induced lung injury. Int J Pharm 2020; 583:119359. [PMID: 32334066 DOI: 10.1016/j.ijpharm.2020.119359] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 04/14/2020] [Accepted: 04/19/2020] [Indexed: 01/22/2023]
Abstract
Mechanical ventilation may contribute to the impairment of the pulmonary surfactant system, which is one of the mechanisms leading to the progression of acute lung injury. To investigate the potential protective effects of pulmonary surfactant in a rat model of ventilator-induced lung injury, the surfactant powder was aerosolized using an in-house made device designed to deliver the aerosolized powder to the inspiratory line of a rodent ventilator circuit. Rats were randomized to (i) administration of aerosolized recombinant surfactant protein C based pulmonary surfactant, (ii) intratracheally instillation of the same surfactant re-constituted in saline, and (iii) no treatment. Animals were monitored during 2 h of high-tidal volume mechanical ventilation, after which rats were sacrificed, and further analysis of lung mechanics and surfactant function were completed. Blood gas measurements during ventilation showed extended maintenance of oxygen levels above 400 mmHg in aerosol treated animals over non-treated and instilled groups, while total protein analysis showed reduced levels in the aerosol compared to non-treated groups. Dynamic captive bubble surface tension measurements showed the activity of surfactant recovered from aerosol treated animals is maintained below 1 mN/m. The prophylactic treatment of aerosolized surfactant powder reduced the severity of lung injury in this model.
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Affiliation(s)
- Derek Daniher
- Biomedical Engineering Graduate Program, The University of Western Ontario, London, Canada
| | - Lynda McCaig
- Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
| | - Yuqing Ye
- Biomedical Engineering Graduate Program, The University of Western Ontario, London, Canada
| | - Ruud Veldhuizen
- Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
| | - James Lewis
- Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
| | - Yingliang Ma
- Department of Chemical & Biochemical Engineering, The University of Western Ontario, London, Canada
| | - Jesse Zhu
- Biomedical Engineering Graduate Program, The University of Western Ontario, London, Canada; Department of Chemical & Biochemical Engineering, The University of Western Ontario, London, Canada.
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Abstract
Ventilation-induced lung injury results from mechanical stress and strain that occur during tidal ventilation in the susceptible lung. Classical descriptions of ventilation-induced lung injury have focused on harm from positive pressure ventilation. However, injurious forces also can be generated by patient effort and patient–ventilator interactions. While the role of global mechanics has long been recognized, regional mechanical heterogeneity within the lungs also appears to be an important factor propagating clinically significant lung injury. The resulting clinical phenotype includes worsening lung injury and a systemic inflammatory response that drives extrapulmonary organ failures. Bedside recognition of ventilation-induced lung injury requires a high degree of clinical acuity given its indistinct presentation and lack of definitive diagnostics. Yet the clinical importance of ventilation-induced lung injury is clear. Preventing such biophysical injury remains the most effective management strategy to decrease morbidity and mortality in patients with acute respiratory distress syndrome and likely benefits others at risk.
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Affiliation(s)
- Purnema Madahar
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
| | - Jeremy R Beitler
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
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Kollisch-Singule M, Satalin J, Blair SJ, Andrews PL, Gatto LA, Nieman GF, Habashi NM. Mechanical Ventilation Lessons Learned From Alveolar Micromechanics. Front Physiol 2020; 11:233. [PMID: 32265735 PMCID: PMC7105828 DOI: 10.3389/fphys.2020.00233] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/28/2020] [Indexed: 01/05/2023] Open
Abstract
Morbidity and mortality associated with lung injury remains disappointingly unchanged over the last two decades, in part due to the current reliance on lung macro-parameters set on the ventilator instead of considering the micro-environment and the response of the alveoli and alveolar ducts to ventilator adjustments. The response of alveoli and alveolar ducts to mechanical ventilation modes cannot be predicted with current bedside methods of assessment including lung compliance, oxygenation, and pressure-volume curves. Alveolar tidal volumes (Vt) are less determined by the Vt set on the mechanical ventilator and more dependent on the number of recruited alveoli available to accommodate that Vt and their heterogeneous mechanical properties, such that high lung Vt can lead to a low alveolar Vt and low Vt can lead to high alveolar Vt. The degree of alveolar heterogeneity that exists cannot be predicted based on lung calculations that average the individual alveolar Vt and compliance. Finally, the importance of time in promoting alveolar stability, specifically the inspiratory and expiratory times set on the ventilator, are currently under-appreciated. In order to improve outcomes related to lung injury, the respiratory physiology of the individual patient, specifically at the level of the alveolus, must be targeted. With experimental data, this review highlights some of the known mechanical ventilation adjustments that are helpful or harmful at the level of the alveolus.
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Affiliation(s)
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Sarah J. Blair
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Penny L. Andrews
- Department of Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, United States
| | - Louis A. Gatto
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, United States
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Nader M. Habashi
- Department of Critical Care, R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, United States
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Nieman GF, Al-Khalisy H, Kollisch-Singule M, Satalin J, Blair S, Trikha G, Andrews P, Madden M, Gatto LA, Habashi NM. A Physiologically Informed Strategy to Effectively Open, Stabilize, and Protect the Acutely Injured Lung. Front Physiol 2020; 11:227. [PMID: 32265734 PMCID: PMC7096584 DOI: 10.3389/fphys.2020.00227] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/27/2020] [Indexed: 12/16/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) causes a heterogeneous lung injury and remains a serious medical problem, with one of the only treatments being supportive care in the form of mechanical ventilation. It is very difficult, however, to mechanically ventilate the heterogeneously damaged lung without causing secondary ventilator-induced lung injury (VILI). The acutely injured lung becomes time and pressure dependent, meaning that it takes more time and pressure to open the lung, and it recollapses more quickly and at higher pressure. Current protective ventilation strategies, ARDSnet low tidal volume (LVt) and the open lung approach (OLA), have been unsuccessful at further reducing ARDS mortality. We postulate that this is because the LVt strategy is constrained to ventilating a lung with a heterogeneous mix of normal and focalized injured tissue, and the OLA, although designed to fully open and stabilize the lung, is often unsuccessful at doing so. In this review we analyzed the pathophysiology of ARDS that renders the lung susceptible to VILI. We also analyzed the alterations in alveolar and alveolar duct mechanics that occur in the acutely injured lung and discussed how these alterations are a key mechanism driving VILI. Our analysis suggests that the time component of each mechanical breath, at both inspiration and expiration, is critical to normalize alveolar mechanics and protect the lung from VILI. Animal studies and a meta-analysis have suggested that the time-controlled adaptive ventilation (TCAV) method, using the airway pressure release ventilation mode, eliminates the constraints of ventilating a lung with heterogeneous injury, since it is highly effective at opening and stabilizing the time- and pressure-dependent lung. In animal studies it has been shown that by “casting open” the acutely injured lung with TCAV we can (1) reestablish normal expiratory lung volume as assessed by direct observation of subpleural alveoli; (2) return normal parenchymal microanatomical structural support, known as alveolar interdependence and parenchymal tethering, as assessed by morphometric analysis of lung histology; (3) facilitate regeneration of normal surfactant function measured as increases in surfactant proteins A and B; and (4) significantly increase lung compliance, which reduces the pathologic impact of driving pressure and mechanical power at any given tidal volume.
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Affiliation(s)
- Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Hassan Al-Khalisy
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States
| | | | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Sarah Blair
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Girish Trikha
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Penny Andrews
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Maria Madden
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Biological Sciences, SUNY Cortland, Cortland, NY, United States
| | - Nader M Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
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Mechanical ventilation weaning issues can be counted on the fingers of just one hand: part 2. Ultrasound J 2020; 12:15. [PMID: 32166639 PMCID: PMC7067962 DOI: 10.1186/s13089-020-00160-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 02/06/2020] [Indexed: 12/18/2022] Open
Abstract
Assessing heart and diaphragm function constitutes only one of the steps to consider along the weaning path. In this second part of the review, we will deal with the more systematic evaluation of the pulmonary parenchyma—often implicated in the genesis of respiratory failure. We will also consider the other possible causes of weaning failure that lie beyond the cardio-pulmonary-diaphragmatic system. Finally, we will take a moment to consider the remaining unsolved problems arising from mechanical ventilation and describe the so-called protective approach to parenchyma and diaphragm ventilation.
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39
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Bedside respiratory physiology to detect risk of lung injury in acute respiratory distress syndrome. Curr Opin Crit Care 2020; 25:3-11. [PMID: 30531534 DOI: 10.1097/mcc.0000000000000579] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW The most effective strategies for treating the patient with acute respiratory distress syndrome center on minimizing ventilation-induced lung injury (VILI). Yet, current standard-of-care does little to modify mechanical ventilation to patient-specific risk. This review focuses on evaluation of bedside respiratory mechanics, which when interpreted in patient-specific context, affords opportunity to individualize lung-protective ventilation in patients with acute respiratory distress syndrome. RECENT FINDINGS Four biophysical mechanisms of VILI are widely accepted: volutrauma, barotrauma, atelectrauma, and stress concentration. Resulting biotrauma, that is, local and systemic inflammation and endothelial activation, may be thought of as the final common pathway that propagates VILI-mediated multiorgan failure. Conventional, widely utilized techniques to assess VILI risk rely on airway pressure, flow, and volume changes, and remain essential tools for determining overdistension of aerated lung regions, particularly when interpreted cognizant of their limitations. Emerging bedside tools identify regional differences in mechanics, but further study is required to identify how they might best be incorporated into clinical practice. SUMMARY Quantifying patient-specific risk of VILI requires understanding each patient's pulmonary mechanics in context of biological predisposition. Tailoring support at bedside according to these factors affords the greatest opportunity to date for mitigating VILI and alleviating associated morbidity.
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Abstract
Sepsis, pneumonia, and shock are the most common conditions predisposing to acute respiratory distress syndrome (ARDS) and certain host genetic variants have been associated with the development of ARDS. Risk modifiers include abuse of alcohol and tobacco, malnutrition, and obesity. The Lung Injury Prediction Score (LIPS) and the simplified Early Acute Lung Injury Score predict ARDS based on clinical and investigational criteria. Hospital-acquired ARDS may result from a medley factors of which high tidal volume ventilation, high oxygen concentration, and plasma transfusion are most commonly implicated. The Checklist for Lung Injury Prevention (CLIP) has been developed to ensure compliance with evidence-based practice that may affect ARDS occurrence. To date, no pharmacologic intervention has been shown to prevent ARDS
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41
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Viola H, Chang J, Grunwell JR, Hecker L, Tirouvanziam R, Grotberg JB, Takayama S. Microphysiological systems modeling acute respiratory distress syndrome that capture mechanical force-induced injury-inflammation-repair. APL Bioeng 2019; 3:041503. [PMID: 31768486 PMCID: PMC6874511 DOI: 10.1063/1.5111549] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 11/08/2019] [Indexed: 12/14/2022] Open
Abstract
Complex in vitro models of the tissue microenvironment, termed microphysiological systems, have enormous potential to transform the process of discovering drugs and disease mechanisms. Such a paradigm shift is urgently needed in acute respiratory distress syndrome (ARDS), an acute lung condition with no successful therapies and a 40% mortality rate. Here, we consider how microphysiological systems could improve understanding of biological mechanisms driving ARDS and ultimately improve the success of therapies in clinical trials. We first discuss how microphysiological systems could explain the biological mechanisms underlying the segregation of ARDS patients into two clinically distinct phenotypes. Then, we contend that ARDS-mimetic microphysiological systems should recapitulate three critical aspects of the distal airway microenvironment, namely, mechanical force, inflammation, and fibrosis, and we review models that incorporate each of these aspects. Finally, we recognize the substantial challenges associated with combining inflammation, fibrosis, and/or mechanical force in microphysiological systems. Nevertheless, complex in vitro models are a novel paradigm for studying ARDS, and they could ultimately improve patient care.
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Affiliation(s)
| | - Jonathan Chang
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory School of Medicine, Atlanta, Georgia 30332, USA
| | - Jocelyn R. Grunwell
- Department of Pediatrics, Division of Critical Care Medicine, Children's Healthcare of Atlanta at Egleston, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Louise Hecker
- Division of Pulmonary, Allergy and Critical Care and Sleep Medicine, University of Arizona, Tucson, Arizona 85724, USA and Southern Arizona Veterans Affairs Health Care System, Tucson, Arizona 85723, USA
| | - Rabindra Tirouvanziam
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA and Center for CF and Airways Disease Research, Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - James B. Grotberg
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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Does Regional Lung Strain Correlate With Regional Inflammation in Acute Respiratory Distress Syndrome During Nonprotective Ventilation? An Experimental Porcine Study. Crit Care Med 2019. [PMID: 29528946 DOI: 10.1097/ccm.0000000000003072] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
OBJECTIVE It is known that ventilator-induced lung injury causes increased pulmonary inflammation. It has been suggested that one of the underlying mechanisms may be strain. The aim of this study was to investigate whether lung regional strain correlates with regional inflammation in a porcine model of acute respiratory distress syndrome. DESIGN Retrospective analysis of CT images and positron emission tomography images using [F]fluoro-2-deoxy-D-glucose. SETTING University animal research laboratory. SUBJECTS Seven piglets subjected to experimental acute respiratory distress syndrome and five ventilated controls. INTERVENTIONS Acute respiratory distress syndrome was induced by repeated lung lavages, followed by 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressures (mean, 4 cm H2O) and high inspiratory pressures (mean plateau pressure, 45 cm H2O). All animals were subsequently studied with CT scans acquired at end-expiration and end-inspiration, to obtain maps of volumetric strain (inspiratory volume - expiratory volume)/expiratory volume, and dynamic positron emission tomography imaging. Strain maps and positron emission tomography images were divided into 10 isogravitational horizontal regions-of-interest, from which spatial correlation was calculated for each animal. MEASUREMENTS AND MAIN RESULTS The acute respiratory distress syndrome model resulted in a decrease in respiratory system compliance (20.3 ± 3.4 to 14.0 ± 4.9 mL/cm H2O; p < 0.05) and oxygenation (PaO2/FIO2, 489 ± 80 to 92 ± 59; p < 0.05), whereas the control animals did not exhibit changes. In the acute respiratory distress syndrome group, strain maps showed a heterogeneous distribution with a greater concentration in the intermediate gravitational regions, which was similar to the distribution of [F]fluoro-2-deoxy-D-glucose uptake observed in the positron emission tomography images, resulting in a positive spatial correlation between both variables (median R = 0.71 [0.02-0.84]; p < 0.05 in five of seven animals), which was not observed in the control animals. CONCLUSION In this porcine acute respiratory distress syndrome model, regional lung strain was spatially correlated with regional inflammation, supporting that strain is a relevant and prominent determinant of ventilator-induced lung injury.
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Motta-Ribeiro GC, Hashimoto S, Winkler T, Baron RM, Grogg K, Paula LFSC, Santos A, Zeng C, Hibbert K, Harris RS, Bajwa E, Vidal Melo MF. Deterioration of Regional Lung Strain and Inflammation during Early Lung Injury. Am J Respir Crit Care Med 2019; 198:891-902. [PMID: 29787304 DOI: 10.1164/rccm.201710-2038oc] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE The contribution of aeration heterogeneity to lung injury during early mechanical ventilation of uninjured lungs is unknown. OBJECTIVES To test the hypotheses that a strategy consistent with clinical practice does not protect from worsening in lung strains during the first 24 hours of ventilation of initially normal lungs exposed to mild systemic endotoxemia in supine versus prone position, and that local neutrophilic inflammation is associated with local strain and blood volume at global strains below a proposed injurious threshold. METHODS Voxel-level aeration and tidal strain were assessed by computed tomography in sheep ventilated with low Vt and positive end-expiratory pressure while receiving intravenous endotoxin. Regional inflammation and blood volume were estimated from 2-deoxy-2-[(18)F]fluoro-d-glucose (18F-FDG) positron emission tomography. MEASUREMENTS AND MAIN RESULTS Spatial heterogeneity of aeration and strain increased only in supine lungs (P < 0.001), with higher strains and atelectasis than prone at 24 hours. Absolute strains were lower than those considered globally injurious. Strains redistributed to higher aeration areas as lung injury progressed in supine lungs. At 24 hours, tissue-normalized 18F-FDG uptake increased more in atelectatic and moderately high-aeration regions (>70%) than in normally aerated regions (P < 0.01), with differential mechanistically relevant regional gene expression. 18F-FDG phosphorylation rate was associated with strain and blood volume. Imaging findings were confirmed in ventilated patients with sepsis. CONCLUSIONS Mechanical ventilation consistent with clinical practice did not generate excessive regional strain in heterogeneously aerated supine lungs. However, it allowed worsening of spatial strain distribution in these lungs, associated with increased inflammation. Our results support the implementation of early aeration homogenization in normal lungs.
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Affiliation(s)
- Gabriel C Motta-Ribeiro
- 1 Department of Anesthesia, Critical Care and Pain Medicine.,2 Biomedical Engineering Program, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Soshi Hashimoto
- 1 Department of Anesthesia, Critical Care and Pain Medicine.,3 Department of Anesthesiology and Intensive Care, Kyoto Prefectural University of Medicine, Kyoto, Japan; and
| | - Tilo Winkler
- 1 Department of Anesthesia, Critical Care and Pain Medicine
| | - Rebecca M Baron
- 4 Department of Medicine (Pulmonary and Critical Care), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | | | - Arnoldo Santos
- 1 Department of Anesthesia, Critical Care and Pain Medicine.,6 CIBER de Enfermedades Respiratorias, Madrid, Spain
| | - Congli Zeng
- 1 Department of Anesthesia, Critical Care and Pain Medicine
| | - Kathryn Hibbert
- 7 Department of Medicine (Pulmonary and Critical Care), Massachusetts General Hospital, and
| | - Robert S Harris
- 7 Department of Medicine (Pulmonary and Critical Care), Massachusetts General Hospital, and
| | - Ednan Bajwa
- 7 Department of Medicine (Pulmonary and Critical Care), Massachusetts General Hospital, and
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Nugent K, Dobbe L, Rahman R, Elmassry M, Paz P. Lung morphology and surfactant function in cardiogenic pulmonary edema: a narrative review. J Thorac Dis 2019; 11:4031-4038. [PMID: 31656679 DOI: 10.21037/jtd.2019.09.02] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The conventional analysis of acute cardiogenic pulmonary edema involves the development of high pulmonary capillary pressures resulting in hydrostatic gradients for fluid flux out of capillaries into the interstitial space and alveolar spaces. However, some patients respond poorly to diuretic management. The PubMed database was searched to identify experimental studies on pulmonary edema in animals, experimental studies on surfactant function, including patients with pulmonary edema, and clinical studies reporting barrier dysfunction and/or injury in patients with acute pulmonary edema. Studies with animal models demonstrate that high capillary pressures can cause barrier disruption in alveolar capillary units which increases permeability and the transfer of fluid and protein into lung parenchyma. Fluid in alveolar spaces alters surfactant function which increases fluid flux out of capillaries into the lung parenchyma secondary to larger transcapillary hydrostatic gradients. Patients with acute cardiogenic pulmonary edema have increased levels of surfactant protein B in their plasma which reflect barrier disruption and increased levels of tumor necrosis factor alpha which reflect acute tissue injury. Increased surfactant protein B plasma levels are associated with abnormal gas exchange in patients with chronic heart failure. Patients with exercise-induced left ventricular dysfunction have increased levels of surfactant protein B after short periods of exercise. Pathology studies in patients with chronic heart failure have found increased connective tissue in alveolar capillary units and increased numbers of type II alveolar cells, and these changes represent an adaptive response in these patients. Clinicians need to consider the possibility of barrier dysfunction and disruption in patients with both acute and chronic pulmonary edema and understand that diuresis may have a limited effect on symptoms in some patients.
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Affiliation(s)
- Kenneth Nugent
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Logan Dobbe
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Rubayat Rahman
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Mohamed Elmassry
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Pablo Paz
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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45
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Rühl N, Lopez-Rodriguez E, Albert K, Smith BJ, Weaver TE, Ochs M, Knudsen L. Surfactant Protein B Deficiency Induced High Surface Tension: Relationship between Alveolar Micromechanics, Alveolar Fluid Properties and Alveolar Epithelial Cell Injury. Int J Mol Sci 2019; 20:ijms20174243. [PMID: 31480246 PMCID: PMC6747270 DOI: 10.3390/ijms20174243] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 11/16/2022] Open
Abstract
High surface tension at the alveolar air-liquid interface is a typical feature of acute and chronic lung injury. However, the manner in which high surface tension contributes to lung injury is not well understood. This study investigated the relationship between abnormal alveolar micromechanics, alveolar epithelial injury, intra-alveolar fluid properties and remodeling in the conditional surfactant protein B (SP-B) knockout mouse model. Measurements of pulmonary mechanics, broncho-alveolar lavage fluid (BAL), and design-based stereology were performed as a function of time of SP-B deficiency. After one day of SP-B deficiency the volume of alveolar fluid V(alvfluid,par) as well as BAL protein and albumin levels were normal while the surface area of injured alveolar epithelium S(AEinjure,sep) was significantly increased. Alveoli and alveolar surface area could be recruited by increasing the air inflation pressure. Quasi-static pressure-volume loops were characterized by an increased hysteresis while the inspiratory capacity was reduced. After 3 days, an increase in V(alvfluid,par) as well as BAL protein and albumin levels were linked with a failure of both alveolar recruitment and airway pressure-dependent redistribution of alveolar fluid. Over time, V(alvfluid,par) increased exponentially with S(AEinjure,sep). In conclusion, high surface tension induces alveolar epithelial injury prior to edema formation. After passing a threshold, epithelial injury results in vascular leakage and exponential accumulation of alveolar fluid critically hampering alveolar recruitability.
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Affiliation(s)
- Nina Rühl
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover 30625, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover 30625, Germany
- Biomedical Research in Endstage and Obstructive Lung Diseases (BREATH), Member of the German Center for Lung Research (DLZ), Hannover 30625, Germany
- REBIRTH, Cluster of Excellence, Hannover 30625, Germany
- Institute of Vegetative Anatomy, Charite, Berlin 10117, Germany
| | - Karolin Albert
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover 30625, Germany
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver, Denver, CO 80045, USA
| | - Timothy E Weaver
- Division of Pulmonary Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45221, USA
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover 30625, Germany
- Biomedical Research in Endstage and Obstructive Lung Diseases (BREATH), Member of the German Center for Lung Research (DLZ), Hannover 30625, Germany
- REBIRTH, Cluster of Excellence, Hannover 30625, Germany
- Institute of Vegetative Anatomy, Charite, Berlin 10117, Germany
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover 30625, Germany.
- Biomedical Research in Endstage and Obstructive Lung Diseases (BREATH), Member of the German Center for Lung Research (DLZ), Hannover 30625, Germany.
- REBIRTH, Cluster of Excellence, Hannover 30625, Germany.
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46
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Closer to Nature Through Dynamic Culture Systems. Cells 2019; 8:cells8090942. [PMID: 31438519 PMCID: PMC6769584 DOI: 10.3390/cells8090942] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/16/2019] [Accepted: 08/19/2019] [Indexed: 12/12/2022] Open
Abstract
Mechanics in the human body are required for normal cell function at a molecular level. It is now clear that mechanical stimulations play significant roles in cell growth, differentiation, and migration in normal and diseased cells. Recent studies have led to the discovery that normal and cancer cells have different mechanosensing properties. Here, we discuss the application and the physiological and pathological meaning of mechanical stimulations. To reveal the optimal conditions for mimicking an in vivo microenvironment, we must, therefore, discern the mechanotransduction occurring in cells.
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47
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Mellenthin MM, Seong SA, Roy GS, Bartolák-Suki E, Hamlington KL, Bates JHT, Smith BJ. Using injury cost functions from a predictive single-compartment model to assess the severity of mechanical ventilator-induced lung injuries. J Appl Physiol (1985) 2019; 127:58-70. [PMID: 31046518 DOI: 10.1152/japplphysiol.00770.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Identifying safe ventilation patterns for patients with acute respiratory distress syndrome remains challenging because of the delicate balance between gas exchange and selection of ventilator settings to prevent further ventilator-induced lung injury (VILI). Accordingly, this work seeks to link ventilator settings to graded levels of VILI to identify injury cost functions that predict injury by using a computational model to process pressures and flows measured at the airway opening. Pressure-volume loops were acquired over the course of ~2 h of mechanical ventilation in four different groups of BALB/c mice. A cohort of these animals were subjected to an injurious bronchoalveolar lavage before ventilation. The data were analyzed with a single-compartment model that predicts recruitment/derecruitment and tissue distension at each time step in measured pressure-volume loops. We compared several injury cost functions to markers of VILI-induced blood-gas barrier disruption. Of the cost functions considered, we conclude that mechanical power dissipation and strain heterogeneity are the best at distinguishing between graded levels of injury and are good candidates for forecasting the development of VILI. NEW & NOTEWORTHY This work uses a predictive single-compartment model and injury cost functions to assess graded levels of mechanical ventilator-induced lung injury. The most promising measures include strain heterogeneity and mechanical power dissipation.
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Affiliation(s)
| | - Siyeon A Seong
- College of Medicine, University of Vermont , Burlington, Vermont
| | - Gregory S Roy
- College of Medicine, University of Vermont , Burlington, Vermont
| | | | - Katharine L Hamlington
- College of Medicine, University of Vermont , Burlington, Vermont.,University of Colorado at Children's Hospital Colorado , Aurora, Colorado
| | - Jason H T Bates
- College of Medicine, University of Vermont , Burlington, Vermont
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver , Aurora, Colorado.,College of Medicine, University of Vermont , Burlington, Vermont
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48
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Abstract
The acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in critically ill patients and is defined by the acute onset of noncardiogenic pulmonary oedema, hypoxaemia and the need for mechanical ventilation. ARDS occurs most often in the setting of pneumonia, sepsis, aspiration of gastric contents or severe trauma and is present in ~10% of all patients in intensive care units worldwide. Despite some improvements, mortality remains high at 30-40% in most studies. Pathological specimens from patients with ARDS frequently reveal diffuse alveolar damage, and laboratory studies have demonstrated both alveolar epithelial and lung endothelial injury, resulting in accumulation of protein-rich inflammatory oedematous fluid in the alveolar space. Diagnosis is based on consensus syndromic criteria, with modifications for under-resourced settings and in paediatric patients. Treatment focuses on lung-protective ventilation; no specific pharmacotherapies have been identified. Long-term outcomes of patients with ARDS are increasingly recognized as important research targets, as many patients survive ARDS only to have ongoing functional and/or psychological sequelae. Future directions include efforts to facilitate earlier recognition of ARDS, identifying responsive subsets of patients and ongoing efforts to understand fundamental mechanisms of lung injury to design specific treatments.
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49
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Knudsen L, Lopez-Rodriguez E, Berndt L, Steffen L, Ruppert C, Bates JHT, Ochs M, Smith BJ. Alveolar Micromechanics in Bleomycin-induced Lung Injury. Am J Respir Cell Mol Biol 2018; 59:757-769. [PMID: 30095988 PMCID: PMC6293074 DOI: 10.1165/rcmb.2018-0044oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/29/2018] [Indexed: 12/22/2022] Open
Abstract
Lung injury results in intratidal alveolar recruitment and derecruitment and alveolar collapse, creating stress concentrators that increase strain and aggravate injury. In this work, we sought to describe alveolar micromechanics during mechanical ventilation in bleomycin-induced lung injury and surfactant replacement therapy. Structure and function were assessed in rats 1 day and 3 days after intratracheal bleomycin instillation and after surfactant replacement therapy. Pulmonary system mechanics were measured during ventilation with positive end-expiratory pressures (PEEPs) between 1 and 10 cm H2O, followed by perfusion fixation at end-expiratory pressure at airway opening (Pao) values of 1, 5, 10, and 20 cm H2O for quantitative analyses of lung structure. Lung structure and function were used to parameterize a physiologically based, multicompartment computational model of alveolar micromechanics. In healthy controls, the numbers of open alveoli remained stable in a range of Pao = 1-20 cm H2O, whereas bleomycin-challenged lungs demonstrated progressive alveolar derecruitment with Pao < 10 cm H2O. At Day 3, ∼40% of the alveoli remained closed at high Pao, and alveolar size heterogeneity increased. Simulations of injured lungs predicted that alveolar recruitment pressures were much greater than the derecruitment pressures, so that minimal intratidal recruitment and derecruitment occurred during mechanical ventilation with a tidal volume of 10 ml/kg body weight over a range of PEEPs. However, the simulations also predicted a dramatic increase in alveolar strain with injury that we attribute to alveolar interdependence. These findings suggest that in progressive lung injury, alveolar collapse with increased distension of patent (open) alveoli dominates alveolar micromechanics. PEEP and surfactant substitution reduce alveolar collapse and dynamic strain but increase static strain.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | | | | | - Clemens Ruppert
- Department of Internal Medicine, and
- Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
| | | | - Matthias Ochs
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver, Denver, Colorado
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50
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Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochem Cell Biol 2018; 150:661-676. [PMID: 30390118 PMCID: PMC6267411 DOI: 10.1007/s00418-018-1747-9] [Citation(s) in RCA: 206] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/14/2022]
Abstract
The mammalian lung´s structural design is optimized to serve its main function: gas exchange. It takes place in the alveolar region (parenchyma) where air and blood are brought in close proximity over a large surface. Air reaches the alveolar lumen via a conducting airway tree. Blood flows in a capillary network embedded in inter-alveolar septa. The barrier between air and blood consists of a continuous alveolar epithelium (a mosaic of type I and type II alveolar epithelial cells), a continuous capillary endothelium and the connective tissue layer in-between. By virtue of its respiratory movements, the lung has to withstand mechanical challenges throughout life. Alveoli must be protected from over-distension as well as from collapse by inherent stabilizing factors. The mechanical stability of the parenchyma is ensured by two components: a connective tissue fiber network and the surfactant system. The connective tissue fibers form a continuous tensegrity (tension + integrity) backbone consisting of axial, peripheral and septal fibers. Surfactant (surface active agent) is the secretory product of type II alveolar epithelial cells and covers the alveolar epithelium as a biophysically active thin and continuous film. Here, we briefly review the structural components relevant for gas exchange. Then we describe our current understanding of how these components function under normal conditions and how lung injury results in dysfunction of alveolar micromechanics finally leading to lung fibrosis.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
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