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Sousa MLA, Katira BH, Bouch S, Hsing V, Engelberts D, Amato MBP, Post M, Brochard LJ. Limiting Overdistention or Collapse When Mechanically Ventilating Injured Lungs: A Randomized Study in a Porcine Model. Am J Respir Crit Care Med 2024; 209:1441-1452. [PMID: 38354065 DOI: 10.1164/rccm.202310-1895oc] [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: 10/29/2023] [Accepted: 02/14/2024] [Indexed: 02/16/2024] Open
Abstract
Rationale: It is unknown whether preventing overdistention or collapse is more important when titrating positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). Objectives: To compare PEEP targeting minimal overdistention or minimal collapse or using a compromise between collapse and overdistention in a randomized trial and to assess the impact on respiratory mechanics, gas exchange, inflammation, and hemodynamics. Methods: In a porcine model of ARDS, lung collapse and overdistention were estimated using electrical impedance tomography during a decremental PEEP titration. Pigs were randomized to three groups and ventilated for 12 hours: PEEP set at ⩽3% of overdistention (low overdistention), ⩽3% of collapse (low collapse), and the crossing point of collapse and overdistention. Measurements and Main Results: Thirty-six pigs (12 per group) were included. Median (interquartile range) values of PEEP were 7 (6-8), 11 (10-11), and 15 (12-16) cm H2O in the three groups (P < 0.001). With low overdistension, 6 (50%) pigs died, whereas survival was 100% in both other groups. Cause of death was hemodynamic in nature, with high transpulmonary vascular gradient and high epinephrine requirements. Compared with the other groups, pigs surviving with low overdistension had worse respiratory mechanics and gas exchange during the entire protocol. Minimal differences existed between crossing-point and low-collapse animals in physiological parameters, but postmortem alveolar density was more homogeneous in the crossing-point group. Inflammatory markers were not significantly different. Conclusions: PEEP to minimize overdistention resulted in high mortality in an animal model of ARDS. Minimizing collapse or choosing a compromise between collapse and overdistention may result in less lung injury, with potential benefits of the compromise approach.
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Affiliation(s)
- Mayson L A Sousa
- Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Interdepartmental Division of Critical Care Medicine and
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bhushan H Katira
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
- Pediatric Critical Care Medicine, Washington University in St. Louis, St. Louis, Missouri
| | - Sheena Bouch
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Vanessa Hsing
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Doreen Engelberts
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Marcelo B P Amato
- Divisão de Pneumologia, Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil
- Instituto do Coração - InCor, Hospital das Clinicas, Faculade de Medicina da Universidade de São Paulo, São Paulo, Brazil; and
| | - Martin Post
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Translational Medicine Program, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Laurent J Brochard
- Keenan Centre for Biomedical Research, Critical Care Department, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Interdepartmental Division of Critical Care Medicine and
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Karmali D, Sowho M, Bose S, Pearce J, Tejwani V, Diamant Z, Yarlagadda K, Ponce E, Eikelis N, Otvos T, Khan A, Lester M, Fouras A, Kirkness J, Siddharthan T. Functional imaging for assessing regional lung ventilation in preclinical and clinical research. Front Med (Lausanne) 2023; 10:1160292. [PMID: 37261124 PMCID: PMC10228734 DOI: 10.3389/fmed.2023.1160292] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/17/2023] [Indexed: 06/02/2023] Open
Abstract
Dynamic heterogeneity in lung ventilation is an important measure of pulmonary function and may be characteristic of early pulmonary disease. While standard indices like spirometry, body plethysmography, and blood gases have been utilized to assess lung function, they do not provide adequate information on regional ventilatory distribution nor function assessments of ventilation during the respiratory cycle. Emerging technologies such as xenon CT, volumetric CT, functional MRI and X-ray velocimetry can assess regional ventilation using non-invasive radiographic methods that may complement current methods of assessing lung function. As a supplement to current modalities of pulmonary function assessment, functional lung imaging has the potential to identify respiratory disease phenotypes with distinct natural histories. Moreover, these novel technologies may offer an optimal strategy to evaluate the effectiveness of novel therapies and therapies targeting localized small airways disease in preclinical and clinical research. In this review, we aim to discuss the features of functional lung imaging, as well as its potential application and limitations to adoption in research.
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Affiliation(s)
- Dipan Karmali
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | - Mudiaga Sowho
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Sonali Bose
- Division of Pulmonary and Critical Care, Icahn School of Medicine, Mount Sinai, NY, United States
| | - Jackson Pearce
- School of Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Vickram Tejwani
- Respiratory Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Zuzana Diamant
- Department of Microbiology Immunology and Transplantation, KU Leuven, Catholic University of Leuven, Leuven, Belgium
- Department of Respiratory Medicine and Allergology, Institute for Clinical Science, Skane University Hospital, Lund University, Lund, Sweden
- Department Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Keerthi Yarlagadda
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | - Erick Ponce
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
| | | | | | - Akram Khan
- Division of Pulmonary and Critical Care, Oregon Health and Science University, Portland, OR, United States
| | - Michael Lester
- Department of Pulmonary and Critical Care Medicine, Vanderbilt Medical Center, Nashville, CA, United States
| | | | | | - Trishul Siddharthan
- Division of Pulmonary and Critical Care, Leonard M. Miller School of Medicine, University of Miami, Coral Gables, FL, United States
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Preclinical MRI Using Hyperpolarized 129Xe. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238338. [PMID: 36500430 PMCID: PMC9738892 DOI: 10.3390/molecules27238338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/05/2022]
Abstract
Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases over short distances, on which proper function relies, is not readily visualized. In this review we summarize progress introducing hyperpolarized 129Xe imaging as a method to follow these processes in vivo. The work is organized in sections highlighting methods to observe the gas replacement effects of breathing (Gas Dynamics during the Breathing Cycle) and gas diffusion throughout the parenchymal airspaces (3). We then describe the spectral signatures indicative of gas dissolution and uptake (4), and how these features can be used to follow the gas as it enters the tissue and capillary bed, is taken up by hemoglobin in the red blood cells (5), re-enters the gas phase prior to exhalation (6), or is carried via the vasculature to other organs and body structures (7). We conclude with a discussion of practical imaging and spectroscopy techniques that deliver quantifiable metrics despite the small size, rapid motion and decay of signal and coherence characteristic of the magnetically inhomogeneous lung in preclinical models (8).
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Katira BH, Engelberts D, Bouch S, Fliss J, Bastia L, Osada K, Connelly KA, Amato MBP, Ferguson ND, Kuebler WM, Kavanagh BP, Brochard LJ, Post M. Repeated endo-tracheal tube disconnection generates pulmonary edema in a model of volume overload: an experimental study. Crit Care 2022; 26:47. [PMID: 35180891 PMCID: PMC8857825 DOI: 10.1186/s13054-022-03924-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An abrupt lung deflation in rodents results in lung injury through vascular mechanisms. Ventilator disconnections during endo-tracheal suctioning in humans often cause cardio-respiratory instability. Whether repeated disconnections or lung deflations cause lung injury or oedema is not known and was tested here in a porcine large animal model. METHODS Yorkshire pigs (~ 12 weeks) were studied in three series. First, we compared PEEP abruptly deflated from 26 cmH2O or from PEEP 5 cmH2O to zero. Second, pigs were randomly crossed over to receive rapid versus gradual PEEP removal from 20 cmH2O. Third, pigs with relative volume overload, were ventilated with PEEP 15 cmH2O and randomized to repeated ETT disconnections (15 s every 15 min) or no disconnection for 3 h. Hemodynamics, pulmonary variables were monitored, and lung histology and bronchoalveolar lavage studied. RESULTS As compared to PEEP 5 cmH2O, abrupt deflation from PEEP 26 cmH2O increased PVR, lowered oxygenation, and increased lung wet-to-dry ratio. From PEEP 20 cmH2O, gradual versus abrupt deflation mitigated the changes in oxygenation and vascular resistance. From PEEP 15, repeated disconnections in presence of fluid loading led to reduced compliance, lower oxygenation, higher pulmonary artery pressure, higher lung wet-to-dry ratio, higher lung injury score and increased oedema on morphometry, compared to no disconnects. CONCLUSION Single abrupt deflation from high PEEP, and repeated short deflations from moderate PEEP cause pulmonary oedema, impaired oxygenation, and increased PVR, in this large animal model, thus replicating our previous finding from rodents. Rapid deflation may thus be a clinically relevant cause of impaired lung function, which may be attenuated by gradual pressure release.
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Affiliation(s)
- Bhushan H Katira
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
- The Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Division of Critical Care Medicine, Department of Paediatrics, Washington University School of Medicine, St Louis, MO, USA
| | - Doreen Engelberts
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
| | - Sheena Bouch
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
| | - Jordan Fliss
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Luca Bastia
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
- School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Kohei Osada
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
| | - Kim A Connelly
- Keenan Research Centre for Biomedical Sciences, Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Canada
| | - Marcelo B P Amato
- Laboratório de Pneumologia LIM-09, Disciplina de Pneumologia, Instituto do Coração (Incor) Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Niall D Ferguson
- Division of Respirology, Department of Medicine, University Health Network and Sinai Health Systems, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Wolfgang M Kuebler
- Institute of Physiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Brian P Kavanagh
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada
- The Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Departments of Critical Care Medicine and Anaesthesiology, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Laurent J Brochard
- Keenan Research Centre for Biomedical Sciences, Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
| | - Martin Post
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay St., 9th Floor, Toronto, ON, M5G 0A4, Canada.
- The Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
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