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Bayat S, Wild J, Winkler T. Lung functional imaging. Breathe (Sheff) 2023; 19:220272. [PMID: 38020338 PMCID: PMC10644108 DOI: 10.1183/20734735.0272-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 10/08/2023] [Indexed: 12/01/2023] Open
Abstract
Pulmonary functional imaging modalities such as computed tomography, magnetic resonance imaging and nuclear imaging can quantitatively assess regional lung functional parameters and their distributions. These include ventilation, perfusion, gas exchange at the microvascular level and biomechanical properties, among other variables. This review describes the rationale, strengths and limitations of the various imaging modalities employed for lung functional imaging. It also aims to explain some of the most commonly measured parameters of regional lung function. A brief review of evidence on the role and utility of lung functional imaging in early diagnosis, accurate lung functional characterisation, disease phenotyping and advancing the understanding of disease mechanisms in major respiratory disorders is provided.
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Affiliation(s)
- Sam Bayat
- Department of Pulmonology and Physiology, CHU Grenoble Alpes, Grenoble, France
- Univ. Grenoble Alpes, STROBE Laboratory, INSERM UA07, Grenoble, France
| | - Jim Wild
- POLARIS, Imaging Group, Department of Infection Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - Tilo Winkler
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Herrmann J, Kollisch-Singule M, Satalin J, Nieman GF, Kaczka DW. Assessment of Heterogeneity in Lung Structure and Function During Mechanical Ventilation: A Review of Methodologies. JOURNAL OF ENGINEERING AND SCIENCE IN MEDICAL DIAGNOSTICS AND THERAPY 2022; 5:040801. [PMID: 35832339 PMCID: PMC9132008 DOI: 10.1115/1.4054386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/13/2022] [Indexed: 06/15/2023]
Abstract
The mammalian lung is characterized by heterogeneity in both its structure and function, by incorporating an asymmetric branching airway tree optimized for maintenance of efficient ventilation, perfusion, and gas exchange. Despite potential benefits of naturally occurring heterogeneity in the lungs, there may also be detrimental effects arising from pathologic processes, which may result in deficiencies in gas transport and exchange. Regardless of etiology, pathologic heterogeneity results in the maldistribution of regional ventilation and perfusion, impairments in gas exchange, and increased work of breathing. In extreme situations, heterogeneity may result in respiratory failure, necessitating support with a mechanical ventilator. This review will present a summary of measurement techniques for assessing and quantifying heterogeneity in respiratory system structure and function during mechanical ventilation. These methods have been grouped according to four broad categories: (1) inverse modeling of heterogeneous mechanical function; (2) capnography and washout techniques to measure heterogeneity of gas transport; (3) measurements of heterogeneous deformation on the surface of the lung; and finally (4) imaging techniques used to observe spatially-distributed ventilation or regional deformation. Each technique varies with regard to spatial and temporal resolution, degrees of invasiveness, risks posed to patients, as well as suitability for clinical implementation. Nonetheless, each technique provides a unique perspective on the manifestations and consequences of mechanical heterogeneity in the diseased lung.
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Affiliation(s)
- Jacob Herrmann
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242
| | | | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY 13210
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY 13210
| | - David W. Kaczka
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242; Department of Anesthesia, University of Iowa, Iowa City, IA 52242; Department of Radiology, University of Iowa, Iowa City, IA 52242
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Herrmann J, Tawhai MH, Kaczka DW. Regional gas transport in the heterogeneous lung during oscillatory ventilation. J Appl Physiol (1985) 2016; 121:1306-1318. [PMID: 27763872 PMCID: PMC5206385 DOI: 10.1152/japplphysiol.00097.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/29/2016] [Accepted: 09/29/2016] [Indexed: 11/22/2022] Open
Abstract
Regional ventilation in the injured lung is heterogeneous and frequency dependent, making it difficult to predict how an oscillatory flow waveform at a specified frequency will be distributed throughout the periphery. To predict the impact of mechanical heterogeneity on regional ventilation distribution and gas transport, we developed a computational model of distributed gas flow and CO2 elimination during oscillatory ventilation from 0.1 to 30 Hz. The model consists of a three-dimensional airway network of a canine lung, with heterogeneous parenchymal tissues to mimic effects of gravity and injury. Model CO2 elimination during single frequency oscillation was validated against previously published experimental data (Venegas JG, Hales CA, Strieder DJ, J Appl Physiol 60: 1025-1030, 1986). Simulations of gas transport demonstrated a critical transition in flow distribution at the resonant frequency, where the reactive components of mechanical impedance due to airway inertia and parenchymal elastance were equal. For frequencies above resonance, the distribution of ventilation became spatially clustered and frequency dependent. These results highlight the importance of oscillatory frequency in managing the regional distribution of ventilation and gas exchange in the heterogeneous lung.
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Affiliation(s)
- Jacob Herrmann
- Department of Anesthesia, University of Iowa, Iowa City, Iowa.,Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; and
| | - David W Kaczka
- Department of Anesthesia, University of Iowa, Iowa City, Iowa; .,Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa.,Department of Radiology, University of Iowa, Iowa City, Iowa
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Katz I, Pichelin M, Montesantos S, Kang MY, Sapoval B, Zhu K, Thevenin CP, McCoy R, Martin AR, Caillibotte G. An in silico analysis of oxygen uptake of a mild COPD patient during rest and exercise using a portable oxygen concentrator. Int J Chron Obstruct Pulmon Dis 2016; 11:2427-2434. [PMID: 27729783 PMCID: PMC5047718 DOI: 10.2147/copd.s112473] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Oxygen treatment based on intermittent-flow devices with pulse delivery modes available from portable oxygen concentrators (POCs) depends on the characteristics of the delivered pulse such as volume, pulse width (the time of the pulse to be delivered), and pulse delay (the time for the pulse to be initiated from the start of inhalation) as well as a patient's breathing characteristics, disease state, and respiratory morphology. This article presents a physiological-based analysis of the performance, in terms of blood oxygenation, of a commercial POC at different settings using an in silico model of a COPD patient at rest and during exercise. The analysis encompasses experimental measurements of pulse volume, width, and time delay of the POC at three different settings and two breathing rates related to rest and exercise. These experimental data of device performance are inputs to a physiological-based model of oxygen uptake that takes into account the real dynamic nature of gas exchange to illustrate how device- and patient-specific factors can affect patient oxygenation. This type of physiological analysis that considers the true effectiveness of oxygen transfer to the blood, as opposed to delivery to the nose (or mouth), can be instructive in applying therapies and designing new devices.
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Affiliation(s)
- Ira Katz
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France; Department of Mechanical Engineering, Lafayette College, Easton, PA, USA
| | - Marine Pichelin
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France
| | - Spyridon Montesantos
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France
| | - Min-Yeong Kang
- Physique de la Matière Condensée, CNRS, Ecole Polytechnique, Palaiseau
| | - Bernard Sapoval
- Physique de la Matière Condensée, CNRS, Ecole Polytechnique, Palaiseau; Centre de Mathématiques et de leurs Applications, CNRS, UniverSud, Cachan
| | - Kaixian Zhu
- Centre Explor!, Air Liquide Healthcare, Gentilly, France
| | | | - Robert McCoy
- Valley Inspired Products, Inc, Apple Valley, MN, USA
| | - Andrew R Martin
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada
| | - Georges Caillibotte
- Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay, Les Loges-en-Josas, France
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Johansen T, Venegas JG. 3D mapping of oxygen and CO2 transport rates in the lung: a new imaging tool for use in lung surgery, intensive care and basic research. Expert Rev Respir Med 2016; 10:935-7. [PMID: 27348193 DOI: 10.1080/17476348.2016.1206818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Troels Johansen
- a Department of Respiratory Diseases , Aarhus University Hospital , Aarhus , Denmark
| | - Jose Gabriel Venegas
- b Department of Anesthesia , Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School , Boston , MA , USA
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