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Kaminsky DA, Simpson SJ, Berger KI, Calverley P, de Melo PL, Dandurand R, Dellacà RL, Farah CS, Farré R, Hall GL, Ioan I, Irvin CG, Kaczka DW, King GG, Kurosawa H, Lombardi E, Maksym GN, Marchal F, Oostveen E, Oppenheimer BW, Robinson PD, van den Berge M, Thamrin C. Clinical significance and applications of oscillometry. Eur Respir Rev 2022; 31:31/163/210208. [PMID: 35140105 PMCID: PMC9488764 DOI: 10.1183/16000617.0208-2021] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 10/29/2021] [Indexed: 12/28/2022] Open
Abstract
Recently, “Technical standards for respiratory oscillometry” was published, which reviewed the physiological basis of oscillometric measures and detailed the technical factors related to equipment and test performance, quality assurance and reporting of results. Here we present a review of the clinical significance and applications of oscillometry. We briefly review the physiological principles of oscillometry and the basics of oscillometry interpretation, and then describe what is currently known about oscillometry in its role as a sensitive measure of airway resistance, bronchodilator responsiveness and bronchial challenge testing, and response to medical therapy, particularly in asthma and COPD. The technique may have unique advantages in situations where spirometry and other lung function tests are not suitable, such as in infants, neuromuscular disease, sleep apnoea and critical care. Other potential applications include detection of bronchiolitis obliterans, vocal cord dysfunction and the effects of environmental exposures. However, despite great promise as a useful clinical tool, we identify a number of areas in which more evidence of clinical utility is needed before oscillometry becomes routinely used for diagnosing or monitoring respiratory disease. This paper provides a current review of the interpretation, clinical significance and application of oscillometry in respiratory medicine, with special emphasis on limitations of evidence and suggestions for future research.https://bit.ly/3GQPViA
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Affiliation(s)
- David A Kaminsky
- Dept of Medicine, Pulmonary and Critical Care Medicine, University of Vermont, Larner College of Medicine, Burlington, VT, USA.,These authors have contributed equally to this manuscript
| | - Shannon J Simpson
- Children's Lung Health, Telethon Kids Institute, School of Allied Health, Curtin University, Perth, Australia.,These authors have contributed equally to this manuscript
| | - Kenneth I Berger
- Division of Pulmonary, Critical Care, and Sleep Medicine, NYU School of Medicine and André Cournand Pulmonary Physiology Laboratory, Belleuve Hospital, New York, NY, USA
| | - Peter Calverley
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Pedro L de Melo
- Dept of Physiology, Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ronald Dandurand
- Lakeshore General Hospital, Pointe-Claire, QC, Canada.,Montreal Chest Institute, Meakins-Christie Labs, Oscillometry Unit of the Centre for Innovative Medicine, McGill University Health Centre and Research Institute, and McGill University, Montreal, QC, Canada
| | - Raffaele L Dellacà
- Dipartimento di Elettronica, Informazione e Bioingegneria - DEIB, Politecnico di Milano University, Milan, Italy
| | - Claude S Farah
- Dept of Respiratory Medicine, Concord Repatriation General Hospital, Sydney, Australia
| | - Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona-IDIBAPS, Barcelona, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
| | - Graham L Hall
- Children's Lung Health, Telethon Kids Institute, School of Allied Health, Curtin University, Perth, Australia
| | - Iulia Ioan
- Dept of Paediatric Lung Function Testing, Children's Hospital, Vandoeuvre-lès-Nancy, France.,EA 3450 DevAH - Laboratory of Physiology, Faculty of Medicine, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Charles G Irvin
- Dept of Medicine, Pulmonary and Critical Care Medicine, University of Vermont, Larner College of Medicine, Burlington, VT, USA
| | - David W Kaczka
- Depts of Anaesthesia, Biomedical Engineering and Radiology, University of Iowa, Iowa City, IA, USA
| | - Gregory G King
- Dept of Respiratory Medicine and Airway Physiology and Imaging Group, Royal North Shore Hospital, St Leonards, Australia.,Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
| | - Hajime Kurosawa
- Dept of Occupational Health, Tohoku University School of Medicine, Sendai, Japan
| | - Enrico Lombardi
- Paediatric Pulmonary Unit, Meyer Paediatric University Hospital, Florence, Italy
| | - Geoffrey N Maksym
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
| | - François Marchal
- Dept of Paediatric Lung Function Testing, Children's Hospital, Vandoeuvre-lès-Nancy, France.,EA 3450 DevAH - Laboratory of Physiology, Faculty of Medicine, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Ellie Oostveen
- Dept of Respiratory Medicine, Antwerp University Hospital and University of Antwerp, Belgium
| | - Beno W Oppenheimer
- Division of Pulmonary, Critical Care, and Sleep Medicine, NYU School of Medicine and André Cournand Pulmonary Physiology Laboratory, Belleuve Hospital, New York, NY, USA
| | - Paul D Robinson
- Woolcock Institute of Medical Research, Children's Hospital at Westmead, Sydney, Australia
| | - Maarten van den Berge
- Dept of Pulmonary Diseases, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Cindy Thamrin
- Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
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Calverley PMA, Farré R. Oscillometry: old physiology with a bright future. Eur Respir J 2020; 56:56/3/2001815. [PMID: 32912925 DOI: 10.1183/13993003.01815-2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 05/15/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Peter M A Calverley
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain.,Institut d'Investigacions Biomediques August Pi Sunyer, Barcelona, Spain
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King GG, Bates J, Berger KI, Calverley P, de Melo PL, Dellacà RL, Farré R, Hall GL, Ioan I, Irvin CG, Kaczka DW, Kaminsky DA, Kurosawa H, Lombardi E, Maksym GN, Marchal F, Oppenheimer BW, Simpson SJ, Thamrin C, van den Berge M, Oostveen E. Technical standards for respiratory oscillometry. Eur Respir J 2020; 55:13993003.00753-2019. [PMID: 31772002 DOI: 10.1183/13993003.00753-2019] [Citation(s) in RCA: 284] [Impact Index Per Article: 71.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 10/15/2019] [Indexed: 12/11/2022]
Abstract
Oscillometry (also known as the forced oscillation technique) measures the mechanical properties of the respiratory system (upper and intrathoracic airways, lung tissue and chest wall) during quiet tidal breathing, by the application of an oscillating pressure signal (input or forcing signal), most commonly at the mouth. With increased clinical and research use, it is critical that all technical details of the hardware design, signal processing and analyses, and testing protocols are transparent and clearly reported to allow standardisation, comparison and replication of clinical and research studies. Because of this need, an update of the 2003 European Respiratory Society (ERS) technical standards document was produced by an ERS task force of experts who are active in clinical oscillometry research.The aim of the task force was to provide technical recommendations regarding oscillometry measurement including hardware, software, testing protocols and quality control.The main changes in this update, compared with the 2003 ERS task force document are 1) new quality control procedures which reflect use of "within-breath" analysis, and methods of handling artefacts; 2) recommendation to disclose signal processing, quality control, artefact handling and breathing protocols (e.g. number and duration of acquisitions) in reports and publications to allow comparability and replication between devices and laboratories; 3) a summary review of new data to support threshold values for bronchodilator and bronchial challenge tests; and 4) updated list of predicted impedance values in adults and children.
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Affiliation(s)
- Gregory G King
- Dept of Respiratory Medicine and Airway Physiology and Imaging Group, Royal North Shore Hospital and The Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
| | - Jason Bates
- Dept of Medicine, Pulmonary/Critical Care Division, University of Vermont, Larner College of Medicine, Burlington, VT, USA
| | - Kenneth I Berger
- Division of Pulmonary, Critical Care, and Sleep Medicine, NYU School of Medicine and André Cournand Pulmonary Physiology Laboratory, Belleuve Hospital, New York, NY, USA
| | - Peter Calverley
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Pedro L de Melo
- Institute of Biology and Faculty of Engineering, Department of Physiology, Biomedical Instrumentation Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Raffaele L Dellacà
- Dipartimento di Elettronica, Informazione e Bioingegneria - DEIB, Politecnico di Milano University, Milano, Italy
| | - Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona-IDIBAPS, Barcelona, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
| | - Graham L Hall
- Children's Lung Health, Telethon Kids Institute, School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia
| | - Iulia Ioan
- Dept of Pediatric Lung Function Testing, Children's Hospital, Vandoeuvre-lès-Nancy, France.,EA 3450 DevAH - Laboratory of Physiology, Faculty of Medicine, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Charles G Irvin
- Dept of Medicine, Pulmonary/Critical Care Division, University of Vermont, Larner College of Medicine, Burlington, VT, USA
| | - David W Kaczka
- Depts of Anesthesia, Biomedical Engineering and Radiology, University of Iowa, Iowa City, IA, USA
| | - David A Kaminsky
- Dept of Medicine, Pulmonary/Critical Care Division, University of Vermont, Larner College of Medicine, Burlington, VT, USA
| | - Hajime Kurosawa
- Dept of Occupational Health, Tohoku University School of Medicine, Sendai, Japan
| | - Enrico Lombardi
- Pediatric Pulmonary Unit, Meyer Pediatric University Hospital, Florence, Italy
| | - Geoffrey N Maksym
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
| | - François Marchal
- Dept of Pediatric Lung Function Testing, Children's Hospital, Vandoeuvre-lès-Nancy, France.,EA 3450 DevAH - Laboratory of Physiology, Faculty of Medicine, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Beno W Oppenheimer
- Division of Pulmonary, Critical Care, and Sleep Medicine, NYU School of Medicine and André Cournand Pulmonary Physiology Laboratory, Belleuve Hospital, New York, NY, USA
| | - Shannon J Simpson
- Children's Lung Health, Telethon Kids Institute, School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia
| | - Cindy Thamrin
- Dept of Respiratory Medicine and Airway Physiology and Imaging Group, Royal North Shore Hospital and The Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
| | - Maarten van den Berge
- University of Groningen, University Medical Center Groningen, Dept of Pulmonary Diseases, Groningen, The Netherlands
| | - Ellie Oostveen
- Dept of Respiratory Medicine, Antwerp University Hospital and University of Antwerp, Antwerp, Belgium
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Lorx A, Czövek D, Gingl Z, Makan G, Radics B, Bartusek D, Szigeti S, Gál J, Losonczy G, Sly PD, Hantos Z. Airway dynamics in COPD patients by within-breath impedance tracking: effects of continuous positive airway pressure. Eur Respir J 2017; 49:49/2/1601270. [DOI: 10.1183/13993003.01270-2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 11/08/2016] [Indexed: 11/05/2022]
Abstract
Tracking of the within-breath changes of respiratory mechanics using the forced oscillation technique may provide outcomes that characterise the dynamic behaviour of the airways during normal breathing.We measured respiratory resistance (Rrs) and reactance (Xrs) at 8 Hz in 55 chronic obstructive pulmonary disease (COPD) patients and 20 healthy controls, and evaluated Rrs and Xrs as functions of gas flow (V′) and volume (V) during normal breathing cycles. In 12 COPD patients, additional measurements were made at continuous positive airway pressure (CPAP) levels of 4, 8, 14 and 20 hPa.The Rrs and Xrsversus V′ and V relationships displayed a variety of loop patterns, allowing characterisation of physiological and pathological processes. The main outcomes emerging from the within-breath analysis were the Xrsversus V loop area (AXV) quantifying expiratory flow limitation, and the tidal change in Xrs during inspiration (ΔXI) reflecting alteration in lung inhomogeneity in COPD. With increasing CPAP, AXV and ΔXI approached the normal ranges, although with a large variability between individuals, whereas mean Rrs remained unchanged.Within-breath tracking of Rrs and Xrs allows an improved assessment of expiratory flow limitation and functional inhomogeneity in COPD; thereby it may help identify the physiological phenotypes of COPD and determine the optimal level of respiratory support.
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Takahashi A, Hamakawa H, Sakai H, Zhao X, Chen F, Fujinaga T, Shoji T, Bando T, Wada H, Date H. Noninvasive assessment for acute allograft rejection in a rat lung transplantation model. Physiol Rep 2014; 2:2/12/e12244. [PMID: 25524280 PMCID: PMC4332222 DOI: 10.14814/phy2.12244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
After lung transplantation, early detection of acute allograft rejection is important not only for timely and optimal treatment, but also for the prediction of chronic rejection which is a major cause of late death. Many biological and immunological approaches have been developed to detect acute rejection; however, it is not well known whether lung mechanics correlate with disease severity, especially with pathological rejection grade. In this study, we examined the relationship between lung mechanics and rejection grade development in a rat acute rejection model using the forced oscillation technique, which provides noninvasive assessment of lung function. To this end, we assessed lung resistance and elastance (RL and EL) from implanted left lung of these animals. The perivascular/interstitial component of rejection severity grade (A‐grade) was also quantified from histological images using tissue fraction (TF; tissue + cell infiltration area/total area). We found that TF, RL, and EL increased according to A‐grade. There was a strong positive correlation between EL at the lowest frequency (Elow; EL at 0.5 Hz) and TF (r2 = 0.930). Furthermore, the absolute difference between maximum value of EL (Emax) and Elow (Ehet; Emax − Elow) showed the strong relationship with standard deviation of TF (r2 = 0.709), and A‐grade (Spearman's correlation coefficients; rs = 0.964, P < 0.0001). Our results suggest that the dynamic elastance as well as its frequency dependence have the ability to predict A‐grade. These indexes should prove useful for noninvasive detection and monitoring the progression of disease in acute rejection. After lung transplantation, early detection of acute allograft rejection is important for both in timely treatment and prediction of chronic rejection which is a major cause of late death. We examined the relationship between lung mechanics and rejection grade development in a rat acute rejection model using the forced oscillation technique, which provides noninvasive assessment of lung function. Our results suggest that the dynamic elastance as well as its frequency dependence reflect the perivascular‐interstitial component of rejection severity grade (A‐grade), and this method should prove useful for noninvasive detection and monitoring the progression of disease in acute rejection.
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Affiliation(s)
- Ayuko Takahashi
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroshi Hamakawa
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan Department of Thoracic Surgery, Kobe City Medical Center General Hospital, Hyogo, Japan
| | - Hiroaki Sakai
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Xiangdong Zhao
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan Department of Surgery, Graduate school of Medicine, Kyoto University, Kyoto, Japan
| | - Fengshi Chen
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takuji Fujinaga
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tsuyoshi Shoji
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Toru Bando
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiromi Wada
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroshi Date
- Department of Thoracic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Abstract
COPD is characterized by airflow limitation that is not fully reversible. The morphological basis for airflow obstruction results from a varying combination of obstructive changes in peripheral conducting airways and destructive changes in respiratory bronchioles, alveolar ducts, and alveoli. A reduction of vascularity within the alveolar septa has been reported in emphysema. Typical physiological changes reflect these structural abnormalities. Spirometry documents airflow obstruction when the FEV1/FVC ratio is reduced below the lower limit of normality, although in early disease stages FEV1 and airway conductance are not affected. Current guidelines recommend testing for bronchoreversibility at least once and the postbronchodilator FEV1/FVC be used for COPD diagnosis; the nature of bronchodilator response remains controversial, however. One major functional consequence of altered lung mechanics is lung hyperinflation. FRC may increase as a result of static or dynamic mechanisms, or both. The link between dynamic lung hyperinflation and expiratory flow limitation during tidal breathing has been demonstrated. Hyperinflation may increase the load on inspiratory muscles, with resulting length adaptation of diaphragm. Reduction of exercise tolerance is frequently noted, with compelling evidence that breathlessness and altered lung mechanics play a major role. Lung function measurements have been traditionally used as prognostic indices and to monitor disease progression; FEV1 has been most widely used. An increase in FVC is also considered as proof of bronchodilatation. Decades of work has provided insight into the histological, functional, and biological features of COPD. This has provided a clearer understanding of important pathobiological processes and has provided additional therapeutic options.
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Bates JHT, Irvin CG, Farré R, Hantos Z. Oscillation mechanics of the respiratory system. Compr Physiol 2013; 1:1233-72. [PMID: 23733641 DOI: 10.1002/cphy.c100058] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanical impedance of the respiratory system defines the pressure profile required to drive a unit of oscillatory flow into the lungs. Impedance is a function of oscillation frequency, and is measured using the forced oscillation technique. Digital signal processing methods, most notably the Fourier transform, are used to calculate impedance from measured oscillatory pressures and flows. Impedance is a complex function of frequency, having both real and imaginary parts that vary with frequency in ways that can be used empirically to distinguish normal lung function from a variety of different pathologies. The most useful diagnostic information is gained when anatomically based mathematical models are fit to measurements of impedance. The simplest such model consists of a single flow-resistive conduit connecting to a single elastic compartment. Models of greater complexity may have two or more compartments, and provide more accurate fits to impedance measurements over a variety of different frequency ranges. The model that currently enjoys the widest application in studies of animal models of lung disease consists of a single airway serving an alveolar compartment comprising tissue with a constant-phase impedance. This model has been shown to fit very accurately to a wide range of impedance data, yet contains only four free parameters, and as such is highly parsimonious. The measurement of impedance in human patients is also now rapidly gaining acceptance, and promises to provide a more comprehensible assessment of lung function than parameters derived from conventional spirometry.
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Affiliation(s)
- Jason H T Bates
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA.
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Vidal Melo MF, Musch G, Kaczka DW. Pulmonary pathophysiology and lung mechanics in anesthesiology: a case-based overview. Anesthesiol Clin 2012; 30:759-784. [PMID: 23089508 PMCID: PMC3479443 DOI: 10.1016/j.anclin.2012.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Anesthesia, surgical requirements, and patients' unique pathophysiology all combine to make the accumulated knowledge of respiratory physiology and lung mechanics vital in patient management. This article take a case-based approach to discuss how the complex interactions between anesthesia, surgery, and patient disease affect patient care with respect to pulmonary pathophysiology and clinical decision making. Two disparate scenarios are examined: a patient with chronic obstructive pulmonary disease undergoing a lung resection, and a patient with coronary artery disease undergoing cardiopulmonary bypass. The impacts of important concepts in pulmonary physiology and respiratory mechanics on clinical management decisions are discussed.
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Affiliation(s)
| | - Guido Musch
- Harvard Medical School, Boston, MA
- Massachusetts General Hospital, Boston, MA
| | - David W. Kaczka
- Harvard Medical School, Boston, MA
- Beth Israel Deaconess Medical Center, Boston, MA
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Kaczka DW, Dellacá RL. Oscillation mechanics of the respiratory system: applications to lung disease. Crit Rev Biomed Eng 2011; 39:337-59. [PMID: 22011237 DOI: 10.1615/critrevbiomedeng.v39.i4.60] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Since its introduction in the 1950s, the forced oscillation technique (FOT) and the measurement of respiratory impedance have evolved into powerful tools for the assessment of various mechanical phenomena in the mammalian lung during health and disease. In this review, we highlight the most recent developments in instrumentation, signal processing, and modeling relevant to FOT measurements. We demonstrate how FOT provides unparalleled information on the mechanical status of the respiratory system compared to more widely used pulmonary function tests. The concept of mechanical impedance is reviewed, as well as the various measurement techniques used to acquire such data. Emphasis is placed on the analysis of lower, physiologic frequency ranges (typically less than 10 Hz) that are most sensitive to normal physical processes as well as pathologic structural alterations. Various inverse modeling approaches used to interpret alterations in impedance are also discussed, specifically in the context of three common respiratory diseases: asthma, chronic obstructive pulmonary disease, and acute lung injury. Finally, we speculate on the potential role for FOT in the clinical arena.
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Affiliation(s)
- David W Kaczka
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, USA.
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Kaczka DW, Lutchen KR, Hantos Z. Emergent behavior of regional heterogeneity in the lung and its effects on respiratory impedance. J Appl Physiol (1985) 2011; 110:1473-81. [PMID: 21292840 DOI: 10.1152/japplphysiol.01287.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The ability to maintain adequate gas exchange depends on the relatively homogeneous distribution of inhaled gas throughout the lung. Structural alterations associated with many respiratory diseases may significantly depress this function during tidal breathing. These alterations frequently occur in a heterogeneous manner due to complex, emergent interactions among the many constitutive elements of the airways and parenchyma, resulting in unique signature changes in the mechanical impedance spectrum of the lungs and total respiratory system as measured by forced oscillations techniques (FOT). When such impedance spectra are characterized by appropriate inverse models, one may obtain functional insight into derangements in global respiratory mechanics. In this review, we provide an overview of the impact of structural heterogeneity with respect to dynamic lung function. Recent studies linking functional impedance measurements to the structural heterogeneity observed in acute lung injury, asthma, and chronic obstructive pulmonary disease are highlighted, as well as current approaches for the modeling and interpretation of impedance. Finally, we discuss the potential diagnostic role of FOT in the context of therapeutic interventions.
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Affiliation(s)
- David W Kaczka
- Department of Anesthesia, Harvard Medical School, Boston, MA, USA.
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Lorx A, Szabó B, Hercsuth M, Pénzes I, Hantos Z. Low-frequency assessment of airway and tissue mechanics in ventilated COPD patients. J Appl Physiol (1985) 2009; 107:1884-92. [DOI: 10.1152/japplphysiol.00151.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Low-frequency forced oscillations have increasingly been employed to characterize airway and tissue mechanics separately in the normal respiratory system and animal models of lung disease; however, few data are available on the use of this method in chronic obstructive pulmonary disease (COPD). We studied 30 intubated and mechanically ventilated patients (COPD, n = 9; acute exacerbation of COPD, n = 21) during short apneic intervals at different levels of positive end-expiratory pressure (PEEP), with small-amplitude forced oscillations between 0.4 and 4.8 Hz. In 16 patients, measurements were made before and after inhalation of fenoterol hydrobromide plus ipratropium bromide (Berodual). Newtonian resistance and coefficients of tissue resistance (G) and elastance (H) were estimated from the respiratory system impedance (Zrs) data by model fitting. Apart from some extremely high Zrs data obtained primarily at relatively low PEEP levels, the model yielded a reasonable partitioning of the airway and tissue parameters, and the inclusion of further parameters did not improve the model performance. With increasing PEEP, Newtonian resistance and the ratio G/H decreased, reflecting the volume dependence of the airway caliber and the improved homogeneity of the lungs, respectively. Bronchodilation after the administration of Berodual was also associated with simultaneous decreases in G and H, indicating recruitment of lung units. In conclusion, the measurement of low-frequency Zrs can be accomplished in ventilated COPD patients during short apneic periods and offers valuable information on the mechanical status of the airways and tissues.
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Affiliation(s)
- András Lorx
- Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - Barna Szabó
- Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - Magdolna Hercsuth
- Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - István Pénzes
- Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - Zoltán Hantos
- Department of Medical Informatics and Engineering, University of Szeged, Szeged, Hungary
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Bellardine Black CL, Hoffman AM, Tsai LW, Ingenito EP, Suki B, Kaczka DW, Simon BA, Lutchen KR. Impact of positive end-expiratory pressure during heterogeneous lung injury: insights from computed tomographic image functional modeling. Ann Biomed Eng 2008; 36:980-91. [PMID: 18340535 DOI: 10.1007/s10439-008-9451-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Accepted: 01/28/2008] [Indexed: 12/01/2022]
Abstract
Image Functional Modeling (IFM) synthesizes three dimensional airway networks with imaging and mechanics data to relate structure to function. The goal of this study was to advance IFM to establish a method of exploring how heterogeneous alveolar flooding and collapse during lung injury would impact regional respiratory mechanics and flow distributions within the lung at distinct positive end-expiratory pressure (PEEP) levels. We estimated regional respiratory system elastance from computed tomography (CT) scans taken in 5 saline-lavaged sheep at PEEP levels from 7.5 to 20 cmH(2)O. These data were anatomically mapped into a computational sheep lung model, which was used to predict the corresponding impact of PEEP on dynamic flow distribution. Under pre-injury conditions and during lung injury, respiratory system elastance was determined to be spatially heterogeneous and the values were distributed with a hyperbolic distribution in the range of measured values. Increases in PEEP appear to modulate the heterogeneity of the flow distribution throughout the injured lung. Moderate increases in PEEP decreased the heterogeneity of elastance and predicted flow distribution, although heterogeneity began to increase for PEEP levels above 12.5-15 cmH(2)O. By combining regional respiratory system elastance estimated from CT with our computational lung model, we can potentially predict the dynamic distribution of the tidal volume during mechanical ventilation and thus identify specific areas of the lung at risk of being overdistended.
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Affiliation(s)
- C L Bellardine Black
- Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA 02215, USA
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13
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Cohen JC, Hudak J. Lung impedance measurements are/are not more useful than simpler measurements of lung function in animal models of pulmonary disease. J Appl Physiol (1985) 2007; 103:1907-8; author reply 1909-10. [DOI: 10.1152/japplphysiol.00759.2007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Bellardine Black CL, Hoffman AM, Tsai LW, Ingenito EP, Suki B, Kaczka DW, Simon BA, Lutchen KR. Relationship between dynamic respiratory mechanics and disease heterogeneity in sheep lavage injury*. Crit Care Med 2007; 35:870-8. [PMID: 17255854 DOI: 10.1097/01.ccm.0000257331.42485.94] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Acute respiratory distress syndrome and acute lung injury are characterized by heterogeneous flooding/collapse of lung tissue. An emerging concept for managing these diseases is to set mechanical ventilation so as to minimize the impact of disease heterogeneity on lung mechanical stress and ventilation distribution. The goal of this study was to determine whether changes in lung mechanical heterogeneity with increasing positive end-expiratory pressure in an animal model of acute lung injury could be detected from the frequency responses of resistance and elastance. DESIGN Prospective, experimental study. SETTING Research laboratory at a veterinary hospital. SUBJECTS Female sheep weighing 48 +/- 2 kg. INTERVENTIONS In five saline-lavaged sheep, we acquired whole-lung computed tomography scans, oxygenation, static elastance, and dynamic respiratory resistance and elastance at end-expiratory pressure levels of 7.5-20 cm H2O. MEASUREMENTS AND MAIN RESULTS As end-expiratory pressure increased, computed tomography-determined alveolar recruitment significantly increased but was accompanied by significant alveolar overdistension at 20 cm H2O. An optimal range of end-expiratory pressures (15-17.5 cm H2O) was identified where alveolar recruitment was significantly increased without significant overdistension. This range corresponded to the end-expiratory pressure levels that maximized oxygenation, minimized peak-to-peak ventilation pressures, and minimized indexes reflective of the mechanical heterogeneity (e.g., frequency dependence of respiratory resistance and low-frequency elastance). Static elastance did not demonstrate any significant pressure dependence or reveal an optimal end-expiratory pressure level. CONCLUSIONS We conclude that dynamic mechanics are more sensitive than static mechanics in the assessment of the functional trade-off of recruitment relative to overdistension in a sheep model of lung injury. We anticipate that monitoring of dynamic respiratory resistance and elastance ventilator settings can be used to optimize ventilator management in acute lung injury.
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Henderson AC, Ingenito EP, Salcedo ES, Moy ML, Reilly JJ, Lutchen KR. Dynamic lung mechanics in late-stage emphysema before and after lung volume reduction surgery. Respir Physiol Neurobiol 2007; 155:234-42. [DOI: 10.1016/j.resp.2006.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 05/26/2006] [Accepted: 05/29/2006] [Indexed: 10/24/2022]
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Barbini P, Brighenti C, Gnudi G. A Simulation Study of Expiratory Flow Limitation in Obstructive Patients during Mechanical Ventilation. Ann Biomed Eng 2006; 34:1879-89. [PMID: 17061156 DOI: 10.1007/s10439-006-9213-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Accepted: 09/27/2006] [Indexed: 11/24/2022]
Abstract
Although normal lungs may be represented satisfactorily by symmetrical architecture, pathological conditions generally require accounting for asymmetrical branching of the bronchial tree, since lung heterogeneity may be significant in respiratory diseases. In the present study, a recently proposed symmetrical dynamic morphometric model of the human lung, based on Weibel's regular dichotomy, was adapted to simulate different physiopathological scenarios of lung heterogeneity. The asymmetrical architecture was mimicked by modeling different conductive airway compartments below the main bronchi, each compartment being characterized by regular branching. The respiratory zone and chest wall were described by a Voigt body and a constant elastance, respectively. Simulation results allowed us to investigate the influence of the main mechanisms involved in expiratory flow limitation and dynamic hyperinflation in mechanically ventilated COPD patients. In brief, they showed that convective gas acceleration plays a key role in reproducing a negative relationship between driving pressure and expiratory flow. Moreover, reduced lung elastance due to emphysema resulted in a remarkable increase in dynamic hyperinflation, although it did not significantly modify expiratory flow limitation. Finally, the presence of a normal lung compartment masked pathological behaviors, preventing standard techniques from revealing expiratory flow limitation in affected compartments.
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Affiliation(s)
- Paolo Barbini
- Dipartimento di Chirurgia e Bioingegneria, Università di Siena, Viale Bracci 2, 53100, Siena, Italy.
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Bellardine CL, Hoffman AM, Tsai L, Ingenito EP, Arold SP, Lutchen KR, Suki B. Comparison of variable and conventional ventilation in a sheep saline lavage lung injury model*. Crit Care Med 2006; 34:439-45. [PMID: 16424726 DOI: 10.1097/01.ccm.0000196208.01682.87] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE There has recently been considerable interest in alternative lung-protective ventilation strategies such as variable ventilation (VV). We aimed at testing VV in a large animal lung injury model and exploring the mechanism of improvement in gas exchange seen with VV. DESIGN Randomized, controlled comparative ventilation study. SETTING Research laboratory at a veterinary hospital. SUBJECTS Female sheep weighing 59.8 +/- 10.57 kg and excised calf lungs. INTERVENTIONS In a sheep saline lavage model of lung injury, we applied VV, whereby tidal volume (VT) and frequency (f) varied on each breath. Sheep were randomized into one of two groups (VV, n = 7; or control, n = 6) and ventilated for 4 hrs with all mean ventilation settings matched. MEASUREMENTS AND MAIN RESULTS Gas exchange, lung mechanics, and hemodynamic measures were recorded over the 4 hrs. VV sheep showed improvement in gas exchange (i.e., oxygenation and carbon dioxide elimination) and ventilation pressures (i.e., reduced mean and peak airway pressures) but control sheep did not. VV sheep also displayed lower-lung elastance and mechanical heterogeneity in comparison with control sheep from 2 to 4 hrs of ventilation. To study the mechanism behind improvements seen with VV, we examined the time course associated with the enhanced recruitment occurring during VV in eight saline-lavaged excised calf lungs. We found that the recruitment associated with a larger VT during VV lasted over 200 secs, nearly an order of magnitude greater than the average time interval between large VT deliveries during VV. CONCLUSIONS The application of VV in a large animal model of lung injury results in improved gas exchange and superior lung mechanics in comparison with CV that can be explained at least partially by the long-lasting effects of the recruitments occurring during VV.
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Ingenito EP, Tsai LW, Mentzer SJ, Jaklitsch MT, Reilly JJ, Lutchen K, Mazan M, Hoffman A. Respiratory impedance following bronchoscopic or surgical lung volume reduction for emphysema. Respiration 2005; 72:406-17. [PMID: 16088285 DOI: 10.1159/000086256] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Accepted: 11/01/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Bronchoscopic methods for achieving lung volume reduction (BLVR) are presently undergoing clinical trials, and will soon be clinically available. Understanding the differential effects of surgical volume reduction therapy (LVRS) and BLVR on lung and chest wall physiology will assist physicians in selecting an optimal approach for patients. OBJECTIVES Determine whether LVRS adversely affects lung or chest wall physiology at 3-month follow-up relative to BLVR in an experimental model of sheep emphysema. METHODS Twelve mixed-breed sheep were treated with papain to produce experimental emphysema, and were divided into control, LVRS, and BLVR treatment groups. Lung and chest wall impedance was measured at 0, 5, and 10 cm H2O positive end-expiratory pressure at baseline and 3-month follow-up. RESULTS Emphysema was associated with increased airway resistance, decreased lung tissue resistance and elastance, and increased chest wall tissue resistance. Following treatment, equivalent increases in lung elastance occurred in the LVRS and BLVR groups compared to controls. LVRS did not adversely affect chest wall impedance despite causing extensive pleural scarring. CONCLUSIONS (1) Experimental emphysema following prolonged papain exposure progresses after cessation of treatment. (2) BLVR and LVRS produced equivalent lung and chest wall impedance responses at 3-month follow-up. (3) LVRS did not adversely affect chest wall impedance despite being associated with extensive pleural scarring.
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Affiliation(s)
- Edward P Ingenito
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Bellardine CL, Ingenito EP, Hoffman A, Lopez F, Sanborn W, Suki B, Lutchen KR. Heterogeneous Airway Versus Tissue Mechanics and Their Relation to Gas Exchange Function During Mechanical Ventilation. Ann Biomed Eng 2005; 33:626-41. [PMID: 15981863 DOI: 10.1007/s10439-005-1540-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We have advanced a commercially available ventilator (NPB840, Puritan Bennett/Tyco Healthcare, Pleasanton, CA) to deliver an Enhanced Ventilation Waveform (EVW). This EVW delivers a broadband waveform that contains discrete frequencies blended to provide a tidal breath, followed by passive exhalation. The EVW allows breath-by-breath estimates of frequency dependence of lung and total respiratory resistance (R) and elastance (E) from 0.2 to 8 Hz. We hypothesized that the EVW approach could provide continuous ventilation simultaneously with an advanced evaluation of mechanical heterogeneities under heterogeneous airway and tissue disease conditions. We applied the EVW in five sheep before and after a bronchial challenge and an oleic acid (OA) acute lung injury model. In all sheep, the EVW maintained gas exchange during and after bronchoconstriction, as well as during OA injury. Data revealed a range of disease conditions from mild to severe with heterogeneities and airway closures. Correlations were found between the arterial partial pressure of oxygen (PaO2) and the levels and frequency-dependent features of R and E that are indicative of mechanical heterogeneity and tissue disease. Lumped parameter models provided additional insight on heterogeneous airway and tissue disease. In summary, information obtained from EVW analysis can provide enhanced guidance on the efficiency of ventilator settings and on patient status during mechanical ventilation.
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Affiliation(s)
- C L Bellardine
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
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Barbini P, Brighenti C, Cevenini G, Gnudi G. A Dynamic Morphometric Model of the Normal Lung for Studying Expiratory Flow Limitation in Mechanical Ventilation. Ann Biomed Eng 2005; 33:518-30. [PMID: 15909658 DOI: 10.1007/s10439-005-2511-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A nonlinear dynamic morphometric model of breathing mechanics during artificial ventilation is described. On the basis of the Weibel symmetrical representation of the tracheo-bronchial tree, the model accurately accounts for the geometrical and mechanical characteristics of the conductive zone and packs the respiratory zone into a viscoelastic Voigt body. The model also accounts for the main mechanisms limiting expiratory flow (wave speed limitation and viscous flow limitation), in order to reproduce satisfactorily, under dynamic conditions, the expiratory flow limitation phenomenon occurring in normal subjects when the difference between alveolar pressure and tracheal pressure (driving pressure) is high. Several expirations characterized by different levels of driving pressure are simulated and expiratory flow limitation is detected by plotting the isovolume pressure-flow curves. The model is used to study the time course of resistance and total cross-sectional area as well as the ratio of fluid velocity to wave speed (speed index), in conductive airway generations. The results highlight that the coupling between dissipative pressure losses and airway compliance leads to onset of expiratory flow limitation in normal lungs when driving pressure is increased significantly by applying a subatmospheric pressure to the outlet of the ventilator expiratory channel; wave speed limitation becomes predominant at still higher driving pressures.
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Affiliation(s)
- Paolo Barbini
- Dipartimento di Chirurgia e Bioingegneria, Università di Siena, Viale Bracci 2, Siena, Italy.
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Lin CC, Wu KM, Chou CS, Liaw SF. Oral airway resistance during wakefulness in eucapnic and hypercapnic sleep apnea syndrome. Respir Physiol Neurobiol 2004; 139:215-24. [PMID: 15123004 DOI: 10.1016/j.resp.2003.10.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2003] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to evaluate whether there was an abnormal increase of upper airway resistance in the sitting and supine positions in hypercapnic obstructive sleep apnea syndrome (OSAS) patients compared with eucapnic OSAS or normal controls as measured by impulse oscillometry (IOS) while awake. Twenty subjects without OSAS served as controls (group I), and 20 patients with moderate or severe eucapnic OSAS (group II) and another eight hypercapnic severe OSAS patients (group III) were studied. Group II was further divided into two subgroups. Group IIa consisted of 14 subjects whose BMI was less than 35 and group IIb of six subjects whose BMI was greater than 35. All subjects also had an overnight sleep study. Oral airway resistance (AR) (including impedance (Zrs), resistance (R) and reactance (X)) was measured by impulse oscillometry (IOS) (MasterScreen IOS, VIASYS Healthcare GmbH, Germany) in the upright (seated) position and then in the supine position while awake. The results demonstrated that in both group I and group II, Zrs was normal in the sitting position. However, there was a high Zrs in the supine position for group II patients. In contrast, in group III patients, there was a high Zrs in both the sitting and supine positions. In conclusion, upper airway resistance was increased both sitting and supine in the hypercapnic OSAS patients; this would presumably increase the work of breathing and might explain why these subjects were hypercapnic while awake, while eucapnic OSAS patients and normal controls were not. Secondly, the increased upper airway resistance in the supine position in the eucapnic OSAS patients may contribute to their OSAS.
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Affiliation(s)
- Ching-Chi Lin
- Chest Division, Department of Internal Medicine, Mackay Memorial Hospital, 92, Sec 2, Chung Shan North Road, Taipei, Taiwan, ROC.
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Peták F, Babik B, Asztalos T, Hall GL, Deák ZI, Sly PD, Hantos Z. Airway and tissue mechanics in anesthetized paralyzed children. Pediatr Pulmonol 2003; 35:169-76. [PMID: 12567384 DOI: 10.1002/ppul.10252] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To estimate the mechanical properties of the airways and respiratory tissues, respiratory system impedance (Zrs) was measured with low-frequency forced oscillations in 26 anesthetized, paralyzed children (aged 3 months-10 years) undergoing surgical correction of congenital heart diseases. Zrs was determined from the signals of tracheal flow and pressure between 0.4-12 Hz before surgery at zero mean transrespiratory pressure. The pulmonary (Z(L)) and chest wall (Z(W)) components of Zrs were also determined in 5 children by measuring esophageal pressure. A model containing frequency-independent resistance (R) and inertance (I), and coefficients of tissue-damping (G) and elastance (H), was fitted to the Zrs, Z(L), and Z(W) spectra. The total respiratory parameters normalized to body weights were 82.2 +/- 8.5 (SE) hPa x sec x l(-1) x kg, 0.152 +/- 0.05 hPa x sec(2) x l(-1) x kg, 293.8 +/- 20.0 hPa. l(-1) x kg, and 1,583 +/- 65.5 hPa x l(-1) x kg, for R, I, G, and H, respectively. The measurements of Z(L) and Z(W) revealed the dominance of the lungs in R (91 +/- 4.3%) and I (109 +/- 16%), and the major contribution of the lung parenchyma to G (61 +/- 7.3%) and H (66 +/- 7.4%) of the total respiratory system. It is concluded that anesthesia-paralysis provides an ideal condition for the measurement of low-frequency forced oscillatory impedance and its partitioning into airway and tissue components in mechanically ventilated children. The separation of pulmonary and chest wall mechanics demonstrates that airway properties can be estimated appropriately from Zrs data, while the chest wall may damp the changes in parenchymal properties.
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Affiliation(s)
- Ferenc Peták
- Department of Medical Informatics and Engineering, University of Szeged, Szeged, Hungary.
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Assessment of Lung Function in Mechanically Ventilated Patients. Intensive Care Med 2002. [DOI: 10.1007/978-1-4757-5551-0_52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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