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Gobbi A, Antonelli A, Dellaca R, Pellegrino GM, Pellegrino R, Fredberg JJ, Solway J, Brusasco V. Effects of increasing tidal volume and end-expiratory lung volume on induced bronchoconstriction in healthy humans. Respir Res 2024; 25:298. [PMID: 39113017 PMCID: PMC11304934 DOI: 10.1186/s12931-024-02909-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 07/07/2024] [Indexed: 08/11/2024] Open
Abstract
BACKGROUND Increasing functional residual capacity (FRC) or tidal volume (VT) reduces airway resistance and attenuates the response to bronchoconstrictor stimuli in animals and humans. What is unknown is which one of the above mechanisms is more effective in modulating airway caliber and whether their combination yields additive or synergistic effects. To address this question, we investigated the effects of increased FRC and increased VT in attenuating the bronchoconstriction induced by inhaled methacholine (MCh) in healthy humans. METHODS Nineteen healthy volunteers were challenged with a single-dose of MCh and forced oscillation was used to measure inspiratory resistance at 5 and 19 Hz (R5 and R19), their difference (R5-19), and reactance at 5 Hz (X5) during spontaneous breathing and during imposed breathing patterns with increased FRC, or VT, or both. Importantly, in our experimental design we held the product of VT and breathing frequency (BF), i.e, minute ventilation (VE) fixed so as to better isolate the effects of changes in VT alone. RESULTS Tripling VT from baseline FRC significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Doubling VT while halving BF had insignificant effects. Increasing FRC by either one or two VT significantly attenuated the effects of MCh on R5, R19, R5-19 and X5. Increasing both VT and FRC had additive effects on R5, R19, R5-19 and X5, but the effect of increasing FRC was more consistent than increasing VT thus suggesting larger bronchodilation. When compared at iso-volume, there were no differences among breathing patterns with the exception of when VT was three times larger than during spontaneous breathing. CONCLUSIONS These data show that increasing FRC and VT can attenuate induced bronchoconstriction in healthy humans by additive effects that are mainly related to an increase of mean operational lung volume. We suggest that static stretching as with increasing FRC is more effective than tidal stretching at constant VE, possibly through a combination of effects on airway geometry and airway smooth muscle dynamics.
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Affiliation(s)
- Alessandro Gobbi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, 20133, Italy
- Restech Srl, Milano, 20124, Italy
| | - Andrea Antonelli
- Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, 12100, Cuneo, Italy
| | - Raffaele Dellaca
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, 20133, Italy.
| | - Giulia M Pellegrino
- Casa di Cura del Policlinico, Dipartimento di Scienze Neuroriabilitative, Milano, Italy
| | | | - Jeffrey J Fredberg
- Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, 02115, USA
| | - Julian Solway
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Vito Brusasco
- Dipartimento di Medicina Sperimentale, Università di Genova, 16132, Genova, Italy
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2
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Kumar AK, Jain S, Jain S, Ritam M, Xia Y, Chandra R. Physics-informed neural entangled-ladder network for inhalation impedance of the respiratory system. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 231:107421. [PMID: 36805280 DOI: 10.1016/j.cmpb.2023.107421] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 02/11/2023] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND AND OBJECTIVES The use of machine learning methods for modelling bio-systems is becoming prominent which can further improve bio-medical technologies. Physics-informed neural networks (PINNs) can embed the knowledge of physical laws that govern a system during the model training process. PINNs utilise differential equations in the model which traditionally used numerical methods that are computationally complex. METHODS We integrate PINNs with an entangled ladder network for modelling respiratory systems by considering a lungs conduction zone to evaluate the respiratory impedance for different initial conditions. We evaluate the respiratory impedance for the inhalation phase of breathing for a symmetric model of the human lungs using entanglement and continued fractions. RESULTS We obtain the impedance of the conduction zone of the lungs pulmonary airways using PINNs for nine different combinations of velocity and pressure of inhalation. We compare the results from PINNs with the finite element method using the mean absolute error and root mean square error. The results show that the impedance obtained with PINNs contrasts with the conventional forced oscillation test used for deducing the respiratory impedance. The results show similarity with the impedance plots for different respiratory diseases. CONCLUSION We find a decrease in impedance when the velocity of breathing is lowered gradually by 20%. Hence, the methodology can be used to design smart ventilators to the improve flow of breathing.
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Affiliation(s)
- Amit Krishan Kumar
- Faculty of Electrical-Electronic Engineering, Duy Tan University, Da Nang, 550000, Vietnam; State Key Laboratory of Intelligent Control and Decision of Complex Systems, School of Automation, Beijing Institute of Technology, Beijing, 100081, China.
| | - Snigdha Jain
- Department of Electronics and Communications Engineering, Indian Institute of Technology Guwahati, Assam, India.
| | - Shirin Jain
- Department of Electronics and Communications Engineering, Indian Institute of Technology Guwahati, Assam, India.
| | - M Ritam
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam, India.
| | - Yuanqing Xia
- State Key Laboratory of Intelligent Control and Decision of Complex Systems, School of Automation, Beijing Institute of Technology, Beijing, 100081, China.
| | - Rohitash Chandra
- Transitional Artificial Intelligence Research Group, School of Mathematics and Statistics, UNSW Sydney, NSW 2052, Australia.
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3
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Lilien TA, Gunjak M, Myti D, Casado F, van Woensel JBM, Morty RE, Bem RA. Long-Term Pulmonary Dysfunction by Hyperoxia Exposure during Severe Viral Lower Respiratory Tract Infection in Mice. Pathogens 2022; 11:1334. [PMID: 36422586 PMCID: PMC9696792 DOI: 10.3390/pathogens11111334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/08/2022] [Accepted: 11/10/2022] [Indexed: 10/28/2023] Open
Abstract
Viral-induced lower respiratory tract infection (LRTI), mainly by respiratory syncytial virus (RSV), causes a major health burden among young children and has been associated with long-term respiratory dysfunction. Children with severe viral LRTI are frequently treated with oxygen therapy, hypothetically posing an additional risk factor for pulmonary sequelae. The main goal of this study was to determine the effect of concurrent hyperoxia exposure during the acute phase of viral LRTI on long-term pulmonary outcome. As an experimental model for severe RSV LRTI in infants, C57Bl/6J mice received an intranasal inoculation with the pneumonia virus of mice J3666 strain at post-natal day 7, and were subsequently exposed to hyperoxia (85% O2) or normoxia (21% O2) from post-natal day 10 to 17 during the acute phase of disease. Long-term outcomes, including lung function and structural development, were assessed 3 weeks post-inoculation at post-natal day 28. Compared to normoxic conditions, hyperoxia exposure in PVM-inoculated mice induced a transient growth arrest without subsequent catchup growth, as well as a long-term increase in airway resistance. This hyperoxia-induced pulmonary dysfunction was not associated with developmental changes to the airway or lung structure. These findings suggest that hyperoxia exposure during viral LRTI at young age may aggravate subsequent long-term pulmonary sequelae. Further research is needed to investigate the specific mechanisms underlying this alteration to pulmonary function.
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Affiliation(s)
- Thijs A. Lilien
- Pediatric Intensive Care Unit, Emma Children’s Hospital, Amsterdam UMC Location University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Miša Gunjak
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), German Center for Lung Research (DZL), 35392 Giessen, Germany
- Department of Translational Pulmonology, and Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany
| | - Despoina Myti
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), German Center for Lung Research (DZL), 35392 Giessen, Germany
- Department of Translational Pulmonology, and Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany
| | - Francisco Casado
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), German Center for Lung Research (DZL), 35392 Giessen, Germany
- Department of Translational Pulmonology, and Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany
| | - Job B. M. van Woensel
- Pediatric Intensive Care Unit, Emma Children’s Hospital, Amsterdam UMC Location University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Rory E. Morty
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
- Department of Translational Pulmonology, and Translational Lung Research Center (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany
| | - Reinout A. Bem
- Pediatric Intensive Care Unit, Emma Children’s Hospital, Amsterdam UMC Location University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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4
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Bossé Y. Understanding the fundamentals of oscillometry from a strip of lung tissue. Front Physiol 2022; 13:978332. [PMID: 36203932 PMCID: PMC9530782 DOI: 10.3389/fphys.2022.978332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 09/08/2022] [Indexed: 11/19/2022] Open
Abstract
Metrics used in spirometry caught on in respiratory medicine not only because they provide information of clinical importance but also because of a keen understanding of what is being measured. The forced expiratory volume in 1 s (FEV1), for example, is the maximal volume of air that can be expelled during the first second of a forced expiratory maneuver starting from a lung inflated to total lung capacity (TLC). Although it represents a very gross measurement of lung function, it is now used to guide the diagnosis and management of many lung disorders. Metrics used in oscillometry are not as concrete. Resistance, for example, has several connotations and its proper meaning in the context of a lung probed by an external device is not always intuitive. I think that the popularization of oscillometry and its firm implementation in respiratory guidelines starts with a keen understanding of what exactly is being measured. This review is an attempt to clearly explain the basic metrics of oscillometry. In my opinion, the fundamentals of oscillometry can be understood using a simple example of an excised strip of lung tissue subjected to a sinusoidal strain. The key notion is to divide the sinusoidal reacting force from the tissue strip into two sinusoids, one in phase with the strain and one preceding the strain by exactly a quarter of a cycle. Similar notions can then be applied to a whole lung subjected to a sinusoidal flow imposed at the mouth by an external device to understand basic metrics of oscillometry, including resistance, elastance, impedance, inertance, reactance and resonant frequency.
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Adrish M, Anand MP, Hanania NA. Phenotypes of Asthma–Chronic Obstructive Pulmonary Disease Overlap. Immunol Allergy Clin North Am 2022; 42:645-655. [PMID: 35965051 DOI: 10.1016/j.iac.2022.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Torchio R, Gobbi A, Gulotta C, Antonelli A, Dellacà RL, Pellegrino GM, Pellegrino R, Brusasco V. Role of hyperpnea in the relaxant effect of inspired CO 2 on methacholine-induced bronchoconstriction. J Appl Physiol (1985) 2022; 132:1137-1144. [PMID: 35358399 DOI: 10.1152/japplphysiol.00763.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inhaling carbon dioxide (CO2) in humans is known to cause inconsistent effects on airway function. These could be due to direct effects of CO2 on airway smooth muscle or to changes in minute ventilation (e). To address this issue, we examined the responses of the respiratory system to inhaled methacholine in healthy and mild asthmatics while breathing air or gas mixtures containing 2% or 4% CO2. Respiratory mechanics were measured by a forced oscillation technique at 5 Hz during tidal breathing. At baseline, respiratory resistance (R5) was significantly higher in asthmatics (2.53±0.38 cm H2O•L-1•s) than healthy subjects (2.11±0.42 cm H2O•L-1•s) (p=0.008) with room air. Similar values were observed with CO2 2% or 4% in the two groups. e, tidal volume (VT), and breathing frequency (BF) significantly increased with CO2-containing mixtures (p<0.001) with insignificant differences between groups. After methacholine, the increase in R5 and the decrease in respiratory reactance (X5) were significantly attenuated up to about 50% with CO2-containing mixtures instead of room air in both asthmatic (p<0.001) and controls (p<0.001). Mediation analysis showed that the attenuation of methacholine-induced changes in respiratory mechanics by CO2 was due to the increase in e (p=0.006 for R5 and p=0.014 for X5) independently of the increase in VT or BF, rather than a direct effect of CO2. These findings suggest that the increased stretching of airway smooth muscle by the CO2-induced increase in e is a mechanism through which hypercapnia can attenuate bronchoconstrictor responses in healthy and mild asthmatic subjects.
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Affiliation(s)
- Roberto Torchio
- Pneumologia-Fisiopatologia Respiratoria, Universitaria S. Luigi, VENARIA REALE, Italy
| | - Alessandro Gobbi
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy.,Restech Srl, Milano, Italy
| | - Carlo Gulotta
- Pneumologia-Fisiopatologia Respiratoria, Universitaria S. Luigi, VENARIA REALE, Italy
| | - Andrea Antonelli
- Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy
| | - Raffaele L Dellacà
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Giulia Michela Pellegrino
- Respiratory Unit, ASST Santi Paolo eCarlo, Dipartimento Scienze della Salute, Università degli Studi di Milano, Milan, Italy.,Casa di Cura del Policlinico, Dipartimento di Scienze Neuroriabilitative, Milan, Italy
| | | | - Vito Brusasco
- Centro Polifunzionale di Scienze Motorie, Dipartimento di Medicina Sperimentale, Università di Genova, Genova, Italy
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7
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Nozawa S, Urushihata K, Yasuo M, Droma Y, Machida R, Hanaoka M. Characteristics of airway resistance in obstructive sleep apnea patients with asthma on oscillometry. Respir Med Res 2021; 81:100878. [PMID: 34971905 DOI: 10.1016/j.resmer.2021.100878] [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: 08/05/2021] [Revised: 12/01/2021] [Accepted: 12/04/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Asthma and obstructive sleep apnea (OSA) are prevalent chronic respiratory disorders with a high tendency to coexist. Both diseases involve increased airway resistance in the upright position because of narrow upper or lower airways. Moreover, there is a marked increase in airway resistance in the supine position in patients with OSA. We verified the characteristics of OSA in combination with asthma. METHODS Airway resistance was measured by oscillometry in the upright and supine position in 11 healthy participants (control), 59 patients with OSA alone, and 33 OSA patients with asthma (coexistence) in the hospital between April 2014 and July 2020. We compared the differences in airway resistance between the upright and supine positions among the three groups. In addition, we performed cephalometry to evaluate the upper airway structure in patients with OSA alone and in patients with both OSA and asthma. RESULTS A marked increase in airway resistance due to postural change was observed in the "OSA alone" group compared to that in the control group. However, this was not observed in the "coexistence" and control groups. Moreover, the "coexistence" group had fewer structural abnormalities in the upper airway than the "OSA alone" group on cephalometry. CONCLUSIONS The airway resistance of patients with OSA alone markedly increased with posture change because of upper airway abnormalities. However, there was a smaller increase with postural changes in OSA patients with asthma, suggesting the possibility of a smaller degree of upper airway abnormality compared to patients with OSA alone. CLINICAL TRIAL REGISTRATION NUMBER This study is approved by the research ethics committee of the Shinshu University School of Medicine (permission number: 4272).
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Affiliation(s)
- Shuhei Nozawa
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan.
| | - Kazuhisa Urushihata
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Masanori Yasuo
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Yuden Droma
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Ryosuke Machida
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Masayuki Hanaoka
- First Department of Internal Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
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8
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Pellegrino GM, Corbo M, Di Marco F, Pompilio P, Dellacà R, Banfi P, Pellegrino R, Sferrazza Papa GF. Effects of Air Stacking on Dyspnea and Lung Function in Neuromuscular Diseases. Arch Phys Med Rehabil 2021; 102:1562-1567. [PMID: 33711277 DOI: 10.1016/j.apmr.2021.01.092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To investigate whether the decrease in dyspnea in neuromuscular diseases after air stacking (AS) occurs mostly in patients with decreased inspiratory muscle force and ensuing chest wall restriction or heterogeneous ventilation across the lungs. DESIGN Interventional, before-after study. SETTING A neurorehabilitation inpatient and outpatient center. PARTICIPANTS Fifteen consecutive adult patients affected by neuromuscular diseases (N=15). INTERVENTIONS AS treatment. MAIN OUTCOME MEASURES Patients had vital capacity (VC) and sniff nasal inspiratory pressure (SNIP) measured. We measured Borg score, oxygen saturation, and ventilation heterogeneity across the lung as estimated from the difference between respiratory resistance at 5 and 19 Hz (R5-19) with the forced oscillation technique before and 5, 30, 60, and 120 minutes after applying AS. RESULTS Before AS, Borg score was significantly related to R5-19 (r2 0.46, P<.05) but not to VC % predicted, SNIP % predicted, and time since symptom onset. After AS, average Borg score gradually decreased (P=.005), whereas inspiratory flow resistance at 5 Hz, R5-19, and inspiratory reactance at 5 Hz tended to improve, despite not reaching statistical significance. The decrease in dyspnea at 60 and 120 minutes after AS significantly correlated with baseline R5-19 (r2 0.49, P<.01 and r2 0.29, P<.05, respectively), but not with VC % predicted, SNIP % predicted, time since symptom onset, and clinical severity score for patients affected by amyotrophic lateral sclerosis. CONCLUSIONS These findings suggest that dyspnea in neuromuscular diseases is related to heterogeneous ventilation rather than inspiratory muscle force and/or lung volumes decrease. Restoring ventilation distribution across the lungs with AS appears to improve dyspnea.
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Affiliation(s)
- Giulia Michela Pellegrino
- Casa di Cura del Policlinico, Department of Neurorehabilitation Sciences, Milan; Dipartimento Scienze della Salute, Università degli Studi di Milano, Milan.
| | - Massimo Corbo
- Casa di Cura del Policlinico, Department of Neurorehabilitation Sciences, Milan
| | - Fabiano Di Marco
- Dipartimento Scienze della Salute, Università degli Studi di Milano, Milan; Respiratory Unit, Papa Giovanni XXIII Hospital, Bergamo
| | | | - Raffaele Dellacà
- Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milan
| | - Paolo Banfi
- Pulmonary Rehabilitation Unit, Don Gnocchi Foundation IRCCS, Milan
| | | | - Giuseppe Francesco Sferrazza Papa
- Casa di Cura del Policlinico, Department of Neurorehabilitation Sciences, Milan; Dipartimento Scienze della Salute, Università degli Studi di Milano, Milan
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9
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Sood N, Wasilewski NV, Day AG, Wall T, Fisher T, Fisher JT, Lougheed MD. Methacholine-Induced Cough in the Absence of Asthma: Insights From Impulse Oscillometry. Front Physiol 2020; 11:554679. [PMID: 33123021 PMCID: PMC7573225 DOI: 10.3389/fphys.2020.554679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 09/11/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction The pathophysiologic differences between methacholine-induced cough but normal airway sensitivity (COUGH) and healthy individuals (CONTROL) are incompletely understood and may be due to differences in the bronchodilating effect of deep inspirations (DIs). The purpose of this study is to compare the bronchodilating effect of DIs in individuals with classic asthma (CA), cough variant asthma (CVA), and COUGH with CONTROL and to assess impulse oscillometry (IOS) measures as predictors of the bronchodilating effect of DIs. Methods A total of 43 adults [18 female; 44.8 ± 12.3 years (mean ± SD); n = 11 CA, n = 10 CVA, n = 7 COUGH, n = 15 CONTROL] underwent modified high-dose methacholine challenge, with IOS and partial/maximal expiratory flow volume (PEFV/MEFV) maneuvers (used to calculate DI Index) to a maximum change (Δ) in FEV1 of 50% from baseline (MAX). Cough count and dyspnea were measured at each dose. The relation between IOS parameters and DI Index was assessed at baseline and MAX using multivariable linear regression analysis. Results Cough frequency, dyspnea intensity, and baseline peripheral resistance (R5-R20) were significantly greater in COUGH compared with CONTROL (p = 0.006, p = 0.029, and p = 0.035, respectively). At MAX, the DI Index was significantly lower in COUGH (0.01 ± 0.36) compared with CA (0.67 ± 0.97, p = 0.008), CVA (0.51 ± 0.73, p = 0.012), and CONTROL (0.68 ± 0.45, p = 0.005). Fres and R5-R20 were independent IOS predictors of the DI Index. Conclusion The bronchodilating effect is impaired in COUGH and preserved in mild CA, CVA, and CONTROL. Increased peripheral airway resistance and decreased resonant frequency are associated with a decreased DI Index. COUGH is a clinical phenotype distinct from healthy normals and asthma.
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Affiliation(s)
- Nilita Sood
- Department of Medicine, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada.,Department of Biomedical and Molecular Sciences, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Nastasia V Wasilewski
- Department of Medicine, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada.,Department of Biomedical and Molecular Sciences, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Andrew G Day
- Kingston General Health Research Institute, Kingston Health Sciences Centre, Queen's University, Kingston, ON, Canada
| | - Taylar Wall
- Department of Medicine, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Thomas Fisher
- Department of Medicine, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - John T Fisher
- Department of Biomedical and Molecular Sciences, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - M Diane Lougheed
- Department of Medicine, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada.,Department of Biomedical and Molecular Sciences, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada.,Kingston General Health Research Institute, Kingston Health Sciences Centre, Queen's University, Kingston, ON, Canada
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10
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Bou Jawde S, Walkey AJ, Majumdar A, O'Connor GT, Smith BJ, Bates JHT, Lutchen KR, Suki B. Tracking respiratory mechanics around natural breathing rates via variable ventilation. Sci Rep 2020; 10:6722. [PMID: 32317734 PMCID: PMC7174375 DOI: 10.1038/s41598-020-63663-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/26/2020] [Indexed: 11/08/2022] Open
Abstract
Measuring respiratory resistance and elastance as a function of time, tidal volume, respiratory rate, and positive end-expiratory pressure can guide mechanical ventilation. However, current measurement techniques are limited since they are assessed intermittently at non-physiological frequencies or involve specialized equipment. To this end, we introduce ZVV, a practical approach to continuously track resistance and elastance during Variable Ventilation (VV), in which frequency and tidal volume vary from breath-to-breath. ZVV segments airway pressure and flow recordings into individual breaths, calculates resistance and elastance for each breath, bins them according to frequency or tidal volume and plots the results against bin means. ZVV's feasibility was assessed clinically in five human patients with acute lung injury, experimentally in five mice ventilated before and after lavage injury, and computationally using a viscoelastic respiratory model. ZVV provided continuous measurements in both settings, while the computational study revealed <2% estimation errors. Our findings support ZVV as a feasible technique to assess respiratory mechanics under physiological conditions. Additionally, in humans, ZVV detected a decrease in resistance and elastance with time by 12.8% and 6.2%, respectively, suggesting that VV can improve lung recruitment in some patients and can therefore potentially serve both as a dual diagnostic and therapeutic tool.
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Affiliation(s)
- Samer Bou Jawde
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Allan J Walkey
- Department of Medicine, Pulmonary, Allergy, Sleep, & Critical Care Medicine, Boston University, Boston, MA, USA
| | - Arnab Majumdar
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - George T O'Connor
- Department of Medicine, Pulmonary, Allergy, Sleep, & Critical Care Medicine, Boston University, Boston, MA, USA
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
| | - Jason H T Bates
- Pulmonary/Critical Care Division, University of Vermont, Burlington, VT, USA
| | - Kenneth R Lutchen
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
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11
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Bokov P, Bafunyembaka G, Medjahdi N, Bernard A, Essalhi M, Houdouin V, Peiffer C, Delclaux C. Cross-sectional phenotyping of small airway dysfunction in preschool asthma using the impulse oscillometry system. J Asthma 2020; 58:573-585. [PMID: 31958254 DOI: 10.1080/02770903.2020.1719133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Objective. Asthma is a chronic inflammatory airway disorder known to induce small airways dysfunction (SAD). It is important to develop tools to assess the presence and extent of SAD in daily clinical practice. An Impulse Oscillometry System (IOS) might detect SAD, but the validity of the underlying model (serial Resistive airway and Compliant tissue model: RC model) in diseased lungs remains questionable.Methods. Our objective was to evaluate the usefulness of parameters obtained from six electrical circuit models that were fitted to the measurements of impedance obtained with IOS in asthmatic children characterized by an abnormal lung function defined by an increased baseline interrupter resistance (Rint, z-score > +1.645).Results. The six models were tested in 102 asthmatic children (median age: 5.5 years). Two models allowed the description of 92/102 (90%) children: 74 by the extended RIC model (central and peripheral Resistance, Inertance and peripheral airway Compliance) and 18 by the Mead1969 model (extended RIC plus lung compliance). Thus, peripheral airway compliance and resistance were essential to describe lung function abnormalities of these asthmatic children. Parenchyma impairment (increased lung compliance) which was responsive to salbutamol was present in 18% of asthmatic children. After salbutamol, peripheral airway resistance decreased while peripheral airway compliance increased, arguing for asthma-related SAD. R5-20Hz independently correlated with the two latter parameters but was increased in two thirds of children with increased Rint only.Conclusion. Additional modeling of IOS results can be a reliable tool to assess the presence and extent of SAD in young asthmatic children.
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Affiliation(s)
- Plamen Bokov
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France.,Equipe NeoPhen, INSERM co-Tutelle, Université de Paris, UMR1141, Paris, France
| | - Gabriel Bafunyembaka
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France
| | - Noria Medjahdi
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France
| | - Agnès Bernard
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France
| | - Mohamed Essalhi
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France
| | - Véronique Houdouin
- Hôpital Robert Debré, AP-HP, Unité de Pneumologie Pédiatrique, Paris, France.,INSERM co-Tutelle, Université de Paris, UMR1149, Paris, France
| | - Claudine Peiffer
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France
| | - Christophe Delclaux
- Service de Physiologie Pédiatrique, Centre Pédiatrique Des Pathologies du Sommeil, AP-HP, Hôpital Robert Debré, Paris, France.,Equipe NeoPhen, INSERM co-Tutelle, Université de Paris, UMR1141, Paris, France
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12
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Jaworski J, Bates JHT. Sources of breathing pattern variability in the respiratory feedback control loop. J Theor Biol 2019; 469:148-162. [PMID: 30831172 DOI: 10.1016/j.jtbi.2019.03.001] [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] [Received: 05/10/2018] [Revised: 02/25/2019] [Accepted: 03/01/2019] [Indexed: 11/28/2022]
Abstract
The variability of the breath-to-breath breathing pattern, and its alterations in disease, may hold information of physiologic and/or diagnostic value. We hypothesized that this variability arises from the way that noise is processed within the respiratory feedback control loop, and that pathologic alterations to specific components within the system give rise to characteristic alterations in breathing pattern variability. We explored this hypothesis using a computational model of the respiratory control system that integrates mechanical factors, gas exchange processes, and chemoreceptor signals to simulate breathing patterns subject to the influences of random variability in each of the system components. We found that the greatest changes in the coefficient of variation (CV) of both breathing amplitude and timing were caused by increases in lung resistance and impairments in gas exchange, both common features of pulmonary disease. This suggests that breathing pattern variability may reflect discernible deterministic processes involved in the control of breathing.
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Affiliation(s)
- Jacek Jaworski
- Department of Applied Signal Processing, Blekinge Institute of Technology, Karlskrona, Sweden
| | - Jason H T Bates
- Department of Medicine, Larner College of Medicine, University of Vermont, 149 Beaumont Avenue, Burlington, VT 05405, United States.
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13
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Polak AG, Wysoczański D, Mroczka J. Effects of homogeneous and heterogeneous changes in the lung periphery on spirometry results. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2019; 173:139-145. [PMID: 31046988 DOI: 10.1016/j.cmpb.2019.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 03/13/2019] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND AND OBJECTIVES The most widespread chronic pulmonary disorders are associated with heterogeneous changes in the lung periphery and spirometry is the most commonly used test to monitor these diseases. So far only a few attempts have been undertaken to investigate the effects of lung inhomogeneity on spirometry results. The aim of this work was to evaluate whether the spirometric curve and indexes are sensitive to parallel peripheral inhomogeneities, and if the level of heterogeneity can be deduced from this test. METHODS To this end, an enhanced computational model for forced expiration, taking into account a heterogeneous structure and properties of the respiratory system, was used. Two main phenomena were mimicked: small airways narrowing and the loss of tissue elastic recoil. Numerical simulations were performed with the model having 76 separate peripheral compartments. For a given degree of mean change, three heterogeneity levels were investigated and compared to the effects of homogeneous alterations. RESULTS All spirometric curves representing different patterns of inhomogeneous constriction, computed for each of the investigated cases, almost coincided with the curve originating from homogeneous changes, regardless of the heterogeneity level. Also the differences between the spirometric indexes obtained for heterogeneous and homogeneous alterations were negligible in comparison to their values. CONCLUSION The main finding is that the spirometry results are insensitive to the level of heterogeneity in the lung periphery and that it is practically impossible to distinguish between the homogeneous or heterogeneous nature of pathological processes occurring in this lung region.
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Affiliation(s)
- Adam G Polak
- Faculty of Electronics, Wrocław University of Science and Technology, B. Prusa Str. 53/55, Wrocław, Poland.
| | - Dariusz Wysoczański
- Faculty of Electronics, Wrocław University of Science and Technology, B. Prusa Str. 53/55, Wrocław, Poland
| | - Janusz Mroczka
- Faculty of Electronics, Wrocław University of Science and Technology, B. Prusa Str. 53/55, Wrocław, Poland
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14
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Khattab AM, Abd Elfattah N, Farghaly A, Hassan A. Assessment of lung functions using impulse oscillometry before and after bronchoscopic lung volume reduction with histoacryl gel. THE EGYPTIAN JOURNAL OF BRONCHOLOGY 2019. [DOI: 10.4103/ejb.ejb_79_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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15
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Bossé Y. The Strain on Airway Smooth Muscle During a Deep Inspiration to Total Lung Capacity. JOURNAL OF ENGINEERING AND SCIENCE IN MEDICAL DIAGNOSTICS AND THERAPY 2019; 2:0108021-1080221. [PMID: 32328568 PMCID: PMC7164505 DOI: 10.1115/1.4042309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/06/2018] [Indexed: 02/05/2023]
Abstract
The deep inspiration (DI) maneuver entices a great deal of interest because of its ability to temporarily ease the flow of air into the lungs. This salutary effect of a DI is proposed to be mediated, at least partially, by momentarily increasing the operating length of airway smooth muscle (ASM). Concerningly, this premise is largely derived from a growing body of in vitro studies investigating the effect of stretching ASM by different magnitudes on its contractility. The relevance of these in vitro findings remains uncertain, as the real range of strains ASM undergoes in vivo during a DI is somewhat elusive. In order to understand the regulation of ASM contractility by a DI and to infer on its putative contribution to the bronchodilator effect of a DI, it is imperative that in vitro studies incorporate levels of strains that are physiologically relevant. This review summarizes the methods that may be used in vivo in humans to estimate the strain experienced by ASM during a DI from functional residual capacity (FRC) to total lung capacity (TLC). The strengths and limitations of each method, as well as the potential confounders, are also discussed. A rough estimated range of ASM strains is provided for the purpose of guiding future in vitro studies that aim at quantifying the regulatory effect of DI on ASM contractility. However, it is emphasized that, owing to the many limitations and confounders, more studies will be needed to reach conclusive statements.
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Affiliation(s)
- Ynuk Bossé
- Université Laval, Faculty of Medicine, Department of Medicine, IUCPQ, M2694, Pavillon Mallet, Chemin Sainte-Foy, Québec, QC G1V 4G5, Canada e-mail:
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16
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Ribeiro CO, Faria ACD, Lopes AJ, de Melo PL. Forced oscillation technique for early detection of the effects of smoking and COPD: contribution of fractional-order modeling. Int J Chron Obstruct Pulmon Dis 2018; 13:3281-3295. [PMID: 30349233 PMCID: PMC6188181 DOI: 10.2147/copd.s173686] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purpose The aim of the present study was to evaluate the performance of the forced oscillation technique (FOT) for the early diagnosis of the effects of smoking and COPD. The contributions of the integer-order (InOr) and fractional-order (FrOr) models were also evaluated. Patients and methods In total, 120 subjects were analyzed: 40 controls, 40 smokers (20.3±9.3 pack-years) and 40 patients with mild COPD. Results Initially, it was observed that traditional FOT parameters and the InOr and FrOr models provided a consistent description of the COPD pathophysiology. Mild COPD introduced significant increases in the FrOr inertance, damping factor and hysteresivity (P<0.0001). These parameters were significantly correlated with the spirometric parameters of central and small airway obstruction (P<0.0001). The diagnostic accuracy analyses indicated that FOT parameters and InOr modeling may adequately identify these changes (area under the receiver operating characteristic curve – AUC >0.8). The use of FrOr modeling significantly improved this process (P<0.05), allowing the early diagnosis of smokers and patients with mild COPD with high accuracy (AUC >0.9). Conclusion FrOr modeling improves our knowledge of modifications that occur in the early stages of COPD. Additionally, the findings of the present study provide evidence that these models may play an important role in the early diagnosis of COPD, which is crucial for improving the clinical management of the disease.
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Affiliation(s)
- Caroline Oliveira Ribeiro
- Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil,
| | - Alvaro Camilo Dias Faria
- Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil,
| | - Agnaldo José Lopes
- Pulmonary Function Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil.,Pulmonary Rehabilitation Laboratory, Augusto Motta University Center, Rio de Janeiro, Brazil
| | - Pedro Lopes de Melo
- Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil,
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Peters U, Dechman G, Hernandez P, Bhatawadekar SA, Ellsmere J, Maksym G. Improvement in upright and supine lung mechanics with bariatric surgery affects bronchodilator responsiveness and sleep quality. J Appl Physiol (1985) 2018; 125:1305-1314. [PMID: 30048205 DOI: 10.1152/japplphysiol.00694.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Obesity and weight-loss have complex effects on respiratory physiology, but these have been insufficiently studied, particularly at early time points following weight-loss surgery and in the supine position. We evaluated 15 severely obese female participants before, and 5 weeks and 6 months after bariatric surgery using the Pittsburgh Sleep Quality Index (PSQI), spirometry, plethysmography, and oscillometry to measure respiratory system mechanics. Oscillometry and spirometry were conducted in the upright and supine position, and pre- and post-bronchodilation with 200µg of salbutamol. At 5 weeks post-surgery, weight-loss was 11.9±2.7kg with no effect on spirometric outcomes and a slight effect on oscillometric outcomes. However, at 6 months, weight-loss was 21.4±7.1kg with a 14.1±6.1% and 17.8±5.4% reduction in upright and supine Rrs,6, respectively. Ers also decreased by 25.7±9.4% and 20.2±7.2% in the upright and supine positions. No changes were observed in spirometry, but sleep quality improved from PSQI of 8.4±3.5 to 4.1±2.9. Bronchodilator responsiveness was low at baseline but increased significantly post-surgery, and this response was comparable to the improvement in Rrs produced by weight-loss. Modeling the impedance spectra with a two-compartment model demonstrated that improvements in lung mechanics with weight-loss begin in the upper or central compartment of the lungs and progress to include the peripheral compartment. Respiratory mechanics are impaired in the severely obese and is associated with poor sleep quality, but these improved substantially with weight-loss. Our data provide new evidence that severely obese individuals may have poor sleep quality due to abnormal respiratory mechanics that weight-loss improves.
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Affiliation(s)
- Ubong Peters
- Larner College of Medicine, University of Vermont, United States
| | | | - Paul Hernandez
- Department of Medicine, University and Division of Respirology
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18
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Marinho CDL, Maioli MCP, do Amaral JLM, Lopes AJ, de Melo PL. Respiratory resistance and reactance in adults with sickle cell anemia: Correlation with functional exercise capacity and diagnostic use. PLoS One 2017; 12:e0187833. [PMID: 29220407 PMCID: PMC5722327 DOI: 10.1371/journal.pone.0187833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/26/2017] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The improvement in sickle cell anemia (SCA) care resulted in the emergence of a large population of adults living with this disease. The mechanisms of lung injury in this new population are largely unknown. The forced oscillation technique (FOT) represents the current state-of-the-art in the assessment of lung function. The present work uses the FOT to improve our knowledge about the respiratory abnormalities in SCA, evaluates the associations of FOT with the functional exercise capacity and investigates the early detection of respiratory abnormalities. METHODOLOGY/PRINCIPAL FINDINGS Spirometric classification of restrictive abnormalities resulted in three categories: controls (n = 23), patients with a normal exam (n = 21) and presenting pulmonary restriction (n = 24). FOT analysis showed that, besides restrictive changes (reduced compliance; p<0.001), there is also an increase in respiratory resistance (p<0.001) and ventilation heterogeneity (p<0.01). FOT parameters are associated with functional exercise capacity (R = -0.38), pulmonary diffusion (R = 0.66), respiratory muscle performance (R = 0.41), pulmonary volumes (R = 0.56) and airway obstruction (R = 0.54). The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC). A combination of FOT and machine learning (ML) classifiers showed adequate diagnostic accuracy in the detection of early respiratory abnormalities (AUC = 0.82). CONCLUSIONS In this study, the use of FOT showed that adults with SCA develop a mixed pattern of respiratory disease. Changes in FOT parameters are associated with functional exercise capacity decline, abnormal pulmonary mechanics and diffusion. FOT associated with ML methods accurately diagnosed early respiratory abnormalities. This suggested the potential utility of the FOT and ML clinical decision support systems in the identification of respiratory abnormalities in patients with SCA.
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Affiliation(s)
- Cirlene de Lima Marinho
- Biomedical Instrumentation Laboratory—Institute of Biology and Faculty of Engineering, and BioVasc Research Laboratory—Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro—Brazil
| | | | - Jorge Luis Machado do Amaral
- Department of Electronics and Telecommunications Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnaldo José Lopes
- School of Medical Sciences, Pulmonary Function Testing Laboratory, Rio de Janeiro/RJ, State University of Rio de Janeiro, Rio de Janeiro–Brazil
- Rehabilitation Sciences Post-Graduation Program, Augusto Motta University Centre, Rio de Janeiro, Brazil
| | - Pedro Lopes de Melo
- Biomedical Instrumentation Laboratory—Institute of Biology and Faculty of Engineering, and BioVasc Research Laboratory—Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro—Brazil
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Lui JK, Lutchen KR. The role of heterogeneity in asthma: a structure-to-function perspective. Clin Transl Med 2017; 6:29. [PMID: 28776171 PMCID: PMC5543015 DOI: 10.1186/s40169-017-0159-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/26/2017] [Indexed: 02/07/2023] Open
Abstract
A number of methods have evolved through the years in probing the dysfunction that impacts mechanics and ventilation in asthma. What has been consistently found is the notion of heterogeneity that is not only captured in the frequency dependence of lung mechanics measurements but also rendered on imaging as patchy diffuse areas of ventilation defects. The degree of heterogeneity has been linked to airway hyperresponsiveness, a hallmark feature of asthma. How these heterogeneous constriction patterns lead to functional impairment in asthma have only been recently explored using computational airway tree models. By synthesizing measurements of lung mechanics and advances in imaging, computational airway tree models serve as a powerful engine to accelerate our understanding of the physiologic changes that occur in asthma. This review will be focused on the current state of investigational work on the role of heterogeneity in asthma, specifically exploring the structural and functional relationships.
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Affiliation(s)
- Justin K. Lui
- Department of Medicine, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655 USA
| | - Kenneth R. Lutchen
- Department of Biomedical Engineering, Boston University, Boston, MA 02215 USA
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20
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Early Diagnosis of Respiratory Abnormalities in Asbestos-Exposed Workers by the Forced Oscillation Technique. PLoS One 2016; 11:e0161981. [PMID: 27612198 PMCID: PMC5017649 DOI: 10.1371/journal.pone.0161981] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/15/2016] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The current reference test for the detection of respiratory abnormalities in asbestos-exposed workers is spirometry. However, spirometry has several shortcomings that greatly affect the efficacy of current asbestos control programs. The forced oscillation technique (FOT) represents the current state-of-the-art technique in the assessment of lung function. This method provides a detailed analysis of respiratory resistance and reactance at different oscillatory frequencies during tidal breathing. Here, we evaluate the FOT as an alternative method to standard spirometry for the early detection and quantification of respiratory abnormalities in asbestos-exposed workers. METHODOLOGY/PRINCIPAL FINDINGS Seventy-two subjects were analyzed. The control group was composed of 33 subjects with a normal spirometric exam who had no history of smoking or pulmonary disease. Thirty-nine subjects exposed to asbestos were also studied, including 32 volunteers in radiological category 0/0 and 7 volunteers with radiological categories of 0/1 or 1/1. FOT data were interpreted using classical parameters as well as integer (InOr) and fractional-order (FrOr) modeling. The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC). Exposed workers presented increased obstruction (resistance p<0.001) and a reduced compliance (p<0.001), with a predominance of obstructive changes. The FOT parameter changes were correlated with the standard pulmonary function analysis methods (R = -0.52, p<0.001). Early respiratory abnormalities were identified with a high diagnostic accuracy (AUC = 0.987) using parameters obtained from the FrOr modeling. This accuracy was significantly better than those obtained with classical (p<0.001) and InOr (p<0.001) model parameters. CONCLUSIONS The FOT improved our knowledge about the biomechanical abnormalities in workers exposed to asbestos. Additionally, a high diagnostic accuracy in the diagnosis of early respiratory abnormalities in asbestos-exposed workers was obtained. This makes the FOT particularly useful as a screening tool in the context of asbestos control and elimination. Moreover, it can facilitate epidemiological research and the longitudinal follow-up of asbestos exposure and asbestos-related diseases.
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Nakano S, Nakahira J, Sawai T, Kuzukawa Y, Ishio J, Minami T. Perioperative evaluation of respiratory impedance using the forced oscillation technique: a prospective observational study. BMC Anesthesiol 2016; 16:32. [PMID: 27389091 PMCID: PMC4936309 DOI: 10.1186/s12871-016-0197-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 06/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Intravascular fluid shifts, mechanical ventilation and inhalational anesthetic drugs may contribute to intraoperative lung injury. This prospective observational study measured the changes in respiratory impedance resulting from inhalational anesthesia and mechanical ventilation in adults undergoing transurethral resection of bladder tumors. The components of respiratory impedance (resistance and reactance) were measured using the forced oscillation technique (FOT). METHODS Respiratory resistance at 5 Hz (R5) and 20 Hz (R20), respiratory reactance at 5 Hz (X5), resonant frequency (Fres) and area of low reactance (ALX) were measured before and immediately after surgery in 30 adults. In addition, preoperative vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1.0) were evaluated using spirometry. All patients were intubated with an endotracheal tube and were mechanically ventilated, with anesthesia maintained with sevoflurane. Pre- and postoperative FOT measurements were compared using Wilcoxon paired rank tests, and the relationships between FOT measurements and preoperative spirometry findings were determined by Spearman's rank correlation analysis. RESULTS Twenty-six patients were included in the final analysis: postoperative FOT could not be performed in four because of postoperative restlessness or nausea. The mean duration of surgery was 47 min. All components of respiratory resistance deteriorated significantly over the course of surgery, with median increases in R5, R20, and R5-R20 of 1.67 cmH2O/L/s (p < 0.0001), 1.28 cmH2O/L/s (p < 0.0001) and 0.46 cmH2O/L/s (p = 0.0004), respectively. The components of respiratory reactance also deteriorated significantly, with X5 decreasing 1.7 cmH2O/L/s (p < 0.0001), Fres increasing 5.57 Hz (p < 0.0001) and ALX increasing 10.51 cmH2O/L/s (p < 0.0001). There were statistically significant and directly proportional relationships between pre- and postoperative X5 and %VC, %FEV1.0 and %FVC, with inverse relationships between pre- and postoperative Fres and ALX. CONCLUSIONS All components measured by FOT deteriorated significantly after a relatively short period of general anesthesia and mechanical ventilation. All components of resistance increased. Of the reactance components, X5 decreased and Fres and ALX increased. Pre- and postoperative respiratory reactance correlated with parameters measured by spirometry. TRIAL REGISTRATION JMA-IIA00136 .
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Affiliation(s)
- Shoko Nakano
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan
| | - Junko Nakahira
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan.
| | - Toshiyuki Sawai
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan
| | - Yosuke Kuzukawa
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan
| | - Junichi Ishio
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan
| | - Toshiaki Minami
- Department of Anesthesiology, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan
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Kadota N, Shinohara T, Machida H, Nakanishi H, Suehiro F, Toda H, Yoshino T, Ogushi F. Asymptomatic tracheal MALT lymphoma discovered on spirometric findings presenting with elevated respiratory resistance. BMC Res Notes 2015; 8:223. [PMID: 26048050 PMCID: PMC4467634 DOI: 10.1186/s13104-015-1218-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 05/29/2015] [Indexed: 01/26/2023] Open
Abstract
Background Central airway obstruction (CAO) may be caused by various etiologies. However, conventional chest X-rays are rarely diagnostic for patients with CAO. Case presentation We here described a 64-year-old asymptomatic female with tracheal mucosa-associated lymphoid tissue lymphoma discovered on spirometric findings during a complete physical examination. The plateau of forced expiratory flow was consistent with CAO. A decreased peak expiratory flow rate was noted at least 3 years before the diagnosis, and was attributed to an insufficient effort by the patient. Impulse oscillometric measurements, which were taken during quiet breathing and were effort-independent, suggested elevated respiratory resistance. These abnormalities completely disappeared after radiation therapy. Conclusion The addition of impulse oscillometry to spirometry may be useful for screening CAO in routine health examinations.
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Affiliation(s)
- Naoki Kadota
- Division of Pulmonary Medicine, National Hospital Organization National Kochi Hospital, 1-2-25 Asakuranishimachi, Kochi, 780-8077, Japan.
| | - Tsutomu Shinohara
- Department of Clinical Investigation, National Hospital Organization National Kochi Hospital, 1-2-25 Asakuranishimachi, Kochi, 780-8077, Japan.
| | - Hisanori Machida
- Division of Pulmonary Medicine, National Hospital Organization National Kochi Hospital, 1-2-25 Asakuranishimachi, Kochi, 780-8077, Japan.
| | | | - Fumie Suehiro
- Kochi Kenshin Clinic, 2-4-36 Chiyori-cho, Kochi, 780-0806, Japan.
| | - Hiroko Toda
- Department of Pathology, Okayama University, 2-5-1 Shikata-cho, Okayama, 700-8525, Japan.
| | - Tadashi Yoshino
- Department of Pathology, Okayama University, 2-5-1 Shikata-cho, Okayama, 700-8525, Japan.
| | - Fumitaka Ogushi
- Division of Pulmonary Medicine, National Hospital Organization National Kochi Hospital, 1-2-25 Asakuranishimachi, Kochi, 780-8077, Japan.
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Lipworth B, Manoharan A, Anderson W. Unlocking the quiet zone: the small airway asthma phenotype. THE LANCET RESPIRATORY MEDICINE 2015; 2:497-506. [PMID: 24899370 DOI: 10.1016/s2213-2600(14)70103-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The small airways in the distal lung have been called the quiet zone because they are difficult to assess and treat in patients with asthma who have disproportionate impairment of small airway function. Evidence is accumulating to support a distinct clinical phenotype for patients with asthma who have impaired small airway function. The small airway asthma phenotype, which is prevalent in patients at all steps of management guidelines, seems to be associated with poor disease control. Alternatively, small airway dysfunction might be a sensitive indicator of early disease rather than a phenotype. Conventional coarse-particle inhalers, which emit particles larger than 2 μm, might not address persistent small airway dysfunction in patients with asthma. To target the entire lung with extra-fine particle formulations (smaller than 2 μm) of inhaled corticosteroids alone or in combination with long-acting β-agonists might result in improved long-term asthma control along with a commensurate improvement in small airway function. Prospective randomised controlled trials with extra-fine-particle inhaled drugs are now needed for patients with the small airway asthma phenotype.
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Affiliation(s)
- Brian Lipworth
- Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK.
| | - Arvind Manoharan
- Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK
| | - William Anderson
- Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School, Dundee, UK
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24
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Gonem S, Natarajan S, Desai D, Corkill S, Singapuri A, Bradding P, Gustafsson P, Costanza R, Kajekar R, Parmar H, Brightling CE, Siddiqui S. Clinical significance of small airway obstruction markers in patients with asthma. Clin Exp Allergy 2014; 44:499-507. [PMID: 24341600 DOI: 10.1111/cea.12257] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/07/2013] [Accepted: 11/19/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND The role of small airway obstruction in the clinical expression of asthma is incompletely understood. OBJECTIVE We tested the hypotheses that markers of small airway obstruction are associated with (i) increased asthma severity, (ii) impaired asthma control and quality of life and (iii) frequent exacerbations. METHODS Seventy-four adults with asthma and 18 healthy control subjects underwent impulse oscillometry (IOS), multiple breath inert gas washout (MBW), body plethysmography, single-breath determination of carbon monoxide uptake and spirometry. Patients completed the six-point Asthma Control Questionnaire (ACQ-6) and standardized Asthma Quality of Life Questionnaire [AQLQ(S)]. Asthma severity was classified according to the Global Initiative for Asthma (GINA) treatment steps. RESULTS The putative small airway obstruction markers Sacin , resistance at 5 Hz minus resistance at 20 Hz (R5-R20) and reactance area (AX) were not independently associated with asthma severity, control, quality of life or exacerbations. In contrast, markers of total (R5) and mean airway resistance of large and small airways (R20) were significantly higher in the severe asthma group compared with the mild-moderate group (0.47 vs. 0.37, P < 0.05 for R5; 0.39 vs. 0.31, P < 0.01 for R20). The strongest independent contributors to ACQ-6 score were R20 and forced expiratory volume in one second (% pred.), and the strongest independent contributors to AQLQ(S) score were R20 and forced vital capacity (% pred.). A history of one or more exacerbations within the previous year was independently associated with R20. CONCLUSIONS AND CLINICAL RELEVANCE Previously reported markers of small airway obstruction do not appear to be independently associated with asthma disease expression. In contrast, the IOS parameter R20, a marker of mean airway resistance of both large and small airways, appears to have independent clinical significance. These observations require confirmation in prospective longitudinal studies.
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Affiliation(s)
- S Gonem
- Department of Infection, Immunity and Inflammation, Institute for Lung Health, University of Leicester, Leicester, UK
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Pellegrino R, Gobbi A, Antonelli A, Torchio R, Gulotta C, Pellegrino GM, Dellacà R, Hyatt RE, Brusasco V. Ventilation heterogeneity in obesity. J Appl Physiol (1985) 2014; 116:1175-81. [PMID: 24651986 DOI: 10.1152/japplphysiol.01339.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5-11-19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m(2). Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5-19_IQR). FRC % predicted negatively correlated with BMI (r = -0.72, P < 0.001) and with an increase in slope of either maximal (r = -0.34, P < 0.01) or partial flow-volume curves (r = -0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5-19_IQR against FRC % predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models (r(2) = 0.40 vs. 0.30 for FRC % predicted and r(2) = 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil.
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Affiliation(s)
- Riccardo Pellegrino
- Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy
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26
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Antonelli A, Crimi E, Gobbi A, Torchio R, Gulotta C, Dellaca R, Scano G, Brusasco V, Pellegrino R. Mechanical correlates of dyspnea in bronchial asthma. Physiol Rep 2013; 1:e00166. [PMID: 24744853 PMCID: PMC3970739 DOI: 10.1002/phy2.166] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 10/29/2013] [Indexed: 12/03/2022] Open
Abstract
We hypothesized that dyspnea and its descriptors, that is, chest tightness, inspiratory effort, unrewarded inspiration, and expiratory difficulty in asthma reflect different mechanisms of airflow obstruction and their perception varies with the severity of bronchoconstriction. Eighty-three asthmatics were studied before and after inhalation of methacholine doses decreasing the 1-sec forced expiratory volume by ~15% (mild bronchoconstriction) and ~25% (moderate bronchoconstriction). Symptoms were examined as a function of changes in lung mechanics. Dyspnea increased with the severity of obstruction, mostly because of inspiratory effort and chest tightness. At mild bronchoconstriction, multivariate analysis showed that dyspnea was related to the increase in inspiratory resistance at 5 Hz (R 5) (r (2) = 0.10, P = 0.004), chest tightness to the decrease in maximal flow at 40% of control forced vital capacity, and the increase in R 5 at full lung inflation (r (2) = 0.15, P = 0.006), inspiratory effort to the temporal variability in R 5-19 (r (2) = 0.13, P = 0.003), and unrewarded inspiration to the recovery of R 5 after deep breath (r (2) = 0.07, P = 0.01). At moderate bronchoconstriction, multivariate analysis showed that dyspnea and inspiratory effort were related to the increase in temporal variability in inspiratory reactance at 5 Hz (X 5) (r (2) = 0.12, P = 0.04 and r (2) = 0.18, P < 0.001, respectively), and unrewarded inspiration to the decrease in X 5 at maximum lung inflation (r (2) = 0.07, P = 0.04). We conclude that symptom perception is partly explained by indexes of airway narrowing and loss of bronchodilatation with deep breath at low levels of bronchoconstriction, but by markers of ventilation heterogeneity and lung volume recruitment when bronchoconstriction becomes more severe.
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Affiliation(s)
- Andrea Antonelli
- Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy
| | - Emanuele Crimi
- Fisiopatologia Respiratoria, Dipartimento di Medicina Interna, Università di Genova, Genova, Italy
| | - Alessandro Gobbi
- TBM Lab, Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Roberto Torchio
- Pneumologia‐Fisiopatologia Respiratoria, AOU S. Luigi Gonzaga, Orbassano (Torino), Italy
| | - Carlo Gulotta
- Pneumologia‐Fisiopatologia Respiratoria, AOU S. Luigi Gonzaga, Orbassano (Torino), Italy
| | - Raffaele Dellaca
- TBM Lab, Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Giorgio Scano
- Dipartimento di Medicina Interna, Sezione di Immunologia Clinica, Allergologia e Malattie Respiratorie, Università di Firenze, Firenze, Italy
| | - Vito Brusasco
- Fisiopatologia Respiratoria, Dipartimento di Medicina Interna, Università di Genova, Genova, Italy
| | - Riccardo Pellegrino
- Allergologia e Fisiopatologia Respiratoria, ASO S. Croce e Carle, Cuneo, Italy
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27
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Gobbi A, Pellegrino R, Gulotta C, Antonelli A, Pompilio P, Crimi C, Torchio R, Dutto L, Parola P, Dellacà RL, Brusasco V. Short-term variability in respiratory impedance and effect of deep breath in asthmatic and healthy subjects with airway smooth muscle activation and unloading. J Appl Physiol (1985) 2013; 115:708-15. [PMID: 23766502 DOI: 10.1152/japplphysiol.00013.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Inspiratory resistance (RINSP) and reactance (XINSP) were measured for 7 min at 5 Hz in 10 subjects with mild asymptomatic asthma and 9 healthy subjects to assess the effects of airway smooth muscle (ASM) activation by methacholine (MCh) and unloading by chest wall strapping (CWS) on the variability of lung function and the effects of deep inspiration (DI). Subjects were studied at control conditions, after MCh, with CWS, and after MCh with CWS. In all experimental conditions XINSP was significantly more negative in subjects with asthma than in healthy subjects, suggesting greater inhomogeneity in the former. However, the variability in both RINSP and XINSP was increased by either ASM activation or CWS, without significant difference between groups. DI significantly reversed MCh-induced changes in RINSP both in subjects with asthma and healthy subjects, but XINSP in the former only. This effect was impaired by CWS more in subjects with asthma than in healthy subjects. The velocity of RINSP and XINSP recovery after DI was faster in subjects with asthma than healthy subjects. In conclusion, these results support the opinion that the short-term variability in respiratory impedance is related to ASM tone or operating length, rather than to the disease. Nevertheless, ASM in individuals with asthma differs from that in healthy individuals in an increased velocity of shortening and a reduced sensitivity to mechanical stress when strain is reduced.
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Affiliation(s)
- Alessandro Gobbi
- TBM Lab, Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
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28
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Gonem S, Raj V, Wardlaw AJ, Pavord ID, Green R, Siddiqui S. Phenotyping airways disease: an A to E approach. Clin Exp Allergy 2013. [PMID: 23181785 DOI: 10.1111/j.1365-2222.2012.04008.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The airway diseases asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous conditions with overlapping pathophysiological and clinical features. It has previously been proposed that this heterogeneity may be characterized in terms of five relatively independent domains labelled from A to E, namely airway hyperresponsiveness (AHR), bronchitis, cough reflex hypersensitivity, damage to the airways and surrounding lung parenchyma, and extrapulmonary factors. Airway hyperresponsiveness occurs in both asthma and COPD, accounting for variable day to day symptoms, although the mechanisms most likely differ between the two conditions. Bronchitis, or airway inflammation, may be predominantly eosinophilic or neutrophilic, with different treatments required for each. Cough reflex hypersensitivity is thought to underlie the chronic dry cough out of proportion to other symptoms that can occur in association with airways disease. Structural changes associated with airway disease (damage) include bronchial wall thickening, airway smooth muscle hypertrophy, bronchiectasis and emphysema. Finally, a variety of extrapulmonary factors may impact upon airway disease, including rhinosinusitis, gastroesophageal reflux disease, obesity and dysfunctional breathing. This article discusses the A to E concept in detail and describes how this framework may be used to assess and treat patients with airway diseases in the clinic.
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Affiliation(s)
- S Gonem
- Department of Infection, Immunity & Inflammation, Institute for Lung Health, University of Leicester, Leicester, UK
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29
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West AR, Syyong HT, Siddiqui S, Pascoe CD, Murphy TM, Maarsingh H, Deng L, Maksym GN, Bossé Y. Airway contractility and remodeling: links to asthma symptoms. Pulm Pharmacol Ther 2012; 26:3-12. [PMID: 22989721 DOI: 10.1016/j.pupt.2012.08.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 02/07/2023]
Abstract
Respiratory symptoms are largely caused by obstruction of the airways. In asthma, airway narrowing mediated by airway smooth muscle (ASM) contraction contributes significantly to obstruction. The spasmogens produced following exposure to environmental triggers, such as viruses or allergens, are initially responsible for ASM activation. However, the extent of narrowing of the airway lumen due to ASM shortening can be influenced by many factors and it remains a real challenge to decipher the exact role of ASM in causing asthmatic symptoms. Innovative tools, such as the forced oscillation technique, continue to develop and have been proven useful to assess some features of ASM function in vivo. Despite these technologic advances, it is still not clear whether excessive narrowing in asthma is driven by ASM abnormalities, by other alterations in non-muscle factors or simply because of the overexpression of spasmogens. This is because a multitude of forces are acting on the airway wall, and because not only are these forces constantly changing but they are also intricately interconnected. To counteract these limitations, investigators have utilized in vitro and ex vivo systems to assess and compare asthmatic and non-asthmatic ASM contractility. This review describes: 1- some muscle and non-muscle factors that are altered in asthma that may lead to airway narrowing and asthma symptoms; 2- some technologies such as the forced oscillation technique that have the potential to unveil the role of ASM in airway narrowing in vivo; and 3- some data from ex vivo and in vitro methods that probe the possibility that airway hyperresponsiveness is due to the altered environment surrounding the ASM or, alternatively, to a hypercontractile ASM phenotype that can be either innate or acquired.
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Affiliation(s)
- Adrian R West
- School of Biomedical Engineering, Dalhousie University, Nova Scotia, Canada
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30
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Faria ACD, Barbosa WR, Lopes AJ, Pinheiro GDRC, Melo PLD. Contrasting diagnosis performance of forced oscillation and spirometry in patients with rheumatoid arthritis and respiratory symptoms. Clinics (Sao Paulo) 2012; 67:987-94. [PMID: 23018292 PMCID: PMC3438257 DOI: 10.6061/clinics/2012(09)01] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 04/01/2012] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVES Pulmonary involvement in rheumatoid arthritis is directly responsible for 10% to 20% of all mortality. The best way to improve the prognosis is early detection and treatment. The forced oscillation technique is easy to perform and offers a detailed exam, which may be helpful in the early detection of respiratory changes. This study was undertaken to (1) evaluate the clinical potential of the forced oscillation technique in the detection of early respiratory alterations in rheumatoid arthritis patients with respiratory complaints and (2) to compare the sensitivity of forced oscillation technique and spirometric parameters. METHODS A total of 40 individuals were analyzed: 20 healthy and 20 with rheumatoid arthritis (90% with respiratory complaints). The clinical usefulness of the parameters was evaluated by investigating the sensibility, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01641705. RESULTS The early adverse respiratory effects of rheumatoid arthritis were adequately detected by the forced oscillation technique parameters, and a high accuracy for clinical use was obtained (AUC.0.9, Se = 80%, Sp = 95%). The use of spirometric parameters did not obtain an appropriate accuracy for clinical use. The diagnostic performance of the forced oscillation technique parameters was significantly higher than that of spirometry. CONCLUSIONS The results of the present study provide substantial evidence that the forced oscillation technique can contribute to the easy identification of initial respiratory abnormalities in rheumatoid arthritis patients that are not detectable by spirometric exams. Therefore, we believe that the forced oscillation technique can be used as a complementary exam that may help to improve the treatment of breathing disorders in rheumatoid arthritis patients.
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Affiliation(s)
- Alvaro Camilo Dias Faria
- Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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31
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Abstract
Noninvasive physiological measurements are reviewed that have been reported in the literature with the specific aim being to study the small airways in lung disease. This has mostly involved at-the-mouth noninvasive measurement of flow, pressure or inert gas concentration, with the intent of deriving one or more indices that are representative of small airway structure and function. While these measurements have remained relatively low-tech, the effort and sophistication increasingly reside with the interpretation of such indices. When aspiring to derive information at the mouth about structural and mechanical processes occurring several airway generations away in a complex cyclically changing cul-de-sac structure, conceptual or semi-quantitative lung models can be valuable. Two assumptions that are central to small airway structure-function measurement are that of an average airway change at a given peripheral lung generation and of a parallel heterogeneity in airway changes. While these are complementary pieces of information, they can affect certain small airways tests in confounding ways. We critically analyzed the various small airway tests under review, while contending that negative outcomes of these tests are probably a true reflection of the fact that no change occurred in the small airways. Utmost care has been taken to not favor one technique over another, given that most current small airways tests still have room for improvement in terms of rendering their content more specific to the small airways. One way to achieve this could consist of the coupling of signals collected at the mouth to spatial information gathered from imaging in the same patient.
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Affiliation(s)
- Sylvia Verbanck
- Respiratory Division, University Hospital UZ Brussel, Brussels, Belgium.
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32
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Yamauchi Y, Kohyama T, Jo T, Nagase T. Dynamic change in respiratory resistance during inspiratory and expiratory phases of tidal breathing in patients with chronic obstructive pulmonary disease. Int J Chron Obstruct Pulmon Dis 2012; 7:259-69. [PMID: 22589578 PMCID: PMC3346211 DOI: 10.2147/copd.s30399] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation consisting of airway obstruction and parenchymal emphysema, with loss of elastic recoil. The forced oscillation technique can detect impairment of lung function by measuring lung impedance during normal tidal breathing. Respiratory resistance (Rrs) in COPD has been well-studied, but the differences in Rrs in the inspiratory and expiratory phases between mild and moderate COPD remain poorly understood. Since airway obstruction in COPD is known to change dynamically during tidal breathing and might affect Rrs, the differences in Rrs during tidal breathing between mild and moderate COPD were evaluated. METHODS Mild (n = 13) and moderate (n = 13) COPD patients were recruited at Tokyo University Hospital (Tokyo, Japan). Rrs was measured using MostGraph-01 (Chest MI, Inc, Tokyo, Japan), which depicted Rrs in a frequency-and respiratory cycle-dependent manner in three-dimensional graphics. Rrs was evaluated at 4-35 Hz during tidal breathing. RESULTS Rrs changed dynamically during tidal breathing in COPD. The mean Rrs values were significantly greater in the moderate COPD group than in the mild group. The maximal and minimal Rrs values at higher frequencies in the respiratory cycle were significantly greater in moderate COPD. In inspiratory-expiratory breath analysis, the maximal and minimal Rrs values at 20 Hz and 35 Hz were significantly greater in the moderate group, whereas at 4 Hz they did not differ significantly between the groups. CONCLUSION Rrs changed dynamically during tidal breathing in patients with COPD. The Rrs values at higher frequencies were greater in moderate COPD than in mild COPD. Rrs at higher frequencies might reflect the degree of airway obstruction in tidal breathing in patients with COPD and might be a useful marker for evaluation of airway obstruction at an early stage of COPD.
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Affiliation(s)
- Yasuhiro Yamauchi
- Division of Health Promotion Center, University of Tokyo, Tokyo, Japan.
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Ito S, Ko SBH, Morioka M, Imaizumi K, Kondo M, Mizuno N, Hasegawa Y. Three cases of bronchial asthma preceding IgG4-related autoimmune pancreatitis. Allergol Int 2012; 61:171-4. [PMID: 22189588 DOI: 10.2332/allergolint.11-cr-0352] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 08/05/2011] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Autoimmune pancreatitis is characterized by diffuse swelling of the pancreas and a high serum immunoglobulin (Ig) G4 concentration. Histopathologically, dense infiltration of lymphocytes and IgG4-positive plasma cells with fibrosis are seen in the pancreas. Although allergic diseases complicating autoimmune pancreatitis have been reported, the clinical features of bronchial asthma complicated by autoimmune pancreatitis remain unclear. CASE SUMMARY We report three cases of bronchial asthma preceding the onset of type 1 autoimmune pancreatitis by 3 months to 30 years. All three cases were males with high serum IgG, IgG4, and IgE concentrations. The radioallergosorbent tests were positive for common allergens such as mites and house dust. One case had a pulmonary manifestation that proved to be an inflammatory pseudotumor of the lung with an accumulation of IgG4-positive plasma cells. The asthma symptom was ameliorated by oral prednisolone therapy for autoimmune pancreatitis, and when the corticosteroid doses were reduced, asthma became worse in all three cases. DISCUSSION It is possible that atopy and increased Th2 cell activity are related to a higher coincidence of IgG4-related diseases such as type 1 autoimmune pancreatitis. Because the present cases are few in number, further studies are necessary.
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Affiliation(s)
- Satoru Ito
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan. −u.ac.jp
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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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35
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Brightling CE, Gupta S, Gonem S, Siddiqui S. Lung damage and airway remodelling in severe asthma. Clin Exp Allergy 2011; 42:638-49. [PMID: 22192725 DOI: 10.1111/j.1365-2222.2011.03917.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/16/2011] [Accepted: 11/08/2011] [Indexed: 02/07/2023]
Abstract
Severe asthma is a heterogeneous disease with substantial unmet clinical need. Airway damage and remodelling is a consequence of complex host-environment interactions and is considered to be the cardinal feature leading onto the development and persistence of airflow obstruction. In this review, we shall bring together recent insights into the causes of airway damage and remodelling that propose key roles for pathogens and mechanical damage in addition to allergens, underlying genetic susceptibility, inflammatory and structural cell interactions, and impaired resolution of damage. We shall consider the consequences of airway remodelling in terms of airway geometry, mechanics and clinical expression of disease. Understanding the causes and consequences of airway damage and remodelling will shed light upon the structure-function relationships required to begin to unravel the complexity of severe asthma and will enable us to target current and novel therapies as we begin to move towards realizing personalized medicine.
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Affiliation(s)
- C E Brightling
- Department of Infection, Inflammation and Immunity, Institute for Lung Health, University of Leicester, Leicester, UK.
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36
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Ohishi J, Kurosawa H, Ogawa H, Irokawa T, Hida W, Kohzuki M. Application of impulse oscillometry for within-breath analysis in patients with chronic obstructive pulmonary disease: pilot study. BMJ Open 2011; 1:e000184. [PMID: 22021880 PMCID: PMC3191594 DOI: 10.1136/bmjopen-2011-000184] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND The impulse oscillometry is increasingly used for assessing the oscillatory mechanics of the respiratory system. The within-breath behaviour of the oscillatory mechanics in chronic obstructive pulmonary disease (COPD) is a well-known physiological feature. The purpose of this study was to develop a new approach for assessing this feature using impulse oscillometry. METHODS The oscillatory mechanics were assessed by a commercially available impulse oscillometry device. The respiratory system resistance (Rrs) and reactance (Xrs) were measured during tidal breathing in patients with COPD (n=39) and healthy subjects (n=5). Selected data, the Rrs at 5 Hz (R5), Rrs at 20 Hz (R20), Xrs at 5 Hz (X5), and resonant frequency of Xrs (Fres) every 0.2 s, were extracted from the device. These data were divided into eight time fractions during the respiratory cycle to form averaged respiratory phases. RESULTS The time courses of the R5 and X5 were notably dependent on the respiratory cycles in patients with COPD, while there was little such dependency in healthy subjects. Irrespective of respiratory phase, R5 and Fres increased, and X5 fell to a more negative level in patients with COPD in a severity-dependent fashion. The increase in the R5 and negative level in the X5 were more prominent in the middle of the expiratory phase. The severity dependence in the R20 was relatively small compared with that in the R5. CONCLUSIONS The results of this study suggest that impulse oscillometry can assess the within-breath behaviour of the oscillatory mechanics with high temporal resolution, which may be helpful for evaluating the severity of COPD. Further studies are needed to reveal which biomarkers obtained with this approach would be suitable for evaluating the airway obstruction.
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Affiliation(s)
- Junichi Ohishi
- Department of Occupational Health, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hajime Kurosawa
- Department of Occupational Health, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiromasa Ogawa
- Department of Occupational Health, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Toshiya Irokawa
- Department of Occupational Health, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Wataru Hida
- Health Administration Centre, Tohoku University, Sendai, Japan
| | - Masahiro Kohzuki
- Department of Internal Medicine and Rehabilitation Science, Tohoku University Graduate School of Medicine, Sendai, Japan
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37
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Current world literature. Curr Opin Allergy Clin Immunol 2010; 10:161-6. [PMID: 20357579 DOI: 10.1097/aci.0b013e32833846d5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Muskulus M, Slats AM, Sterk PJ, Verduyn-Lunel S. Fluctuations and determinism of respiratory impedance in asthma and chronic obstructive pulmonary disease. J Appl Physiol (1985) 2010; 109:1582-91. [PMID: 20813978 DOI: 10.1152/japplphysiol.01414.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Asthma and COPD are chronic respiratory diseases that fluctuate widely with regard to clinical symptoms and airway obstruction, complicating treatment and prediction of exacerbations. Time series of respiratory impedance obtained by the forced oscillation technique are a convenient tool to study the respiratory system with high temporal resolution. In previous studies it was suggested that power-law-like fluctuations exist also in the healthy lung and that respiratory system impedance variability differs in asthma. In this study we elucidate such differences in a population of well-characterized subjects with asthma (n = 13, GINA 1+2), COPD (n = 12, GOLD I+II), and controls (n = 10) from time series at single frequency (12 min, f = 8 Hz). Maximum likelihood estimation did not rule out power-law behavior, accepting the null hypothesis in 17/35 cases (P > 0.05) and with significant differences in exponents for COPD (P < 0.03). Detrended fluctuation analysis exhibited scaling exponents close to 0.5, indicating few correlations, with no differences between groups (P > 0.14). In a second approach, we considered asthma and COPD as dynamic diseases, corresponding to changes of unknown parameters in a deterministic system. The similarity in shape between the combined probability distributions of normalized resistance and reactance was quantified by Wasserstein distances and reliably distinguished the two diseases (cross-validated predictive accuracy 0.80; sensitivity 0.83, specificity 0.77 for COPD). Wasserstein distances between 3+3 dimensional phase space reconstructions resulted in marginally better classification (accuracy 0.84, sensitivity 0.83, specificity 0.85). These latter findings suggest that the dynamics of respiratory impedance contain valuable information for the diagnosis and monitoring of patients with asthma and COPD, whereas the value of the stochastic approach is not clear presently.
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Affiliation(s)
- Michael Muskulus
- Mathematical Institute, Leiden University, Leiden, the Netherlands.
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Quint SR, Vaughn BV. Heart period sensitivity to forced oscillations in ventilatory pressure. Eur J Appl Physiol 2010; 110:133-42. [DOI: 10.1007/s00421-010-1478-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2010] [Indexed: 11/30/2022]
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Bitzén U, Niklason L, Göransson I, Jonson B. Measurement and mathematical modelling of elastic and resistive lung mechanical properties studied at sinusoidal expiratory flow. Clin Physiol Funct Imaging 2010; 30:439-46. [PMID: 20726995 DOI: 10.1111/j.1475-097x.2010.00963.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Elastic pressure/volume (P(el) /V) and elastic pressure/resistance (P(el) /R) diagrams reflect parenchymal and bronchial properties, respectively. The objective was to develop a method for determination and mathematical characterization of P(el) /V and P(el) /R relationships, simultaneously studied at sinusoidal flow-modulated vital capacity expirations in a body plethysmograph. Analysis was carried out by iterative parameter estimation based on a composite mathematical model describing a three-segment P(el) /V curve and a hyperbolic P(el) /R curve. The hypothesis was tested that the sigmoid P(el) /V curve is non-symmetric. Thirty healthy subjects were studied. The hypothesis of a non-symmetric P(el) /V curve was verified. Its upper volume asymptote was nearly equal to total lung capacity (TLC), indicating lung stiffness increasing at high lung volume as the main factor limiting TLC at health. The asymptotic minimal resistance of the hyperbolic P(el) /R relationship reflected lung size. A detailed description of both P(el) /V and P(el) /R relationships was simultaneously derived from sinusoidal flow-modulated vital capacity expirations. The nature of the P(el) /V curve merits the use of a non-symmetric P(el) /V model.
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Affiliation(s)
- Ulrika Bitzén
- Department of Clinical Physiology, Lund University, Skåne University Hospital, Lund, Sweden.
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Veiga J, Lopes AJ, Jansen JM, de Melo PL. Effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of patients with asthma. J Bras Pneumol 2010; 35:645-52. [PMID: 19669002 DOI: 10.1590/s1806-37132009000700005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Accepted: 03/02/2009] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE To investigate the effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of adult patients with asthma. METHODS This study comprised 24 healthy controls and 69 patients with asthma, all of whom were nonsmokers. The patients were divided into three groups according to the severity of airway obstruction (mild, moderate or severe). Each of the three groups was divided into two subgroups according to the bronchodilator response (BR): positive (BR+) or negative (BR(-)). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. These measurements were conducted before and after albuterol use (300 microg). RESULTS The resistance at the intercept (R(0)) presented greater reductions in the groups with higher obstruction. This reduction was more evident in the BR+ subgroups than in the BR(-) subgroups (p < 0.02 and p < 0.03, respectively). There was a significant difference between the control group and the BR+ subgroup with severe obstruction (p < 0.002). The reductions in dynamic elastance (Edyn) were significantly greater in proportion to the degree of obstruction, in the BR(-) subgroups (p < 0.03), and in the BR+ subgroups (p < 0.003). The reductions in Edyn were significantly greater in the BR- subgroup with moderate obstruction (p < 0.008) and in the BR+ subgroup with severe obstruction (p < 0.0005) than in the control group. CONCLUSIONS In patients with asthma, increased airway obstruction results in greater reductions in R(0) and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR(-) patients.
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Affiliation(s)
- Juliana Veiga
- Universidade Castelo Branco, Rio de Janeiro, RJ, Brasil
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Faria ACD, Lopes AJ, Jansen JM, Melo PL. Evaluating the forced oscillation technique in the detection of early smoking-induced respiratory changes. Biomed Eng Online 2009; 8:22. [PMID: 19781078 PMCID: PMC2760559 DOI: 10.1186/1475-925x-8-22] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 09/25/2009] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Early detection of the effects of smoking is of the utmost importance in the prevention of chronic obstructive pulmonary disease (COPD). The forced oscillation technique (FOT) is easy to perform since it requires only tidal breathing and offers a detailed approach to investigate the mechanical properties of the respiratory system. The FOT was recently suggested as an attractive alternative for diagnosing initial obstruction in COPD, which may be helpful in detecting COPD in its initial phases. Thus, the purpose of this study was twofold: (1) to evaluate the ability of FOT to detect early smoking-induced respiratory alterations; and (2) to compare the sensitivity of FOT with spirometry in a sample of low tobacco-dose subjects. METHODS Results from a group of 28 smokers with a tobacco consumption of 11.2 +/- 7.3 pack-years were compared with a control group formed by 28 healthy subjects using receiver operating characteristic (ROC) curves and a questionnaire as a gold standard. The early adverse effects of smoking were adequately detected by the absolute value of the respiratory impedance (Z4Hz), the intercept resistance (R0), and the respiratory system dynamic compliance (Crs, dyn). Z4Hz was the most accurate parameter (Se = 75%, Sp = 75%), followed by R0 and Crs, dyn. The performances of the FOT parameters in the detection of the early effects of smoking were higher than that of spirometry (p < 0.05). CONCLUSION This study shows that FOT can be used to detect early smoking-induced respiratory changes while these pathologic changes are still potentially reversible. These findings support the use of FOT as a versatile clinical diagnostic tool in aiding COPD prevention and treatment.
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Affiliation(s)
- Alvaro CD Faria
- Department of Physiology, Biomedical Instrumentation Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnaldo J Lopes
- Faculty of Medical Sciences, Pulmonary Function Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - José M Jansen
- Faculty of Medical Sciences, Pulmonary Function Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro L Melo
- Department of Physiology, Biomedical Instrumentation Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
- Department of Physiology, BioVasc Research Laboratory, State University of Rio de Janeiro, Rio de Janeiro, Brazil
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e Tramont CVV, Faria ACD, Lopes AJ, Jansen JM, de Melo PL. Influence of the ageing process on the resistive and reactive properties of the respiratory system. Clinics (Sao Paulo) 2009; 64:1065-73. [PMID: 19936180 PMCID: PMC2780523 DOI: 10.1590/s1807-59322009001100006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 08/03/2009] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION In an increasingly old society, the study of the respiratory system changes and new techniques dedicated to older patients are of interest in physiologic studies as well as in the diagnosis of respiratory diseases. OBJECTIVES (1) To investigate the impact of ageing on the resistive and reactive properties of the respiratory system, and (2) to compare the easiness of accomplishment of spirometry and forced oscillation for assessing lung function. METHODS We conducted a cross-sectional study in which forced oscillation was used to investigate respiratory system resistive and reactive properties, while spirometry was used as a reference test to evaluate 80 normal subjects aged between 20 and 86 years. A questionnaire was used to evaluate the easiness of accomplishment of spirometry and forced oscillation. RESULTS There was a significant increase in the respiratory system resonance frequency (p<0.003) and a reduction in the mean reactance (p<0.004) with increasing age. Respiratory system resistance and dynamic compliance were not related to the ageing process. The easiness of accomplishment of forced oscillation measurements was greater than that of spirometry. This result was particularly relevant in subjects over 70 years old (p<0.05). CONCLUSIONS Respiratory system resistance and dynamic compliance are not modified with ageing. On the other hand, respiratory system homogeneity decreases during the ageing process. Forced oscillation is easy to perform and provides information complementary to spirometry. This technique may be a promising alternative and/or complement to other conventional exams used to evaluate older people who are unable to adequately perform spirometric tests.
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Affiliation(s)
| | | | - Agnaldo José Lopes
- Pulmonary Function Laboratory - Faculty of Medical Sciences - Rio de Janeiro/RJ, Brazil.
, Tel: 55 21 2587.7773
| | - José Manoel Jansen
- Pulmonary Function Laboratory - Faculty of Medical Sciences - Rio de Janeiro/RJ, Brazil.
, Tel: 55 21 2587.7773
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Veiga J, Lopes AJ, Jansen JM, de Melo PL. Within-breath analysis of respiratory mechanics in asthmatic patients by forced oscillation. Clinics (Sao Paulo) 2009; 64:649-56. [PMID: 19606241 PMCID: PMC2710438 DOI: 10.1590/s1807-59322009000700008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 04/15/2009] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION The within-breath analysis of respiratory mechanics by the monofrequency Forced Oscillation Technique (mFOT) is of great interest in both physiopathology studies and the diagnosis of respiratory diseases. However, there are limited data on the use of this technique in the analysis of asthma. This study evaluates within-breath mechanics of asthmatic individuals and the contribution of the mFOT in the asthma diagnosis. METHODS Twenty-two healthy and twenty-two asthmatic subjects, including patients with mild (n=8), moderate (n=8), and severe (n=6) obstruction, were studied. Forced Oscillation Technique data were interpreted using the mean respiratory impedance (Zt), the impedance during inspiration (Zi), expiration (Ze), at the beginning of inspiration (Zii), and at expiration (Zie). The peak-to-peak impedance (Zpp) was also calculated by the subtraction of Zii from Zie. Receiver operating characteristic curves were used to determine the sensitivity (Se) and specificity (Sp) of m Forced Oscillation Technique parameters in identifying asthma. RESULTS Respiratory impedance values were significantly higher in asthmatics: Zt (p<0.001), Zi (p<0.001), Ze (p<0.001), Zii (p<0.001), Zie (p<0.001), and Zpp (p<0.003). The best parameters for detecting asthma were Zi, Zii, and Zie (Se=90.9%, Sp=90.9%), followed by Zt and Ze. These results are in close agreement with recently published theories and pathophysiological fundamentals. CONCLUSIONS mFOT permits a non-invasive and detailed analysis in different phases of the respiratory cycle, providing parameters that are adequate for the diagnosis of asthma with high accuracy. These results confirm the high clinical and scientific potential of this methodology in the evaluation of asthmatic patients.
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Affiliation(s)
- Juliana Veiga
- Biomedical Instrumentation Laboratory and BioVasc Clinical and Experimental Research Laboratory, Institute of Biology, State University of Rio de Janeiro - Rio de Janeiro/RJ, Brazil
| | - Agnaldo José Lopes
- Pulmonary Function Laboratory, Faculty of Medical Sciences, State University of Rio de Janeiro - Rio de Janeiro/RJ, Brazil.
, Tel: 55 21 2587.7773
| | - José Manoel Jansen
- Pulmonary Function Laboratory, Faculty of Medical Sciences, State University of Rio de Janeiro - Rio de Janeiro/RJ, Brazil.
, Tel: 55 21 2587.7773
| | - Pedro Lopes de Melo
- Biomedical Instrumentation Laboratory and BioVasc Clinical and Experimental Research Laboratory, Institute of Biology, State University of Rio de Janeiro - Rio de Janeiro/RJ, Brazil
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