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Gill R, Boucher M, Henry C, Bossé Y. A Quick Method to Assess Airway Distensibility in Mice. Ann Biomed Eng 2024; 52:2193-2202. [PMID: 38619723 PMCID: PMC11247055 DOI: 10.1007/s10439-024-03518-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/11/2024] [Indexed: 04/16/2024]
Abstract
Airway distensibility is defined as the ease whereby airways are dilating in response to inflating lung pressure. If measured swiftly and accurately, airway distensibility would be a useful readout to parse the various elements contributing to airway wall stiffening, such as smooth muscle contraction, surface tension, and airway remodeling. The goal of the present study was to develop a method for measuring airway distensibility in mice. Lungs of BALB/c and C57BL/6 mice from either sex were subjected to stepwise changes in pressure. At each pressure step, an oscillometric perturbation was used to measure the impedance spectrum, on which the constant-phase model was fitted to deduce a surrogate for airway caliber called Newtonian conductance (GN). The change in GN over the change in pressure was subsequently used as an index of airway distensibility. An additional group of mice was infused with methacholine to confirm that smooth muscle contraction changes airway distensibility. GN increased with increasing steps in pressure, suggesting that the extent to which this occurs can be used as an index of airway distensibility. Airway distensibility was greater in BALB/c than C57BL/6 mice, and its variation by sex was mouse strain dependent, being greater in female than male in BALB/c mice with an inverse trend in C57BL/6 mice. Airway distensibility was also decreased by methacholine. This novel method swiftly measures airway distensibility in mice. Airway distensibility was also shown to vary with sex and mouse strain and to be sensitive to the contraction of smooth muscle.
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Affiliation(s)
- Rebecka Gill
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada.
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2
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Donohue PA, Kaminsky DA. The role of oscillometry in asthma. Curr Opin Pulm Med 2024; 30:268-275. [PMID: 38411171 DOI: 10.1097/mcp.0000000000001057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
PURPOSE OF REVIEW Oscillometry is a noninvasive pulmonary function test that has gained significant interest in the evaluation of lung disease. Currently, oscillometry is primarily a research tool, but there is a growing body of evidence supporting its clinical use. This review describes the recent work evaluating the role of oscillometry in the diagnosis and treatment of asthma. RECENT FINDINGS A large body of observational data supports the ability of oscillometry to distinguish healthy individuals from those with respiratory symptoms or lung disease. Oscillometry may not be as useful as an isolated diagnostic test in asthma, but the combination with other pulmonary function tests may improve its diagnostic ability. Oscillometry can detect peripheral airways dysfunction in asthma, which is associated with symptoms and the risk for exacerbations. To help guide future research, minimal clinically important differences for specific oscillometry variables have been developed. Oscillometry may be useful in monitoring the response to biological therapy and has potential for personalizing treatment for individual patients. Oscillometry also has potential in uncovering unique aspects of the pathophysiology of asthma in obesity. SUMMARY Oscillometry is a promising tool in the diagnosis and management of asthma. More research is needed to support its routine clinical use.
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Affiliation(s)
- Patrick A Donohue
- Division of Pulmonary and Critical Care Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - David A Kaminsky
- Division of Pulmonary and Critical Care, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
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3
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Song R, Broytman O, Liang N, Setzke J, Setzke C, Wojdyla G, Pegelow DF, Osman F, Sorkness RL, Watters JJ, Teodorescu M. Four weeks of repetitive acute hypoxic preconditioning did not alleviate allergen-induced airway dysfunction in rats. Respir Physiol Neurobiol 2023; 307:103982. [PMID: 36332748 DOI: 10.1016/j.resp.2022.103982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/26/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022]
Abstract
Clinical case series suggest beneficial effects of low-dose intermittent hypoxia in asthma. We tested cardiopulmonary effects of repetitive acute hypoxic preconditioning (RAHP) during allergic inflammation. Brown Norway rats were sensitized to house dust mites (HDM) and exposed to 4-week RAHP or normoxia (SHAM), concurrent with weekly HDM or saline (SAL) challenges. We assessed methacholine responses and lung HIF-1α expression at endpoint, and weekly blood pressure (BP). RAHP relative to SHAM: 1) in HDM-challenged rats, showed no protection against HDM-induced airway dysfunction and did not significantly impact BP (week 4 mean BP difference = 10.51 mmHg, p = 0.09) or HIF-1α expression; 2) in SAL-challenged rats, attenuated airway responses to methacholine, reduced BP (week 4 mean BP average difference = -8.72 mmHg, p = 0.04) and amplified HIF-1α expression (p = 0.0086). Four weeks of RAHP did not mitigate the allergen-induced lower airway dysfunction and may detrimentally affect BP. However, it elicited beneficial cardiopulmonary responses in SAL-challenged rats, concurrent with increased HIF-1α expression.
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Affiliation(s)
- Ruolin Song
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Oleg Broytman
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Nicole Liang
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Jonathan Setzke
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | | | - Gabriela Wojdyla
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - David F Pegelow
- Department of Pediatrics, School of Medicine and Public Health,University of Wisconsin, Madison, WI, USA
| | - Fauzia Osman
- Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Ronald L Sorkness
- Department of Medicine, University of Wisconsin, Madison, WI, USA; School of Pharmacy, University of Wisconsin, Madison, WI, USA
| | - Jyoti J Watters
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA
| | - Mihaela Teodorescu
- Department of Medicine, University of Wisconsin, Madison, WI, USA; William S. Middleton Memorial VA Medical Center, Madison, WI, USA.
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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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O'Sullivan CF, Nilsen K, Borg BM, Ellis MJ, Matsas P, Thien F, Douglass JA, Stuart-Andrews C, King GG, Prisk GK, Thompson BR. Small Airways Dysfunction is Associated with Increased Exacerbations in Patients with Asthma. J Appl Physiol (1985) 2022; 133:629-636. [PMID: 35861519 DOI: 10.1152/japplphysiol.00103.2022] [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
There is poor understanding of why some patients with asthma experience recurrent exacerbations despite high levels of treatment. We compared measurements of peripheral ventilation heterogeneity and respiratory system mechanics in participants with asthma who were differentiated according to exacerbation history, to ascertain whether peripheral airway dysfunction was related to exacerbations. Three asthmatic groups: "Stable" (no exacerbations for >12 months, n=18), "Exacerbation-prone" (≥1 exacerbation requiring systemic corticosteroids within the last 12 months, but stable for ≥1-month, n=9) and "Treated-exacerbation" (exacerbation requiring systemic corticosteroids within the last 1 month, n=12) were studied. All participants were current non-smokers with <10pack/years smoking history. Spirometry, static lung volumes, ventilation heterogeneity from multi-breath nitrogen washout (MBW) and respiratory system mechanics from oscillometry were measured. The Exacerbation-prone group compared to the Stable group had slightly worse spirometry (FEV1 Z-score -3.58(1.13) vs -2.32(1.06), p=0.03), however acinar ventilation heterogeneity (Sacin Z-score 7.43(8.59) vs 3.63(3.88), p=0.006) and respiratory system reactance (Xrs cmH2O.s.L-1 -2.74(3.82) vs -1.32(1.94), p=0.01) were much worse in this group. The Treated-exacerbation group had worse spirometry but similar small airway function, compared with the Stable group. Patients with asthma who exacerbate have worse small airway function as evidenced by increases in Sacin measured by MBW and delta Xrs from oscillometry, both markers of small airway dysfunction, compared with those that do not.
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Affiliation(s)
- Claire F O'Sullivan
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia.,Monash University, Melbourne, VIC, Australia
| | - Kris Nilsen
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia.,School of Health Science, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Brigitte M Borg
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia.,Monash University, Melbourne, VIC, Australia
| | - Matthew J Ellis
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia
| | - Pam Matsas
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia
| | - Frank Thien
- Monash University, Melbourne, VIC, Australia.,Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
| | - Jo A Douglass
- The Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, VIC, Australia
| | | | - Gregory G King
- Airway Physiology and Imaging Group, The Woolcock Institute, Sydney, NSW, Australia
| | - Gordon Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Bruce R Thompson
- Respiratory Medicine, The Alfred Hospital, Melbourne, VIC, Australia.,School of Health Science, University of Melbourne, Melbourne, VIC, Australia
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Minagawa S, Araya J, Watanabe N, Fujimoto S, Watanabe J, Hara H, Numata T, Kuwano K, Matsuwaki Y. Real-life effectiveness of dupilumab in patients with mild to moderate bronchial asthma comorbid with CRSwNP. BMC Pulm Med 2022; 22:258. [PMID: 35764984 PMCID: PMC9241284 DOI: 10.1186/s12890-022-02046-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/20/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dupilumab, an anti-IL-4α receptor antibody, is a new treatment for severe or refractory asthma. However, real-world evidence on the efficacy of dupilumab in patients with mild to moderate bronchial asthma is lacking. METHODS We retrospectively evaluated the effects of dupilumab in 62 patients who received dupilumab for eosinophilic sinusitis comorbid with asthma at a single centre in Japan. Type 2 inflammatory markers, ACT, respiratory function tests, and forced oscillation technique (FOT) were analysed before, three months after, and one year after dupilumab administration, mainly in patients with mild to moderate asthma. RESULTS FEV1, %FEV1, %FVC, treatment steps for asthma and ACT improved significantly after three months of dupilumab treatment. FeNO was markedly decreased, whereas IgE and eosinophil counts showed no significant changes. Pre- and post-treatment respiratory resistance (Rrs) and respiratory reactance (Xrs) correlated significantly with FEV1. Improvement in %FEV1 was associated with higher FeNO and higher serum IgE before dupilumab treatment. CONCLUSION Dupilumab treatment for sinusitis may improve respiratory functions, asthma symptoms, and asthma treatment reduction, even if the associated bronchial asthma is not severe.
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Affiliation(s)
- Shunsuke Minagawa
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan. .,Matsuwaki Clinic Shinagawa, 6-7-29 Kitashinagawa Shinagawa-ku, Tokyo, 140-0001, Japan.
| | - Jun Araya
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Naoaki Watanabe
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.,Matsuwaki Clinic Shinagawa, 6-7-29 Kitashinagawa Shinagawa-ku, Tokyo, 140-0001, Japan
| | - Shota Fujimoto
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.,Matsuwaki Clinic Shinagawa, 6-7-29 Kitashinagawa Shinagawa-ku, Tokyo, 140-0001, Japan
| | - Junko Watanabe
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.,Matsuwaki Clinic Shinagawa, 6-7-29 Kitashinagawa Shinagawa-ku, Tokyo, 140-0001, Japan
| | - Hiromichi Hara
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Takanori Numata
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Kazuyoshi Kuwano
- Division of Respiratory Diseases, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Yoshinori Matsuwaki
- Matsuwaki Clinic Shinagawa, 6-7-29 Kitashinagawa Shinagawa-ku, Tokyo, 140-0001, Japan
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Rutting S, Thamrin C, Cross TJ, King GG, Tonga KO. Fixed Airflow Obstruction in Asthma: A Problem of the Whole Lung Not of Just the Airways. Front Physiol 2022; 13:898208. [PMID: 35677089 PMCID: PMC9169051 DOI: 10.3389/fphys.2022.898208] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract Asthma with irreversible or fixed airflow obstruction (FAO) is a severe clinical phenotype that is difficult to treat and is associated with an accelerated decline in lung function and excess morbidity. There are no current treatments to reverse or prevent this excessive decline in lung function in these patients, due to a lack of understanding of the underlying pathophysiology. The current paradigm is that FAO in asthma is due to airway remodeling driven by chronic inflammation. However, emerging evidence indicates significant and critical structural and functional changes to the lung parenchyma and its lung elastic properties in asthma with FAO, suggesting that FAO is a ‘whole lung’ problem and not just of the airways. In this Perspective we draw upon what is known thus far on the pathophysiological mechanisms contributing to FAO in asthma, and focus on recent advances and future directions. We propose the view that structural and functional changes in parenchymal tissue, are just as (if not more) important than airway remodeling in causing persistent lung function decline in asthma. We believe this paradigm of FAO should be considered when developing novel treatments.
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Affiliation(s)
- Sandra Rutting
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
- The Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia
| | - Cindy Thamrin
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Troy J. Cross
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Gregory G. King
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
- The Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Katrina O. Tonga
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
- The Department of Thoracic and Transplant Medicine, St Vincent’s Hospital, Sydney, NSW, Australia
- St Vincent’s Healthcare Clinical Campus, School of Clinical Medicine, UNSW Medicine and Health, University of New South Wales Sydney, Sydney, NSW, Australia
- *Correspondence: Katrina O. Tonga,
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Oscillometry and Asthma Control in Patients With and Without Fixed Airflow Obstruction. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY. IN PRACTICE 2022; 10:1260-1267.e1. [PMID: 34979333 DOI: 10.1016/j.jaip.2021.12.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Asthma is defined by the presence of reversible airflow limitation, yet persistently abnormal spirometry may develop despite appropriate asthma treatment. Fixed airflow obstruction (FAO) describes abnormal postbronchodilator spirometry that is associated with greater symptom burden and disease severity. Respiratory oscillometry measures the mechanics of the entire airway tree, including peripheral airway changes that have been shown to influence asthma symptoms. OBJECTIVE To evaluate the relationship between abnormal oscillometry following bronchodilator and symptom control in adults with asthma. METHODS A prospective cohort of patients with asthma attending an airways clinic completed oscillometry (resistance and reactance), spirometry, and the Asthma Control Test. Postbronchodilator lung function below the lower limit of normal was considered abnormal. Spirometric FAO was defined as FEV1/forced vital capacity below the lower limit of normal. Spearman's rank coefficient and multiple linear regression were performed to assess associations of lung function parameters with Asthma Control Test. The discriminative ability of abnormal lung function to identify poor asthma control was determined using Cohen's kappa. RESULTS Ninety patients with asthma were included; 48% had spirometric FAO. Only reactance parameters, not spirometry, significantly related to (rs ≥ 0.315; P < .05) and identified asthma control (r2 = 0.236; P < .001). Lung function was more strongly associated with asthma control in patients with FAO compared with those without. Abnormal oscillometry identified an additional 24% of patients with poor asthma control as compared with spirometric FAO. CONCLUSIONS Reactance related to asthma control, independently of spirometric FAO. Abnormal postbronchodilator reactance identified more patients with poor asthma control compared with spirometry. These findings confirm that oscillometry is a relevant lung function test in the clinical assessment of asthma.
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10
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Denlinger LC, Phillips BR, Sorkness RL, Bleecker ER, Castro M, DeBoer MD, Fitzpatrick AM, Hastie AT, Gaffin JM, Moore WC, Peters MC, Peters SP, Phipatanakul W, Cardet JC, Erzurum SC, Fahy JV, Fajt ML, Gaston B, Levy BD, Meyers DA, Ross K, Teague WG, Wenzel SE, Woodruff PG, Zein J, Jarjour NN, Mauger DT, Israel E. Responsiveness to Parenteral Corticosteroids and Lung Function Trajectory in Adults with Moderate-to-Severe Asthma. Am J Respir Crit Care Med 2021; 203:841-852. [PMID: 33290668 DOI: 10.1164/rccm.202002-0454oc] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Rationale: It is unclear why select patients with moderate-to-severe asthma continue to lose lung function despite therapy. We hypothesized that participants with the smallest responses to parenteral corticosteroids have the greatest risk of undergoing a severe decline in lung function.Objectives: To evaluate corticosteroid-response phenotypes as longitudinal predictors of lung decline.Methods: Adults within the NHLBI SARP III (Severe Asthma Research Program III) who had undergone a course of intramuscular triamcinolone at baseline and at ≥2 annual follow-up visits were evaluated. Longitudinal slopes were calculated for each participant's post-bronchodilator FEV1% predicted. Categories of participant FEV1 slope were defined: severe decline, >2% loss/yr; mild decline, >0.5-2.0% loss/yr; no change, 0.5% loss/yr to <1% gain/yr; and improvement, ≥1% gain/yr. Regression models were used to develop predictors of severe decline.Measurements and Main Results: Of 396 participants, 78 had severe decline, 91 had mild decline, 114 had no change, and 113 showed improvement. The triamcinolone-induced difference in the post-bronchodilator FEV1% predicted (derived by baseline subtraction) was related to the 4-year change in lung function or slope category in univariable models (P < 0.001). For each 5% decrement in the triamcinolone-induced difference the FEV1% predicted, there was a 50% increase in the odds of being in the severe decline group (odds ratio, 1.5; 95% confidence interval, 1.3-1.8), when adjusted for baseline FEV1, exacerbation history, blood eosinophils and body mass index.Conclusions: Failure to improve the post-bronchodilator FEV1 after a challenge with parenteral corticosteroids is an evoked biomarker for patients at risk for a severe decline in lung function.
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Affiliation(s)
- Loren C Denlinger
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Brenda R Phillips
- Division of Biostatistics and Bioinformatics, Department of Public Health Sciences, Penn State College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania
| | - Ronald L Sorkness
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Eugene R Bleecker
- Division of Genetics, Genomics and Precision Medicine, Department of Medicine, College of Medicine, The University of Arizona, Tucson, Arizona
| | - Mario Castro
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, KU School of Medicine, The University of Kansas, Kansas City, Kansas
| | - Mark D DeBoer
- Divisions of Pediatric Diabetes and Endocrinology and Pediatric Respiratory Medicine, Allergy, Immunology and Sleep, Department of Pediatrics, School of Medicine, University of Virginia, Charlottesville, Virginia
| | - Anne M Fitzpatrick
- Division of Pulmonary, Allergy and Immunology, Cystic Fibrosis and Sleep, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia
| | - Annette T Hastie
- Section of Pulmonary, Critical Care, Allergy and Immunologic Disease, Department of Internal Medicine, School of Medicine, Wake Forest University, Winston-Salem, North Carolina
| | - Jonathan M Gaffin
- Divisions of Pulmonary Medicine and Allergy and Immunology, Department of Pediatrics, Boston Children's Hospital, and
| | - Wendy C Moore
- Section of Pulmonary, Critical Care, Allergy and Immunologic Disease, Department of Internal Medicine, School of Medicine, Wake Forest University, Winston-Salem, North Carolina
| | - Michael C Peters
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine, UCSF School of Medicine, University of California, San Francisco, San Francisco, California
| | - Stephen P Peters
- Section of Pulmonary, Critical Care, Allergy and Immunologic Disease, Department of Internal Medicine, School of Medicine, Wake Forest University, Winston-Salem, North Carolina
| | - Wanda Phipatanakul
- Divisions of Pulmonary Medicine and Allergy and Immunology, Department of Pediatrics, Boston Children's Hospital, and
| | - Juan Carlos Cardet
- Divisions of Pulmonary Medicine and Allergy and Immunology, Department of Pediatrics, Boston Children's Hospital, and
| | - Serpil C Erzurum
- Lerner Research Institute and the Respiratory Institute, The Cleveland Clinic, Cleveland, Ohio
| | - John V Fahy
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine, UCSF School of Medicine, University of California, San Francisco, San Francisco, California
| | - Merritt L Fajt
- Division of Pulmonary, Allergy and Critical Care, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Benjamin Gaston
- Division of Pediatric Pulmonary, Allergy and Sleep Medicine, Department of Pediatrics, School of Medicine, Indiana University, Indianapolis, Indiana; and
| | - Bruce D Levy
- Divisions of Pulmonary Medicine and Allergy and Immunology, Department of Pediatrics, Boston Children's Hospital, and
| | - Deborah A Meyers
- Section of Pulmonary, Critical Care, Allergy and Immunologic Disease, Department of Internal Medicine, School of Medicine, Wake Forest University, Winston-Salem, North Carolina
| | - Kristie Ross
- Division of Pediatric Pulmonology and Sleep Medicine, Department of Pediatrics, UH Rainbow Babies and Children's Hospital, Case Western Reserve University School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - W Gerald Teague
- Divisions of Pediatric Diabetes and Endocrinology and Pediatric Respiratory Medicine, Allergy, Immunology and Sleep, Department of Pediatrics, School of Medicine, University of Virginia, Charlottesville, Virginia
| | - Sally E Wenzel
- Division of Pulmonary, Allergy and Critical Care, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Prescott G Woodruff
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine, UCSF School of Medicine, University of California, San Francisco, San Francisco, California
| | - Joe Zein
- Lerner Research Institute and the Respiratory Institute, The Cleveland Clinic, Cleveland, Ohio
| | - Nizar N Jarjour
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - David T Mauger
- Division of Biostatistics and Bioinformatics, Department of Public Health Sciences, Penn State College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania
| | - Elliot Israel
- Divisions of Pulmonary and Critical Care and of Allergy and Immunology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard University, Boston, Massachusetts
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Cottee AM, Seccombe LM, Thamrin C, Badal T, King GG, Peters MJ, Farah CS. Longitudinal monitoring of asthma in the clinic using respiratory oscillometry. Respirology 2021; 26:566-573. [PMID: 33797141 DOI: 10.1111/resp.14053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 02/23/2021] [Indexed: 01/18/2023]
Abstract
BACKGROUND AND OBJECTIVE Asthma guidelines emphasize the importance of assessing lung function and symptoms. The forced oscillation technique (FOT) and its longitudinal relationship with spirometry and symptoms are unresolved. We examined concordance between longitudinal spirometry, FOT and symptom control, and determined FOT limits of agreement in stable asthma. METHODS Over a 3-year period, adults with asthma attending a tertiary clinic completed the asthma control test (ACT), fraction of exhaled nitric oxide (FeNO), FOT and spirometry. Analysis included between-visit concordance for significant change using Cohen's kappa (κ) and stable asthma FOT limits of agreement. RESULTS Data (n = 186) from 855 visits (mean ± SD 4.6 ± 3.0 visits), 114 ± 95 days apart, were analysed. Between-visit concordance was moderate between reactance at 5 Hz (X5) and forced expiratory volume in 1 s (FEV1 ) (κ = 0.34, p = 0.001), and weak between ACT and FEV1 (κ = 0.18, p = 0.001). Change in FeNO did not correlate with lung function or ACT (κ < 0.05, p > 0.1). Stable asthma between visits (n = 75; 132 visits) had reduced lung function variability, but comparable concordance to the entire cohort. Limits of agreement for FEV1 (0.42 L), resistance at 5 Hz (2.06 cm H2 O s L-1 ) and X5 (2.75 cm H2 O s L-1 ) in stable asthma were at least twofold greater than published values in health. CONCLUSION In adults with asthma, there is moderate concordance between longitudinal change in FOT and spirometry. Both tests relate poorly to changes in asthma control, highlighting the need for multi-modal assessment in asthma rather than symptoms alone. The derivation of longitudinal FOT limits of agreement will assist in its clinical interpretation.
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Affiliation(s)
- Alice M Cottee
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia.,Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Leigh M Seccombe
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Cindy Thamrin
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia
| | - Tanya Badal
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia.,Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Gregory G King
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Matthew J Peters
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, New South Wales, Australia
| | - Claude S Farah
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia.,Airway Physiology and Imaging Group and Woolcock Emphysema Centre, Woolcock Institute of Medical Research, Glebe, New South Wales, Australia.,Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, New South Wales, Australia
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12
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Veneroni C, Van Muylem A, Malinovschi A, Michils A, Dellaca' RL. Closing volume detection by single-breath gas washout and forced oscillation technique. J Appl Physiol (1985) 2021; 130:903-913. [PMID: 33475458 DOI: 10.1152/japplphysiol.00440.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Closing volume (CV) is commonly measured by single-breath nitrogen washout (CVSBW). A method based on the forced oscillation technique was recently introduced to detect a surrogate CV (CVFOT). As the two approaches are based on different physiological mechanisms, we aim to investigate CVFOT and CVSBW relationship at different degrees and patterns of airway obstruction. A mathematical model was developed to evaluate the CVSBW and CVFOT sensitivity to different patterns of airway obstruction, either located in a specific lung region or equally distributed throughout the lung. The two CVs were also assessed during slow vital capacity (VC) maneuvers in triplicate in 13 healthy subjects and pre- and postmethacholine challenge (Mch) in 12 subjects with mild-moderate asthma. Model simulations suggest that CVSBW is more sensitive than CVFOT to the presence of few flow-limited or closed airways that modify the contribution of tracer-poor and tracer-rich lung regions to the overall exhaled gas. Conversely, CVFOT occurs only when at least ∼65% of lung units are flow limited or closed, regardless of their regional distribution. CVSBW did not differ between healthy subjects and those with asthma (17 ± 9% VC vs. 22 ± 10% VC), whereas CVFOT did (16 ± 5% VC vs. 23 ± 6% VC, P < 0.01). In patients with asthma, both CVSBW and CVFOT increased post-Mch (33 ± 7% VC P < 0.001 and 43 ± 12% VC P < 0.001, respectively). CVSBW weakly correlated with CVFOT (r = 0.45, P < 0.01). The closing capacities (CV + residual volume) were correlated (r = 0.74, P < 0.001), but the changes with Mch in both CVs and closing capacities did not correlate. CVFOT is easy to measure and provides a reproducible parameter useful for describing airway impairment in obstructive respiratory diseases.NEW & NOTEWORTHY The forced oscillation technique can identify a surrogate of closing volume (CVFOT). We investigated its relationship with the one measured by single-breath washout (CVSBW). CVFOT weakly correlates with CVSBW. The respective closing capacities were correlated, but their increases after methacholine challenge in asthmatics did not. Our results suggest that CVFOT is less sensitive than CVSBW to few flow-limited/closed airways but more specific in detecting increases in flow-limited/closed airways involving the majority of the lung.
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Affiliation(s)
- Chiara Veneroni
- TechRes Lab, Department of Electronics, Information and Biomedical Engineering, Politecnico di Milano University, Milan, Italy
| | - Alain Van Muylem
- Chest Department, Erasme University Hospital/Université Libre de Bruxelles, Brussels, Belgium
| | - Andrei Malinovschi
- Department of Medical Sciences, Clinical Physiology, Uppsala University, Uppsala, Sweden
| | - Alain Michils
- Chest Department, Erasme University Hospital/Université Libre de Bruxelles, Brussels, Belgium
| | - Raffaele L Dellaca'
- TechRes Lab, Department of Electronics, Information and Biomedical Engineering, Politecnico di Milano University, Milan, Italy
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13
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Bates JHT, Peters U, Daphtary N, MacLean ES, Hodgdon K, Kaminsky DA, Bhatawadekar S, Dixon AE. Altered airway mechanics in the context of obesity and asthma. J Appl Physiol (1985) 2021; 130:36-47. [PMID: 33119471 PMCID: PMC7944930 DOI: 10.1152/japplphysiol.00666.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 12/29/2022] Open
Abstract
The obesity epidemic is causing a rise in asthma incidence due to the appearance of an obesity-specific late-onset nonallergic (LONA) phenotype. We investigated why only a subset of obese participants develop LONA asthma by determining how obesity, both alone and in combination with LONA asthma, affects the volume dependence of respiratory system impedance. We also determined how obesity and asthma affect impedance during and following challenge with the PC20 dose of methacholine. We found during passive exhalation that all obese participants, in contrast to lean controls and lean asthmatics, experienced similarly profound elevations in lung elastance as they approached functional residual capacity. We also found, however, that the LONA asthmatics had a greater negative dependence of airway resistance on lung volume over the middle of the volume range compared with the other groups. Methacholine challenge with the PC20 dose led to comparable changes in respiratory system impedance in the four study groups, but the doses themselves were substantially lower in both obese and lean asthmatic participants compared with obese and lean controls. Also, the obese LONA asthmatics had higher breathing frequencies and lower tidal volumes postchallenge compared with the other participants. Taken together, these results suggest that all obese individuals experience substantial lung collapse as they approach functional residual capacity, presumably due to the weight of the chest wall. It remains unclear why obese LONA asthmatics are hyperresponsive to methacholine while obese nonasthmatic individuals are not.NEW & NOTEWORTHY Why only a subset of severely obese subjects develop late-onset nonallergic (LONA) asthma remains unknown, although it is widely assumed that compression of the lungs by the chest wall is somehow involved. We show that lung compression is common to obese individuals both without asthma and with LONA asthma but that those with LONA asthma may have increased airway wall compliance and possibly also a reduced ability to recruit collapsed lung.
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Affiliation(s)
- Jason H T Bates
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Ubong Peters
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Nirav Daphtary
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Erick S MacLean
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Kevin Hodgdon
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - David A Kaminsky
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Swati Bhatawadekar
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Anne E Dixon
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont
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14
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Abstract
This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.
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Affiliation(s)
- David A Kaminsky
- University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - David G Chapman
- University of Technology Sydney, Sydney, New South Wales, Australia
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15
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Chapman DG, King GG, Robinson PD, Farah CS, Thamrin C. The need for physiological phenotyping to develop new drugs for airways disease. Pharmacol Res 2020; 159:105029. [PMID: 32565310 DOI: 10.1016/j.phrs.2020.105029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/01/2020] [Accepted: 06/12/2020] [Indexed: 11/25/2022]
Abstract
Asthma and COPD make up the majority of obstructive airways diseases (OADs), which affects ∼11 % of the population. The main drugs used to treat OADs have not changed in the past five decades, with advancements mainly comprising variations on existing treatments. The recent biologics are beneficial to only specific subsets of patients. Part of this may lie in our inability to adequately characterise the tremendous heterogeneity in every aspect of OAD. The field is currently moving towards the concept of personalised medicine, based on a focus on treatable traits that are objective, measurable and modifiable. We propose extending this concept via the use of emerging clinical tools for comprehensive physiological phenotyping. We describe, based on published data, the evidence for the use of functional imaging, gas washout techniques and oscillometry, as well as potential future applications, to more comprehensively assess and predict treatment response in OADs. In this way, we hope to demonstrate how physiological phenotyping tools will improve the way in which drugs are prescribed, but most importantly, will facilitate development of new drugs for OADs.
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Affiliation(s)
- David G Chapman
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, The Woolcock Institute of Medical Research, The University of Sydney, Glebe NSW 2037, Australia; School of Life Sciences, Faculty of Science, University of Technology Sydney, Ultimo NSW 2007, Australia.
| | - G G King
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, The Woolcock Institute of Medical Research, The University of Sydney, Glebe NSW 2037, Australia; Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia; NHMRC Centre of Excellence in Severe Asthma, New Lambton Heights NSW 2305, Australia; Faculty of Medicine and Health Sciences, The University of Sydney, NSW 2006, Australia
| | - Paul D Robinson
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, The Woolcock Institute of Medical Research, The University of Sydney, Glebe NSW 2037, Australia; Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Faculty of Medicine and Health Sciences, The University of Sydney, NSW 2006, Australia
| | - Claude S Farah
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, The Woolcock Institute of Medical Research, The University of Sydney, Glebe NSW 2037, Australia; Faculty of Medicine and Health Sciences, The University of Sydney, NSW 2006, Australia; Department of Thoracic Medicine, Concord Repatriation General Hospital, Concord, NSW 2137, Australia
| | - Cindy Thamrin
- Airway Physiology and Imaging Group and Woolcock Emphysema Centre, The Woolcock Institute of Medical Research, The University of Sydney, Glebe NSW 2037, Australia; Faculty of Medicine and Health Sciences, The University of Sydney, NSW 2006, Australia
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16
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Cottee AM, Seccombe LM, Thamrin C, King GG, Peters MJ, Farah CS. Bronchodilator Response Assessed by the Forced Oscillation Technique Identifies Poor Asthma Control With Greater Sensitivity Than Spirometry. Chest 2020; 157:1435-1441. [PMID: 31982392 DOI: 10.1016/j.chest.2019.12.035] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 12/06/2019] [Accepted: 12/16/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Persistent bronchodilator response (BDR) following diagnosis of asthma is an underrecognized treatable trait, associated with worse lung function and asthma control. The forced oscillation technique (FOT) measures respiratory system impedance, and BDR cutoffs have been proposed for healthy adults; however, the relevance in asthma is unknown. We compared BDR cutoffs, using FOT and spirometry, in asthma and the relationship with asthma control. METHODS Data from patients with asthma who withheld bronchodilator medication for at least 8 h before a tertiary airway clinic visit were reviewed. All subjects performed FOT and spirometry before and after salbutamol administration, and completed the Asthma Control Test. FOT parameters examined included respiratory system resistance (R5) and reactance (X5) at 5 Hz, and area under the reactance curve (AX). BDR was defined by standard recommendations for spirometry and based on the 95th percentile of BDR in healthy adults for FOT. RESULTS Fifty-two subjects (18 men; mean age, 53 ± 18 years) were included. BDR was identified more frequently by FOT than spirometry (54% vs 27% of subjects). BDR assessed by X5 and AX, but not R5, was associated with spirometric BDR (χ2, P < .01) and correlated with asthma control (X5: rs = -0.36, P < .01; AX: rs = 0.34, P = .01). BDR measured by reactance parameters identified more subjects with poor asthma control than did spirometry (AX, 69% vs spirometry, 41%). CONCLUSIONS BDR assessed by FOT can identify poor asthma control. Reactance parameters were more sensitive in identifying poor asthma control than spirometry, supporting the use of FOT to complement spirometry in the clinical management of asthma.
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Affiliation(s)
- Alice M Cottee
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia; Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, Glebe, NSW, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.
| | - Leigh M Seccombe
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Cindy Thamrin
- Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, Glebe, NSW, Australia
| | - Gregory G King
- Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, Glebe, NSW, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Department of Respiratory Medicine, Royal North Shore Hospital, NSW, Australia
| | - Matthew J Peters
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Claude S Farah
- Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia; Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, Glebe, NSW, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
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17
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Rutting S, Mahadev S, Tonga KO, Bailey DL, Dame Carroll JR, Farrow CE, Thamrin C, Chapman DG, King GG. Obesity alters the topographical distribution of ventilation and the regional response to bronchoconstriction. J Appl Physiol (1985) 2020; 128:168-177. [DOI: 10.1152/japplphysiol.00482.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Obesity is associated with reduced operating lung volumes that may contribute to increased airway closure during tidal breathing and abnormalities in ventilation distribution. We investigated the effect of obesity on the topographical distribution of ventilation before and after methacholine-induced bronchoconstriction using single-photon emission computed tomography (SPECT)-computed tomography (CT) in healthy subjects. Subjects with obesity ( n = 9) and subjects without obesity ( n = 10) underwent baseline and postbronchoprovocation SPECT-CT imaging, in which Technegas was inhaled upright and followed by supine scanning. Lung regions that were nonventilated (Ventnon), low ventilated (Ventlow), or well ventilated (Ventwell) were calculated using an adaptive threshold method and were expressed as a percentage of total lung volume. To determine regional ventilation, lungs were divided into upper, middle, and lower thirds of axial length, derived from CT. At baseline, Ventnon and Ventlow for the entire lung were similar in subjects with and without obesity. However, in the upper lung zone, Ventnon (17.5 ± 10.6% vs. 34.7 ± 7.8%, P < 0.001) and Ventlow (25.7 ± 6.3% vs. 33.6 ± 5.1%, P < 0.05) were decreased in subjects with obesity, with a consequent increase in Ventwell (56.8 ± 9.2% vs. 31.7 ± 10.1%, P < 0.001). The greater diversion of ventilation to the upper zone was correlated with body mass index ( rs = 0.74, P < 0.001), respiratory system resistance ( rs = 0.72, P < 0.001), and respiratory system reactance ( rs = −0.64, P = 0.003) but not with lung volumes or basal airway closure. Following bronchoprovocation, overall Ventnon increased similarly in both groups; however, in subjects without obesity, Ventnon only increased in the lower zone, whereas in subjects with obesity, Ventnon increased more evenly across all lung zones. In conclusion, obesity is associated with altered ventilation distribution during baseline and following bronchoprovocation, independent of reduced lung volumes. NEW & NOTEWORTHY Using ventilation SPECT-computed tomography imaging in healthy subjects, we demonstrate that ventilation in obesity is diverted to the upper lung zone and that this is strongly correlated with body mass index but is independent of operating lung volumes and of airway closure. Furthermore, methacholine-induced bronchoconstriction only occurred in the lower lung zone in individuals who were not obese, whereas in subjects who were obese, it occurred more evenly across all lung zones. These findings show that obesity-associated factors alter the topographical distribution of ventilation.
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Affiliation(s)
- S. Rutting
- Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
| | - S. Mahadev
- Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
| | - K. O. Tonga
- Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
- Department of Thoracic and Transplant Medicine, St. Vincent's Hospital, Darlinghurst, NSW, Australia
- Faculty of Medicine & Health, University of Sydney, NSW, Australia
| | - D. L. Bailey
- Faculty of Medicine & Health, University of Sydney, NSW, Australia
- Department of Nuclear Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia
| | - J. R. Dame Carroll
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
| | - C. E. Farrow
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
- Faculty of Medicine & Health, University of Sydney, NSW, Australia
- Department of Respiratory Medicine, Westmead Hospital, Westmead, NSW, Australia
| | - C. Thamrin
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
| | - D. G. Chapman
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
- School of Life Sciences, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - G. G. King
- Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia
- Airway Physiology and Imaging Group, The Woolcock Institute of Medical Research, The University of Sydney, NSW, Australia
- NHMRC Centre of Excellence in Severe Asthma, New Lambton Heights, NSW, Australia
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18
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Physiological and morphological differences of airways between COPD and asthma-COPD overlap. Sci Rep 2019; 9:7818. [PMID: 31127165 PMCID: PMC6534606 DOI: 10.1038/s41598-019-44345-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 05/14/2019] [Indexed: 01/12/2023] Open
Abstract
Overlap of asthma and COPD has attracted attention recently. We aimed to clarify physiological and morphological differences of the airways between COPD and asthma–COPD overlap (ACO). Respiratory resistance and reactance and three-dimensional computed tomography data were evaluated in 167 patients with COPD. Among them, 43 patients who fulfilled the diagnosis of asthma were defined as having ACO. Among 124 patients with COPD without ACO, 86 with a comparable smoking history and airflow limitation as those with ACO were selected using propensity score matching (matched COPD). The intraluminal area (Ai) and wall thickness (WT) of third- to sixth-generation bronchi were measured and adjusted by body surface area (BSA; Ai/BSA and WT/√BSA, respectively). Patients with ACO had higher respiratory resistance and reactance during tidal breathing, but a smaller gap between the inspiratory and expiratory phases, compared with matched patients with COPD. Patients with ACO had a greater WT/√BSA in third- to fourth-generation bronchi, smaller Ai/BSA in fifth- to sixth-generation bronchi, and less emphysematous changes than did matched patients with COPD. Even when patients with ACO and those with COPD have a comparable smoking history and fixed airflow limitation, they have different physiological and morphological features of the airways.
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Faria ACD, Carvalho ARS, Guimarães ARM, Lopes AJ, Melo PL. Association of respiratory integer and fractional-order models with structural abnormalities in silicosis. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2019; 172:53-63. [PMID: 30902127 DOI: 10.1016/j.cmpb.2019.02.003] [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: 11/05/2018] [Revised: 01/23/2019] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND AND OBJECTIVE Integer and fractional-order models have emerged as powerful methods for obtaining information regarding the anatomical or pathophysiological changes that occur during respiratory diseases. However, the precise interpretation of the model parameters in light of the lung structural changes is not known. This study analyzed the associations of the integer and fractional-order models with structural changes obtained using multidetector computed tomography densitometry (MDCT) and pulmonary function analysis. METHODS Integer and fractional-order models were adjusted to data obtained using the forced oscillation technique (FOT). The results obtained in controls (n = 20) were compared with those obtained in patients with silicosis (n = 32), who were submitted to spirometry, body plethysmograph, FOT, diffusing capacity of the lungs for carbon monoxide (DLCO), and MDCT. The diagnostic accuracy was also investigated using ROC analysis. RESULTS The observed changes in the integer and fractional-order models were consistent with the pathophysiology of silicosis. The integer-order model showed association only between inertance and the non-aerated compartment (R = -0.69). This parameter also presented the highest associations with spirometry (R = 0.81), plethysmography (-0.61) and pulmonary diffusion (R = 0.53). Considering the fractional-order model, the increase in the poorly aerated and non-aerated regions presented direct correlations with the fractional inertance (R = 0.48), respiratory damping (R = 0.37) and hysteresivity (R = 0.54) and inverse associations with its fractional exponent (R = -0.62) and elastance (-0.35). Significant associations were also observed with spirometry (R = 0.63), plethysmography (0.37) and pulmonary diffusion (R = 0.51). Receiver operator characteristic analysis showed a higher accuracy in the FrOr model (0.908) than the eRIC model (0.789). CONCLUSIONS Our study has shown clear associations of the integer and fractional-order parameters with anatomical changes obtained via MDCT and pulmonary function measurements. These findings help to elucidate the physiological interpretation of the integer and fractional-order parameters and provide evidence that these parameters are reflective of the abnormal changes in silicosis. We also observed that the fractional-order model showed smaller curve-fitting errors, which resulted in a higher diagnostic accuracy than that of the eRIC model. Taken together, these results provide strong motivation for further studies exploring the clinical and scientific use of these models in respiratory medicine.
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Affiliation(s)
- Alvaro C D Faria
- Biomedical Instrumentation Laboratory, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil; Laboratory of Clinical and Experimental Research in Vascular Biology (BioVasc), State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alysson Roncally Silva Carvalho
- Laboratory of Respiration Physiology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Laboratory of Pulmonary Engineering, Biomedical Engineering Program, Alberto Luis Coimbra Institute of Postgraduation and Research in Engineering, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alan Ranieri Medeiros Guimarães
- Laboratory of Respiration Physiology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Laboratory of Pulmonary Engineering, Biomedical Engineering Program, Alberto Luis Coimbra Institute of Postgraduation and Research in Engineering, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnaldo J Lopes
- Pulmonary Function Laboratory, Pedro Ernesto University Hospital, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro L Melo
- Biomedical Instrumentation Laboratory, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil; Laboratory of Clinical and Experimental Research in Vascular Biology (BioVasc), State University of Rio de Janeiro, Rio de Janeiro, Brazil.
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20
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Zimmermann SC, Tonga KO, Thamrin C. Dismantling airway disease with the use of new pulmonary function indices. Eur Respir Rev 2019; 28:28/151/180122. [PMID: 30918023 PMCID: PMC9488242 DOI: 10.1183/16000617.0122-2018] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 02/15/2019] [Indexed: 11/27/2022] Open
Abstract
We are currently limited in our abilities to diagnose, monitor disease status and manage chronic airway disease like asthma and chronic obstructive pulmonary disease (COPD). Conventional lung function measures often poorly reflect patient symptoms or are insensitive to changes, particularly in the small airways where disease may originate or manifest. Novel pulmonary function tests are becoming available which help us better characterise and understand chronic airway disease, and their translation and adoption from the research arena would potentially enable individualised patient care. In this article, we aim to describe two emerging lung function tests yielding novel pulmonary function indices, the forced oscillation technique (FOT) and multiple breath nitrogen washout (MBNW). With a particular focus on asthma and COPD, this article demonstrates how chronic airway disease mechanisms have been dismantled with the use of the FOT and MBNW. We describe their ability to assess detailed pulmonary mechanics for diagnostic and management purposes including response to bronchodilation and other treatments, relationship with symptoms, evaluation of acute exacerbations and recovery, and telemonitoring. The current limitations of both tests, as well as open questions/directions for further research, are also discussed. Spirometry is used to diagnose and manage airway disease such as asthma and COPD, but relates poorly to symptoms, lacks sensitivity and is effort dependent. FOT and MBNW are emerging clinical lung function tests that help us dismantle disease mechanisms.http://ow.ly/nM0G30nS6Ct
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Affiliation(s)
- Sabine C Zimmermann
- Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, Sydney, Australia.,Sydney Medical School Northern, The University of Sydney, Sydney, Australia.,Woolcock Emphysema Centre, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
| | - Katrina O Tonga
- Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, Sydney, Australia.,Sydney Medical School Northern, The University of Sydney, Sydney, Australia.,Woolcock Emphysema Centre, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia.,Dept of Thoracic and Transplant Medicine, St Vincent's Hospital, Sydney, Australia.,Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Cindy Thamrin
- Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia .,Woolcock Emphysema Centre, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia
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21
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Sorkness RL, Kienert C, O'Brien MJ, Fain SB, Jarjour NN. Compressive air trapping in asthma: effects of age, sex, and severity. J Appl Physiol (1985) 2019; 126:1265-1271. [PMID: 30844338 DOI: 10.1152/japplphysiol.00924.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Air trapping due to airway closure has been associated with unstable asthma. In addition to airway closure that occurs at lower lung volumes during slow expiration, there may be further closure during a forced expiration because of airway compression. The purpose of this study was to define a reference range from a nonasthmatic population and investigate the characteristics of compressive air trapping in asthma. Spirometry and plethysmography were performed in 117 nonasthmatic subjects (ages 18-87 yr) and 153 asthma subjects (ages 12-72 yr). Air trapping was assessed as residual lung volume and the ratio of forced expiratory vital capacity (FVC) to slow inspiratory vital capacity (iVC) (FVC/iVC). There were no significant age or sex effects on the FVC/iVC ratio in the nonasthmatic subjects, and a fifth percentile lower limit of normal (LLN) of 0.93 was computed. An FVC/iVC ratio less than LLN defined compressive air trapping. Asthma subjects exhibited an age-related decline in the FVC/iVC ratio of 0.0027 per year (P < 0.0001) in a mixed effects model, with additional decreases associated with severe asthma and male sex. FVC/iVC ratios< LLN were infrequent in subjects <30 yr but evident in most asthma subjects >50 yr. Lung residual volumes followed similar patterns of greater elevations in subjects with severe asthma, older age, and male sex. Compressive air trapping occurs frequently in older asthmatics, appearing to be a feature of the natural history of asthma that is greater in severe asthma and men. This component of premature airway closure affects spirometric assessment of airway function and may contribute to asthma symptoms during physical exertion. NEW & NOTEWORTHY Premature airway closure during exhalation is a component of airway obstruction that is associated with asthma severity and instability. Compressive air trapping is airway closure that is more extensive during a forced exhalation than with a slow, passive exhalation. We report that compressive air trapping occurs in most people > 50 yr with asthma, affects men more than women, and persists after bronchodilator treatment. This component of obstruction appears to be part of the natural history of asthma.
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Affiliation(s)
- Ronald L Sorkness
- School of Pharmacy; School of Medicine and Public Health, University of Wisconsin , Madison, Wisconsin.,Department of Medicine, University of Wisconsin , Madison, Wisconsin
| | - Casey Kienert
- School of Pharmacy; School of Medicine and Public Health, University of Wisconsin , Madison, Wisconsin
| | - Matthew J O'Brien
- Pulmonary Function Lab, University Hospitals and Clinics, University of Wisconsin , Madison, Wisconsin
| | - Sean B Fain
- Department of Medical Physics, University of Wisconsin , Madison, Wisconsin
| | - Nizar N Jarjour
- Department of Medicine, University of Wisconsin , Madison, Wisconsin
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22
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Kaminsky DA, Chapman DG, Holbrook JT, Henderson RJ, Sugar EA, Mastronarde J, Teague WG, Busk M, Sumino K, Dixon AE, Wise RA, Irvin CG. Older age and obesity are associated with increased airway closure in response to methacholine in patients with asthma. Respirology 2019; 24:638-645. [PMID: 30838750 DOI: 10.1111/resp.13496] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 11/29/2018] [Accepted: 01/02/2019] [Indexed: 01/31/2023]
Abstract
BACKGROUND AND OBJECTIVE The reduction of forced expiratory volume in 1 s (FEV1 ) in response to methacholine challenge in asthma may reflect two components: airway narrowing, assessed by the change in FEV1 /forced vital capacity (FVC), and airway closure, assessed by the change in FVC. The purpose of this study was to determine the degree and determinants of airway closure in response to methacholine in a large group of asthmatic patients participating in studies conducted by the American Lung Association-Airways Clinical Research Centers (ALA-ACRC). METHODS We used the methacholine challenge data from participants in five studies of the ALA-ACRC to determine the closing index, defined as the contribution of airway closure to the decrease in FEV1 , and calculated as %ΔFVC/%ΔFEV1 . RESULTS There were a total of 936 participants with asthma, among whom the median closing index was 0.67 relative to that of a published healthy population of 0.54. A higher closing index was associated with increased age (10-year increments) (0.04, 95% CI = 0.02, 0.05, P < 0.005) and obesity (0.07, 95% CI = 0.03, 0.10, P < 0.001). There was no association between the closing index and asthma control. CONCLUSION Our findings confirm that airway closure in response to methacholine occurs in a large, diverse population of asthmatic participants, and that increased airway closure is associated with older age and obesity. These findings suggest that therapies targeting airway closure may be important in patients with a high closing index.
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Affiliation(s)
- David A Kaminsky
- Pulmonary and Critical Care, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - David G Chapman
- Pulmonary and Critical Care, University of Vermont Larner College of Medicine, Burlington, VT, USA.,Translational Airways Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia.,Airway Physiology and Imaging Group, Woolcock Institute of Medical Research, Sydney, NSW, Australia
| | - Janet T Holbrook
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Robert J Henderson
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Elizabeth A Sugar
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - John Mastronarde
- Division of Pulmonary Medicine, Providence Portland Medical Center, Portland, OR, USA
| | - William G Teague
- Division of Pediatric Respiratory Medicine and Allergy, University of Virginia, Charlottesville, VA, USA
| | - Michael Busk
- Division of Pulmonary Medicine, St. Vincent Hospital and Health Care Center, Inc., Indianapolis, IN, USA
| | - Kaharu Sumino
- Division of Pulmonary and Critical Care Medicine, Washington University, St. Louis, MO, USA
| | - Anne E Dixon
- Pulmonary and Critical Care, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Robert A Wise
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Charles G Irvin
- Pulmonary and Critical Care, University of Vermont Larner College of Medicine, Burlington, VT, USA
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23
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Nilsen K, Thien F, Thamrin C, Ellis MJ, Prisk GK, King GG, Thompson BR. Early onset of airway derecruitment assessed using the forced oscillation technique in subjects with asthma. J Appl Physiol (1985) 2019; 126:1399-1408. [PMID: 30702975 DOI: 10.1152/japplphysiol.00534.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Derecruitment of air spaces in the lung occurs when airways close during exhalation and is related to ventilation heterogeneity and symptoms in asthma. The forced oscillation technique has been used to identify surrogate measures of airway closure via the reactance (Xrs) versus lung volume relationship. This study used a new algorithm to identify derecruitment from the Xrs versus lung volume relationship from a slow vital capacity maneuver. We aimed to compare two derecruitment markers on the Xrs versus volume curve, the onset reduction of Xrs (DR1vol) and the onset of more rapid reduction of Xrs (DR2vol), between control and asthmatic subjects. We hypothesized that the onset of DR1vol and DR2vol occurred at higher lung volume in asthmatic subjects. DR1vol and DR2vol were measured in 18 subjects with asthma and 18 healthy controls, and their relationships with age and height were examined using linear regression. In the control group, DR1vol and DR2vol increased with age (r2 = 0.68, P < 0.001 and r2 = 0.71, P < 0.001, respectively). DR1vol and DR2vol in subjects with asthma [76.58% of total lung capacity (TLC) and 56.79%TLC, respectively] were at higher lung volume compared with control subjects (46.1 and 37.69%TLC, respectively) (P < 0.001). DR2vol correlated with predicted values of closing capacity (r = 0.94, P < 0.001). This study demonstrates that derecruitment occurs at two points along the Xrs-volume relationship. Both derecruitment points occurred at significantly higher lung volumes in subjects with asthma compared with healthy control subjects. This technique offers a novel way to measure the effects of changes in airways/lung mechanics. NEW & NOTEWORTHY This study demonstrates that the forced oscillation technique can be used to identify two lung volume points where lung derecruitment occurs: 1) where derecruitment is initiated and 2) where onset of rapid derecruitment commences. Measurements of derecruitment increase with age. The onset of rapid derecruitment was highly correlated with predicted closing capacity. Also, the initiation and rate of derecruitment are significantly altered in subjects with asthma.
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Affiliation(s)
- Kris Nilsen
- Central Clinical School, Monash University , Melbourne, Victoria , Australia.,Allergy Immunology and Respiratory Medicine, The Alfred Hospital , Melbourne, Victoria , Australia
| | - Francis Thien
- Eastern Health Clinical School, Monash University , Melbourne, Victoria , Australia.,Box Hill Hospital , Melbourne, Victoria , Australia
| | - Cindy Thamrin
- Woolcock Institute of Medical Research, University of Sydney , Sydney, New South Wales , Australia.,Department of Respiratory Medicine, Royal North Shore Hospital , St. Leonards, New South Wales , Australia
| | - Matt J Ellis
- Allergy Immunology and Respiratory Medicine, The Alfred Hospital , Melbourne, Victoria , Australia
| | - G Kim Prisk
- Department of Medicine, Division of Physiology, University of California , San Diego, California
| | - Gregory G King
- Woolcock Institute of Medical Research, University of Sydney , Sydney, New South Wales , Australia.,Department of Respiratory Medicine, Royal North Shore Hospital , St. Leonards, New South Wales , Australia
| | - Bruce R Thompson
- Central Clinical School, Monash University , Melbourne, Victoria , Australia.,Allergy Immunology and Respiratory Medicine, The Alfred Hospital , Melbourne, Victoria , Australia
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24
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Sorkness RL, Zoratti EM, Kattan M, Gergen PJ, Evans MD, Visness CM, Gill M, Khurana Hershey GK, Kercsmar CM, Liu AH, O'Connor GT, Pongracic JA, Pillai D, Sorkness CA, Togias A, Wood RA, Busse WW. Obstruction phenotype as a predictor of asthma severity and instability in children. J Allergy Clin Immunol 2018; 142:1090-1099.e4. [PMID: 29146272 PMCID: PMC5951738 DOI: 10.1016/j.jaci.2017.09.047] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/12/2017] [Accepted: 09/21/2017] [Indexed: 01/25/2023]
Abstract
BACKGROUND Small-airways instability resulting in premature airway closure has been recognized as a risk for asthma severity and poor control. Although spirometry has limited sensitivity for detecting small-airways dysfunction, a focus on the air-trapping component of obstruction might identify a risk factor for asthma instability. OBJECTIVE We sought to use spirometric measurements to identify patterns of airway obstruction in children and define obstruction phenotypes that relate to asthma instability. METHODS Prebronchodilation and postbronchodilation spirometric data were obtained from 560 children in the Asthma Phenotypes in the Inner City study. An air-trapping obstruction phenotype (A Trpg) was defined as a forced vital capacity (FVC) z score of less than -1.64 or an increase in FVC of 10% of predicted value or greater with bronchodilation. The airflow limitation phenotype (A Limit) had an FEV1/FVC z score of less than -1.64 but not A Trpg. The no airflow limitation or air-trapping criteria (None) phenotype had neither A Trpg nor A Limit. The 3 obstruction phenotypes were assessed as predictors of number of exacerbations, asthma severity, and airway lability. RESULTS Patients with the A Trpg phenotype (14% of the cohort) had more exacerbations during the 12-month study compared with those with the A Limit (P < .03) and None (P < .001) phenotypes. Patients with the A Trpg phenotype also had the highest Composite Asthma Severity Index score, the highest asthma treatment step, the greatest variability in FEV1 over time, and the greatest sensitivity to methacholine challenge. CONCLUSIONS A Trpg and A Limit patterns of obstruction, as defined by using routine spirometric measurements, can identify obstruction phenotypes that are indicators of risk for asthma severity and instability.
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Affiliation(s)
- Ronald L Sorkness
- University of Wisconsin-Madison School of Pharmacy, Madison, Wis; Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wis; Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wis.
| | - Edward M Zoratti
- Henry Ford Health Systems and Wayne State University School of Medicine, Detroit, Mich
| | - Meyer Kattan
- College of Physicians and Surgeons, Columbia University, New York, NY
| | - Peter J Gergen
- National Institute of Allergy and Infectious Diseases, Bethesda, Md
| | - Michael D Evans
- Department of Biostatistics & Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, Wis
| | | | - Michelle Gill
- University of Texas Southwestern Medical Center, Dallas, Tex
| | | | | | - Andrew H Liu
- Children's Hospital Colorado and University of Colorado School of Medicine, Aurora, Colo
| | | | | | - Dinesh Pillai
- Children's National Health System and the George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Christine A Sorkness
- University of Wisconsin-Madison School of Pharmacy, Madison, Wis; Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wis
| | - Alkis Togias
- National Institute of Allergy and Infectious Diseases, Bethesda, Md
| | | | - William W Busse
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wis
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25
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Comparison of two methods of determining lung de-recruitment, using the forced oscillation technique. Eur J Appl Physiol 2018; 118:2213-2224. [PMID: 30062516 DOI: 10.1007/s00421-018-3949-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 07/21/2018] [Indexed: 10/28/2022]
Abstract
Airway closure has proved to be important in a number of respiratory diseases and may be the primary functional defect in asthma. A surrogate measure of closing volume can be identified using the forced oscillation technique (FOT), by performing a deflation maneuver and examining the resultant reactance (Xrs) lung volume relationship. This study aims to determine if a slow vital capacity maneuver can be used instead of this deflation maneuver and compare it to existing more complex techniques. Three subject groups were included in the study; healthy (n = 29), asthmatic (n = 18), and COPD (n = 10) for a total of 57 subjects. Reactance lung volume curves were generated via FOT recordings during two different breathing manoeuvres (both pre and post bronchodilator). The correlation and agreement between surrogate closing volume (Volcrit) and reactance (Xrscrit) at this volume was analysed. The changes in Volcrit and Xrscrit pre and post bronchodilator were also analysed. Across all three subject groups, the two different measures of Volcrit were shown to be statistically equivalent (p > 0.05) and demonstrated a strong fit to the data (R2 = 0.49, 0.78, 0.59, for asthmatic, COPD and healthy subject groups, respectively). A bias was evident between the two measurements of Xrscrit with statistically different means (p < 0.05). However, the two measurements of Xrscrit displayed the same trends. In conclusion, we have developed an alternative technique for measuring airway closure from FOT recordings. The technique delivers equivalent and possibly more sensitive results to previous methods while being simple and easily performed by the patient.
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26
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Karayama M, Inui N, Mori K, Kono M, Hozumi H, Suzuki Y, Furuhashi K, Hashimoto D, Enomoto N, Fujisawa T, Nakamura Y, Watanabe H, Suda T. Respiratory impedance is correlated with airway narrowing in asthma using three-dimensional computed tomography. Clin Exp Allergy 2018; 48:278-287. [PMID: 29315896 DOI: 10.1111/cea.13083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/15/2017] [Accepted: 12/21/2017] [Indexed: 01/20/2023]
Abstract
BACKGROUND Respiratory impedance comprises the resistance and reactance of the respiratory system and can provide detailed information on respiratory function. However, details of the relationship between impedance and morphological airway changes in asthma are unknown. OBJECTIVE We aimed to evaluate the correlation between imaging-based airway changes and respiratory impedance in patients with asthma. METHODS Respiratory impedance and spirometric data were evaluated in 72 patients with asthma and 29 reference subjects. We measured the intraluminal area (Ai) and wall thickness (WT) of third- to sixth-generation bronchi using three-dimensional computed tomographic analyses, and values were adjusted by body surface area (BSA, Ai/BSA, and WT/the square root (√) of BSA). RESULTS Asthma patients had significantly increased respiratory impedance, decreased Ai/BSA, and increased WT/√BSA, as was the case in those without airflow limitation as assessed by spirometry. Ai/BSA was inversely correlated with respiratory resistance at 5 Hz (R5) and 20 Hz (R20). R20 had a stronger correlation with Ai/BSA than did R5. Ai/BSA was positively correlated with forced expiratory volume in 1 second/forced vital capacity ratio, percentage predicted forced expiratory volume in 1 second, and percentage predicted mid-expiratory flow. WT/√BSA had no significant correlation with spirometry or respiratory impedance. CONCLUSIONS & CLINICAL RELEVANCE Respiratory resistance is associated with airway narrowing.
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Affiliation(s)
- M Karayama
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - N Inui
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Clinical Pharmacology and Therapeutics, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - K Mori
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - M Kono
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - H Hozumi
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Y Suzuki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - K Furuhashi
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - D Hashimoto
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - N Enomoto
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - T Fujisawa
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Y Nakamura
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - H Watanabe
- Department of Clinical Pharmacology and Therapeutics, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - T Suda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
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27
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King GG, James A, Harkness L, Wark PAB. Pathophysiology of severe asthma: We've only just started. Respirology 2018; 23:262-271. [PMID: 29316003 DOI: 10.1111/resp.13251] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 11/14/2017] [Accepted: 12/07/2017] [Indexed: 12/01/2022]
Abstract
Severe asthma is defined by the high treatment requirements to partly or fully control the clinical manifestations of disease. It remains a problem worldwide with a large burden for individuals and health services. The key to improving targeted treatments, reducing disease burden and improving patient outcomes is a better understanding of the pathophysiology and mechanisms of severe disease. The heterogeneity, complexity and difficulties in undertaking clinical studies in severe asthma remain challenges to achieving better understanding and better outcomes. In this review, we focus on the structural, mechanical and inflammatory abnormalities that are relevant in severe asthma.
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Affiliation(s)
- Gregory G King
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, NSW, Australia.,The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
| | - Alan James
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Perth, WA, Australia.,School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia
| | - Louise Harkness
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,The Woolcock Institute of Medical Research, The University of Sydney, Sydney, NSW, Australia
| | - Peter A B Wark
- NHMRC Centre for Excellence in Severe Asthma, Newcastle, NSW, Australia.,Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute, University of Newcastle, Newcastle, NSW, Australia.,Department of Respiratory Medicine, John Hunter Hospital, Newcastle, NSW, Australia
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28
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Donovan GM. Clustered ventilation defects and bilinear respiratory reactance in asthma. J Theor Biol 2016; 406:166-75. [PMID: 27374171 DOI: 10.1016/j.jtbi.2016.06.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/08/2016] [Accepted: 06/27/2016] [Indexed: 11/24/2022]
Abstract
Imaging studies of asthmatics typically reveal clustered ventilation patterns, rather than homogeneous ventilation; furthermore, the variation of these clusters suggests that the causes are at least partially dynamic, rather than structural. Theoretical studies have indicated dynamic mechanisms by which homogeneous ventilation solutions lose stability and clustered solutions emerge. At the same time, it has been demonstrated experimentally that respiratory reactance characteristically has a bilinear relationship with lung volume, and that changes to this relationship are indicative of various aspects of disease progression and control. Moreover, the transition point in the bilinear reactance relationship is thought to relate to reopening/recruitment of airway units, and thus may be connected to the bifurcation via which clustered ventilation solutions emerge. In order to investigate this possibility we develop a new model, including both airway-airway coupling and airway-parenchymal coupling, which exhibits both clustered ventilation defects and also a bilinear reactance relationship. Studying this model reveals that (1) the reactance breakpoint is not coincident with the bifurcation; (2) numerous changes to underlying behaviour can alter the reactance breakpoint in ways which mimic the experimental data; and (3) the location of ventilation defects can be a combination of both structural and dynamic factors.
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Affiliation(s)
- Graham M Donovan
- Department of Mathematics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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29
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O'Toole J, Mikulic L, Kaminsky DA. Epidemiology and Pulmonary Physiology of Severe Asthma. Immunol Allergy Clin North Am 2016; 36:425-38. [PMID: 27401616 DOI: 10.1016/j.iac.2016.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The epidemiology and physiology of severe asthma are inherently linked because of varying phenotypes and expressions of asthma throughout the population. To understand how to better treat severe asthma, we must use both population data and physiologic principles to individualize therapies among groups with similar expressions of this disease.
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Affiliation(s)
- Jacqueline O'Toole
- Department of Medicine, University of Vermont Medical Center, 111 Colchester Avenue, Burlington, VT 05401, USA
| | - Lucas Mikulic
- Division of Pulmonary and Critical Care Medicine, University of Vermont Medical Center, Given D208, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - David A Kaminsky
- Division of Pulmonary and Critical Care Medicine, University of Vermont College of Medicine, Given D213, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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30
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Svenningsen S, Nair P, Guo F, McCormack DG, Parraga G. Is ventilation heterogeneity related to asthma control? Eur Respir J 2016; 48:370-9. [DOI: 10.1183/13993003.00393-2016] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/13/2016] [Indexed: 11/05/2022]
Abstract
In asthma patients, magnetic resonance imaging (MRI) and the lung clearance index (LCI) have revealed persistent ventilation heterogeneity, although its relationship to asthma control is not well understood. Therefore, our goal was to explore the relationship of MRI ventilation defects and the LCI with asthma control and quality of life in patients with severe, poorly controlled asthma.18 patients with severe, poorly controlled asthma (mean±sd 46±12 years, six males/12 females) provided written informed consent to an ethics board approved protocol, and underwent spirometry, LCI and 3He MRI during a single 2-h visit. Asthma control and quality of life were evaluated using the Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ). Ventilation heterogeneity was quantified using the LCI and 3He MRI ventilation defect percent (VDP).All participants reported poorly controlled disease (mean±sd ACQ score=2.3±0.9) and highly heterogeneous ventilation (mean±sd VDP=12±11% and LCI=10.5±3.0). While VDP and LCI were strongly correlated (r=0.86, p<0.0001), in a multivariate model that included forced expiratory volume in 1 s, VDP and LCI, VDP was the only independent predictor of asthma control (R2=0.38, p=0.01). There was also a significantly worse VDP, but not LCI in asthma patients with an ACQ score >2 (p=0.04) and AQLQ score <5 (p=0.04), and a trend towards worse VDP (p=0.053), but not LCI in asthma patients reporting ≥1 exacerbation in the past 6 months.In patients with poorly controlled, severe asthma MRI ventilation, but not LCI was significantly worse in those with worse ACQ and AQLQ.
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31
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Faria ACD, Veiga J, Lopes AJ, Melo PL. Forced oscillation, integer and fractional-order modeling in asthma. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2016; 128:12-26. [PMID: 27040828 DOI: 10.1016/j.cmpb.2016.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 01/04/2016] [Accepted: 02/16/2016] [Indexed: 06/05/2023]
Abstract
The purpose of this study was to evaluate the use of fractional-order (FrOr) modeling in asthma. To this end, three FrOr models were compared with traditional parameters and an integer-order model (InOr). We investigated which model would best fit the data, the correlation with traditional lung function tests and the contribution to the diagnostic of airway obstruction. The data consisted of forced oscillation (FO) measurements obtained from healthy (n=22) and asthmatic volunteers with mild (n=22), moderate (n=19) and severe (n=19) obstructions. The first part of this study showed that a FrOr was the model that best fit the data (relative distance: FrOr=4.3±2.4; InOr=5.1±2.6%). The correlation analysis resulted in reasonable (R=0.36) to very good (R=0.77) associations between FrOr parameters and spirometry. The closest associations were observed between parameters related to peripheral airway obstruction, showing a clear relationship between the FrOr models and lung mechanics. Receiver-operator analysis showed that FrOr parameters presented a high potential to contribute to the detection of the mild obstruction in a clinical setting. The accuracy [area under the Receiver Operating Characteristic curve (AUC)] observed in these parameters (AUC=0.954) was higher than that observed in traditional FO parameters (AUC=0.732) and that obtained from the InOr model (AUC=0.861). Patients with moderate and severe obstruction were identified with high accuracy (AUC=0.972 and 0.977, respectively). In conclusion, the results obtained are in close agreement with asthma pathology, and provide evidence that FO measurement associated with FrOr models is a non-invasive, simple and radiation-free method for the detection of biomechanical abnormalities in asthma.
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Affiliation(s)
- Alvaro C D Faria
- Biomedical Instrumentation Laboratory, Institute of Biology Roberto Alcantara Gomes and Laboratory of Clinical and Experimental Research in Vascular Biology (BioVasc), State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Juliana Veiga
- Biomedical Instrumentation Laboratory, Institute of Biology Roberto Alcantara Gomes and Laboratory of Clinical and Experimental Research in Vascular Biology (BioVasc), State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Agnaldo J Lopes
- Pulmonary Function Laboratory, Pedro Ernesto University Hospital, Brazil
| | - Pedro L Melo
- Biomedical Instrumentation Laboratory, Institute of Biology Roberto Alcantara Gomes and Laboratory of Clinical and Experimental Research in Vascular Biology (BioVasc), State University of Rio de Janeiro, Rio de Janeiro, Brazil.
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Kaminsky DA, Irvin CG. What long-term changes in lung function can tell us about asthma control. Curr Allergy Asthma Rep 2015; 15:505. [PMID: 25638285 DOI: 10.1007/s11882-014-0505-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Asthma severity is typically classified according to lung function, but asthma control in relation to lung function is often harder to define. In this paper, we will review how lung function measured at rest, as well as over time, relates to asthma control. We will explore not only conventional lung function as measured by spirometry, such as peak expiratory flow and forced expiratory volume in 1 s, but also more sophisticated measurements of peripheral airway function related to respiratory system impedance and ventilation heterogeneity. In particular, we will review the emerging area of assessing the fluctuation of lung function over time and how it may correlate to both past and future asthma control.
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Affiliation(s)
- David A Kaminsky
- Pulmonary and Critical Care Medicine, College of Medicine, University of Vermont, Given D213, 89 Beaumont Avenue, Burlington, VT, 05405, USA,
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Lima AN, Faria ACD, Lopes AJ, Jansen JM, Melo PL. Forced oscillations and respiratory system modeling in adults with cystic fibrosis. Biomed Eng Online 2015; 14:11. [PMID: 25889005 PMCID: PMC4334397 DOI: 10.1186/s12938-015-0007-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/28/2015] [Indexed: 11/26/2022] Open
Abstract
Background The Forced Oscillation Technique (FOT) has the potential to increase our knowledge about the biomechanical changes that occur in Cystic Fibrosis (CF). Thus, the aims of this study were to investigate changes in the resistive and reactive properties of the respiratory systems of adults with CF. Methods The study was conducted in a group of 27 adults with CF over 18 years old and a control group of 23 healthy individuals, both of which were assessed by the FOT, plethysmography and spirometry. An equivalent electrical circuit model was also used to quantify biomechanical changes and to gain physiological insight. Results and discussion The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p < 0.0006) and reduced dynamic compliance (p < 0.0001). In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p < 0.0005) and reduced compliance (p < 0.0004) and inertance (p < 0.005). Significant reasonable to good correlations were observed between the resistive parameters and spirometric and plethysmographic indexes. Similar associations were observed for the reactive parameters. Peripheral resistance, obtained by the model analysis, presented reasonable (R = 0.35) to good (R = 0.64) relationships with plethysmographic parameters. Conclusions The FOT adequately assessed the biomechanical changes associated with CF. The model used provides sensitive indicators of lung function and has the capacity to differentiate between obstructed and non-obstructed airway conditions. The FOT shows great potential for the clinical assessment of respiratory mechanics in adults with CF.
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Affiliation(s)
- Adma N Lima
- Pulmonary Function Laboratory - Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Alvaro C D Faria
- Biomedical Instrumentation Laboratory - Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Agnaldo J Lopes
- Pulmonary Function Laboratory - Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - José M Jansen
- Pulmonary Function Laboratory - Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Pedro L Melo
- Biomedical Instrumentation Laboratory - Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil. .,BioVasc Research Laboratory - Institute of Biology, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
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Robinson PD, Brown NJ, Turner M, Van Asperen P, Selvadurai H, King GG. Increased Day-to-Day Variability of Forced Oscillatory Resistance in Poorly Controlled or Persistent Pediatric Asthma. Chest 2014; 146:974-981. [DOI: 10.1378/chest.14-0288] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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