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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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Demey L, Van Muylem A, Malinovschi A, Haccuria A, Perez-Bogerd S, Michils A. Exploring the sites and kinetics of bronchodilator response to β-2 agonists in asthma. J Appl Physiol (1985) 2021; 130:1106-1113. [PMID: 33444118 DOI: 10.1152/japplphysiol.00643.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously documented, in patients with asthma, three different profiles of bronchodilation induced by short-acting β-2 mimetics (SABA), characterized by dilation up to central, preacinar, and intra-acinar airways assessed by ventilation distribution tests and associated with no change, increase, and decrease of fractional exhaled nitric oxide concentration (FENO), respectively. To investigate the dynamics of these profiles over the entire SABA action period, assuming that bronchodilation of proximal and peripheral airways could exhibit varying kinetics due to differences in the distribution of β-2 receptors in both the central and peripheral human airways. FENO, forced expired volume in one second (FEV1), and the slope (S) of He and SF6 phase III (single-breath test) were measured in asthma patients before, and up to 6 h after SABA inhalation (salbutamol 400 µg). SHe and SSF6 decrease reflects pre- and intra-acinar obstruction relief, respectively. Thirty patients with asthma (12F/18M, aged 45 ± 18 yr) were divided into groups with positive (NO+, n = 9), negative (NO-, n = 11), and no (NO=, n = 10) FENO acute change. In the NO- group, FEV1 increased for up to 4 h, whereas FENO, SHe, and SF6 decreased in the early phase only. In stark contrast, in the NO+ group, FEV1 increased in the early phase only whereas the FENO increase and the SHe decrease lasted for up to 4 h. This study documents various profiles of SABA-induced bronchodilation in patients with asthma, differing both by sites and dynamics of the bronchodilator process. So, detailed understanding of the bronchodilator effect of β2-agonists in asthma should not solely be limited to studying their impact on FEV1.NEW & NOTEWORTHY FEV1 increase usually observed after the inhalation of short-acting β2-agonists in asthma patients tends to involve peripheral airways. This study shows that the heterogeneity of responses to short-acting β2-agonists in asthma not only involves distinct sites of bronchodilation, but also distinct sequences between these sites. This indicates that a detailed understanding of the bronchodilator effect of β2-agonists in asthma should not be limited to studying its early impact on FEV1.
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Affiliation(s)
- Lucas Demey
- Chest Department, Erasme University Hospital, Université libre de Bruxelles, Brussels, Belgium
| | - 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
| | - Amaryllis Haccuria
- Chest Department, Erasme University Hospital, Université libre de Bruxelles, Brussels, Belgium
| | - Silvia Perez-Bogerd
- Chest Department, Erasme University Hospital, Université libre de Bruxelles, Brussels, Belgium
| | - Alain Michils
- Chest Department, Erasme University Hospital, Université libre de Bruxelles, Brussels, Belgium
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Exhaled nitric oxide and its predictive power related to lung function and bronchial inflammation. Biochem Pharmacol 2020; 179:114101. [DOI: 10.1016/j.bcp.2020.114101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 11/22/2022]
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Cox CA, Vonk JM, Kerstjens HA, den Berge M. Factors associated with hyperresponsiveness to adenosine 5'-monophosphate in healthy subjects. Allergy 2019; 74:2268-2270. [PMID: 31077400 PMCID: PMC6899818 DOI: 10.1111/all.13864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Claire Alette Cox
- Department of Pulmonary Diseases University Medical Center Groningen University of Groningen Groningen The Netherlands
- University Medical Center Groningen Groningen Research Institute for Asthma and COPD University of Groningen Groningen The Netherlands
| | - Judith M. Vonk
- University Medical Center Groningen Groningen Research Institute for Asthma and COPD University of Groningen Groningen The Netherlands
- Department of Epidemiology University Medical Center Groningen University of Groningen Groningen The Netherlands
| | - Huib A.M. Kerstjens
- Department of Pulmonary Diseases University Medical Center Groningen University of Groningen Groningen The Netherlands
- University Medical Center Groningen Groningen Research Institute for Asthma and COPD University of Groningen Groningen The Netherlands
| | - Maarten den Berge
- Department of Pulmonary Diseases University Medical Center Groningen University of Groningen Groningen The Netherlands
- University Medical Center Groningen Groningen Research Institute for Asthma and COPD University of Groningen Groningen The Netherlands
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Pérez-Bogerd S, Michils A, Malinovschi A, Van Muylem A. COPD patients with peripheral airway obstruction reversibility identified by exhaled nitric oxide. J Breath Res 2019; 13:036002. [PMID: 30802891 DOI: 10.1088/1752-7163/ab0a14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RATIONALE Besides its role as an inflammatory marker in asthma, fractional exhaled nitric oxide (FENO) provides information on the extent of the airway obstruction process through evaluating its change after bronchodilation. OBJECTIVE To investigate whether FENO change after bronchodilation can identify different sites of airway obstruction in COPD patients. METHODS FENO, FEV1 and the slopes (S) of the alveolar plateau of the single breath washout test (SBWT) were measured in 61 stable COPD patients (FEV1 34.5% predicted) before and after the inhalation of 400 μg salbutamol. SBWT used Helium (He), and sulfur-hexafluoride (SF6). Obstruction relief occurring in pre-acinar and intra-acinar small airways is expected to decrease SHe and SSF6, respectively. Indices changes (Δ) after bronchodilation were expressed as a percentage of pre-bronchodilation values. RESULTS FENO stability (∣ΔFENO∣ ≤ 11%) was observed in 19 patients [-2.7(6.7)%] [mean (SD)] (NO = group); ΔFENO > 11% [+37.4(27.7)%] in 20 patients (NO+ group) and ΔFENO < -11% in 22 patients [-31.2(9.8)%] (NO- group). A similar ΔFEV1 (p = 0.583; [+9.4(9.6)%]) was found in the three groups. In NO = and NO+ groups, neither SHe nor SSF6 changed; in NO- both SHe [-12.4(27.5)%, p = 0.007] and SSF6 [-20.2(20.4)%, p < 0.001] significantly decreased. CONCLUSION Different patterns of FENO response to β 2-agonists were observed in COPD most likely depending on the extent of the dilation process. A profile of airway obstruction with an extensive β 2-agonist response down to lung periphery is identified by FENO reduction after acute bronchodilation in 30% of COPD patients. The clinical relevance of this profile requires further investigation.
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Affiliation(s)
- Silvia Pérez-Bogerd
- Chest Department, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
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Karamaoun C, Haut B, Van Muylem A. A new role for the exhaled nitric oxide as a functional marker of peripheral airway caliber changes: a theoretical study. J Appl Physiol (1985) 2018; 124:1025-1033. [DOI: 10.1152/japplphysiol.00530.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although considered as an inflammation marker, exhaled nitric oxide (FENO) was shown to be sensitive to airway caliber changes to such an extent that it might be considered as a marker of them. It is thus important to understand how these changes and their localization mechanically affect the total NO flux penetrating the airway lumen ( JawNO), and hence FENO, independently from any inflammatory status change. In this work, a new model was used. It simulates NO production, consumption, and diffusion inside the airway epithelium, NO excretion from the epithelial wall into the airway lumen and, finally, its axial transport by diffusion and convection in the airway lumen. This model may also consider the possible presence of a fluid layer coating the epithelial wall. Simulations were performed. They show the great sensitivity of JawNO to peripheral airway caliber changes. Moreover, FENO shows distinct behaviors, depending on the location of the caliber change. Considering a bronchodilation, absence of FENO change was associated with dilation of central airways, FENO increase with dilation down to pre-acinar small airways, and FENO decrease with intra-acinar dilation due to the amplification of the back diffusion flux. The presence of a fluid layer was also shown to play a significant role in FENO changes. Altogether, the present work theoretically supports that specific FENO changes in acute situations are linked to specifically located airway caliber changes in the lung periphery. This opens the way for a new role for FENO as a functional marker of peripheral airway caliber change. NEW & NOTEWORTHY Using a new model of nitric oxide production and transport, allowing realistic simulation of airway caliber change, the present work theoretically supports that specific changes of the molar fraction of nitric oxide in the exhaled air, occurring without any change in the inflammatory status, are linked to specifically located airway caliber changes in the lung periphery. This opens the way for a new role for FENO as a functional marker of peripheral airway caliber change.
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Affiliation(s)
- Cyril Karamaoun
- Ecole polytechnique de Bruxelles, Transfers Interfaces and Processes, Université libre de Bruxelles, Brussels, Belgium
| | - Benoit Haut
- Ecole polytechnique de Bruxelles, Transfers Interfaces and Processes, Université libre de Bruxelles, Brussels, Belgium
| | - Alain Van Muylem
- Chest Department, Erasme University Hospital, Université libre de Bruxelles, Brussels, Belgium
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Haccuria A, Van Muylem A, Malinovschi A, Doan V, Michils A. Small airways dysfunction: the link between allergic rhinitis and allergic asthma. Eur Respir J 2018; 51:51/2/1701749. [PMID: 29467201 DOI: 10.1183/13993003.01749-2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 12/07/2017] [Indexed: 11/05/2022]
Abstract
Abnormal airway reactivity and overproduction of nitric oxide (NO) occurring in small airways have been found in asthma. If the "one airway, one disease" concept is consistent, such dysfunctions should also be detected in the peripheral airways of patients suffering from allergic rhinitis.We investigated whether peripheral airway reactivity and NO overproduction could be documented in distal airways in patients with allergic rhinitis. Exhaled NO fraction (FeNO) and the slope (S) of phase III of the single-breath washout test (SBWT) of helium (He) and sulfur hexafluoride (SF6) were measured in 31 patients with allergic asthma, 23 allergic rhinitis patients and 24 controls, before and after sputum induction. SBWT is sensitive to airway calibre change occurring in the lung periphery.The FeNO decrease was more significant in asthma and rhinitis than in controls (-55.1% and -50.0%, respectively, versus -40.8%) (p=0.007 and p=0.029, respectively). SSF6 and SHe increased in all groups. Change in SHe (ΔSHe) > ΔSSF6 was observed in rhinitis (p=0.004) and asthma (p<0.001), whereas ΔSSF6 = ΔSHe in controls (p=0.431).This study provides evidence of peripheral airway dysfunction in patients with allergic rhinitis quite similar to that described in asthma. Furthermore, a large proportion of the increased NO production reported in allergic rhinitis appears to originate in the peripheral airways.
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Affiliation(s)
- Amaryllis Haccuria
- Chest Dept, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Alain Van Muylem
- Chest Dept, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Andrei Malinovschi
- Dept of Medical Sciences: Clinical Physiology, Uppsala University, Uppsala, Sweden
| | - Vi Doan
- Chest Dept, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Alain Michils
- Chest Dept, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
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Different patterns of exhaled nitric oxide response to β2-agonists in asthmatic patients according to the site of bronchodilation. J Allergy Clin Immunol 2015; 137:806-12. [PMID: 26688519 DOI: 10.1016/j.jaci.2015.09.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 09/18/2015] [Accepted: 09/24/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND In asthmatic patients undergoing airway challenge, fraction of exhaled nitric oxide (FENO) levels decrease after bronchoconstriction. In contrast, model simulations have predicted both decreased and increased FENO levels after bronchodilation, depending on the site of airway obstruction relief. OBJECTIVE We sought to investigate whether β2-agonists might induce divergent effects on FENO values in asthmatic patients as a result of airway obstruction relief occurring at different lung depths. METHODS FENO, FEV1, and the slope of phase III of the single-breath washout test (S) of He (S(He)) and sulfur hexafluoride (S(SF6)) were measured in 68 asthmatic patients before and after salbutamol inhalation. S(He) and S(SF6) decreases reflected preacinar and intra-acinar obstruction relief, respectively. Changes (Δ) were expressed as a percentage from the baseline. RESULTS No FENO change (|ΔFENO| ≤ 10%) was found in 16 patients (mean [SD]: 2.5% [5.2%]; ie, FENO= group); a ΔFENO value of greater than 10% was found in 23 patients (31.7% [20.3%]; ie, the FENO+ group); and a ΔFENO value of less than -10% was found in 29 patients (-31.5% [17.3%]; ie, the FENO- group). All groups had similar ΔFEV1 values. In the FENO= group neither S(He) nor S(SF6) changed, in the FENO+ group only S(He) decreased significantly (-21.8% [SD 28.5%], P = .03), and in the FENO- group both S(He) (-29.8% [24.0%], P < .001) and S(SF6) (-27.2% [23.3%], P < .001) decreased. DISCUSSION Three FENO behaviors were observed in response to β2-agonists: a decrease likely caused by relief of an intra-acinar airway obstruction that we propose reflects amplification of nitric oxide back-diffusion, an increase likely associated with a predominant dilation up to the preacinar airways, and FENO stability when obstruction relief involved predominantly the central airways. In combination, these results suggest a new role for FENO in identifying the site of airway obstruction in asthmatic patients.
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Chapman DG, Irvin CG. Mechanisms of airway hyper-responsiveness in asthma: the past, present and yet to come. Clin Exp Allergy 2015; 45:706-19. [PMID: 25651937 DOI: 10.1111/cea.12506] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Airway hyper-responsiveness (AHR) has long been considered a cardinal feature of asthma. The development of the measurement of AHR 40 years ago initiated many important contributions to our understanding of asthma and other airway diseases. However, our understanding of AHR in asthma remains complicated by the multitude of potential underlying mechanisms which in reality are likely to have different contributions amongst individual patients. Therefore, the present review will discuss the current state of understanding of the major mechanisms proposed to contribute to AHR and highlight the way in which AHR testing is beginning to highlight distinct abnormalities associated with clinically relevant patient populations. In doing so we aim to provide a foundation by which future research can begin to ascribe certain mechanisms to specific patterns of bronchoconstriction and subsequently match phenotypes of bronchoconstriction with clinical phenotypes. We believe that this approach is not only within our grasp but will lead to improved mechanistic understanding of asthma phenotypes and we hoped to better inform the development of phenotype-targeted therapy.
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Affiliation(s)
- D G Chapman
- Woolcock Institute of Medical Research, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Department of Medicine, University of Vermont College of Medicine, Burlington, VT, USA
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Prieto L, Palop J, Llusar R, Herrera S, Perez-Frances C, Lanuza A, Aguilar D. Effects of cigarette smoke on methacholine- and AMP-induced air trapping in asthmatics. J Asthma 2015; 52:26-33. [PMID: 25019351 DOI: 10.3109/02770903.2014.944981] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
UNLABELLED Abstract Objective: No information is available on the effect of cigarette smoke on bronchoconstrictor-induced air trapping in asthma. The aim of this study was to evaluate the additional influence of smoking on methacholine- and adenosine 5'-monophosphate (AMP)-induced air trapping in subjects with asthma. METHODS Airway responsiveness to methacholine and AMP, bronchial (J'awNO) and alveolar (CANO) nitric oxide (NO) and exhaled breath condensate pH were measured in 68 adults (23 current smokers with asthma, 23 non-smokers with asthma and 22 current or former smokers with chronic obstructive pulmonary disease; COPD). The degree of air trapping induced by each bronchoconstrictor agent was expressed by the percent fall in forced vital capacity (FVC) at a 20% fall in forced expiratory volume in 1 s relative to FVC after saline inhalation (ΔFVC%). RESULTS The ΔFVC% for AMP was higher in both smokers with asthma and patients with COPD than in non-smokers with asthma (p<0.001). By contrast, ΔFVC% for methacholine was similar in the three groups of subjects (p=0.69). In smokers with asthma, but not in the other two groups, there was a correlation between the residual volume/total lung capacity at baseline and the ΔFVC% induced by each bronchoconstrictor agent. Mean values for J'awNO were higher in non-smokers with asthma than in the other two groups (p<0.05). CONCLUSIONS The results of this study suggest that factors underlying bronchoconstriction induced by indirect agonists are different in smokers and non-smokers with asthma. These observations might be clinically relevant, because triggers that frequently induce bronchial obstruction in the real world act by an indirect mechanism.
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Affiliation(s)
- Luis Prieto
- Department of Medicine, University of Valencia , Medicina , Spain
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Usmani OS. Small airways dysfunction in asthma: evaluation and management to improve asthma control. ALLERGY, ASTHMA & IMMUNOLOGY RESEARCH 2014; 6:376-88. [PMID: 25228994 PMCID: PMC4161678 DOI: 10.4168/aair.2014.6.5.376] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 04/01/2014] [Indexed: 01/24/2023]
Abstract
The small airways have been neglected for many years, but interest in the topic has been rekindled with recent advances in measurement techniques to assess this region and also the ability to deliver therapeutics to the distal airways. Current levels of disease control in asthmatic patients remain poor and there are several contributory factors including; poor treatment compliance, heterogeneity of asthma phenotypes and associated comorbidities. However, the proposition that we may not be targeting all the inflammation that is present throughout the whole respiratory tree may also be an important factor. Indeed decades ago, pathologists and physiologists clearly identified the importance of small airways dysfunction in asthmatic patients. With improved inhaler technology to deliver drug to target the whole respiratory tree and more sensitive measures to assess the distal airways, we should certainly give greater consideration to treating the small airway region when seeing our asthmatic patients in clinic. The aim of this review is to address the relevance of small airways dysfunction in the daily clinical management of patients with asthma. In particular the role of small particle aerosols in the management of patients with asthma will be explored.
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Affiliation(s)
- Omar S Usmani
- Airway Disease Section, National Heart and Lung Institute, Imperial College London & Royal Brompton Hospital, London, UK
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Singer F, Abbas C, Yammine S, Casaulta C, Frey U, Latzin P. Abnormal small airways function in children with mild asthma. Chest 2014; 145:492-499. [PMID: 24091465 DOI: 10.1378/chest.13-0784] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Small airways disease is a hallmark in adults with persistent asthma, but little is known about small airways function in children with mild asthma and normal spirometry. We assessed ventilation heterogeneity, a marker of small airways function, with an easy tidal breath single-breath washout (SBW) technique in school-aged children with mild asthma and normal FEV1 and healthy age-matched control subjects. METHODS The primary outcome was the double-tracer gas phase III slope (SDTG), an index of ventilation heterogeneity in acinar airways derived from the tidal double-tracer gas SBW test. The second outcome was the nitrogen phase III slope (SN2), an index of global ventilation heterogeneity derived from the tidal nitrogen SBW test using pure oxygen. Triplicate SBW and spirometry tests were performed in healthy children (n=35) and children with asthma (n=31) at baseline and in children with asthma after bronchodilation. RESULTS Acinar (SDTG) but not global (SN2) ventilation heterogeneity was significantly increased in asthma despite normal FEV1. Of the 31 children with asthma, abnormal results were found for SDTG (≤-2 z scores) in 11; forced expiratory flow, midexpiratory phase (FEF25%-75%) in three; and FEV1 in zero. After bronchodilation, SDTG, SN2, FEF25%-75%, and FEV1 significantly changed (mean [95% CI] change from baseline, 36% [15%-56%], 38% [18%-58%], 17% [9-25%], and 6% [3%-9%], respectively). CONCLUSIONS Abnormal acinar ventilation heterogeneity in one-third of the children suggests that small airways disease may be present despite rare and mild asthma symptoms and normal spirometry. The easy tidal SBW technique has considerable potential as a clinical and research outcome in children with asthma.
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Affiliation(s)
- Florian Singer
- University Children's Hospital Zurich, Zurich; University Children's Hospital Bern, Bern
| | | | - Sophie Yammine
- University Children's Hospital Bern, Bern; University Children's Hospital Basel, Basel, Switzerland
| | | | - Urs Frey
- University Children's Hospital Zurich, Zurich; University Children's Hospital Basel, Basel, Switzerland
| | - Philipp Latzin
- University Children's Hospital Bern, Bern; University Children's Hospital Basel, Basel, Switzerland.
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Haccuria A, Michils A, Michiels S, Van Muylem A. Exhaled nitric oxide: a biomarker integrating both lung function and airway inflammation changes. J Allergy Clin Immunol 2014; 134:554-9. [PMID: 24522091 DOI: 10.1016/j.jaci.2013.12.1070] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 11/28/2013] [Accepted: 12/10/2013] [Indexed: 10/25/2022]
Abstract
BACKGROUND The increased fraction of exhaled nitric oxide (Feno) values observed in asthmatic patients are thought to reflect increased airway inflammation. However, Feno values can be affected by airway caliber reduction, representing a bias when using Feno values to assess asthma control. OBJECTIVE We sought to determine the effect of changes in both airway caliber and inflammation on Feno values using the allergen challenge model. METHODS FEV1 and Feno values were measured during early airway responses (EARs) and late airway responses after challenge with house dust mite allergens in 15 patients with mild allergic asthma. Helium and sulfur hexafluoride (SF6) phase III expired concentration slopes (SHe and SSF6, respectively) from single-breath washout tests were measured to identify sites of airway constriction. RESULTS In EARs, FEV1 and Feno value decreases reached 36.8% and 22%, respectively (P < .001). ΔSHe was greater than ΔSSF6 (+189.4% vs +82.2%, P = .001). In late airway responses FEV1 and Feno value decreases reached 31.7% and 28.7%, respectively (P < .001), with the same ΔSHe and ΔSSF6 pattern (+155.8% vs +76%, P = .001). Eight hours after the EAR, FEV1 was still decreased (P < .001), whereas Feno values had returned to baseline. At 24 hours, FEV1 had returned to baseline, with Feno values increased by 38.7% (P = .04). CONCLUSION In patients with mild allergic asthma, airway caliber changes modulate changes in Feno values resulting from airway inflammation. Therefore Feno should no longer be considered solely an inflammation biomarker but rather a biomarker that integrates both airway inflammation and lung function changes. Furthermore, early and late phases resulting from allergen exposure were shown to involve similar lung regions.
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Affiliation(s)
- Amaryllis Haccuria
- Chest Department, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium; Chest Department, Centre Hospitalier Régional de Namur, Namur, Belgium
| | - Alain Michils
- Chest Department, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Sébastien Michiels
- Chest Department, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Alain Van Muylem
- Chest Department, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium.
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Downie SR, Salome CM, Verbanck S, Thompson BR, Berend N, King GG. Effect of methacholine on peripheral lung mechanics and ventilation heterogeneity in asthma. J Appl Physiol (1985) 2013; 114:770-7. [DOI: 10.1152/japplphysiol.01198.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) are noninvasive tests that are potentially sensitive to peripheral airways, with MBNW indexes being especially sensitive to heterogeneous changes in ventilation. The objective was to study methacholine-induced changes in the lung periphery of asthmatic patients and determine how changes in FOT variables of respiratory system reactance (Xrs) and resistance (Rrs) and frequency dependence of resistance (Rrs5-Rrs19) can be linked to changes in ventilation heterogeneity. The contributions of air trapping and airway closure, as extreme forms of heterogeneity, were also investigated. Xrs5, Rrs5, Rrs19, Rrs5-Rrs19, and inspiratory capacity (IC) were calculated from the FOT. Ventilation heterogeneity in acinar and conducting airways, and trapped gas (percent volume of trapped gas at functional residual capacity/vital capacity), were calculated from the MBNW. Measurements were repeated following methacholine. Methacholine-induced airway closure (percent change in forced vital capacity) and hyperinflation (change in IC) were also recorded. In 40 mild to moderate asthmatic patients, increase in Xrs5 after methacholine was predicted by increases in ventilation heterogeneity in acinar airways and forced vital capacity ( r2 = 0.37, P < 0.001), but had no correlation with ventilation heterogeneity in conducting airway increase or IC decrease. Increases in Rrs5 and Rrs5-Rrs19 after methacholine were not correlated with increases in ventilation heterogeneity, trapped gas, hyperinflation, or airway closure. Increased reactance in asthmatic patients after methacholine was indicative of heterogeneous changes in the lung periphery and airway closure. By contrast, increases in resistance and frequency dependence of resistance were not related to ventilation heterogeneity or airway closure and were more indicative of changes in central airway caliber than of heterogeneity.
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Affiliation(s)
- Sue R. Downie
- Woolcock Institute of Medical Research, Glebe, Sydney, New South Wales, Australia
- Department of Medicine, University of Sydney, New South Wales, Australia
- Cooperative Research Centre for Asthma, Glebe, Sydney, New South Wales, Australia
| | - Cheryl M. Salome
- Woolcock Institute of Medical Research, Glebe, Sydney, New South Wales, Australia
- Department of Medicine, University of Sydney, New South Wales, Australia
- Cooperative Research Centre for Asthma, Glebe, Sydney, New South Wales, Australia
| | - Sylvia Verbanck
- Respiratory Division, Academic Hospital, Vrije Universiteit Brussels, Brussels, Belgium
| | - Bruce R. Thompson
- Cooperative Research Centre for Asthma, Glebe, Sydney, New South Wales, Australia
- Department of Allergy, Immunology, and Respiratory Medicine, The Alfred Hospital and Monash University, Melbourne, Victoria, Australia; and
| | - Norbert Berend
- Woolcock Institute of Medical Research, Glebe, Sydney, New South Wales, Australia
- Department of Medicine, University of Sydney, New South Wales, Australia
- Cooperative Research Centre for Asthma, Glebe, Sydney, New South Wales, Australia
- Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - Gregory G. King
- Woolcock Institute of Medical Research, Glebe, Sydney, New South Wales, Australia
- Department of Medicine, University of Sydney, New South Wales, Australia
- Cooperative Research Centre for Asthma, Glebe, Sydney, New South Wales, Australia
- Department of Respiratory Medicine, Royal North Shore Hospital, Sydney, New South Wales, Australia
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15
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Axial distribution of nitric oxide airway production in asthma patients. Respir Physiol Neurobiol 2012; 185:313-8. [PMID: 23059373 DOI: 10.1016/j.resp.2012.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/21/2012] [Accepted: 09/21/2012] [Indexed: 11/23/2022]
Abstract
In healthy subjects, axial distribution of nitric oxide (NO) airway production is likely heterogeneous: notably a distal peak of production in terminal bronchioles and a quasi-nil NO production in the most of the conducting airways. In asthma, few information exists about the contributions of the proximal and distal airways to NO overproduction. In 18 asthma patients, sites of constriction after methacholine and adenosine 5'-monophosphate (AMP) challenges were assessed by ventilation distribution tests with He and SF(6). The resulting decreases in fractional exhaled NO (FENO) were measured. Changes in He and SF(6) slopes indicated a pre-acinar bronchoconstriction due to AMP and a more proximal action for methacholine. FENO decreased by 38.7% and 20.2% (p<0.001) after AMP and methacholine challenges, respectively. Significant FENO decreases after AMP and methacholine implies substantial pre-acinar but also, contrary to healthy subjects, more proximal airway production. In conclusion, nitric oxide overproduction in asthma patients appears to involve the most part of the conducting airways.
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16
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Abstract
Noninvasive physiological measurements are reviewed that have been reported in the literature with the specific aim being to study the small airways in lung disease. This has mostly involved at-the-mouth noninvasive measurement of flow, pressure or inert gas concentration, with the intent of deriving one or more indices that are representative of small airway structure and function. While these measurements have remained relatively low-tech, the effort and sophistication increasingly reside with the interpretation of such indices. When aspiring to derive information at the mouth about structural and mechanical processes occurring several airway generations away in a complex cyclically changing cul-de-sac structure, conceptual or semi-quantitative lung models can be valuable. Two assumptions that are central to small airway structure-function measurement are that of an average airway change at a given peripheral lung generation and of a parallel heterogeneity in airway changes. While these are complementary pieces of information, they can affect certain small airways tests in confounding ways. We critically analyzed the various small airway tests under review, while contending that negative outcomes of these tests are probably a true reflection of the fact that no change occurred in the small airways. Utmost care has been taken to not favor one technique over another, given that most current small airways tests still have room for improvement in terms of rendering their content more specific to the small airways. One way to achieve this could consist of the coupling of signals collected at the mouth to spatial information gathered from imaging in the same patient.
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Affiliation(s)
- Sylvia Verbanck
- Respiratory Division, University Hospital UZ Brussel, Brussels, Belgium.
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Kang SH, Kim HY, Seo JH, Kwon JW, Jung YH, Song YH, Hong SJ. Bronchial Hyperresponsiveness to Methacholine and AMP in Children With Atopic Asthma. ALLERGY, ASTHMA & IMMUNOLOGY RESEARCH 2012; 4:341-5. [PMID: 23115730 PMCID: PMC3479227 DOI: 10.4168/aair.2012.4.6.341] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 02/03/2012] [Accepted: 03/02/2012] [Indexed: 11/20/2022]
Abstract
Purpose Bronchial hyperresponsiveness (BHR) is typically measured by bronchial challenge tests that employ direct stimulation by methacholine or indirect stimulation by adenosine 5'-monophosphate (AMP). Some studies have shown that the AMP challenge test provides a better reflection of airway inflammation, but few studies have examined the relationship between the AMP and methacholine challenge tests in children with asthma. We investigated the relationship between AMP and methacholine testing in children and adolescents with atopic asthma. Methods The medical records of 130 children with atopic asthma (mean age, 10.63 years) were reviewed retrospectively. Methacholine and AMP test results, spirometry, skin prick test results, and blood tests for inflammatory markers (total IgE, eosinophils [total count, percent of white blood cells]) were analyzed. Results The concentration of AMP that induces a 20% decline in forced expiratory volume in 1 second [FEV1] (PC20) of methacholine correlated with the PC20 of AMP (r2=0.189, P<0.001). No significant differences were observed in the levels of inflammatory markers (total eosinophil count, eosinophil percentage, and total IgE) between groups that were positive and negative for BHR to methacholine. However, significant differences in inflammatory markers were observed in groups that were positive and negative for BHR to AMP (log total eosinophil count, P=0.023; log total IgE, P=0.020, eosinophil percentage, P<0.001). In contrast, body mass index (BMI) was significantly different in the methacholine positive and negative groups (P=0.027), but not in the AMP positive and negative groups (P=0.62). The PC20 of methacholine correlated with FEV1, FEV1/forced vital capacity (FVC), and maximum mid-expiratory flow (MMEF) (P=0.001, 0.011, 0.001, respectively), and the PC20 of AMP correlated with FEV1, FEV1/FVC, and MMEF (P=0.008, 0.046, 0.001, respectively). Conclusions Our results suggest that the AMP and methacholine challenge test results correlated well with respect to determining BHR. The BHR to AMP more likely implicated airway inflammation in children with atopic asthma. In contrast, the BHR to methacholine was related to BMI.
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Affiliation(s)
- Sung Han Kang
- Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. ; Childhood Asthma Atopy Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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