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Gochicoa-Rangel L, Jiménez C, Lechuga-Trejo I, Benítez-Pérez RE, Thirion-Romero I, Hernández-Rocha FI, Ceballos-Zúñiga O, Cortes-Telles A, Guerrero-Zuñiga S, Díaz-García R, Hernández-Morales AP, Aguilar-Zanela JL, Torre-Bouscoulet L. [Small airway: from definition to treatment]. REVISTA ALERGIA MÉXICO 2023; 70:22-37. [PMID: 37566753 DOI: 10.29262/ram.v70i1.1190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/14/2023] [Indexed: 08/13/2023] Open
Abstract
The small airway, present since the origins of humanity and described barely a century ago, has recently been discovered as the anatomical site where inflammation begins in some obstructive lung diseases, such as asthma and Chronic Obstructive Pulmonary Disease (COPD), per se. Small airway dysfuction was identified in up to 91% of asthmatic patients and in a large proportion of COPD patients. In subjects without pathology, small airway represent 98.8% (approximately 4500 ml) of the total lung volume, contributing only between 10-25% of the total lung resistance; however, in subjects with obstruction, it can represent up to 90% of the total resistance. Despite this, its morphological and functional characteristics allow its dysfunction to remain undetected by conventional diagnostic methods, such as spirometry. Hence the importance of this review, which offers an overview of the tools available to assess small airway dysfunction and the possible therapies that act in this silent zone.
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Affiliation(s)
- Laura Gochicoa-Rangel
- Departamento de Fisiología Respiratoria, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México
| | - Carlos Jiménez
- Facultad de Medicina de la Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Irma Lechuga-Trejo
- Departamento de Neumopediatría, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México
| | - Rosaura Esperanza Benítez-Pérez
- Departamento de Fisiología Respiratoria, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México
| | - Ireri Thirion-Romero
- Sociedad Latinoamericana de Fisiología Respiratoria (SOLAFIRE), Ciudad de México
| | | | | | - Arturo Cortes-Telles
- Clínica de Enfermedades Respiratorias, Hospital Regional De Alta Especialidad de la Península de Yucatán, Mérida, México
| | - Selene Guerrero-Zuñiga
- Unidad de Medicina del Sueño, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Ciudad de México
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Karvonen T, Lehtimäki L. Effect of exhalation flow rates and level of nitric oxide output on accuracy of linear approximation of pulmonary nitric oxide dynamics. J Breath Res 2021; 15. [PMID: 33784646 DOI: 10.1088/1752-7163/abf3ab] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/30/2021] [Indexed: 11/11/2022]
Abstract
The method of Tsoukias and George (T and G) is a commonly used linear approximation of pulmonary nitric oxide (NO) dynamics that can be used to calculate bronchial NO output (JawNO) and alveolar NO concentration (CANO). We aimed to investigate how flow rate range in exhaled NO measurements and levels of pulmonary NO parameters affect the accuracy of the T and G method. This study has three parts. (a) A theoretical part demonstrating how different exhalation flow rates and NO parameter levels affect the accuracy of the T and G method, (b) testing how exhalation flow rate range affects the method in a sample of asthmatic and healthy subjects, and (c) a meta-analysis of published literature to test whether minimum flow rate has an association with the NO parameter values. We found that both the chosen exhalation flow rates and magnitude of the pulmonary NO parameters affect the accuracy of the T and G method. Underestimation ofJawNO increased with lower flow rates and higher bronchial diffusion factor of NO (DawNO), while overestimation of CANO increased with higher DawNO and bronchial wall NO concentration (CawNO) and lower CANO. Of the NO parameters, CANO was the most prone to bias and high DawNO was the most significant factor causing the bias. Furthermore, we found that using 40 ml s-1as the lowest flow rate in our sample and 50 ml s-1in the meta-analysis compared to 100 ml s-1resulted in higher CANO, but JawNO was not statistically significantly affected. We have provided objective evidence that not only the flow rates used but also the magnitude of NO output in the test subjects affect the accuracy of the T and G method. We suggest that flow rates below 100 ml s-1should not be used with the T and G method to maintain accuracy.
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Affiliation(s)
- Tuomas Karvonen
- Tampere University Respiratory Research Group, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Lauri Lehtimäki
- Tampere University Respiratory Research Group, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Allergy Centre, Tampere University Hospital, Tampere, Finland
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Lehtimäki L, Karvonen T, Högman M. Clinical Values of Nitric Oxide Parameters from the Respiratory System. Curr Med Chem 2021; 27:7189-7199. [PMID: 32493184 DOI: 10.2174/0929867327666200603141847] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/24/2020] [Accepted: 03/16/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Fractional exhaled nitric oxide (FENO) concentration reliably reflects central airway inflammation, but it is not sensitive to changes in the NO dynamics in the lung periphery. By measuring FENO at several different flow rates one can estimate alveolar NO concentration (CANO), bronchial NO flux (JawNO), bronchial wall NO concentration (CawNO) and the bronchial diffusivity of NO (DawNO). OBJECTIVE We aimed to describe the current knowledge and clinical relevance of NO parameters in different pulmonary diseases. METHODS We conducted a systematic literature search to identify publications reporting NO parameters in subjects with pulmonary or systemic diseases affecting the respiratory tract. A narrative review was created for those with clinical relevance. RESULTS Estimation of pulmonary NO parameters allows for differentiation between central and peripheral inflammation and a more precise analysis of central airway NO output. CANO seems to be a promising marker of parenchymal inflammation in interstitial lung diseases and also a marker of tissue damage and altered gas diffusion in chronic obstructive pulmonary disease and systemic diseases affecting the lung. In asthma, CANO can detect small airway involvement left undetected by ordinary FENO measurement. Additionally, CawNO and DawNO can be used in asthma to assess if FENO is increased due to enhanced inflammatory activity (increased CawNO) or tissue changes related to bronchial remodelling (altered DawNO). CONCLUSION NO parameters may be useful for diagnosis, prediction of disease progression and prediction of treatment responses in different parenchymal lung and airway diseases. Formal trials to test the added clinical value of NO parameters are needed.
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Affiliation(s)
- Lauri Lehtimäki
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland,Allergy Centre, Tampere University Hospital, Tampere, Finland
| | - Tuomas Karvonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Marieann Högman
- Department of Medical Sciences, Respiratory, Allergy and Sleep Research, Uppsala University, S-75185 Uppsala, Sweden
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Karvonen T, Lehtimäki L. Flow-independent nitric oxide parameters in asthma: a systematic review and meta-analysis. J Breath Res 2019; 13:044001. [PMID: 31239409 DOI: 10.1088/1752-7163/ab2c99] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Fractional exhaled nitric oxide (FENO) has been proposed as a non-invasive marker of inflammation in the lungs. Measuring FENO at several flow rates enables the calculation of flow independent NO-parameters that describe the NO-exchange dynamics of the lungs more precisely. The purpose of this study was to compare the NO-parameters between asthmatics and healthy subjects in a systematic review and meta-analysis. METHODS A systematic search was performed in Ovid Medline, Web of Science, Scopus and Cochrane Library databases. All studies with asthmatic and healthy control groups with at least one NO-parameter calculated were included. RESULTS From 1137 identified studies, 33 were included in the meta-analysis. All NO-parameters (alveolar NO concentration (CANO), bronchial flux of NO (JawNO), bronchial mucosal NO concentration (CawNO) and bronchial wall NO diffusion capacity (DawNO)) were found increased in glucocorticoid-treated and glucocorticoid-naïve asthma. JawNO and CANO were most notably increased in both study groups. Elevation of DawNO and CawNO seemed less prominent in both asthma groups. DISCUSSION We found that all the NO-parameters are elevated in asthma as compared to healthy subjects. However, results were highly heterogenous and the evidence on CawNO and DawNO is still quite feeble due to only few studies reporting them. To gain more knowledge on the NO-parameters in asthma, nonlinear methods and standardized study protocols should be used in future studies.
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Affiliation(s)
- Tuomas Karvonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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Zinellu E, Piras B, Ruzittu GGM, Fois SS, Fois AG, Pirina P. Recent Advances in Inflammation and Treatment of Small Airways in Asthma. Int J Mol Sci 2019; 20:ijms20112617. [PMID: 31141956 PMCID: PMC6601314 DOI: 10.3390/ijms20112617] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/16/2019] [Accepted: 05/27/2019] [Indexed: 12/14/2022] Open
Abstract
Small airways were historically considered to be almost irrelevant in the development and control of pulmonary chronic diseases but, as a matter of fact, in the past few years we have learned that they are not so "silent". Asthma is still a worldwide health issue due to the great share of patients being far from optimal management. Several studies have shown that the deeper lung inflammation plays a critical role in asthma pathogenesis, mostly in these not well-controlled subjects. Therefore, assessing the degree of small airways inflammation and impairment appears to be a pivotal step in the asthmatic patient's management. It is now possible to evaluate them through direct and indirect measurements, even if some obstacles still affect their clinical application. The success of any treatment obviously depends on several factors but reaching the deeper lung has become a priority and, for inhaled drugs, this is strictly connected to the molecule's size. The aim of the present review is to summarize the recent evidence concerning the small airway involvement in asthma, its physiopathological characteristics and how it can be evaluated in order to undertake a personalized pharmacological treatment and achieve a better disease control.
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Affiliation(s)
- Elisabetta Zinellu
- Respiratory Unit, Azienda Ospedaliero Universitaria (AOU), V.le San Pietro, 07100 Sassari, Italy.
| | - Barbara Piras
- Respiratory Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, V.le San Pietro, 07100 Sassari, Italy.
| | - Giulia G M Ruzittu
- Respiratory Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, V.le San Pietro, 07100 Sassari, Italy.
| | - Sara S Fois
- Respiratory Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, V.le San Pietro, 07100 Sassari, Italy.
| | - Alessandro G Fois
- Respiratory Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, V.le San Pietro, 07100 Sassari, Italy.
| | - Pietro Pirina
- Respiratory Unit, Azienda Ospedaliero Universitaria (AOU), V.le San Pietro, 07100 Sassari, Italy.
- Respiratory Unit, Department of Medical, Surgical and Experimental Sciences, University of Sassari, V.le San Pietro, 07100 Sassari, Italy.
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Morton RL, O'Hagan A, Eid NS. The Role of Small Airways in Childhood Asthma. PEDIATRIC ALLERGY IMMUNOLOGY AND PULMONOLOGY 2012. [DOI: 10.1089/ped.2012.0176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Ronald L. Morton
- Division of Pulmonary Medicine, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
| | - Adrian O'Hagan
- Division of Pulmonary Medicine, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
| | - Nemr S. Eid
- Division of Pulmonary Medicine, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
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Abstract
Asthma is a lung disease characterized by inflammation and remodeling of the airways. It is now widely accepted that airway inflammation and remodeling occur not only in the central airways but also in the small airways and even in the lung parenchyma. Inflammation of the distal lung can be observed even in mild asthmatics with normal or noncompromised lung function. Moreover, the small airways and the lung parenchyma can produce many Th2 cytokines and chemokines involved in initiation and perpetuation of the inflammatory process. In addition, the distal parts of the bronchial tree have been recognized as a predominant site of airflow obstruction in many asthmatics. In fact, the inflammation at this distal site has been described as more severe when compared to the large airway inflammation, and evidence of remodeling in the lung periphery is emerging. Recognition of asthma as a disease of the entire respiratory tract has an important clinical significance, highlighting the need to also consider the distal lung as a target in any therapeutic strategy for effective treatment of this disease.
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Affiliation(s)
- Qutayba Hamid
- Meakins Christie Laboratories, McGill University, Montreal, Que., Canada.
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