International Journal of COPD (Nov 2021)
Small Airways Response to Bronchodilators in Adults with Asthma or COPD: A Systematic Review
Abstract
Mohammed A Almeshari,1,2 Nowaf Y Alobaidi,1,3 Elizabeth Sapey,1,4 Omar Usmani,5 Robert A Stockley,6 James A Stockley7 1Birmingham Acute Care Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, B15 2TT, UK; 2Rehabilitation Health Sciences Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; 3Respiratory Therapy Department, King Saud Bin Abdulaziz University for Health Sciences, Alahsa, Saudi Arabia; 4Acute Medicine, University Hospitals Birmingham NHS Foundation Trust, Birmingham, B15 2GW, UK; 5Imperial College of London, London, UK; 6Department of Respiratory Medicine, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK; 7Lung Function & Sleep Department, Respiratory Medicine, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, UKCorrespondence: Mohammed A AlmeshariRehabilitation Health Science Department, College of Applied Medical Sciences, King Saud University, P. Box 145111,, Riyadh, ZIP 4545, Saudi ArabiaTel +966 50 8033 880Email [email protected]: Bronchodilator responsiveness (BDR) is commonly used in the diagnosis of lung disease. Although small airways dysfunction is a feature of asthma and COPD, physiological tests of small airways are not included in guidelines for BDR testing. This systematic review assessed the current evidence of BDR using small airways function in asthma and COPD.Methods: The systematic review used standard methodology with the protocol prospectively registered on PROSPERO (CRD42020164140). Electronic medical databases (EMBASE and Medline) were searched using related keywords. Abstracts and full texts were screened independently by two reviewers. Studies that reported the change of physiological small airways function and FEV1 were included in the review. The revised Cochrane risk of bias tool for RCT and NIH quality assessment tool for cohort and cross-sectional studies were used to evaluate the studies.Results: A total of 934 articles were identified, with 12 meeting the inclusion criteria. Ten studies included asthma patients, 1 study included COPD patients and 1 study included both asthma and COPD. A total of 1104 participants were included, of whom 941 were asthmatic, 64 had COPD and 109 were healthy controls. Studies were heterogeneous in design including the device, dose and time intervals for BDR assessment. A small airway BDR was seen for most tests in asthma and COPD, including oscillometry (R5-20, reactance (X5), area of reactance (AX) and resonant frequency (Fres)) and Maximal Mid Expiratory Flow.Conclusion: There is a measurable BDR in the small airways. However, with no consensus on how to assess BDR, studies were heterogeneous. Further research is needed to inform how BDR should be assessed, its clinical impact and place in routine clinical practice.Keywords: asthma, COPD, bronchodilator, reversibility, small airways function
