RT Journal Article
SR Electronic
T1 The Bronchodilator Response in FEF<sub>25-75%</sub> Compared to FEV<sub>1</sub> in Assessing Asthma
JF Respiratory Care
FD American Association for Respiratory Care
SP 3608514
VO 66
IS Suppl 10
A1 Mohammed A Almeshari
A1 Nowaf Y Alobaidi
A1 James Stockley
A1 Elizabeth Sapey
YR 2021
UL http://rc.rcjournal.com/content/66/Suppl_10/3608514.abstract
AB Background: Asthma is a common, chronic heterogeneous disease. Tests of large airways function (FEV1) are commonly used to diagnose/monitor disease and bronchodilator responsiveness (BDR: measured by a change in FEV1) is considered the hallmark of asthma. Small airways (&lt;2 mm in diameter) dysfunction (SAD) has been described in asthma, but it is unclear how common BDR in the small airways is in asthma. The aim of this study was to compare BDR in the small airways compared to FEV1. Methods: A retrospective analysis of patients attending a secondary referral hospital in the Midlands, United Kingdom, including non-smoking adults (&gt;18 y) referred to the pulmonary function laboratory as part of an asthma assessment between January 2016 and April 2021. BDR was assessed 20 min after the administration of 2.5 mg of salbutamol using a jet nebulizer. Changes in FEV1 and FEF25-75 were assessed. The study was approved by the Research Ethics Committee and the Health Research Authority of the NHS (20/WM/0024). Results: 219 patients were identified for this initial analysis. The population consisted of 104 (47.5%) males and the mean age was 44.7 y ± 18.9 with a BMI of 28.2 ± 6.5. 28 (12.8%) demonstrated airflow limitation in pre-BDR tests. The mean difference in pre and post bronchodilator %predicted FEV1was 9.7 (95% CI = 8.7-10.8) and 22.3 (95% CI = 19.7-24.9) %predicted FEF25-75; (P &lt; 0.01 for both). In total 73 (33.3%) demonstrated BDR in FEV1, 101 (46.1%) in FEF25-75. All of those with significant BDR response in FEV1 had a significant response in FEF25-75. The BDR in FEF25-75 was noted to be the lowest in severe cases, with no distinctive differences in other patients' characteristics. Conclusions: This study confirms the presence of BDR in more adults with asthma using measures of small airways function than FEV1. It is unclear whether this represents a separate phenotype of asthma.