Exercise‐induced Bronchoconstriction does not Change the Configuration of the Maximal Expiratory Flow‐Volume Curve in Adults with Asthma

• Published in: The FASEB journal 2022-05, Vol.36 (S1), p.n/a
• Main Authors: Luu, Peter, Klimenko, Oksana, Klansky, Andrew, Noggle, Nathan, Petrics, Greg, Haverkamp, Hans C.
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.2022.36.S1.R6131

Background Several indices of airflow and volume derived from the maximal expiratory flow volume (MEFV) curve are used to identify and diagnose the severity of respiratory disease. In addition to the objective measures of expiratory airflow and volume, the shape of the MEFV curve is thought to provide information on pulmonary (patho)physiology. In the asthmatic, the MEFV curve is often convex relative to the volume axis (“scooped”). This “scooped” curve is thought to indicate heterogeneous airway emptying during the forced exhalation. The effect of exercise‐induced airway narrowing on the shape of the MEFV curve is not known. The purpose of this study was to determine the effect of exercise‐induced bronchoconstriction (EIB) on the shape of the MEFV curve in asthmatic adults. We hypothesized that the slope‐ratio (SR) index, and thus the overall shape of the MEFV curve would not be affected by EIB. Methods Adult male and female asthmatics (n=9; age, 26.8 ± 8.4 yrs; BMI, 27.4 ± 4.3 kg/m2) and non‐asthmatics (n=9; age, 25.4 ± 7.8 yrs; BMI, 21.9 ± 2.0 kg/m2) completed a high‐intensity cycle ergometry bout for six minutes at 85% of peak power. Maximal forced exhalations (MFE) were performed before exercise. Following exercise cessation, subjects remained on the ergometer and performed a MFE every two‐minutes for a total 20 minutes. In each MEFV curve, the SR index was calculated in 1% volume increments between 20% and 80% of the vital capacity. To calculate SR, the tangent and chord slope were generated at each point of interest, and the tangent slope was divided by the chord slope. Results Pulmonary function at baseline was lower in asthmatics compared to the control group (FEV1% predicted, 84.9 ± 11.0 vs. 96.5 ± 12.2% in asthmatics vs. control, respectively; P