Positive expiratory pressure: a potential therapy to mitigate acute bronchoconstriction in the asthma of obesity

Abstract

Late-onset nonallergic (LONA) asthma in obesity is characterized by increased peripheral airway closure secondary to abnormally collapsible airways. We hypothesized that positive expiratory pressure (PEP) would mitigate the tendency to airway closure during bronchoconstriction, potentially serving as rescue therapy for LONA asthma of obesity. The PC₂₀ [provocative concentration of methacholine causing 20% drop in forced expiratory volume in 1 s (FEV1)] dose of methacholine was determined in 18 obese participants with LONA asthma. At each of four subsequent visits, we used oscillometry to measure input respiratory impedance (Z_rs) over 8 min; participants received their PC₂₀ concentration of methacholine aerosol during the first 4.5 min. PEP combinations of either 0 or 10 cmH₂O either during and/or after the methacholine delivery were applied, randomized between visits. Parameters characterizing respiratory system mechanics were extracted from the Z_rs spectra. In 18 patients with LONA asthma [14 females, body mass index (BMI): 39.6 ± 3.4 kg/m²], 10 cmH₂O PEP during methacholine reduced elevations in the central airway resistance, peripheral airway resistance, and elastance, and breathing frequency was also reduced. During the 3.5 min following methacholine delivery, PEP of 10 cmH₂O reduced A_x and peripheral elastance compared with no PEP. PEP mitigates the onset of airway narrowing brought on by methacholine challenge and airway closure once it is established. PEP thus might serve as a nonpharmacological therapy to manage acute airway narrowing for obese LONA asthma. NEW & NOTEWORTHY Standard pharmacological treatments are not effective in people with obesity and asthma. We assessed the efficacy of positive expiratory pressure (PEP) as a therapy to mitigate airway hyperresponsiveness in the asthma of obesity. Our results indicate that PEP might serve as a nonpharmacological therapy to manage acute airway narrowing in obese individuals with late-onset nonallergic asthma.