Bronchoprotective effect of deep inspirations in cough variant asthma: A distinguishing feature in the spectrum of airway disease?

Purpose: To assess the effect of deep inspirations (DIs) on airway behaviour in individuals with classic asthma (CA), cough variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) during bronchoprovocation.

Methods: Twenty-five adults (18 female; 44.8 ± 12.3 years (Mean ± SD); n = 9 CA, n = 9 CVA, and n = 7 COUGH) completed two single-dose MCh challenges, with and without DIs. Bronchoprotection was assessed by comparing changes in bronchoconstriction (FEV1, FVC, FEV1/FVC, FEF50, FEF25-75), gas trapping (RV, RV/TLC) and impulse oscillometry (IOS) measurements.

Results: The% changes in FEV1 with and without DIs were not significantly different within any group. Decreases in FEF50 and FEF25-75 were greater in CA (p = 0.041 and p = 0.029), decreases in FVC (% predicted) and FEV1/FVC(%) were less in CVA (p = 0.048 and p = 0.010), and increases in RV (L) and RV/TLC (% predicted) were less in COUGH (p = 0.007 and p = 0.028), respectively. No differences in IOS measurements were noted.

Conclusions: DIs triggered bronchoconstriction in CA, bronchoprotection in CVA, and prevented gas trapping in COUGH.