Background:Alleviating breathlessness is a primary focus in the routine management of patients with interstitial lung disease (ILD). However, therapeutic options for breathlessness in patients with ILD are limited. We performed a randomized controlled trial to investigate the effect of olfactory stimulation with L-menthol (OSM) on breathing patterns, inspiratory neural drive (IND), and the sensory and affective dimensions of dyspnoea induced by inspiratory resistive loading in patients with ILD.

Methods: We contacted 52 patients with stable fibrotic ILD. Of these, 43 underwent interventions to investigate the effect of OSM on breathlessness. Dyspnoea during inspiratory loaded breathing was evaluated using the Japanese version of the Multidimesional Dyspnoea Profile. The IND was assessed by EMGpara%max.

Results:OSM significantly decreased breathing discomfort during inspiratory resistive breathing compared to sham and placebo. OSM significantly reduced air hunger compared with sham and placebo, and mental and physical breathing effort compared with placebo. However, L-menthol caused no significant changes in chest tightness or hyperpnoea during inspiratory resistive-loaded breathing. In addition, L-menthol did not significantly affect the affective component during inspiratory resistive breathing. No significant differences were found in T_I, T_E, T_I/T_TOT, F_b, V_T, and mean inspiratory flow rate among the sham, active, and placebo conditions. In addition, there were no significant changes in EMGpara%max among conditions.

Conclusion: L-menthol is an effective and safe adjunctive therapy for the palliation of dyspnoea in patients with ILD.