• Masashi Kanezaki, Kunihiko Terada, and Satoru Ebihara.
• Department of Physical Therapy, Faculty of Health Care Sciences, Himeji Dokkyo University, Himeji, Hyogo, Japan. Electronic address: kmasashi@gm.himeji-du.ac.jp.
• Chest. 2020 Jun 1; 157 (6): 1455-1465.

BackgroundInhalation of L-menthol as a transient receptor potential melastatin 8 agonist induces a cooling sensation in the airway. This cooling sensation induced through olfactory stimulation by L-menthol (OSM) alleviates dyspnea in healthy humans. Therefore, we investigated effects of OSM on the neural respiratory drive (NRD) and multidimensional aspects of dyspnea induced by inspiratory resistive loaded breathing in COPD.MethodsIn total, 28 patients with COPD and 14 control participants were included in this randomized, single-blinded, placebo-controlled, crossover study. OSM was administered using an L-menthol-scented patch, whereas placebo was administered using olfactory stimulation by strawberry-scented patch: placebo (OSP). Sham condition was measured by breathing through a face mask without a OSP. Dyspnea was evoked by breathing through the inspiratory resistance of 20 or 30 cm H2O/L/s and measured using the Multidimensional Dyspnea Profile. NRD was estimated using the electromyogram activities of the parasternal intercostal muscles.ResultsCompared with sham and OSP, OSM did not alter the breathing pattern/timing and NRD during inspiratory resistive loading; however, it significantly alleviated the physical and mental breathing effort, air hunger, breathing discomfort, anxiety, and fear during inspiratory resistive loaded breathing in patients with COPD. However, although OSM reduced the air hunger, mental breathing effort, and unpleasantness, no significant improvement on affective dimension of dyspnea by OSM was observed in control participants.ConclusionsOur findings suggest that OSM activated the sense of inspiratory flow that achieved dyspnea relief in patients with COPD.Trial RegistryUMIN Clinical Trials Registry (UMIN-CTR); No.: UMIN000033822; URL: https://www.umin.ac.jp/ctr/index.htm.Copyright © 2020 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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