Effects of olfactory stimulation with L-menthol on sensations of discomfort on exertion in patients with chronic lung diseases.

BACKGROUND

Olfactory stimulation with L-menthol may reduce certain discomfort sensations, including dyspnea. Chronic obstructive pulmonary disease (COPD) and idiopathic interstitial pneumonias (IIPs) have distinct physiological characteristics and may elicit different qualitative sensations of dyspnea. Therefore, the qualitative effects of L-menthol inhalation on dyspnea may differ between these chronic lung diseases (CLDs). This study aimed to determine which aspects of dyspnea are influenced by olfactory stimulation with L-menthol in patients with CLDs.

METHODS

Thirty-four patients with stable COPD or IIPs (17 each) performed a 6-min walk test (6MWT) under two conditions: wearing a surgical mask alone (control) or wearing a mask with a peppermint oil aroma sticker (0.105 ml, containing 30% L-menthol). A modified Borg scale, the Multidimensional Dyspnea Profile (MDP), and the Language of Dyspnea Questionnaire (LDQ) were used to evaluate endpoints. The 6MWT was selected to induce breathlessness with and without L-menthol.

RESULTS

In the COPD group, L-menthol significantly improved Mental breathing effort on the MDP, and Rapid, Gasping, and Air hunger on the LDQ. In the IIPs group, L-menthol improved only the MDP Hyperpnea dimension. No significant differences were observed in the modified Borg scale before and after the 6MWT between L-menthol and control conditions in either group.

CONCLUSIONS

Olfactory stimulation with L-menthol selectively improved aspects of dyspnea in patients with COPD and IIPs, likely reflecting differences in the pathophysiology and severity of each disease.

TRIAL REGISTRATION: Japan Registry of Clinical Trials (jRCTs031200400).