Discussion
cough, cough disorders, cough airflow, breathing and breath
ADVERSE EVENTS
A wide body of literature exists on the delivery of various stimuli during cough inhalation challenges (Here, we selected high concentrations of a volatile ester, EB, with previous applications in chemosensory and food industry research to characterize both psychophysical and physiological cough parameters via airborne inhalation using olfactometry among healthy men and women. Results demonstrated that 20%–60% v/v concentrations of EB–paraffin oil liquid dilutions elicited cough in 70% of participants in our sample. This rate of cough responsiveness appears consistent with some other tussigenic agents. Similar rates of coughing in healthy adults have been reported to inhaled citric acid (80% of participants at 32% concentration or below; Participants reported no adverse events with inhaled EB. Volatile esters have been deemed safe for use in foods (To our knowledge, this is the first study to use dynamic olfactometry, a highly controlled system for delivering odorant stimuli in smell research (Given that EB is airborne, additional methodologies from the chemosensory sciences provide further guidance in addressing important factors in human psychophysics experiments. Namely, olfactory and other forms of sensory adaptation to EB may occur (In addition to further validation studies using chemosensory stimuli to elicit cough, there are clinical implications. Given that as many as 214 cough triggers were identified among patients with CHS (Our study failed to find a significant difference in cumulative cough frequency between baseline breathing and breath control techniques. One potential explanation for this observation is that too few coughs were produced at baseline at the selected concentrations of inhaled EB. We hypothesize that higher EB concentrations might result in a more pronounced difference in cumulative coughs, as well as changes in cough airflow parameters. This hypothesis should be tested in future cough studies. Following breath control, the observed discrepancy in changes in the psychophysical properties of UTC, but not the output of cough frequency, suggests that these cough measurements provide different information. As such, clinicians who assess and treat cough disorders may benefit from viewing a patient's cough from both a sensory and motor perspective.We readily acknowledge the limitations of this study. First, only healthy individuals without cough complaints were tested using inhaled EB in a controlled laboratory setting. This makes it challenging to generalize the present findings to patients with CHS. It remains unknown whether patients would temporarily experience reduced UTC following breath control and how long this effect would last. We advocate for further research among patients with cough disorders, in particular to adapt feasible and clinically meaningful methods with chemosensory stimuli for assessment and treatment. Additionally, future investigations are warranted in chemosensory-induced cough that targets components of speech therapy other than breath control, such as psychoeducational counseling. Such studies would better elucidate which specific aspects of behavioral interventions influence improvements in clinical cough outcomes.