Cough reflex induced by capsaicin inhalation in patients with dysphagia

We conclude that the capsaicin inhalation test is useful to directly assess cough reflex and sensation around the larynx, while it indirectly reflects central nervous system function.

To understand the state of the cough reflex before patients with dysphagia start eating.

We studied the cough reflex by the capsaicin inhalation test in 21 patients with dysphagia and 12 healthy persons without dysphagia.

The control group showed a cough reflex at a capsaicin concentration of 2.61 μM (0.98-7.80), while patients with mild dysphagia did so at 7.28 μM (1.95-15.6), those with moderate dysphagia at 22.07 μM (15.6-62.5), and those with severe dysphagia at 71.75 μM (31.2-250). Control vs mild p < 0.01, control vs moderate p < 0.01, control vs severe p < 0.01, mild vs moderate p < 0.01, mild vs severe p < 0.01, moderate vs severe p < 0.05. There was a significant correlation between the grade of dysphagia and the threshold capsaicin concentration that provoked a cough reflex (ρ = -0.796, p < 0.001).