Altering Cough Reflex Sensitivity with Aerosolized Capsaicin Paired with Behavioral Cough Therapy

The feasibility of treating patients with cough hypersensitivity with a progressive desensitization model was suggested to be effective through our preliminary study conducted last year. We exposed five heathy participants to progressive doses of aerosolized capsaicin, a known cough stimulant, while implementing cough suppression strategies. All five participants achieved a reduction in cough sensitivity following treatment. We will now use the same research model with patients with chronic refractory cough (CRC). The study will commence in three phrases. The baseline phase will consist of the following measures: (1) cough sensitivity testing using increasing concentrations of pharmaceutical-grade aerosolized capsaicin, delivered via a Koko digidoser with nebulizer. We will determine the capsaicin concentration that causes two coughs (C2) and five coughs (C5); (2) cough-related quality of life with the Leicester Cough Questionnaire (LCQ); and (3) 24-hour cough frequency measured with surface electromyography of the abdominal muscles. Participants will then be randomly assigned to treatment or placebo group. The Treatment phase will consist of 5-6 treatment sessions, during which participants will be exposed to increasing concentrations of aerosolized capsaicin (treatment) or aerosolized saline (placebo). Participants will implement behavioral cough therapy techniques after each exposure. In the post-treatment phase, the same outcomes measured used in the baseline phase will be measured at one and three-weeks post-treatment. We hypothesize, participants in the treatment group will have higher C2 and C5 scores (i.e., less cough sensitivity), and higher LCQ scores, following treatment