A Prospective Trial of Behavioral Therapy for Chronic Cough

This study seeks to explore whether heart rate variability (HRV) biofeedback can be effective in the treatment of chronic cough. Chronic cough has many causes, including asthma, postnasal drip, and gastroesophageal reflux disease (GERD), each with a specific treatment. However, among a subset of cough patients, no clear cause is found despite extensive workup, and traditional treatment methods do not provide relief. Several studies revealed less common causes of chronic cough and disordered breathing such as vagal neuropathy, paradoxical vocal fold motion, and stress. Additional research identified links between the neurological networks that produce the cough reflex and those that maintain normal breathing. HRV biofeedback is a self-regulation technique that uses computer equipment to monitor heart rate and breathing, two key functions of the autonomic nervous system. By using this non-invasive behavioral technique, cough patients can regulate their breathing and autonomic function, potentially leading to improved autonomic balance and a reduction in cough symptoms.

Randomized controlled trial of 3 groups: 1) standard voice therapy 2) voice therapy and heart rate variability biofeedback and 3) heart rate variability biofeedback

(Group 1) will undergo active training in behavioral cough suppression and laryngeal relaxation exercises, but will not receive HRVB. Traditional cough suppression and laryngeal relaxation exercises include pursed lip breathing, swallowing (water, lozenge, gum, ice chips), sustained semi-occluded voicing, discussion and mitigation of triggers, maintaining a cough journal, addressing muscle tension dysphonia if indicated, and developing prophylaxis suppression and laryngeal relaxation based on stimulability. Participants in Group 1 will receive handwritten guidance indicating exercises to practice at home.

Voice therapy as described in Arm 1. HRVB involves measure respiratory rate, heart rate, body temperature and skin conductance. Participants are guided through reduced breathing rate until a resonant frequency is attained. HRVB breathing simulates resonance between the baroreflex rhythm and respiration based rhythm, increasing heart rate variability and baroreceptor sensitivity. Evidence suggests HRVB improves autonomic regularity. We propose this novel modality to address centrally regulated hypersensitivity that perpetuates coughing.

HRVB as indicated in Arm 2. No instruction will be provided for cough suppression, laryngeal desensitization, voice tasks or hygiene that traditionally reduces cough frequency and severity. This is the experimental arm.

Inclusion Criteria: 8+ weeks of cough, Fluent English speaker, Have access to an electronic mobile device Exclusion Criteria: On neuromodulator therapy, cardiac arrhythmia, dysphagia, prior HRVB or mindfulness, head and neck surgery of the oropharynx, neck or larynx, lung surgery, pulmonary pathology other than asthma, tourette syndrome, ACE inhibitor use, current or recent smoker. Added exclusion criteria as of March 2020 - history of COVID+.