Investigating the Role of ATP Production by Airway Epithelium in Patients With Refractory and Unexplained Chronic Cough (RCC/UCC).

Inclusion criteria

for RCC/UCC:

• Patients with a history of RCC/UCC.
• Normal Chest X-ray in the last 5 years.
• No Evidence of Airflow Obstruction (FEV1/FVC ratio above LLN)
• Cough Severity VAS ≥ 40 mm at screening.

Inclusion criteria

for Healthy Controls:

• No history of chronic cough, asthma, COPD, or clinical history of bronchiectasis or interstitial lung disease
• No current smokers or those with >10 pack year history.
• No evidence of airflow obstruction ( FEV1/FVC ratio above LLN).
• Able to understand and give written informed consent.

Exclusion criteria

• Participants who are currently established on treatment and their chronic cough is well controlled.
• Unable to perform acceptable and reproducible spirometry.
• Participants with a positive covid-19 test within 2 weeks of screening.
• Current smoker or ex-smoker with ≥20 pack year smoking history and abstinence of ≤6 months
• Symptoms of upper respiratory tract infection in the last 1 month which have not resolved
• Lower respiratory tract infection or pneumonia in the last 1 month
• Asthma exacerbation in the previous month requiring an increase or start of an inhaled corticosteroid (ICS) or oral corticosteroid (OCS)
• Significant other primary pulmonary disorders in particular; pulmonary embolism, pulmonary hypertension, lung cancer, cystic fibrosis, significant radiologically proven emphysema, interstitial lung disease or bronchiectasis.
• History of psychiatric illness, drug or alcohol abuse which may interfere in the participation of the trial.
• Allergy or intolerance to sedation medication including fentanyl and midazolam, or a history of complications during procedural sedation
• Severe coagulopathy, bleeding disorder, or medical need for anti- coagulation that would increase the risk of endobronchial biopsy as determined by the investigator