Trial | NCT00977366  Report issue

Title

Neurophysiology of Cough Reflex Hypersensitivity
Pilot Study Investigating Central Sensitisation of the Cough Reflex in Subjects With Chronic Cough and Healthy Volunteers

  • Phase

    N/A

  • Study Type

    Interventional

  • Status

    Completed No Results Posted

  • Study Participants

    27
Central sensitisation is an increase in the excitability of nerves within the central nervous system, which can lead to heightened sensitivity to certain stimuli. This process is involved in some chronic pain conditions e.g. migraines and non-cardiac chest pain. Recent work by our group suggests central sensitisation may be an important mechanism leading to chronic cough.

The main questions in this study include:

Can the investigators induce temporary central sensitisation of the cough reflex in healthy volunteers for testing of new medications?
Can the investigators demonstrate exaggerated sensitisation in patients with chronic cough (indicating these patients are already centrally sensitised)?

In animal studies, acid infusion into the gullet (oesophagus) is able to induce central sensitisation of the cough reflex. Acid infusion into the oesophagus has also been shown to induce central sensitisation in human healthy volunteers, increasing the sensitivity to pain on the front of the chest but this study did not test the the cough reflex. Using human participants, the investigators plan to test whether acid infusion into the oesophagus increases the sensitivity of the cough reflex in healthy volunteers and also patients complaining of chronic cough.
Study Started
Mar 31
2010
Primary Completion
Sep 30
2012
Study Completion
Feb 28
2013
Last Update
Jun 19
2013
Estimate

Other Hydrochloric acid (0.15 molar)

Hydrochloric acid (0.15 molar) will be infused in to the lower oesophagus through a distal infusion port located at the tip of an oesophageal stimulation catheter.

Other Saline

Normal saline will be infused in to the lower oesophagus through a distal infusion port located at the tip of an oesophageal stimulation catheter.

Hydrochloric acid infusion Active Comparator

Saline Placebo Comparator

Criteria 

Inclusion Criteria:

Healthy volunteers inclusion:

Over 18 years
Measurable cough reflex sensitivity - required as is the primary end-point
No current or past history of chronic cough or chronic respiratory disease

Chronic Cough Patients inclusion:

Over 18 years
Chronic persistent cough (> 8 weeks) despite investigation and/or treatment trials for cough variant asthma/post-nasal drip and gastro-oesophageal reflux
Normal chest radiograph - primary respiratory cause for cough excluded
Normal lung function - primary respiratory cause for cough excluded Measurable cough reflex sensitivity - required as primary end-point

Exclusion Criteria:

Recent upper respiratory tract infection (<4 weeks) - this can lead to increased sensitivity of the cough reflex which resolves as the infection settles
Pregnancy/breast-feeding - unknown effects of oesophageal acid infusion
Current smokers or ex-smokers with < 6 month abstinence or history > 20 pack years - smoking can alter the sensitivity of the cough reflex
Opiate or ACE inhibitor use or centrally acting medication - can alter the cough reflex sensitivity
Symptomatic gastro-oesophageal reflux, post-nasal drip or asthma (chronic cough cohort may have been treated for these in the past but cough did not resolve) - these conditions are known to cause cough and alter cough reflex sensitivity
Significant ongoing chronic respiratory/cardiovascular/gastro-intestinal/haematological/ neurological/psychiatric illness. We are aiming to recruit healthy volunteers and chronic cough patients who are otherwise healthy
No Results Posted