Airway rehydration and cough
Research type
Research Study
Full title
Effect of upper airway rehydration on chronic cough and other laryngeal hypersensitivity symptoms: an exploratory study
IRAS ID
317520
Contact name
Kian Fan Chung
Contact email
Sponsor organisation
Research Governance and Integrity, Imperial College London and Imperial College Healthcare NHS Trust
Duration of Study in the UK
1 years, 0 months, 0 days
Research summary
Chronic cough is one of the commonest clinical problems encountered by doctors both in general and hospital practice that can persist for months and years. It remains a difficult problem to manage because of our poor understanding of what causes it and we have very few effective treatments to control it. Because those with a chronic cough report that changes in ambient temperature, laughing, talking on the phone for more than a few minutes, aerosol sprays, or smoky atmospheres trigger bouts of coughing, it is thought that this is caused by a state of hypersensitivity that may be caused by damage to the nerves in the back of the throat and in the voice box.
The lungs emit 25% of daily amount of water lost in moistening the dry air that we inhale which results in water evaporation from the upper airway mucus and from exhalation of moist air (13). We have put forward the possibility that loss of water from the surface of the throat and voice box that happens in dry weather and when we speak leads to a drying process that will serve to stimulate the hypersensitive nerves in this area, creating this hypersensitivity that leads to the chronic cough. It is possible to rehydrate these surfaces by nasal inhalation of hypertonic salt droplets and we wish to find out whether this rehydration process will help reduce chronic cough. Therefore, in this project, we wish to find out whether the airway surface of the throat and voice box is dehydrated in people with a chronic cough and whether when one restores the hydration of this surface the cough would be improved.Lay Summary of Results
This research project was carried out by Imperial College London. This research project was funded by Sensory Cloud, Inc. in Boston, MA, USA, a company based in Boston who has developed the aerosol spray of salt solutions used in this study. This fund has been paid to Imperial College London and covered the investigators’ time spent in the project. The persons involved in the conduct of the study are being paid for their time through this research grant. The study took place at the Royal Brompton Hospital Clinical Studies Unit, Fulham Road, London SW3 6HP. Participants were recruited from the Royal Brompton Hospital Chronic cough clinic. The study started in April 2023 and ended in November 2024.
Chronic cough is a very common clinical problem encountered by doctors and remains a difficult problem to treat because there are very few effective treatments to control it. There is evidence to support that this condition represents a cough hypersensitive state that may be caused by damage to the nerves in the back of the throat and in the voice box. We wished to test the possibility that this hypersensitivity of the nerves is caused by the dehydration of the lining of the voice box through evaporation from the mucus in the upper airway and from exhaling moist air.
In this study, we used an alkaline hypertonic divalent salt (alkaline HDS) solution spray that is breathed through the nose so that the spray deposits on the surface of the voice. This has the effect of rehydrating the dehydrated surface of the voice-box, which we believe would reduce the cough hypersensitivity and therefore reduce the cough of people suffering from a chronic dry cough.
Therefore, we conducted an exploratory, single-blinded, nasal saline-controlled study in 12 participants suffering from a chronic cough that has lasted for at least 2 months and that has not responded to any available treatments. We examined whether the chronic cough counted using a digital cough monitor watch will be reduced by this alkaline HDS composition (SC001) administered by nasal inhalation. As a control solution, we used nasal saline solution inhaled through the nose delivered from the same hand-held pump spray aerosol device. Each subject was monitored continuously using a digital cough monitor watch for 1 week of baseline, 1 week of control treatment and 1 week of active treatment.
We found that the baseline daily cough rates ranged from 4 to 34 coughs per hour with mean visual analogue score of 65 over 100. The cough reduction rate after adjusting for the effect of the control-saline spray ranged from 15% (p=0.015) (from Day 1) to 23% (p=0.002) (from Day 3). Control-adjusted efficacy was highest with SC001 pH 9 (n=5), ranging from 25% (p=0.03) (from Day 1) to 35% (p=0.02) (from Day 3), and lowest for SC001 pH 8 (n=7), ranging from 9% (p=0.08) (from Day 1) to 16% (p=0.02) (from Day 3). No adverse events were reported. P values are the statistical values and the quoted values are all within the significant range.
We conclude that the alkaline (pH 9) HDS aerosol is a promising treatment for refractory chronic cough and should be further evaluated.
This study has been published in the European Respiratory Journal Open Research. The full publication is as follows: Abubakar-Waziri H, Edwards DA, Bhatta DB, Hull JH, Rudd M, Small P, Chung KF. : Inhaled alkaline hypertonic divalent salts reduce refractory chronic cough frequency. ERJ Open Res. 2024 Oct 7;10(5):00241-2024.
Future larger studies are being prepared by the sensory Cloud Inc company. The results of this small study is also leading to the study of the way in which this HDS aerosol works by reducing the cough hypersensitivity.Has the registry been updated to include summary results?: No
If yes - please enter the URL to summary results:
If no – why not?: The study is not in a registry.
However, a paper has been published in a journal as indicated below:Inhaled alkaline hypertonic divalent salts reduce refractory chronic cough frequency.
Abubakar-Waziri H, Edwards DA, Bhatta DB, Hull JH, Rudd M, Small P, Chung KF.
ERJ Open Res. 2024 Oct 7;10(5):00241-2024. doi: 10.1183/23120541.00241-2024. eCollection 2024 Sep.
PMID: 39377090Did you follow your dissemination plan submitted in the IRAS application form (Q A51)?: Yes
If yes, describe or provide URLs to disseminated materials: A publication has been acheived as below:
Inhaled alkaline hypertonic divalent salts reduce refractory chronic cough frequency.
Abubakar-Waziri H, Edwards DA, Bhatta DB, Hull JH, Rudd M, Small P, Chung KF.
ERJ Open Res. 2024 Oct 7;10(5):00241-2024. doi: 10.1183/23120541.00241-2024. eCollection 2024 Sep.
PMID: 39377090The work has also been presented at the European Respiratory Society meeting in Vienna in September 2024.
If pending, date when dissemination is expected:
If no, explain why you didn't follow it:
Have participants been informed of the results of the study?: Pending
If yes, describe and/or provide URLs to materials shared and how they were shared:
If pending, date when feedback is expected: 28/02/2025
If no, explain why they haven't:
Have you enabled sharing of study data with others?: No
If yes, describe or provide URLs to how it has been shared:
If no, explain why sharing hasn't been enabled: We think that this results are preliminary and wiull do so with confirmation b y other follow-up studies taht are being planned by Sensory Cloud Inc.
Have you enabled sharing of tissue samples and associated data with others?: No
If yes, describe or provide a URL:
If no, explain why: There were no tissue samples to share.The dat obtained is ponly limited to 12 participants.
REC name
London - Surrey Borders Research Ethics Committee
REC reference
22/LO/0832
Date of REC Opinion
22 Nov 2022
REC opinion
Favourable Opinion