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Title: Respiratory physiology in chronic cough
Author: Kelsall, Angela
ISNI:       0000 0001 3596 844X
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2008
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Introduction: Varying methods of cough quantification have been used to describe cough frequency, although there is no consensus which method best relates to subjective rating of cough. With increased availability of semi-automated cough recording devices, the capability to carryout anti-tussive studies is greatly increased. However, there is no data available describing the magnitude of change in cough frequency necessary to provide therapeutic benefit. Female patients are over represented in specialist cough clinics. There is little data describing pulmonary function and airway inflammation in phenotyped patients and how these measures may relate to objectively measured cough. Airway inflammation isa common feature of chronic cough, regardless of the trigger for cough. The repetitive mechanical insult of the act of coughing may be responsible for the presence ofthis inflammation. Methods: 100 patients with unexplained chronic cough under went full diagnostic testing in order to determine potential triggers for cough. Procedures included pulmonary function testing; (spirometry, eND, EBC pH, BHR, Cough challenge, induced sputum, objective and subjective cough monitoring), Bronchoscopy, 24 hour impedance monitoring with simultaneous cough monitoring, Gastroscopy and ENT. A subset of cough recordings were quantified in cough sounds, cough seconds and cough epochs to determine the best way to quantify cough. 20 healthy volunteers performed voluntary coughing manoeuvres to determine the acute effects of coughing on airway function and inflammation. Results: Cough sounds and seconds correlate moderately with subjective and QDL . methods. Patients reported a reduced cough frequency whilst undergoing impedance testing; a reduction of33% was seen although patients were unable to quantify the scale of change. Female patients coughed substantially more than male patients, with the largest difference seen at night. Cough frequency was predicted by gender, C5 and age. Cough frequency was not related to a specific trigger for cough. Reduced small airway flows were seen that were independent of BHR. Prominent airway neutrophilia was seen regardless of the trigger for cough. Acute changes in eND and EBC were seen after short periods ofvoluntary coughing. Sputum inflammatory mediator levels showed huge variability and did not change as a result of coughing. Bronchodilation ofthe small airways was also seen after coughing. Conclusion: The use of objective cough monitoring has enabled me for the first time to describe the most appropriate current methods of cough quantification and to demonstrate the magnitude ofreduction in cough frequency that is appreciated by -patients.-I-havereportedimportant significant genderdifferences in cough frequency and shown that cough frequency is predicted not only by gender but also age and cough reflex sensitivity showing important implications for underlying mechanisms of chronic cough. I have also shown for the first time that pulmonary function measures are reduced in patients without indication of asthma. The mechanical act of coughing causes acute bronchodilation of small airways and reduces eND and EBC pH.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available