Autonomic Function in Chronic Cough

Abstract

The autonomic nervous system allows the body to respond to changes in the environment by regulating processes, such as heart rate, blood pressure and body temperature. These unconscious processes change throughout the day, often in response to changes in your environment, such as standing up from a sitting position, or a change in temperature. In some individuals the autonomic nervous system does not respond correctly, causing issues in their day to day well being. This is known as autonomic dysfunction. Coughing is controlled by some of the nerves of the autonomic nervous system and therefore I have investigated the association between chronic idiopathic cough, a condition where patients suffer from a cough with no obvious cause, and autonomic dysfunction. It is thought that chronic cough is due to hypersensitive airway nerves, causing people to cough in response to things which would not normally cause irritation. In other diseases with over-sensitive nerves there is also a dysfunction of the autonomic nervous system. This is the first time that autonomic function has been investigated in this patient group. By looking at changes in patients' heart-rates and blood pressures during autonomic tests and comparing them to a healthy control group, I have shown that chronic cough patients do not have normal autonomic responses. Scores from the COMPASS 31 autonomic symptom questionnaire show that chronic cough patients also suffer from more symptoms of autonomic dysfunction than healthy controls. I have also found that chronic cough patients are more likely to suffer from high blood pressure (hypertension) than healthy subjects, despite not exhibiting the usual risk factors associated with this condition. I have also investigated the effects of cough on heart-rate and blood pressure. In healthy subjects, even one single cough causes a rise in heart-rate and a drop in blood pressure. Peals of voluntary coughs and cough caused by inhaling chilli extract have a greater effect on both heart-rate and blood pressure. This effect differed in healthy volunteers and chronic cough patients, with the patient group taking longer for their measurements to return to normal. All of this information suggests that people suffering from chronic cough also show signs of autonomic dysfunction.

Date of Award	1 Aug 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Jacky Smith (Supervisor), Angela Kelsall (Supervisor) & Douglas Corfield (Supervisor)