Respiratory Kinematics During Voluntary and Reflex Cough in Healthy Adults

Cough is a defensive behavior that involves three stages. A large inspiratory phase, a compression phase where the vocal folds close and subglottal pressure is developed, and an expiratory phase. Cough serves to protect the upper and lower airways from material such as liquids, solids, or saliva, that have been aspirated. There are two types of cough: voluntary and reflex cough. Voluntary cough involves a cough to command. Reflex cough is a cough that is generated secondary to a stimulus in or near the airway. There has been some research regarding the differences between voluntary and reflex cough. However, no research has described the differences in airflow or movement pattern (kinematics) between the two types of cough. This study seeks to determine the respiratory kinematics and airflow differences between voluntary and reflex cough in healthy participants.

As a participant, completion of this study will require the following: Investigators will first place cotton elastic bands around your chest and abdomen so that measures of chest wall and abdominal movements can be measured. Then, tests of your breathing made from pulmonary function testing will be completed. Investigators will then have you complete a maximum inspiration followed by a maximum expiration three times. Investigators will ask you to produce a voluntary cough three times into a facemask which is attached to a computer. Then the investigators will provide you with nebulized water (FOG) through the facemask for up to a minute three times. You will have a minute break in between each presentation. Finally, the investigators will provide you with a nebulized dose of Capsaicin, which is derived from hot peppers, through the same facemask used in all of the above tasks. You will receive three doses of capsaicin and be provided with water at any time during the study.

Participants will be seated in a comfortable chair and fitted with cotton elastic bands designed to measure changes in chest wall and abdominal movement during cough. The participant will hold a facemask attached to a pneumotachograph, nebulized, and dosimeter. The participant will receive 3 nebulized doses of 200 microMolar capsaicin through the facemask. The participants will have a minute in between each presentation and water will be available at all times.

Respiratory kinematic measure: lung volume initiation (LVI) Lung volume initiation is a measure of the volume of air in the lungs prior to a respiratory task.

Airflow measures: Peak expiratory airflow rate Peak expiratory flow rate is a measure of the velocity of air expelled from the respiratory apparatus during cough. Measured in liters/second.

Urge-to-cough: A measure of respiratory sensation that rates the perceived magnitude of the need to cough on a Borg scale (0=no urge-to-cough; 10=maximal urge-to-cough).

Inclusion Criteria: Healthy adults between the ages of 18-80 years. Ability to provide informed consent. Exclusion Criteria: No history of smoking within the last 5 years as this reduces the sensitivity to capsaicin No history of neurological disease (i.e. Parkinson's disease, stroke, traumatic brain injury, etc.) No known allergy to capsaicin No history of respiratory disease (i.e. asthma, chronic obstructive pulmonary disease, or respiratory infection within the last 5 weeks.)