Before we get started: what is a cough?

Cough is an airway defensive reflex consisting of an inspiratory phase followed by a forced expiratory effort initially against a closed glottis, followed by active glottal opening and rapid expiratory flow. The expiration reflex (ER) differentiates from cough for the lack of a preparatory inspiration. The reflexes subserve different functions: cough will clear the lower airways from debris and mucus, while the expiration reflex will prevent aspiration. Clinically, a cough epoch is a sequence of motor acts resulting from a combination of true coughs and ERs that need to be accurately identified and measured for adequate quantitative description.