Medical device that is worn by a patient and that assists breathing by oscillating the chest wall; medical oscillation clothing that is worn by a patient and that assists breathing by oscillating the chest wall; chest wall oscillation vests; medical apparatus, namely, invasive and non-invasive ventilation apparatus and instruments; medical ventilators; portable electro-mechanical medical device, namely, a mechanical insufflation-exsufflation device used to clear secretions from the lungs; portable electro-mechanical medical device, namely, a mechanical insufflation-exsufflation device that applies alternating positive and negative pressure to a patient's airway to assist in clearing secretions