A portable high frequency chest wall oscillation (HFCWO) apparatus for the purposes of airway lung clearance and ventilation includes a circumferential chest band which is placed around a person's chest and a drive which is connected to the chest band for cyclically varying the circumference of the chest...http://www.google.sh/patents/US6736785?utm_source=gb-gplus-sharePatent US6736785 - Mechanical chest wall oscillator
