A pneumatic cushion for a wheel chair and the like is disclosed which comprises an air housing box, a plurality of air opening sin the air housing box, and a plurality of air channels communicating with an air supply the air channels communicate with the air openings to deflate and inflate individual...http://www.google.de/patents/US5379471?utm_source=gb-gplus-sharePatent US5379471 - Pneumatic wheel chair cushion for reducing ischemic injury
