A patient support structure that employs fluid pressure to fluidize granular material for patient support. Fluidizable granular material is received within the structure atop a fluid diffuser surface. Separate plenum chambers are located below the diffuser surface with each plenum chamber being associated...http://www.google.es/patents/US4637083?utm_source=gb-gplus-sharePatente US4637083 - Fluidized patient support apparatus
