US Patent 7287528 Cushion inside a cushion patient interface

A patient interface device including a cushion assembly having a cushion-in-a-cushion arrangement and a system for supplying a flow of gas to a patient using such an interface device. The patient interface includes a mask shell having a patient side and an outer side opposite the patient side adapted for receiving a supply of gas. A seal cushion contacts a first area of a patient's face to form a seal therewith. A support cushion encircles the seal cushion and includes a first end portion that contacts a second area of a patient's face.