A cushion member for a patient interface device that includes a main body portion including a plurality of chambers and a self-sealing cap portion coupled to the main body portion. The cap portion covers each of the chambers and forms a plurality of membrane members, with each membrane member being positioned over and sealing a respective one of the chambers. The cap portion is made of a self-sealing material such that that each of the membrane members is structured to self-seal responsive to having a needle inserted through and pulled out of the membrane member. Also, an apparatus and a method for selectively adjusting the internal pressure of the chambers of such a cushion.