An interface device structured to be connected in fluid communication with a source of pressurized breathing gas and to provide a flow of pressurized breathing gas to the airways of a patient , the interface device comprising: a support ; a deformable portion situated on the support, the deformable portion having at least one high pressure side situated in a high pressure side of the interface device configured, in use, to be in contact with the flow of pressurized breathing gas; and an interface portion situated on the deformable portion and being structured to be engaged with the patient in the vicinity of the airways, the deformable portion comprising a plurality of deformable elements that form a lattice structure and that are connected with the support at a plurality of spaced apart points of connection on the support, the deformable portion further comprising a plurality of interstices situated between the plurality of deformable elements; wherein at least some of the deformable elements of the plurality of deformable elements are mutually interconnected with one another; wherein the interface portion comprises a wall , the plurality of deformable elements being connected with the wall at a plurality of spaced apart additional points of connection on the wall; wherein the interface portion further comprises a barrier apparatus that includes a barrier that extends between the support and the wall and that is formed by providing material within the interstices between some of the plurality of deformable elements at the at least one high pressure side of the deformable portion and is thus structured to resist the flow of pressurized breathing gas from flowing into contact with the plurality of deformable elements and to resist the flow of pressurized breathing gas from flowing into the interstices between the plurality of deformable elements; and wherein the barrier extends along the entirety of the exterior of the deformable portion and thus serves as a membrane that encapsulates the plurality of deformable elements and the plurality of interstices. a support ; a deformable portion situated on the support, the deformable portion having at least one high pressure side situated in a high pressure side of the interface device configured, in use, to be in contact with the flow of pressurized breathing gas; and an interface portion situated on the deformable portion and being structured to be engaged with the patient in the vicinity of the airways, the deformable portion comprising a plurality of deformable elements that form a lattice structure and that are connected with the support at a plurality of spaced apart points of connection on the support, the deformable portion further comprising a plurality of interstices situated between the plurality of deformable elements; wherein at least some of the deformable elements of the plurality of deformable elements are mutually interconnected with one another; wherein the interface portion comprises a wall , the plurality of deformable elements being connected with the wall at a plurality of spaced apart additional points of connection on the wall; wherein the interface portion further comprises a barrier apparatus that includes a barrier that extends between the support and the wall and that is formed by providing material within the interstices between some of the plurality of deformable elements at the at least one high pressure side of the deformable portion and is thus structured to resist the flow of pressurized breathing gas from flowing into contact with the plurality of deformable elements and to resist the flow of pressurized breathing gas from flowing into the interstices between the plurality of deformable elements; and wherein the barrier extends along the entirety of the exterior of the deformable portion and thus serves as a membrane that encapsulates the plurality of deformable elements and the plurality of interstices. <EOS>