A system for intracorporeal gas exchange includes a flexible, rotatable shaft; a plurality of axially spaced agitation mechanisms positioned on the rotatable shaft, such that the rotatable shaft can flex between the axially spaced agitation mechanisms; a plurality of hollow gas permeable fibers adapted to permit diffusion of a gas between an intracorporeal fluid and an interior of the hollow fibers. The plurality of hollow fibers is positioned radially outward from the agitation mechanisms. A blood contacting medical system includes at least one seal, and a purge system via which a flushing fluid is introduced under pressure over a blood-side face of the at least one seal and caused to flow through a space on the blood-side face of the at least one seal. The system can further include a rotatable member. The space on the blood-side face of the at least one seal can be in fluid connection with an annular space adjacent to a rotating element operatively connected to the rotatable member.