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 gas between 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 seal and caused to flow through a space on the blood side of the seal. The system can further include a rotatable member. The space on the blood side of the seal can be in fluid connection with an annular space adjacent to a rotating element operatively connected to the rotatable member.