An extracorporeal gas exchange device includes a housing, a rigid shaft rotatable within the housing, a plurality of agitation mechanisms positioned on the rigid shaft, and a plurality of hollow gas permeable fibers adapted to permit diffusion of gas between fluid flowing within the housing and an interior of the plurality of hollow gas permeable fibers. The plurality of hollow gas permeable fibers are positioned radially outward from the plurality of agitation mechanisms. The rotational speed of the rigid shaft is adjustable independent of the flow rate of fluid through the housing.