A medical device includes a constant-flow pump configured to pump a fluid through a fluid conduit and a rotary valve fluidically connected to the pump. The rotary valve includes at least one rotatable valve member configured to be operatively connected to and rotate relative to the fluid conduit. The rotatable valve member includes at least one aperture. The rotatable valve member is capable of being positioned in a plurality of positions relative to the conduit. The position of the at least one first aperture of the rotatable valve member controls fluid flow through the rotary valve, and thereby through the conduit.
