A medical apparatus flow restrictor includes a housing having an inlet housing member (102) defining an inlet (104) and a separate outlet housing member (110) mated with said inlet housing member and defining an outlet (112) from the flow restrictor. A fluid path is defined through the housing members between the inlet and outlet. Opposed flow restriction surfaces (116,118) are defined between at a location along the fluid path such that fluid delivered to the inlet passes between the opposed flow restriction surfaces prior to flowing from the outlet. The opposed flow restriction surfaces have a relative degree of surface roughness and opposed surface area defined as a function of a desired flow rate of fluid through the restrictor.
