Abstract: Pump assemblies for use with an IV set are described herein. A pump assembly includes a rotatable crank, a piston rod, and a diaphragm assembly. The crank includes a crank profile defining a plurality of lobes. The piston rod includes a first follower and a second follower spaced apart from the first follower. The rotation of the crank relative to the piston rod causes the piston rod to reciprocate relative to the crank. The diaphragm assembly includes a housing and a diaphragm member. The diaphragm member is coupled to the housing and cooperatively defines a volume in fluid communication with the IV set. The diaphragm member is movable between an extended position configured to draw in fluid from the IV set and a contracted position configured to expel fluid into the IV set. The diaphragm member is coupled to the piston rod to reciprocate the diaphragm member.