Abstract: A fluid infusion positive displacement pump includes a plunger driven by a stepping motor which is operated by a motor control system. The control system advances the plunger to expel liquid in a series of incremental steps at a user-set pumping rate and until a preset total dosage has been delivered with the pumping rate being determined by the waiting time between each step. In order to minimize shock to the patient, the pump is operated at a plurality of increasing fractional rates during the start of pumping and at a plurality of decreasing fractional rates at the termination of pumping with the user-set (maximum) pumping rate occurring between such fractional rate pumping periods.

Abstract: A rotatable connecting device which provides for quick and positive interfitment between a venipuncture unit and an intravenous administration set without rotation or twisting of the venipuncture unit or intravenous tubing. A rotatable collar is provided on one of the members constituting the connecting device and is captively held thereon while permitting longitudinal movement. Frictional engaging means are disposed on the body member retaining the collar as well as the collar to provide an interference fitment. Internal threads are defined in the rotatable collar for engagement with a flange member disposed on the catheter hub. A luer lock fitment is afforded between the catheter member and the member carrying the rotatable collar.