Apparatus and method for delivering secondary fluids to a patient using an intravenous administration set feeding a primary fluid

摘要

A device for infusing a secondary fluid through a primary fluid administration set without mixing the primary and secondary fluids is disclosed. Two pistons which are releasably locked in tandem slide within a chamber having an output port, dividing the chamber into two portions. The portion having the outlet port contains the secondary fluid. One piston faces the secondary fluid, while the other has a bore which is in fluid communication with the primary administration set. The pistons can be decoupled, allowing them to move apart to create a third portion in the chamber which can fill with fluid from the primary administration set through the piston which is not in contact with the secondary fluid. When the latter piston is locked in position, a pump in the primary administration set generates pressure in the portion between the pistons. This pressure drives the piston facing the secondary fluid, forcing the secondary fluid out of the chamber and into the patient.