An automatic pump relay system includes controllers coupled to drivers for sequentially discharging fluid from a plurality of medication containers into a coupler having a reflux barrier from which fluid is administered to a patient. The internal fluid pressure of the coupler is determined by a pressure sensing device or devices that provide signals to the controllers that, based at least on the sensor signals, cause the drivers to operate in reverse and forward directions so as to rapidly decrease and raise the fluid pressure within the coupler during a relay from an empty syringe to a filled syringe, thereby avoiding bolus formation and an interruption in infusion therapy. Independently operable syringes pumps are contemplated to be connected in relay fashion to form a modular system. An associated method is also disclosed wherein a fluid administration pressure is stored for use as a reference during a syringe changeover.
