An infusion system for administering multiple infusates at individually programmable rates, volumes, and sequences in any order from any one or more of plural fluid input ports through a patient output port and into the circulatory system of a patient. Infusates may be either continuously or time sequentially administered, and infusates may be either intermittently administered at selectively regular intervals or in time overlap to administer a dilution. Various error conditions are automatically detected and alarms generated in the event of conflicts between infusates, to identify times of no infusions, and to identify system malfunctions. The system is selectively operable, among others, in a priming mode, a maintenance mode, a normal-on mode, and a manual override mode, The system is operative to adapt actual to desired flow rates in normal operation. All fluids flow through a unitary disposable cassette without making any other system contact. Air bubbles in the fluid line are automatically detected and disposed of. Fluid pressures are monitored and system operation adjusted as a function of such pressures. Infusates may be administered from syringes as well as from standard bag or bottle containers. Infusate from a selected input port may be controllably pumped into a syringe for unsticking the syringe plunger. The system is selectively operable to adjust total fluid volume and rate to below preselected values for patients whose total fluid intake must be restricted. The system is operable to maintain an accurate record of total infusion history.