Arrow implantable pump

The Arrow implantable pump is non-programmable and delivers infusate (2-deoxy-5-fluorouridine, morphine sulfate, baclofen, or heparinized saline) at 3 pre-set flow rates. The pump is divided into two chambers by accordion-like movable bellows. Infusate is placed in the inner dmg reservoir chamber and Freon propellant in the outer chamber (Figure 4.19). 

Figure 4.19 The cross-sectional view of the Arrow model 3000 implantable pump, showing the pumping mechanism...

The Infusaid pump is another fixed-rate implantable pump that shares many similar features, including the Freon pumping principle, with the Arrow pump. 

Drug delivery from this pump is powered by the Freon propellant. When the Arrow pump is implanted subcutaneously, it is warmed by the patient s body temperature so that the propellant-containing chamber expands and exerts pressure on the movable bellows. Infusate is thus forced out of the reservoir chamber to an attached catheter through a filter and flow restrictor. This mechanism allows the delivery of infusate at a fairly constant rate to surrounding tissues or blood vessels. It should be noted, however, that the vapour pressure exerted by the outer chamber can be affected by changes in altitude/elevation or body temperature. 

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