Patent ID: 8128616

Claim:
A system for delivering a therapeutic substance at a flow rate to a patient, comprising: a reservoir for holding said therapeutic substance; a delivery path of a known volume operatively coupled to said reservoir and adapted to be operatively coupled to said patient; an adjustable metering device arranged along said delivery path capable of controlling a flow rate of said therapeutic substance to said patient; a controller operatively coupled to said adjustable metering device, said controller being configured to transition from delivery of a first therapeutic substance at a first flow rate to delivery of a second therapeutic substance at a second flow rate; said controller being configured to deliver said first therapeutic substance to said patient at a known flow rate, being configured to calculate a bridge duration equal to said known volume divided by said known flow rate; and being configured to control said adjustable metering device in order to control said flow rate following introduction of said second therapeutic substance into said reservoir such that: if said second flow rate is lower than said first flow rate, said adjustable metering device being configured to control said flow rate at said second flow rate at least as soon as said bridge duration is over; and if said second flow rate is higher than said first flow rate, said adjustable metering device being configured to control said flow rate at said second flow rate at least as late as when said bridge duration is over.