Patent ID: 7255683

Claim:
A system for detecting the status of a vent associated with a fluid container upstream of an infusion pump configured to draw fluid out of the fluid container through a fluid line by means of a pump mechanism in engagement with the fluid line, the vent having an open status at which the vent allows air to vent into the fluid container as fluid is drawn out of the fluid container resulting in pressure in the fluid line reducing at a rate expected under normal venting conditions, the vent having a blocked status at which venting of air into the container is blocked as fluid is drawn out of the fluid container resulting in pressure in the fluid line progressively reducing at a rate in excess of the rate expected under normal venting conditions, the system comprising: a pressure sensor located upstream of the pump mechanism, the pressure sensor configured to provide pressure signals representative of the pressure within the fluid line upstream of the pump mechanism; a processor in communication with the pressure sensor, the processor configured to sample the pressure signals received from the pressure sensor over a plurality of selected pump cycles, to compute for each of the plurality of selected pump cycles an average pressure value from the pressure signals received, to determine a progressive reduction in pressure in the fluid line based at least on the computed average pressure values, and to generate a blocked vent alert when the progressive reduction in pressure in the fluid line is determined to be at a rate in excess of the rate expected under normal venting conditions.