Reservoir monitoring for implantable fluid delivery devices

A fluid delivery system comprising:

• an implantable fluid delivery device comprising:
• a reservoir configured to store a therapeutic fluid;
• a pressure sensor configured to sense one or more pressures within the fluid delivery device;
• and
• a processor configured to sense a pressure within the fluid delivery device using the pressure sensor as a therapeutic fluid is added to or removed from the reservoir, estimate a pressure of the reservoir based on the sensed pressure, an estimated initial temperature of the reservoir as the therapeutic fluid is added or removed based on the sensed pressure, and an estimated temperature of the therapeutic fluid based on the sensed pressure, wherein the estimated pressure of the reservoir is different than the sensed pressure, and determine a volume of the fluid added to or removed from the reservoir based on the sensed pressure and the estimated pressure of the reservoir.

A non-transitory computer-readable storage medium comprising instructions for causing a programmable processor in an implantable fluid delivery system to:

• receive a pressure within a fluid delivery device from a pressure sensor as a therapeutic fluid is added to or removed from a reservoir of the device;
• estimate a pressure of the reservoir based on the sensed pressure, an estimated initial temperature of the reservoir as the therapeutic fluid is added or removed based on the sensed pressure, and an estimated temperature of the therapeutic fluid based on the sensed pressure, wherein the estimated pressure of the reservoir is different than the sensed pressure;
• and
• determine a volume of the fluid added to or removed from the reservoir based on the sensed pressure and the estimated pressure of the reservoir.

A system comprising:

• means for sensing a pressure within a fluid delivery device using a pressure sensor as a therapeutic fluid is added to or removed from a reservoir of the device;
• means for estimating a pressure of the reservoir based on the sensed pressure, an estimated initial temperature of the reservoir as the therapeutic fluid is added or removed based on the sensed pressure, and an estimated temperature of the therapeutic fluid based on the sensed pressure, wherein the estimated pressure of the reservoir is different than the sensed pressure;
• and
• means for determining a volume of the fluid added to or removed from the reservoir based on the sensed pressure and the estimated pressure of the reservoir.

A method comprising:

• sensing a pressure within a fluid delivery device using a pressure sensor as a therapeutic fluid is added to or removed from a reservoir of the device;
• estimating an initial temperature of the reservoir as the therapeutic fluid is added or removed based on the sensed pressure;
• estimating a temperature of the therapeutic fluid based on the sensed pressure;
• determining an estimated pressure of the reservoir based on the estimated initial temperature of the reservoir and the estimated temperature of the therapeutic fluid, wherein the estimated pressure of the reservoir is different than the sensed pressure;
• and
• determining, by a processor, a volume of the fluid added to or removed from the reservoir based on the sensed pressure and the estimated pressure of the reservoir.