# US 2016/0354540 A1 · Pressure based refill status monitor for implantable pumps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0354540 A1 - Document ID: US20160354540A1 - Status: Published application - Kind: A1 - Application number: 15/242,766 - Filed: 2016-08-22 - Published: 2016-12-08 - Earliest claimed: 2008-11-20 - Assignees: Medtronic, Inc. - Applicants: Medtronic, Inc. - Inventors: Scott L. Kalpin - Web page: https://patentgrep.com/patent/US20160354540A1 ## CPC - A61M 5/1684: {by detecting the amount of infusate remaining, e.g. signalling end of infusion} - A61M 5/14276: {specially adapted for implantation} - A61M 5/16809: {by repeated filling and emptying of an intermediate volume} - G01F 23/14: by measurement of pressure - A61M 2205/3331: Pressure; Flow - A61M 2205/3389: Continuous level detection (A61M2205/3393 takes precedence) - A61M 2205/3396: Reservoirs being alternately filled and emptied for measuring flow rate or delivered volume - A61M 2205/3592: using telemetric means, e.g. radio or optical transmission - A61M 2205/502: User interfaces, e.g. screens or keyboards - A61M 2205/702: automatically during use - A61M 2209/045: for filling, e.g. for filling reservoirs - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract The present invention includes systems and methods for detecting fluid flow into or out of a port chamber or a reservoir of an implantable medical device utilizing a pressure sensor and calculating the fluid status of the reservoir. The system detects characteristic pressure profiles associated with fluid flowing into the medical device, out of the medical device, and also whether one or both of the port chamber or reservoir are substantially empty or substantially full. In addition, the present invention may generate a sensory cue to a clinician to indicate the fluid status. ## Claims ### Claim at position 1 1-11. (canceled) ### Claim 12 An implantable infusion device comprising: a housing; a port assembly defining a port chamber, the port assembly being disposed in the housing such that the chamber is accessible by a needle inserted through the exterior of the housing; a re-fillable reservoir in communication with the port chamber; a pressure sensor in fluid communication with the port chamber and configured to sense a rate of change of pressure as fluid is added to the reservoir via the port chamber; and electronics disposed in the housing and operably coupled to the pressure sensor, the electronics configured to determine a fluid flow rate into the reservoir based on the rate of change of the pressure, determine a total volume of fluid added to the reservoir by integrating the fluid flow rate over the time when fluid is added to the reservoir, and combining the total volume of fluid added to the reservoir with a known starting volume of fluid in the reservoir to determine a volume of fluid in the reservoir during the refill procedure. ### Claim 13 (depends on 12) The implantable infusion device of claim 12, wherein the pressure sensor is in the reservoir. ### Claim 14 (depends on 12) The implantable infusion device of claim 12, wherein the pressure sensor is upstream of the reservoir. ### Claim 15 (depends on 14) The implantable infusion device of claim 14, wherein the electronics are configured to calculate the reservoir pressure based on a known fluidic restriction between the upstream pressure sensor and the reservoir. ### Claim 16 (depends on 12) The implantable infusion device of claim 12, wherein the electronics are further configured to determine the known starting volume by subtracting the fluid volume pumped from the implantable medical device since the last time point at which the reservoir was full. ### Claim 17 (depends on 16) The implantable infusion device of claim 16, wherein the electronics are configured to determine the volume pumped from the implantable medical device by multiplying the number of strokes of the pump by the volume of fluid pumped per stroke. ### Claim 18 (depends on 12) The implantable infusion device of claim 12, wherein the electronics are further configured to determine a fluid flow rate out of the reservoir based on the rate of change of the pressure when fluid is removed from the reservoir via the port chamber. ### Claim 19 (depends on 18) The implantable infusion device of claim 18, wherein the electronics are further configured to determine a total volume of fluid removed from the reservoir via the port chamber by integrating the fluid flow rate over the time when fluid is removed from the reservoir via the port chamber. ### Claim 20 An implantable infusion device comprising: a housing; a port assembly defining a port chamber, the port assembly being disposed in the housing such that the chamber is accessible by a needle inserted through the exterior of the housing; a re-fillable reservoir in communication with the port chamber; a pressure sensor in fluid communication with the port chamber and configured to sense a rate of change of pressure as fluid is added to the reservoir via the port chamber; and electronics disposed in the housing and operably coupled to the pressure sensor, the electronics configured to determine a fluid flow rate out of the reservoir based on the rate of change of the pressure, determine a total volume of fluid removed from the reservoir by integrating the fluid flow rate over the time when fluid is removed from the reservoir, and subtracting the total volume of fluid removed from the reservoir from a known starting volume of fluid in the reservoir to determine a volume of fluid in the reservoir. ### Claim 21 (depends on 20) The implantable infusion device of claim 20, wherein the electronics are further configured to determine the known starting volume by subtracting the fluid volume pumped from the implantable medical device since the last time point at which the reservoir was full. ### Claim 22 (depends on 21) The implantable infusion device of claim 21, wherein the electronics are configured to determine the volume pumped from the implantable medical device by multiplying the number of strokes of the pump by the volume of fluid pumped per stroke. ### Claim 23 A method for calculating a fill status of a reservoir in an implantable medical device during a procedure to refill the reservoir, the method comprising: sensing a pressure differential between the reservoir and a fill port using a pressure sensor as fluid is introduced into the reservoir via the fill port; determining a rate of change of the pressure differential as the fluid is introduced into the reservoir; determining a fluid rate at which the fluid is introduced to the reservoir based upon the rate of change of the pressure differential and a known fluidic constant for the medical device; determining a total volume of fluid added to the reservoir by integrating the fluid rate over the time in which fluid is introduced into the reservoir; and combining the total volume of fluid added to—the reservoir with a known starting volume of the reservoir to determine the fill status. ### Claim 24 (depends on 23) The method of claim 23 further comprising: determining a rate of change of the pressure as fluid is removed from the reservoir via the fill port assembly in fluid communication with the reservoir; determining a fluid flow rate out of the reservoir based on the rate of change of the pressure; determining a total volume of fluid removed from the reservoir by integrating the fluid flow rate over the time in which the pressure is sensed using the pressure sensor; and combining the total volume of fluid removed from the reservoir with the known starting volume of fluid in the reservoir to determine the volume of fluid in the reservoir. ### Claim 25 (depends on 23) The method of claim 23, wherein combining the fluid volume added to the reservoir with the known starting volume of fluid in the reservoir is performed by a logic circuit.