ACCURATE FLOW CONTROL IN DRUG PUMP DEVICES

• US 20130184641A1
• Filed: 11/19/2012
• Published: 07/18/2013
• Est. Priority Date: 11/18/2011
• Status: Abandoned Application

• Current Assignee: MiniPumps, LLC
• Original Assignee: MiniPumps, LLC
• Inventors: Li, Po-Ying
• Application Number:
  US13/681,008
• Publication Number:
  US 20130184641A1
• Time in Patent Office: Days
• US Class Current: 604/67
• CPC Class Codes: A61M 2005/14252 with needle insertion means
• CPC Class Codes: A61M 2039/1072 with a septum present in the connector
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 5/14248 of the skin patch type
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/155 pressurised by gas introduced into the reservoir
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence

Abstract

The accuracy of drug delivery with drug pump devices may be improved by a combination of pump operation at high flow resistances and pump pressures, pressure-relief mechanisms, and sensor-based feedback for pump control.

Claims

1. A drug pump device comprising:

a drug reservoir;

an exit member for fluidically connecting the reservoir with a drug injection site;

an electrolysis pump comprising a pump chamber in mechanical communication with the drug reservoir via an intervening displacement member, the electrolysis pump being operable to exert a pressure to drive the displacement member toward the exit member and thereby force therethrough fluid in the drug reservoir; and

a pressure sensor disposed within the pump chamber for measuring a pressure therein;

a direct-measurement flow sensor disposed within the exit member for measuring a flow rate of fluid flow therethrough; and

control circuitry for (i) calculating a flow rate from the measured pressure, (ii) comparing the calculated flow rate with the measured flow rate, and (iii) adjusting an electrolysis current supplied to electrolysis electrodes within the pump chamber based on the measured flow rate if it is within 5% of the calculated flow rate, and otherwise based on the calculated flow rate,

whereby the pump is operated to generate a pressure causing continuous fluid flow through the exit member at a target flow rate.

2. In a drug pump device comprising a drug reservoir, an exit member for fluidically connecting the reservoir with a drug injection site, and an electrolysis pump operable to exert a pressure on the reservoir to thereby force fluid from the drug reservoir into the exit member, a method of controlling a rate of fluid flow through the exit member, the method comprising:

measuring a pressure in a pump chamber of the electrolysis pump and calculating a flow rate therefrom;

measuring a flow rate of fluid flow through the exit member;

comparing the calculated flow rate with the measured flow rate; and

adjusting an electrolysis current based on the measured flow rate if it is within 5% of the calculated flow rate, and otherwise based on the calculated flow rate,

whereby the pump is operated to generate a pressure causing continuous fluid flow through the exit member at a target flow rate.

3. A drug pump device comprising:

a drug reservoir;

an exit member for fluidically connecting the reservoir with a drug injection site;

an electrolysis pump comprising a pump chamber in mechanical communication with the drug reservoir via an intervening displacement member, the electrolysis pump being operable to exert a pressure to drive the displacement member toward the exit member and thereby force therethrough fluid in the drug reservoir;

a pressure sensor for measuring pressure within the electrolysis chamber;

a flow sensor for measuring fluid flow through the exit member; and

a control circuit, responsive to the pressure sensor and the flow sensor, for (i) storing in temporal order a plurality of successively obtained readings from the sensors and (ii) operating the electrolysis pump to achieve a target flow rate based at least in part on a plurality of successive ones of the obtained readings.

4. The device of claim 3 wherein the temporally aligned readings are stored in a circular buffer.

5. The device of claim 4 wherein the readings enter and exit the circular buffer in FIFO order.

6. The device of claim 3 wherein the readings are obtained at discrete time intervals regardless of pump state.

7. The device of claim 3 wherein the readings are obtained upon occurrence of a pump event.

8. The device of claim 7 wherein the pump event is pump actuation and a plurality of time-separated readings are obtained as the pump operates following each pump actuation.

9. In a drug pump device comprising a drug reservoir, an exit member for fluidically connecting the reservoir with a drug injection site, and an electrolysis pump operable to exert a pressure on the reservoir to thereby force fluid from the drug reservoir into the exit member, a method of controlling a rate of fluid flow through the exit member, the method comprising:

storing in temporal order a plurality of successively obtained measurements of (i) pressure within a pump chamber of the electrolysis pump and (ii) a rate of flow through the exit member; and

operating the electrolysis pump to achieve a target flow rate based at least in part on a plurality of successive ones of the obtained readings.

10. The device of claim 9 wherein the temporally aligned readings are stored in a circular buffer.

11. The device of claim 10 wherein the readings enter and exit the circular buffer in FIFO order.

12. The method of claim 9 wherein the readings are obtained at discrete time intervals regardless of pump state.

13. The method of claim 9 wherein the readings are obtained upon occurrence of a pump event.

14. The device of claim 13 wherein the pump event is pump actuation and a plurality of time-separated readings are obtained as the pump operates following each pump actuation.