Pressurized-Gas-Driven Infusion Pump and Method of Operating Such an Infusion Pump

Abstract

A pressurized-gas-driven infusion pump having a bladder that forms a medication chamber and a pressure chamber is provided. The pressure chamber acts on the bladder to expel medication through a catheter that is communicatively connected to the medication chamber. A pressure sensor detects the pressure prevailing in the pressure chamber.

Claims

1. A pressurized-gas-driven infusion pump comprising: a bladder forming a medication chamber; a catheter communicatively connected to the medication chamber; a pressure chamber configured to act on the bladder to cause medication to be expelled through the catheter; and a pressure sensor configured to sense a prevailing pressure in the pressure chamber.

2. The pressurized-gas-driven infusion pump according to claim 1, further comprising a memory unit connected to the pressure sensor and configured to store values detected by the pressure sensor.

3. The pressurized-gas-driven infusion pump according to claim 2, wherein the memory unit is configured to wirelessly transmit memory values or measured values.

4. The pressurized-gas-driven infusion pump according to claim 2, wherein the memory unit is configured to be programmed wirelessly.

5. The pressurized-gas-driven infusion pump according to claim 1, further comprising a controller connected to the pressure sensor and configured to output an alarm when a pressure detected by the pressure sensor exceeds or falls below a predetermined pressure or when a pressure change detected by the pressure sensor exceeds or falls below a predetermined pressure change.

6. The pressurized-gas-driven infusion pump according to claim 5, wherein the controller is configured to wirelessly transmit memory values or measured values.

7. The pressurized-gas-driven infusion pump according to claim 5, wherein the controller is configured to be programmed wirelessly.

8. A method of operating a pressurized-gas-driven infusion pump including a bladder forming a medication chamber, a catheter communicatively connected to the medication chamber and a pressure chamber configured to act on the bladder to cause medication to be expelled through the catheter, the method comprising: detecting a pressure prevailing in the pressure chamber; and outputting a first alarm when the pressure prevailing in the pressure chamber exceeds or falls below a predetermined pressure.

9. The method according to claim 8, wherein outputting the first alarm includes emitting an acoustic signal generated by the infusion pump.

10. The method according to claim 8, further comprising: detecting a pressure change occurring in the pressure chamber; and outputting a second alarm when the pressure change exceeds or falls below a predetermined pressure change.

11. A method of operating a pressurized-gas-driven infusion pump including a bladder forming a medication chamber, a catheter communicatively connected to the medication chamber and a pressure chamber configured to act on the bladder to cause medication to be expelled through the catheter, the method comprising: detecting a pressure change occurring in the pressure chamber; and outputting a first alarm when the pressure change exceeds a predetermined pressure change.

12. The method according to claim 11, wherein outputting the first alarm includes emitting an acoustic signal generated by the infusion pump.

13. The method according to claim 11, further comprising: detecting a pressure prevailing in the pressure chamber; and outputting a second alarm when the pressure prevailing in the pressure chamber exceeds or falls below a predetermined pressure.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] The Figure shows a schematic sectional view of a particularly preferred design for a pressurized-gas-driven infusion pump according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The invention will be explained in more detail below in reference to an especially preferred exemplary embodiment shown in the Figure.

[0021] The Figure shows a schematic sectional view of a particularly preferred design for a pressurized-gas-driven infusion pump 10 according to the invention. The infusion pump 10 has a medication chamber 20 and a pressure chamber 40, which are formed by the housing of the infusion pump 10 and a bladder 30. The pressure chamber 40 is filled with a gas, which acts by expansion on the bladder 30 to expel medication from the medication chamber 20 through a catheter 50. The catheter 50 is communicatively connected to the medication chamber 20 via a throttle section (not labeled). A pressure sensor 60 is provided according to the invention that detects the pressure prevailing in the pressure chamber 40.

[0022] Preferably provided is a controller 70 that is connected to the pressure sensor 60 in the infusion pump 10 and is configured to output an alarm when the pressure detected by the pressure sensor 60 exceeds or falls below a predetermined pressure and/or a pressure change detected by the pressure sensor 60 exceeds or falls below a predetermined pressure change.

[0023] In addition, a further pressure sensor 80, which detects the atmospheric pressure and the pressure acting on the infusion pump 10 due to different body positions of the patient, can be provided in the discharge channel of the medication chamber 20, for example. The knowledge of these further parameters, which are influenced by the flow rate of the medication in conjunction with the knowledge of the pressure prevailing in the pressure chamber 40, can be used for mutual compensation and for setting an exact flow rate. This is of particular importance in medications that have high concentrations and are administered at low flow rates.

[0024] Atmospheric pressure has a large impact on medication delivery by gas-driven infusion pumps. Atmospheric pressure variations correlate with changes in flow rates in implantable infusion pumps that use gas pressure as the driving medium. Certain implantable infusion pumps use n-butane as the driving gas, which produces a pressure of 3.48 bar at a body temperature of 37 C. Hence, atmospheric parameters are an important and inescapable part of the physical environment. Over the course of a day, the air pressure can fluctuate 0.5 to 1 hPa in certain latitudes. However, air pressures between 954.9 and 1060.6 hPa are not uncommon in certain locations (measured at sea level), with a normal air pressure of 1013.25 hPa. Thus, air pressure fluctuations of 105.7 hPa (or 10.43% of the normal air pressure) can be expected. If pressure changes worldwide are considered, air pressure fluctuations of 215.8 hPa (or 21.3%) can be expected. With respect to air pressure changes resulting from altitude changes, the air pressure on a mountain at 2,962 m in altitude can be reduced to 692.8 hPa (or 68.4% of the normal air pressure), for example. Very sensitive pressure sensors should be used to sense these air pressure fluctuations and to set them in relation to the infusion pump pressure of 3.48 bar absolute. This ensures that a flow rate error of +/1% can be realized.

[0025] Also, not depicted in the Figure, but preferably provided, is an antenna for telemetric transmission of the measurement data acquired by the pressure sensor 60 and for receiving control information for the controller 70, e.g., the predetermined pressure values or the predetermined pressure changes, and an acoustic signal generator for outputting the alarm signal.

[0026] Finally, an energy storage mechanism (not depicted) for supplying power to the electronic components is also provided.