Medical infusion apparatus

• US 5,211,626 A
• Filed: 12/17/1990
• Issued: 05/18/1993
• Est. Priority Date: 05/01/1987
• Status: Expired due to Term

• Current Assignee: Product Innovation Holdings Limited
• Original Assignee: Product Innovation Holdings Limited
• Inventors: Giles, Terence G., Frank, Peter
• Primary Examiner(s): Rosenbaum, C. Fred
• Assistant Examiner(s): Bockelman, Mark
• Application Number:
  US07/627,906
• Time in Patent Office: 883 Days
• Field of Search: 604/65, 604/131, 604/134, 604/30, 604/67, 604/50, 604/113, 604/114, 604/246, 604/122, 604/249, 604/250, 128/DIG. 12, 128/DIG. 13, 73/861.95, 73/861.91, 73/202.5, 73/204.11
• US Class Current: 604/65
• CPC Class Codes: A61M 5/148 flexible, e.g. independent bagsA61M5/155 takes precedence
• CPC Class Codes: G01F 1/7044 using thermal tracers
• CPC Class Codes: Y10S 128/12 Pressure infusion
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

Medical infusion apparatus comprises a housing in which a standard flexible liquid reservoir is disposed. A constant-force spring applies pressure to the reservoir to force liquid out of the reservoir and along a conduit to a patient. The spring is energized by the opening of a lid of the housing which permits replacement of the reservoir.

The liquid flowing out of the reservoir passes through a molded conduit part which is configured so that it is positioned at a predetermined location with respect to a flow monitor. The flow monitor injects a pulse of heat, and detects the rate at which the heat pulse travels along the conduit. A microprocessor uses the sensed flow rate to control a stepper motor which regulates fluid flow by squeezing the conduit via a spring-biased member. The apparatus has active and standby modes in which the monitor is operated respectively more and less frequently.

Claims

1. Medical infusion apparatus comprising:

a liquid reservoir;

a conduit for delivering liquid from the reservoir to a patient; and

a monitor for monitoring the flow rate of said liquid along said conduit, said monitor comprising means external of said conduit for applying a pulse of heat to a liquid at a location in the conduit, and radiation sensing means outside a periphery of the conduit including an infra-red sensor spaced from said conduit for sensing a change in temperature of liquid at a position downstream of the location, so that the speed of travel of the heat pulse can be determined in response to radiation sensed by the sensor;

whereby the monitor is non-intrusive to permit removal of the conduit from the monitor.

4. Apparatus as claimed in claim 1, 2 or 3, said radiation sensing means comprising first and second infra-red sensors for sensing temperature changes at two positions spaced along the length of the conduit, whereby the time taken for the heat pulse to pass from said first position to said second position can be determined.

5. Apparatus as claimed in claim 1, 2 or 3, wherein said means for applying a pulse of heat comprises a member of resistive material in proximity to the conduit.

6. Apparatus as claimed in claim 1, 2 or 3, wherein said means for applying a pulse of heat is in resilient engagement with said conduit.

7. Apparatus as claimed in claim 1, 2 or 3, said apparatus further comprising control means for intermittently operating the monitor at predetermined intervals.

8. Apparatus as claimed in claim 7, wherein said control means has first and second operational modes, said predetermined intervals being shorter in said first operational mode than in said second operational mode.

9. Apparatus as claimed in claim 1, 2 or 3, further comprising resilient pressurizing means which can be manually caused to store energy which is then used for applying pressure to said reservoir to cause liquid to flow from said reservoir along said conduit.

10. Apparatus as claimed in claim 9, further comprising an enclosure containing said reservoir, said enclosure having an access member which can be opened to permit access for removal of the reservoir, means being provided for withdrawing the resilient pressurizing means from the reservoir in response to opening of said access member, so as to facilitate the removal of the reservoir from said enclosure.

11. Apparatus as claimed in claim 10, wherein said withdrawing means is arranged to cause energy to be stored by said pressurizing means during withdrawal thereof.

2. Medical infusion apparatus comprising:

a liquid reservoir;

a conduit for delivering liquid from the reservoir to a patient;

a monitor for monitoring the flow rate of said liquid along said conduit, said monitor comprising means external of said conduit for applying a pulse of heat to liquid at a location in the conduit and radiation sensing means outside a periphery of the conduit including an infra-red sensor spaced from said conduit for sensing a change in temperature of liquid at a position downstream of the location, so that the speed of travel of the heat pulse can be determined in response to radiation sensed by the sensor;

whereby the monitor is non-intrusive to permit removal of the conduit from the monitor;

the apparatus further comprising a regulator having an adjustable position for regulating the flow of liquid from the reservoir, and a motor which can be energized to adjust said regulator position, the regulator position being stable while the motor is de-energized.

3. Medical infusion apparatus comprising:

a liquid reservoir;

a conduit for delivering liquid from the reservoir to a patient;

a monitor for monitoring the flow rate of said liquid along said conduit, said monitor comprising means external of said conduit for applying a pulse of heat to liquid at a location in the conduit and radiation sensing means outside a periphery of the conduit including an infra-red sensor spaced from said conduit for sensing a change in temperature of liquid at a position downstream of the location, so that the speed of travel of the heat pulse can be determined in response to radiation sensed by the sensor;

whereby the monitor is non-intrusive to permit removal of the conduit from the monitor;

said apparatus further comprising pressurizing means for applying pressure to the reservoir to cause liquid to flow along the conduit, regulating means for regulating the flow in response to said monitor, and a housing, said housing supporting said reservoir, said conduit, said monitor, said pressurizing means and said regulating means.

12. Medical infusion apparatus comprising:

a liquid reservoir;

a conduit for delivering liquid from the reservoir to a patient;

a flow monitor for monitoring the rate of flow of liquid along the conduit, said monitor comprising means external of said conduit for applying a pulse of heat to liquid at a location in the conduit and radiation sensing means outside a periphery of said conduit including an infrared sensor spaced from said conduit for sensing a change in temperature of liquid at a position downstream of the location so that the speed of travel of the heat pulse can be determined in response to radiation sensed by the sensor; and

support means for supporting said conduit and said flow monitor;

said conduit comprising a unitary, integrally-formed insertion member having first and second portions, said first portion being adapted for insertion into said reservoir; and

said insertion member being removable from said support means and said sensing means, and being configured such that, when carried by said support means, said second portion of said insertion member is located in a predetermined position with respect to the flow monitor, whereby the flow monitor can monitor the rate of flow of liquid through said second portion.

13. Apparatus as claimed in claim 12, wherein said insertion member is formed of material which is substantially transparent to infra-red radiation, said flow monitor comprising means external of said insertion member for applying heat to liquid flowing through said insertion member, and means external of said insertion member for sensing a change in the temperature of the liquid in said insertion member at a position downstream of the location at which the heat is applied.

14. Apparatus as claimed in claim 13, said radiation sensing means comprising first and second infra-red sensors for sensing temperature changes at two positions spaced along the length of the insertion member, whereby the time taken for the heat pulse to pass from said first position to said second position can be determined.

15. Apparatus as claimed in claim 13, wherein said means for applying heat comprises a member of resistive material in proximity to the insertion member.

16. Apparatus as claimed in claim 13, wherein said means for applying heat is in resilient engagement with said insertion member.

17. Apparatus as claimed in claim 12, said apparatus further comprising control means for intermittently operating the flow monitor at predetermined intervals.

18. Apparatus as claimed in claim 17, wherein said control means has first and second operational modes, said predetermined intervals being shorter in said first operational mode than in said second operational mode.

19. Apparatus as claimed in claim 12, further comprising resilient pressurizing means which can be manually caused to store energy which is then used for applying pressure to said reservoir to cause liquid to flow from said reservoir along said conduit.

20. Apparatus as claimed in claim 19, further comprising an enclosure containing said reservoir, said enclosure having an access member which can be opened to permit access for removal of the reservoir, means being provided for withdrawing the resilient pressurizing means from the reservoir in response to opening of said access member, so as to facilitate the removal of the reservoir from said enclosure.

21. Apparatus as claimed in claim 20, wherein said withdrawing means is arranged to cause energy to be stored by said pressurizing means during withdrawal thereof.

22. Apparatus as claimed in claim 12, the apparatus further comprising a regulator having an adjustable position for regulating the flow of liquid from the reservoir, and a motor which can be energized to adjust said regulator position, the regulator position being stable while the motor is de-energized.

23. Apparatus as claimed in claim 12, said apparatus further comprising pressurizing means for applying pressure to the reservoir to cause liquid to flow along the conduit, regulating means for regulating the flow in response to said monitor, and a housing, said housing supporting said reservoir, said conduit, said monitor, said pressurizing means and said regulating means.

24. Apparatus as claimed in claim 12 or 13, wherein said support means is also adapted to support said reservoir.

25. Medical infusion apparatus comprising:

a liquid reservoir;

a conduit for delivering liquid from the reservoir to a patient;

a flow rate monitor for monitoring the rate of flow of liquid from the reservoir to the patient;

control means for intermittently operating the flow rate monitor at predetermined intervals, said control means having first and second operational modes, said predetermined intervals being shorter during the first operational mode than during the second operations mode; and

a flow rate regulator for regulating the flow rate;

said control means having an output for controlling said flow rate regulator, said control means comprising a microprocessor performing processing apparatus in said active mode, and said microprocessor consuming less current in the standby mode than in the active mode, wherein said microprocessor is arranged to be in its active mode during said first operational mode of said control means, and is caused to enter its standby mode when the control means is in its second operational mode, the control means further including means operable during said second operational mode to cause the microprocessor to enter its active mode in response either to a lapsing of a predetermined interval or to detection of a disturbance in the flow of liquid, so that the microprocessor can then determine and if necessary regulate the flow rate,

further including means for sensing disturbances in the flow of liquid caused by the appearance of air bubbles in order to cause the microprocessor to enter its active mode.