Flow control in an intravenous fluid delivery system

• US 20060020255A1
• Filed: 05/27/2005
• Published: 01/26/2006
• Est. Priority Date: 05/28/2004
• Status: Active Grant

• Current Assignee: Vital Signs Incorporated (Becton, Dickinson & Co)
• Original Assignee: General Electric Company
• Inventors: May, Eric, Cassidy, David E., Bucchianeri, Richard
• Granted Patent: US 7,695,448 B2
• Time in Patent Office: Days
• US Class Current: 604/500
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3386 Low level detectors
• CPC Class Codes: A61M 5/1411 Drip chambers A61M5/162, A61M5/1689, A61M5/40 take precedence
• CPC Class Codes: A61M 5/16813 by controlling the degree of opening of the flow line
• CPC Class Codes: A61M 5/36 with means for eliminating or preventing injection or infusion of air into body dialysis systems, blood oxygenators A61M1/14; haemofiltration equipment A61M1/34; automatic tube cut-off A61M39/281
• CPC Class Codes: A61M 5/385 using hydrophobic filters
• CPC Class Codes: A61M 5/40 using low-level float-valve to cut off media flow from reservoir position detection of a floating member A61M5/1685
• CPC Class Codes: A61M 5/44 having means for cooling or heating the devices or media

Abstract

An intravenous flow control system provides closed loop control to maintain a desired flow rate. The actual flow rate is determined by two techniques, a geometrically based technique that uses geometric parameters of the IV system, and a thermally based technique that uses the power input to an IV fluid warmer and the temperature of the IV fluid entering and exiting the warmer.

Claims

1. A system for control of the flow of an intravenous fluid in an intravenous tubing, the system comprising:

a body for retaining an intravenous tubing;

a movable element cooperative with the body to engage an outer wall portion of the tubing disposed in the body and to squeeze the tubing to vary an orifice size of the tubing;

a transducer operative to provide a signal representative of force applied by the movable element to the tubing; and

control apparatus operative in response to the signal from the transducer to drive the movable element to a position to produce an orifice size needed to obtain the intended flow rate of intravenous fluid in the tubing.

2. The system of claim 1, wherein the control apparatus is further operative to calculate a flow rate based on power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

3. The system of claim 1, further comprising:

a fluid warmer coupled to the tubing and operative to warm the intravenous fluid prior to infusion in a patient; and

wherein the control apparatus is operative to determine flow rate based on power input to the fluid warmer and the temperatures of the intravenous fluid entering and exiting the fluid warmer.

4. The system of claim 3, wherein the control apparatus is operative in a first control mode to determine flow rate based on the signal from the transducer, and is operative in a second control mode to determine flow rate based on power input to the fluid warmer and temperatures of the intravenous fluid entering and exiting the fluid warmer;

and wherein the control apparatus can operate in either the first or the second control mode or in both modes to control the flow rate of intravenous fluid in the tubing.

5. The system of claim 1, wherein the body comprises first and second support portions for retaining the tubing therebetween, and the transducer is disposed between one of the support portions in a position to contact an outer wall portion of the tubing disposed in the body.

6. The flow control system of claim 5, wherein the first and second support portions are diametrically opposing the tubing disposed therebetween.

7. The system of claim 5, including a pad between at least one of the support portions and the tubing to prevent slippage of the tubing in the body.

8. The system of claim 1, wherein the control apparatus includes a linear stepper motor coupled to the movable element to cause linear movement of the element along the axis of the element.

9. The system of claim 8, wherein the control apparatus further includes:

an analog to digital converter receiving signals from the transducer and operative to provide digital signals representative of the transducer signals;

a computer operative to receive the digital signals from the analog to digital converter and to provide output signals; and

a driver circuit operative in response to the output signals to drive the linear stepper motor.

10. The system of claim 9, further including a sensor operative to determine the end of the travel position of the moveable element and to provide a signal indication thereof to the computer.

11. The system of claim 1, wherein the control apparatus is operative to determine flow rate based on one of the signal from the transducer and thermal data comprising power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

12. The system of claim 1, wherein the control apparatus is operative to determine flow rate based on tubing diameter determined from signals from the transducer at various positions of the movable element.

13. The system of claim 1, wherein the control apparatus is operative to determine flow rate based on one of tubing geometry data comprising orifice diameter of the tubing and orifice length of the tubing at the movable element, and thermal data comprising power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

14. The system of claim 1, wherein the control apparatus is operative to determine a flow rate based on orifice diameter of the tubing at the movable element and orifice length of the tubing at the movable element.

15. The system of claim 14, wherein the control apparatus is further operative to determine flow rate based on pressure at the movable element and viscosity of the intravenous fluid.

16. The system of claim 1, wherein the control apparatus is operative to determine flow rate based on thermal data comprising power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

17. The system of claim 1, wherein the control apparatus is operative to provide a bolus infusion, wherein the movable element is opened to allow a larger volume of fluid flow therethrough and then closed to allow a smaller volume of fluid flow therethrough.

18. The system of claim 1, wherein the control apparatus is operative to drive the movable element to squeeze the tubing to shut off fluid flow therethrough.

19. A method for controlling flow of an intravenous fluid in an intravenous tubing, comprising:

retaining an intravenous tubing in a body;

engaging an outer wall portion of the tubing with a movable element to squeeze the tubing to vary an orifice size of the tubing;

providing a signal from a transducer representative of force applied by the movable element to the tubing; and

driving the moveable element to a position to produce an orifice size needed to obtain an intended flow rate of intravenous fluid in the tubing.

20. The method of claim 19, further comprising coupling a fluid warmer to the tubing to warm the intravenous fluid prior to infusion in a patient;

and

determining a flow rate of intravenous fluid based on power input to the fluid warmer and temperatures of the intravenous fluid entering and exiting the fluid warmer.

21. The method of claim 19, further comprising in a first mode determining a flow rate based on the signal from the transducer and in a second mode determining flow rate based on power input to a fluid warmer and temperatures of the intravenous fluid entering and exiting the fluid warmer.

22. The method of claim 21, further comprising driving the moveable element to a position to produce an orifice size needed to obtain an intended flow rate of intravenous fluid based on the flow rate determined in the second mode.

23. The method of claim 21, further comprising driving the moveable element to a position to produce an orifice size needed to obtain an intended flow rate of intravenous fluid based on the flow rate determined in the first mode.

24. The method of claim 21, further comprising driving the moveable element to a position to produce an orifice size needed to obtain an intended flow rate of intravenous fluid based on an average of the flow rate determined in the first mode and the flow rate determined in the second mode.

25. The method of claim 19, further comprising in a first mode determining a flow rate based on one of tubing geometry data comprising orifice diameter of the tubing and orifice length of the tubing at the movable element, and thermal data comprising power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

26. The method of claim 19, further comprising determining a flow rate based on thermal data comprising power input to an intravenous fluid warmer and temperatures of an intravenous fluid entering and exiting the fluid warmer.

27. The method of claim 19, further comprising determining a flow rate based on tubing geometry data comprising orifice diameter of the tubing and orifice length of the tubing at the movable element.

28. The method of claim 19, further comprising determining tubing diameter at various positions of the movable element prior to infusing fluid to a patient.