Fluid line condition detection

• US 5,356,378 A
• Filed: 01/24/1994
• Issued: 10/18/1994
• Est. Priority Date: 01/22/1992
• Status: Expired due to Term

• Current Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Original Assignee: Ivax Corporation (Teva Pharmaceutical Industries, Ltd.)
• Inventors: Doan, David B.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US08/185,278
• Time in Patent Office: 267 Days
• Field of Search: 604/65-67, 604/123, 604/153, 128/DIG. 12, 128/DIG. 13, 417/474
• US Class Current: 604/65
• CPC Class Codes: A61M 5/1684 by detecting the amount of infusate remaining, e.g. signalling end of infusion
• CPC Class Codes: A61M 5/16859 Evaluation of pressure response, e.g. to an applied pulse
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A compliant chamber is formed in a fluid line which connects a fluid supply to a fluid receiver. The compliant chamber is alternately in fluid communication with the upstream and downstream segments of the fluid line. When the chamber communicates with the upstream segment it receives and stores fluid at the head pressure. When the segment communicates with the downstream segment, a pressure equalization pulse occurs. A pressure sensor in the downstream segment measures the pressure equalization pulse which is proportional to the head pressure. Processing the equalization pulse with the downstream fluid system resistance, the compliance of the compliant chamber and the equilibrium pressure results in a determination of the head pressure. Comparing the head pressure to thresholds permits determination of an occlusion or empty fluid supply. Where a peristaltic pump is used, the chamber is formed between the end fingers of the pump.

Claims

1. A fluid line condition detection apparatus coupled between a fluid supply and a fluid receiver, the apparatus comprising:

a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the fluid receiver;

a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;

control means for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;

pressure sensor means for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof and for also sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse; and

processor means responsive to said equilibrium signal and to said equalization signal for taking the difference between the equilibrium signal and the equalization signal and for integrating the difference in determining the head pressure.

2. The apparatus of claim 1 further comprising:

resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;

wherein the processor means is also for scaling the integrated difference by the resistance signal in determining head pressure.

3. The apparatus of claim 1 wherein:

the fluid chamber has compliance;

the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber; and

wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.

4. The apparatus of claim 1 wherein the processor is also for scaling the integrated difference and adding the scaled, integrated difference to the equilibrium signal in determining head pressure.

5. The apparatus of claim 1 wherein:

the processor means is also for providing a head pressure signal representative of the determined head pressure; and

the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.

6. The apparatus of claim 1 wherein:

the processor means is also for providing a head pressure signal representative of the determined head pressure; and

the apparatus further comprising an alarm generator which receives the head pressure signal, compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.

7. The apparatus of claim 1 wherein:

the processor means is also for comparing head pressures determined at different times to each other and for providing a head pressure difference signal representative of the difference between compared head pressures; and

the apparatus further comprising an alarm generator which receives the head pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.

8. The apparatus of claim 7 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate from the flow rate signal to the change in head pressure to determine the head pressure difference signal.

9. The apparatus of claim 1 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.

10. The apparatus of claim 9 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.

11. The apparatus of claim 1 wherein:

the fluid chamber is formed of flexible tubing which is connected at one end with the upstream segment of the fluid line and at the other end with the downstream segment of the fluid line; and

the control means comprises a peristaltic pump having a plurality of peristaltic occluding means for sequentially occluding the fluid chamber.

12. The apparatus of claim 1 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.

13. The apparatus of claim 12 wherein said valve means comprises a float valve disposed in fluid communication with the upstream segment of the fluid line between the fluid supply and the fluid chamber.

14. A fluid line condition detection apparatus coupled between a fluid supply and the vascular system of a patient, the apparatus comprising:

a fluid line having an upstream segment coupled to the fluid supply for receiving fluid from the fluid supply at head pressure and a downstream segment coupled to the vascular system of the patient;

a fluid chamber comprising a flexible segment of the fluid line disposed between and in fluid communication with the upstream segment and with the downstream segment of the fluid line;

control means for operating on the flexible segment of the fluid chamber to control the pressure of the fluid in the fluid line and for alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;

pressure sensor means for sensing the pressure equalization pulse and for providing an equalization signal representative of the pressure equalization pulse and for sensing equilibrium pressure in the downstream segment and for providing an equilibrium signal representative thereof;

resistance means for providing a resistance signal representative of the resistance to fluid flow downstream of the fluid chamber;

processor means for taking the difference between the equilibrium signal and the equalization signal, integrating said difference and scaling the integrated difference by the resistance signal in determining the head pressure, said processor means also for providing a head pressure signal representative of the determined head pressure; and

an alarm generator which receives the head pressure signal, compares the received signal to a first threshold and if the head pressure signal is less than the first threshold, provides an occlusion alarm signal.

15. The apparatus of claim 14 wherein:

the fluid chamber has compliance;

the apparatus further comprising compliance means for providing a compliance signal representative of the compliance of the fluid chamber; and

wherein the processor is also for scaling the integrated difference by the compliance signal in determining head pressure.

16. The apparatus of claim 15 wherein the processor means further comprises adder means for adding the scaled, integrated difference to said equilibrium signal in determining the head pressure.

17. The apparatus of claim 14 wherein the processor is also for adding the integrated difference to the equilibrium signal in determining head pressure.

18. The apparatus of claim 14 wherein the alarm generator compares the received signal to a second threshold and if the head pressure signal is less than the second threshold, provides an alarm signal indicating that the fluid supply is empty.

19. The apparatus of claim 14 wherein the processor means is also for comparing determined head pressures to each other and for providing a head pressure difference signal representative of the difference between compared head pressures;

and

the alarm generator receives the pressure difference signal, compares said difference signal to a third threshold and if said difference signal exceeds the third threshold, provides an alarm signal indicating that the fluid supply is empty.

20. The apparatus of claim 19 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.

21. The apparatus of claim 14 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.

22. The apparatus of claim 21 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.

23. The apparatus of claim 14 wherein the fluid pressure control means comprises a peristaltic pump having a plurality of peristaltic means for operating on the flexible segment of the tubing for sequentially occluding the flexible segment wherein said fluid line pumping segment comprises the fluid chamber.

24. The apparatus of claim 14 further comprising valve means for preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.

25. A method for detecting the condition of a fluid delivery system which includes a fluid line having an upstream segment coupled to a fluid supply and a downstream segment coupled to a fluid receiver, the delivery system having a fluid pressure control means for operating on a flexible segment of the fluid line to control the pressure of the fluid in the fluid line, the fluid upstream of the fluid pressure control means being at head pressure, the method comprising the steps of:

storing fluid at the head pressure in a fluid chamber disposed in fluid communication with the upstream segment and with the downstream segment of the fluid line;

alternately opening the fluid chamber to fluid communication with the upstream segment of the fluid line and with the downstream segment of the fluid line, wherein when opened to the upstream segment, the chamber receives and stores fluid at head pressure and wherein when opened to the downstream segment, the chamber communicates the fluid stored at head pressure to fluid residing in the downstream segment thereby causing a pressure equalization pulse in the downstream segment;

sensing the equilibrium pressure in the downstream segment and providing an equilibrium signal representative thereof and also sensing the pressure equalization pulse and providing an equalization signal representative of the pressure equalization pulse; and

processing the equalization signal to determine the head pressure including the steps of taking the difference between the equilibrium signal and the equalization signal and integrating the difference in determining the head pressure.

26. The method of claim 25:

further comprising the steps of determining the resistance to fluid flow downstream of the fluid chamber and providing a resistance signal representative of said resistance;

wherein the step of processing further comprises the step of scaling the integrated difference by the resistance signal in determining head pressure.

27. The method of claim 25:

further comprising the step of determining the compliance of the material forming the fluid chamber; and

wherein the step of processing further comprises the step of scaling the integrated difference by the compliance in determining head pressure.

28. The method of claim 25 wherein the step of processing comprises the steps of scaling the integrated difference and adding the scaled, integrated difference to the equilibrium signal in determining head pressure.

29. The method claim 25:

wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and

further comprising the step of comparing the head pressure signal to a first threshold and providing an occlusion alarm signal if the head pressure is less than the first threshold.

30. The method of claim 25:

wherein the step of processing further comprises providing a head pressure signal representative of the determined head pressure; and

further comprising the step of comparing the head pressure signal to a second threshold and providing an empty supply alarm signal if the head pressure is less than the second threshold.

31. The method of claim 25:

wherein the processing step further comprises the steps of comparing determined head pressures to each other and providing a head pressure difference signal representative of the difference between compared head pressures; and

further comprising the step of comparing said difference signal to a third threshold and providing an alarm signal indicating that the fluid supply is empty if said difference signal exceeds the third threshold.

32. The apparatus of claim 31 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and for comparing the change in the flow rate to the change in head pressure to determine the head pressure difference signal.

33. The apparatus of claim 25 wherein the processor means is also for receiving the size of the fluid line, the size of the fluid supply and the height of the fluid supply and based on head pressure, said sizes and height, determining the quantity of fluid remaining in the fluid supply.

34. The apparatus of claim 33 further comprising:

flow rate means for sensing the flow rate of the fluid and providing a flow rate signal representative of the sensed flow rate;

wherein the processor means is also for receiving the flow rate signal and based on the received flow rate signal and the quantity remaining in the fluid supply, providing a time remaining signal indicative of the amount of time remaining before the fluid supply is empty.

35. The method of claim 25 further comprising the step of preventing the flow of air into the upstream segment of the fluid line when the fluid supply becomes empty.