Wave-based patient line blockage detection

Patent metadata

Field	Value
Publication number	US-10172993-B2
Application number	US-201615098632-A
Country	US
Kind code	B2
Filing date	Apr 14, 2016
Priority date	Apr 14, 2016
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A dialysis machine (e.g., a peritoneal dialysis (PD) machine) can include a pressure sensor mounted at a proximal end of a patient line that provides PD solution to a patient through a catheter. During treatment, an occlusion can occur at different locations in the patient line and/or the catheter. Elastic waves may be generated at a pump that introduces (e.g., for fill cycles) or withdraws (e.g., for drain cycles) the solution into/out of the patient line. For example, when the solution is introduced or withdrawn suddenly, elastic waves travel distally down the patient line until they encounter the occlusion, and are then reflected back (e.g., toward the pressure sensor).

First claim

What is claimed is:

1. A method comprising:
measuring a first pressure at a proximal end of a medical tube connected to a dialysis machine;

measuring a second pressure at the proximal end of the medical tube;
determining an elapsed time between the first pressure measurement and the second pressure measurement; and
determining a location of an occlusion in the medical tube based on the elapsed time.

2. The method of claim 1 , wherein the dialysis machine comprises a peritoneal dialysis (PD) machine.

3. The method of claim 1 , wherein at least one of the first pressure and the second pressure comprises a local extremum of pressure measurements at the proximal end of the medical tube.

4. The method of claim 3 , wherein the local extremum comprises at least one of a local maximum and a local minimum.

5. The method of claim 1 , wherein the first pressure and the second pressure are measured by a pressure sensor mounted at the proximal end of the medical tube.

6. The method of claim 1 , wherein the elapsed time represents a period of oscillations of an elastic wave.

7. The method of claim 6 , comprising determining the location of the occlusion in the medical tube based on the elapsed time and a wave speed of the elastic wave.

8. The method of claim 7 , wherein the wave speed of the elastic wave is based on one or more of dimensions of the medical tube, a material composition of the medical tube, and a density of a fluid flowing through the medical tube.

9. The method of claim 7 , wherein the wave speed of the elastic wave is empirically determined.

10. The method of claim 6 , wherein the elastic wave originates from the proximal end of the medical tube.

11. The method of claim 6 , wherein the elastic wave is generated in response to at least one of an increase and a decrease in pressure in the medical tube.

12. The method of claim 11 , wherein the at least one of an increase and a decrease in pressure is in response to a motion of a pump of the dialysis machine.

13. The method of claim 6 , wherein a fluid flowing through the medical tube is at least partially blocked by the occlusion.

14. The method of claim 13 , wherein the fluid being at least partially blocked by the occlusion causes an increase or a decrease in pressure in the medical tube.

15. The method of claim 6 , wherein the oscillations of the elastic wave are caused at least in part by the elastic wave being reflected back from the location of the occlusion.

16. The method of claim 1 , wherein the medical tube comprises a catheter at a distal end of the medical tube.

17. The method of claim 1 , comprising inferring a type of the occlusion based at least in part on the determined location of the occlusion.

18. The method of claim 17 , wherein the type of the occlusion comprises one or more of a pinch of the medical tube, a kink in the medical tube, a deposit in the medical tube, and a deposit blocking a hole of a catheter at a distal end of the medical tube.

19. The method of claim 18 , wherein the deposit comprises omental fat.

20. The method of claim 1 , comprising performing a calibration prior to determining the location of the occlusion, the calibration for determining a wave speed of an elastic wave propagating through the medical tube.

21. The method of claim 20 , wherein the calibration is for determining the wave speed of the elastic wave propagating through the medical tube for a particular medical tube and cassette configuration used in the dialysis machine.

22. A method comprising:
measuring a plurality of pressures at a proximal end of a medical tube connected to a dialysis machine;
determining one or more elapsed times between local extrema of the measured pressures; and
determining a location of an occlusion in the medical tube based on the one or more elapsed times.

23. The method of claim 22 , wherein the local extrema comprise at least one of a local maximum and a local minimum.

24. The method of claim 22 , comprising removing noise components from the measured pressures before determining the local extrema of the measured pressures.

25. The method of claim 22 , wherein magnitudes of the pressure measurements decay over time when the occlusion is a partial occlusion.

26. The method of claim 25 , comprising subtracting, from the measured pressures, values that approximate the decay of the pressure measurements as a result of the occlusion being a partial occlusion before determining the local extrema.

27. The method of claim 22 , wherein at least one of the local extrema of the measured pressures corresponds to an end of a pump motion that causes fluid to flow through the medical tube.

28. The method of claim 27 , comprising:
determining an elapsed time between i) the end of the pump motion, and ii) an occurrence of a local extrema that occurs after the end of the pump motion; and
determining the location of the occlusion based on the elapsed time.

29. The method of claim 28 , wherein the elapsed time represents a first half-wave period of oscillations of an elastic wave generated in response to at least one of an increase and a decrease in pressure in the medical tube.

30. The method of claim 22 , comprising performing one or more signal processing techniques on the measured pressures.

31. A method comprising:
measuring a first pressure at a proximal end of a medical tube connected to a dialysis machine, the medical tube comprising a plurality of zones;
measuring a second pressure at the proximal end of the medical tube;
determining an elapsed time between the first pressure measurement and the second pressure measurement; and
determining in which of the plurality of zones an occlusion is located based on the elapsed time.

32. The method of claim 31 , wherein the medical tube comprises five zones.

33. The method of claim 31 , wherein the medical tube comprises a catheter at a distal end of the medical tube, and at least one of the zones comprises the catheter.

34. The method of claim 33 , wherein the medical tube comprises a port connecting the catheter to the medical tube, and at least one of the zones comprises the port.

35. A dialysis machine comprising:
a medical tube having a proximal end connected to an outlet of the dialysis machine;
a pressure sensor mounted at the proximal end of the medical tube, the pressure sensor configured for measuring a first and second pressure at the proximal end of the medical tube; and
a processor configured for:
determining an elapsed time between the first pressure measurement and the second pressure measurement; and
determining a location of an occlusion in the medical tube based on the elapsed time.

36. The dialysis machine of claim 35 , wherein the dialysis machine comprises a peritoneal dialysis machine.

Assignees

• Fresenius Medical Care Holdings Inc

Inventors

• Crawford William Scott
• Ohline Robert Matthew

Classifications

• A61M2205/3331

  Pressure; Flow · CPC title

• A61M2205/70

  with testing or calibration facilities · CPC title

• A61M2005/16863

  Occlusion detection · CPC title

• A61M2205/121

  interface between cassette and base · CPC title

• G01N2291/042

  Wave modes · CPC title