REAL TIME CSF FLOW MEASUREMENT SYSTEM & METHOD

• US 20130109998A1
• Filed: 05/27/2011
• Published: 05/02/2013
• Est. Priority Date: 05/28/2010
• Status: Active Grant

• Current Assignee: ShuntCheck, Inc.
• Original Assignee: ShuntCheck, Inc.
• Inventors: Swoboda, Marek, Hochman, Matias Gabriel, Mattiucci, Mark Evan, Fritz, Frederick J.
• Granted Patent: US 8,894,584 B2
• Time in Patent Office: Days
• US Class Current: 600/549
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/032 Spinal fluid pressure
• CPC Class Codes: A61M 27/006 Cerebrospinal drainage; Accessories therefor, e.g. valves
• CPC Class Codes: A61M 5/168 Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body flow control in general G05D7/00
• CPC Class Codes: A61M 5/16836 by sensing tissue properties at the infusion site, e.g. for detecting infiltration detecting tissue temperature for diagnostic purposes A61M39/0247
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow

Abstract

A system for measuring quantitative CSF flow in shunt tubing implanted under the skin. The system includes an array of thermosensors clustered in three sections, cooling device, placed on the skin surface and an associated data acquisition and analysis device. Two sensor sections are placed over the shunt on the skin and measure real time temperature responses related to CSF movement. One array placed adjacent the cooling device collects data on thermal properties of skin including skin thermal condictivity, specific heat, diffusivity, perfusion, and thermal inertia. The method involves assessing thermal properties of skin and measuring CSF flow in shunt tubing. The method is useful for shunt patency assessment, CSF valve adjustment procedures and CSF flow measurements related to CSF over drainage. Alternatively, only one section of sensors need be used when determining relative CSF flow, without the need to determine thermal skin properties and by applying the cooling device continuously.

Claims

1. An apparatus for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said apparatus comprising:

a pad that is placed against the skin of a patient over the location of the CSF shunt, said pad comprising;

a first plurality of temperature sensors that are aligned in a transverse direction with respect to said CSF shunt and wherein one of said first plurality of temperature sensors is aligned with the CSF shunt; and

a second plurality of temperature sensors that are aligned in a transverse direction with respect to said CSF shunt, downstream of said first plurality of temperature sensors, and wherein one of said second plurality of temperature sensors is aligned with the CSF shunt; and

a third plurality of temperature sensors associated with a temperature source that positioned over the CSF shunt whenever said pad is placed against the skin; and

a sensor processing device that is electrically coupled to said pad for receiving temperature data from each of said plurality of temperature sensors, said sensor processing device using said temperature data to remove the effects of skin depth of CSF implantation, skin thermal conductivity and skin thermal diffusivity from temperature data collected by said first, second and third pluralities of temperature sensors, and for determining a flow rate of said CSF through said CSF shunt when a temperature source is applied to said pad.

2. The apparatus of claim 1 wherein said sensor processing device removes the effects of skin depth of CSF implantation by calculating a ratio of a maximum temperature drop detected by a second plurality of temperature sensors, located downstream of said first plurality of temperature sensors, and a time required for said maximum temperature drop to occur.

3. The apparatus of claim 2 wherein each of said first and second plurality of temperature sensors comprises temperature sensors located on either side of said implanted CSF and wherein said sensor processing device subtracts an averaged value of detected temperature values of said second and third temperature sensors of said second plurality of temperature sensors from a detected temperature value of said first temperature sensor of said second plurality of temperature sensors.

4. The apparatus of claim 2 wherein said sensor processing device detects a temperature of said temperature source over a predetermined period of time divided by a temperature value from a temperature sensor at a steady state location after said predetermined period of time.

5. The apparatus of claim 4 wherein said sensor processing device determines skin thermal diffusivity by adding a ratio of heat absorbed by said temperature source versus said skin thermal conductivity to second partial derivatives in orthogonal axes which form a time domain gradient.

6. The apparatus of claim 1 wherein said temperature source is positioned on said pad upstream of said first plurality of temperature sensors.

7. The apparatus of claim 1 wherein said temperature source is a Peltier device.

8. The apparatus of claim 7 wherein said Peltier device is an ice cube.

9. The apparatus of claim 7 wherein said Peltier device is a heating device.

10. The apparatus of claim 1 wherein said pad comprises an adhesive for securing to the skin.

11. The apparatus of claim 1 wherein said pad uses a vacuum for securing to said skin.

12. The apparatus of claim 1 wherein each of said temperature sensors is a thermistor.

13. A method for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said method comprising:

applying a first plurality of temperature sensors against the skin over the location of the CSF shunt and wherein only one of said first plurality of temperature sensors is aligned with the CSF shunt;

applying a second plurality of temperature sensors against the skin over the location of the CSF shunt, downstream of said first plurality of temperature sensors, and wherein only one of said second plurality of temperature sensors is aligned with the CSF shunt;

associating a third plurality of temperature sensors with a temperature source, said temperature source being applied against the skin aligned with the CSF shunt;

collecting temperature data from said first, second and third plurality of temperature sensors after a predetermined period of time has elapsed;

removing the effects of skin depth of CSF implantation, skin thermal conductivity and skin thermal diffusivity; and

determining a flow rate of the CSF through the CSF shunt from said resultant temperature signal.

14. The method of claim 13 wherein said step of removing the effects comprises using said third plurality of temperature sensors to remove the effects of skin depth of CSF implantation, skin thermal conductivity and skin thermal diffusivity from said collected temperature data.

15. The method of claim 14 wherein said step of removing the effects of skin depth of CSF implantation comprises calculating a ratio of a maximum temperature drop detected by a second plurality of temperature sensors, located downstream of said first plurality of temperature sensors, and a time required for said maximum temperature drop to occur.

16. The method of claim 15 wherein said maximum temperature drop comprises:

arranging said second plurality of temperature sensors such that a first temperature sensor is located over said implanted CSF and second and third temperature sensors are located on either side of said implanted CSF respectively; and

subtracting an averaged value of detected temperature values of said second and third temperature sensors from a detected temperature value of said first temperature sensor.

17. The method of claim 14 wherein said step of removing the effects of skin thermal conductivity comprises detecting a temperature of said temperature source over a predetermined period of time divided by a temperature value from a temperature sensor at a steady state location after said predetermined period of time.

18. The method of claim 17 wherein said skin thermal diffusivity is obtained by adding a ratio of heat absorbed by said temperature source versus said skin thermal conductivity to second partial derivatives in orthogonal axes which form a time domain gradient.

19. The method of claim 13 wherein said step of associating a third plurality of temperature sensors comprises said temperature source being applied upstream of said first plurality of temperature sensors.

20. The method of claim 13 wherein said step of associating a third plurality of temperature sensors comprises said temperature source being applied downstream of said second plurality of temperature sensors.

21. The method of claim 13 wherein said step of associating a third plurality of temperature sensors with a temperature source comprises associating a third plurality of temperatuere sensors with a Peltier device.

22. The method of claim 21 wherein said Peltier device is an ice cube.

23. The method of claim 22 wherein said Peltier device is a heating device.

24. The method of claim 13 wherein each of said plurality of sensors is adhesively secured to the skin.

25. The method of claim 13 wherein each of said plurality of sensors is secured by a vacuum to said skin.

26. The method of claim 13 wherein each of said temperature sensors is a thermistor.

27. An apparatus for determining intracranial pressure (ICP) of patient having an implanted cerebrospinal fluid (CSF) shunt with an adjustable shunt valve, said apparatus comprising:

a pad comprising a plurality of temperature sensors and a temperature source, said pad being adaptable to be secured to the skin of the patient over a portion of the implanted CSF, said plurality of temperature sensors detecting the movement of a temperature pulse introduced into the CSF of the CSF shunt;

a sensor processing device that is electrically coupled to said pad for receiving temperature data from each of said plurality of temperature sensors and for displaying a CSF flow or no CSF flow condition to an operator; and

a remote controller for adjusting the adjustable shunt valve; and

wherein an operator of said apparatus monitors said sensor processing device to determine if there is or is not any CSF flow and wherein said operator uses said remote controller to change an opening valve pressure of said adjustable shunt valve from an existing valve pressure to a known opening pressure to either initiate a CSF flow that did not previously exist;

or to stop an existing CSF flow; and

from either of these scenario determine the ICP based upon said known opening pressure

28. The apparatus of claim 27 further comprising a controller to remotely and wirelessly adjust said adjustable shunt valve.

29. A method for determining intracranial pressure (ICP) of a patient having an implanted cerebrospinal fluid (CSF) shunt with an adjustable shunt valve, said method comprising:

positioning a plurality of temperature sensor arrays that can detect the passage of a temperature change experienced by the CSF passing in said CSF shunt and a temperature source, against the skin of a patient over the location of the CSF shunt;

analyzing temperature data collected by said plurality of temperature sensors arrays to determine if there is any CSF flow in the CSF shunt or not, said flow-no flow status being visible to a user;

adjusting the adjustable shunt valve to change an opening valve pressure from an existing valve pressure to a known opening valve pressure to p2 either initiate a CSF flow that did not previously exist;

or

to stop an existing CSF flow; and

determining said ICP based upon said known opening valve pressure.

30. The method of claim 29 wherein said step of adjusting the adjustable shunt valve comprises using a controller to remotely and wirelessly adjust said adjustable shunt valve.

31. An apparatus for controlling cerebrospinal fluid (CSF) flow in an implanted CSF shunt having an adjustable shunt valve, said apparatus comprising:

a pad comprising a plurality of temperature sensors and a temperature source, said pad being adaptable to be secured to the skin of the patient over a portion of the implanted CSF, said plurality of temperature sensors detecting the movement of a temperature pulse introduced into the CSF of the CSF shunt;

a sensor processing device that is electrically coupled to said pad for receiving temperature data from each of said plurality of temperature sensors and for displaying a CSF flow or no CSF flow condition to an operator; and

a remote controller for adjusting the adjustable shunt valve; and

wherein an operator of said apparatus monitors said sensor processing device to determine a flow rate of said CSF in the CSF shunt and then using said remote controller to change an opening valve pressure of said adjustable shunt valve to achieve a desired CSF flow rate.

32. The apparatus of claim 31 further comprising a controller to remotely and wirelessly adjust said adjustable shunt valve.

33. A method for controlling cerebrospinal fluid (CSF) flow in an implanted CSF shunt having an adjustable shunt valve, said method comprising:

positioning a plurality of temperature sensor arrays that can detect the passage of a temperature change experienced by the CSF passing in said CSF shunt and a temperature source, against the skin of a patient over the location of the CSF shunt;

analyzing temperature data collected by said plurality of temperature sensors arrays to inform a user of a CSF flow rate; and

adjusting the adjustable shunt valve by the user to change an opening valve pressure of said adjustable shunt valve to change said CSF flow rate to a desired CSF flow rate.

34. The method of claim 33 wherein said step of adjusting the adjustable shunt valve comprises using a controller to remotely and wirelessly adjust said adjustable shunt valve.

35. An apparatus for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said apparatus comprising:

a pad that is placed against the skin of a patient over the location of the CSF shunt, said pad comprising;

a first plurality of temperature sensors that are aligned in a transverse direction with respect to said CSF shunt and wherein one of said first plurality of temperature sensors is aligned with the CSF shunt; and

at least one temperature sensor associated with a temperature source that is positioned over the CSF shunt whenever said pad is placed against the skin and wherein said temperature source is applied continuously against the skin; and

a sensor processing device that is electrically coupled to said pad for receiving temperature data from each of said temperature sensors during said continuous application of said temperature source, and for determining a flow rate of said CSF through said CSF shunt from said temperature data.

36. The apparatus of claim 35 wherein said sensor processing device controls the activation of said temperature source.

37. The apparatus of claim 35 wherein said temperature source is a Peltier device.

38. The apparatus of claim 37 wherein said Peltier device maintains a temperature that differs from a skin temperature.

39. The apparatus of claim 38 wherein said temperature differs from said skin temperature by approximately 7°

-14°

C.

40. The apparatus of claim 37 wherein said continuous application of said temperature source is at least 5 minutes.

41. The apparatus of claim 35 further comprising a second plurality of temperature sensors that are aligned in a transverse direction with respect to said CSF shunt, downstream of said first plurality of temperature sensors, and wherein one of said second plurality of temperature sensors is aligned with the CSF shunt.

42. The apparatus of claim 35 wherein said at least one temperature sensor associated with a temperature source comprises a temperature sensor that is positioned on said temperature source or positioned between said temperature source and the skin surface.

43. The apparatus of claim 41 A wherein said at least one temperature sensor associated with a temperature source further comprises at least one other temperature sensor disposed adjacent said temperature source.

44. A method for determining cerebrospinal fluid (CSF) flow rate in an implanted CSF shunt, said method comprising:

applying a first plurality of temperature sensors against the skin over the location of the CSF shunt and wherein only one of said first plurality of temperature sensors is aligned with the CSF shunt;

associating at least one temperature sensor with a temperature source;

activating said temperature source against the skin continuously and aligned with the CSF shunt, said activating said temperature source comprises applying a temperature to the skin continuously that is different from a skin temperature;

collecting temperature data from said temperature sensors during said continuous activation of said temperature source; and

determining a flow rate of the CSF through the CSF shunt from said temperature data.

45. The method of claim 44 wherein said temperature source is a Peltier device.

46. The method of claim 45 wherein said Peltier device maintains a temperature that differs from a skin temperature.

47. The method of claim 46 wherein said temperature differs from said skin temperature by approximately 7°

-14°

C.

48. The method of claim 44 wherein said continuous activation of said temperature source is at least 5 minutes.

49. The method of claim 44 wherein said step of applying a first plurality of temperature sensors comprises applying a second plurality of temperature sensors against the skin over the location of the CSF shunt, downstream of said first plurality of temperature sensors, and wherein only one of said second plurality of temperature sensors is aligned with the CSF shunt.

50. The method of claim 44 wherein said step of associating at least one temperature sensor with a temperature source comprises positioning a temperature sensor on said temperature source or positioning said temperature sensor between said temperature source and the skin surface.

51. The method of claim 50 wherein said step of positioning a temperature sensor on said temperature or positioning said temperature sensor between said temperature sensor and the skin surface further comprises positioning at least one other temperature sensor adjacent said temperature source.