Ion imbalance detector

• US 8,903,492 B2
• Filed: 02/07/2006
• Issued: 12/02/2014
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: Mozarc Medical US LLC
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Soykan, Orhan, Robinson, Timothy H., Carney, James K., Nahey, Tara L., Chan, Cygni
• Primary Examiner(s): Bertram, Eric D
• Application Number:
  US11/349,540
• Publication Number:
  US 20060241709A1
• Time in Patent Office: 3,220 Days
• Field of Search: 607/22
• US Class Current: 607/22
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/36135 using physiological parameters
• CPC Class Codes: A61N 1/36167 Timing, e.g. stimulation onset
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

In general, the invention is directed to methods and devices for determining an ion concentration in the extracellular fluid of a patient. As examples, the ion may be one or more of potassium, sodium, chloride, or calcium. A system includes an electrode deployed in or near a tissue, such as a skeletal muscle, of the patient. A pulse generator supplies one or more stimulations to the tissue, and a sensor, such as an accelerometer, detects the response of the tissue to the stimulations. A processor determines a concentration of ions in the extracellular fluid as a function of the response. The system may detect an ion imbalance based upon the determined concentration of ions.

Claims

1. A system comprising:

a pulse generator configured to generate an electrical stimulation;

an electrode configured to deliver the electrical stimulation to a tissue in a patient;

a sensor configured to detect a mechanical response of the tissue to the electrical stimulation; and

a processor configured to determine a concentration of ions in extracellular fluid of the patient as a function of the response.

2. The system of claim 1, wherein the tissue is at least one of skeletal muscle, smooth muscle, cardiac muscle, or skin.

3. The system of claim 1, wherein the ions are at least one of potassium, sodium, chloride, calcium, or magnesium ions.

4. The system of claim 1, wherein the ions are at least one of drugs, small molecules, or endogenously charged molecules.

5. The system of claim 1, wherein the processor is further configured to determine a concentration of ions in the extracellular fluid of the patient by at least one of determining an absolute concentration of ions in the extracellular fluid, determining a relative concentration of ions in the extracellular fluid or determining a change in concentration of ions in the extracellular fluid over time.

6. The system of claim 5, wherein the pulse generator is configured to generate a set of electrical stimulations at a known frequency.

7. The system of claim 5, wherein the processor is further configured to control the timing of a set of electrical stimulations generated by the pulse generator.

8. The system of claim 1, wherein the pulse generator is further configured to generate a set of electrical stimulations.

9. The system of claim 1, wherein the processor is further configured to determine a concentration of ions in the extracellular fluid as a function of at least one of a sustained contraction of the tissue, a rippled contraction of the tissue, a rate of relaxation of the tissue, a pulse width of the response, the occurrence of summation in the response or the amplitude of the response.

10. The system of claim 1, wherein the electrode is a first electrode, the system further comprising a housing and a second electrode in the housing.

11. The system of claim 1, wherein the sensor comprises at least one of an optical sensor, an accelerometer, a pressure sensor, or a piezoelectric sensor.

12. The system of claim 1, wherein the processor is further configured to control delivery of pacing therapy to a heart of the patient.

13. The system of claim 1, further comprising a lead configured to couple the electrode to the pulse generator.

14. The system of claim 1, wherein the system further comprises at least one of a lead configured to deliver a pacing stimulation to a heart, a lead configured to deliver a pacing stimulation to a nerve, or a pump configured to deliver a drug from a reservoir.

15. The system of claim 1, wherein at least one of the pulse generator, electrode, sensor and processor is configured to be implanted in a human or animal body.

16. The system of claim 1, wherein the processor monitors the concentration of ions to predict an arrhythmia.

17. A method comprising:

delivering an electrical stimulation to a tissue in a patient;

detecting a response of the tissue to the electrical stimulation; and

determining a concentration of ions in extracellular fluid of the patient as a function of the response,

wherein the tissue is at least one of skeletal muscle, smooth muscle, cardiac muscle, nerve tissue, or skin.

18. The method of claim 17, wherein the ions are at least one of potassium, sodium, chloride, calcium, or magnesium ions.

19. The method of claim 17, wherein the ions are at least one of drugs, small molecules, or endogenously charged molecules.

20. The method of claim 17, wherein determining the concentration of ions in the extracellular fluid of the patient comprises at least one of determining an absolute concentration of ions in the extracellular fluid, determining a relative concentration of ions in the extracellular fluid, or determining a change in concentration of ions in the extracellular fluid over time.

21. The method of claim 17, wherein determining the concentration of ions in the extracellular fluid of the patient comprises at least one of detecting a sustained contraction of the tissue, detecting a rippled contraction of the tissue, detecting a rate of relaxation of the tissue, detecting a pulse width of the response, detecting the occurrence of summation in the response, or detecting the amplitude of the response.

22. The method of claim 17, further comprising delivering a therapy to the patient as a function of the response.

23. The method of claim 17, wherein the electrical stimulation is a first electrical stimulation and the response is a first response, the method further comprising:

delivering a second electrical stimulation to the tissue;

detecting a second response of the tissue to the second electrical stimulation; and

determining a change in concentration of ions in the extracellular fluid of the patient as a function of the first and second responses.

24. The method of claim 17, further comprising:

detecting a triggering event; and

delivering the electrical stimulation in response to the triggering event.

25. The method of claim 17, further comprising:

determining whether conditions are suitable for determining the concentration of ions; and

delivering the electrical stimulation when the conditions are suitable.

26. The method of claim 17, further comprising monitoring the concentration of ions to predict an arrhythmia.

27. The method of claim 17, further comprising at least one of recording information relating to the determination, or issuing a warning to at least one of the patient or a caregiver based upon the determination.

28. The method of claim 17, further comprising transmitting information relating to the determination to another device.

29. A non-transitory computer-readable medium comprising instructions that cause a programmable processor to:

control a pulse generator to deliver an electrical stimulation to a tissue in a patient;

receive from a sensor a signal indicative of a mechanical response of the tissue to the electrical stimulation; and

determine a concentration of ions in extracellular fluid of the patient as a function of the response.

30. The medium of claim 29, wherein the tissue is at least one of skeletal muscle, smooth muscle, or skin.

31. The medium of claim 29, wherein the ions are at least one of potassium, sodium, chloride, calcium, or magnesium ions.

32. The medium of claim 29, wherein the ions are at least one of drugs, small molecules, or endogenously charged molecules.

33. The medium of claim 29, the instructions further causing the processor to determine the concentration of ions in the extracellular fluid by determining a change in concentration of ions in the extracellular fluid over time.

34. The medium of claim 29, the instructions further causing the processor to determine the concentration of ions in the extracellular fluid by at least one of detecting a sustained contraction of the tissue, detecting a rippled contraction of the tissue, detecting a rate of relaxation of the muscle, detecting a pulse width of the response, detecting the occurrence of summation in the response, or detecting the amplitude of the response.

35. The medium of claim 29, the instructions further causing the processor to control delivery of a therapy to the patient as a function of the response.

36. The medium of claim 29, further comprising instructions that cause the programmable processor to monitor the concentration of ions to predict an arrhythmia.

37. A system comprising:

means for delivering an electrical stimulation to a tissue in a patient;

means for detecting a response of the tissue to the electrical stimulation; and

means for determining a concentration of ions in extracellular fluid of the patient as a function of the response,

wherein the tissue comprises at least one of skeletal muscle, smooth muscle, cardiac muscle, nerve tissue, and skin.

38. The system of claim 37, further comprising means for delivering therapy to the patient as a function of the response.

39. The system of claim 37, further comprising means for monitoring the concentration of ions to predict an arrhythmia.

40. A method comprising:

delivering an electrical stimulation to a tissue in a patient;

detecting a mechanical response of the tissue to the electrical stimulation; and

determining a concentration of ions in extracellular fluid of the patient as a function of the response.