MEDICAL DEVICE AND METHOD FOR MONITORING HEMATOCRIT AND SVO2

• US 20090177145A1
• Filed: 02/22/2007
• Published: 07/09/2009
• Est. Priority Date: 02/28/2006
• Status: Abandoned Application

• Current Assignee: St. Jude Medical AB (Abbott Laboratories)
• Original Assignee: St. Jude Medical AB (Abbott Laboratories)
• Inventors: Lonn, Urban, Hietanen, Mika, Eckerdal, Johan, Nilsson, Kenth, Noren, Kjell, Ohlander, Malin
• Application Number:
  US12/373,356
• Publication Number:
  US 20090177145A1
• Time in Patent Office: Days
• US Class Current: 604/66
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: G16H 20/17 delivered via infusion or injection
• CPC Class Codes: G16H 40/63 for local operation

Abstract

A method, an implantable medical device, and a computer-readable medium encoded with programming instructions allow monitoring of a hematocrit value and an SvO2 level of a patient, making use of at least one medical lead connected to an implantable medical device that carries an optical sensor module that measures at least one hematocrit value and at least one SvO2 value using at least first, second and third light radiation wavelengths, by determining a present hematocrit value from at least one of the measured hematocrit values and determining a present SvO2 value from at least one of the measured SvO2 values, and determining a patient status by evaluating the present hematocrit value and the present SvO2 value, to allow a change in the patient status to be identified.

Claims

1. An implantable medical device for monitoring a hematocrit level and a SvO2 level of a patient comprising:

at least one medical lead including an optical sensor module that measures at least one hematocrit value and at least one SvO2 value using at least first, second, and third light radiation wavelengths;

a blood constituent determining device that obtains measured hematocrit values and SvO2 values, and that determines a present hematocrit level from said at least one hematocrit value and that determines a present SvO2 level from said at least one SvO2 value; and

a patient status determining device that determines a patient status by evaluating said present hematocrit level and said present SvO2 level, to derive a change of a condition of said patient, therefrom, and that makes said patient status or said change available as an output.

2. The implantable medical device according to claim 1, wherein said blood constituents determining device obtains measured hematocrit values and SvO2 values continuously or at predetermined intervals, from which at least one sequence over time of hematocrit levels and SvO2 levels, respectively, are determined.

3. The implantable medical device according to claim 1, further comprising a therapy determining device that obtains a target range for said hematocrit level and said SvO2 level, respectively, and that compares said obtained target ranges with said present hematocrit level and said present SvO2 level, respectively, to determine a therapy for said patient.

4. The implantable medical device according to claim 3, further comprising a temperature sensor that senses a body temperature of said patient, and wherein said therapy determining device determines said therapy also based on said body temperature.

5. The implantable medical device according to claim 4, wherein said patient status determining device is configured:

obtain sensed body temperature values continuously or at predetermined intervals, wherein at least one sequence over time of body temperature values can be determined;

use said sensed body temperature values in said evaluation; and

determine said patient status based on said evaluation, wherein a change of a condition of said patient can be derived.

6. The implantable medical device according to claim 3, further comprising an activity sensor that senses an activity level of said patient.

7. The implantable medical device according to claim 6, wherein said patient status determining device is configured to:

obtain sensed activity levels continuously or at predetermined intervals, wherein at least one sequence over time of an activity level can be determined;

use said sensed activity levels in said evaluation; and

determine said patient status based on said evaluation, wherein a change of a condition of said patient can be derived.

8. The implantable medical device according to claim 3, further comprising an impedance measuring circuit that measures a transthoracic impedance, said impedance measuring circuit connected to electrodes of said at least one medical lead and/or to a housing of said implantable medical device, said impedance measuring circuit to, during impedance measurement sessions, generating electrical signals applied between at least a first electrode and at least a second electrode;

and measuring the impedance in the tissue between said at least first electrode and said at least second electrode to the applied electrical signals, and wherein said therapy determining device determines said therapy also based on said transthoracic impedance.

9. The implantable medical device according to claim 8, wherein said patient status determining device is configured to:

obtain sensed impedance values continuously or at predetermined intervals, wherein at least one sequence over time of impedance values can be determined;

determine at least one sequence of a minute ventilation of said patient using said impedance values;

use said sequence of minute ventilation in said evaluation; and

determine said patient status based on said evaluation, wherein a change of a condition of said patient can be derived.

10. The implantable medical device according to claim 3, further comprising a heart rate sensor that senses a heart rate of said patient, and wherein said therapy determining device determines said therapy also based on said heart rate.

11. The implantable medical device according to claim 10, wherein said patient status determining device is adapted, and wherein said therapy determining device determines said therapy also based on said heart rate:

obtain sensed heart rate level values continuously or at predetermined intervals, wherein a sequence over time of heart rate levels values can be determined;

include said sensed heart rate values in said evaluation; and

determine said patient status based on said evaluation, wherein a change of a condition of said patient can be derived.

13. The implantable medical device according to claim 3, wherein said therapy determining device determines a dosage of a drug based on said determined therapy.

14. The implantable medical device according to claim 13, comprising a drug delivering device connected to said therapy determining device, and wherein said therapy determining controls said drug delivering device so as to deliver a drug to said patient based on said determined dosage.

15. The implantable medical device according to claim 3, further comprising a telemetry communication unit configured for two-way communication with at least one extracorporeal device including a communication unit, said telemetry communication unit being connected to said patient status determining device and said therapy determining device, and wherein patient status related data and/or therapy related data are transferred from said communication device to said extracorporeal device or vice versa.

16. The implantable medical device according to claim 15, wherein said therapy determining device transfers data including said determined dosage to said extracorporeal device via said telemetry communication unit, such that said patient is informed of said determined dosage.

17. The implantable medical device according to claim 15, wherein said extracorporeal device is a monitoring unit or user equipment.

18. The implantable medical device according to claim 15, wherein said patient status related data and/or said therapy related data is transferred to said extracorporeal device at regular intervals.

19. The implantable medical device according to claim 15, wherein said extracorporeal unit is connected to a communication network, wherein said patient status related data and/or said therapy related data are transferred via said network to a monitoring device located at a care institution connected to said network such that a physician is informed of a patient status and/or a determined therapy or dosage.

20. The implantable medical device according to claim 1, wherein said patient status determining device is configured to:

monitor at least one of the hematocrit level, the SvO2 level, body temperature;

heart rate;

activity level, and/or the minute ventilation; and

determine whether said at least one monitored parameter is within predetermined lower and upper limits for respective parameter.

21. The implantable medical device according to claim 20, wherein said patient status determining device provides said patient with a notification that a monitored parameter has exceeded or fallen below said predetermined limits, respectively, by sending an alert signal.

22. The implantable medical device according to claim 21, wherein said alert signal is sent to said extracorporeal device or wherein said alert signal is sent to a vibration unit of said implantable medical device (2;

20) causing it to vibrate.

23. The implantable medical device according to claim 21, wherein said patient status determining device transfers said alert signal and/or information related to a development of said monitored parameter over time to an extracorporeal device via a telemetry communication unit, such that said patient is informed of said event.

24. The implantable medical device according to claim 20, wherein said patient status determining device transfers said alert signal and/or information related to a development of said monitored parameters over time to a monitoring device via a network, such that a physician is informed of said event.

25. The implantable medical device according to claim 3, wherein said therapy determining device calibrates a level of medication by controlling a drug delivering device so as to adjust a delivery of a drug to said patient based on said comparison between said obtained target ranges with said present hematocrit level and said present SvO2 level, respectively.

26. The implantable medical device according to claim 25, wherein said therapy determining device calibrates a level of medication by controlling said drug delivering device so as to adjust a delivery of a drug to said patient based on said measured parameters including any combination of:

the body temperature;

the heart rate;

the activity level, or the minute ventilation.

27. The implantable medical device according to claim 3, wherein said drug delivering device is a device for delivering diuretics, and wherein said therapy determining device is configured to check whether said present hematocrit level is within said target range for the hematocrit level;

and to instruct said drug delivering device to adjust a delivery of diuretics such that said hematocrit level is maintained within said target range.

28. The implantable medical device according to claim 3, wherein said drug delivering device is a device for delivering a medication that affects the heart function of a patient, and wherein said therapy determining device is configured to:

monitor said SvO2 level and said hematocrit level, to check whether said SvO2 level is within a heart function target range for the SvO2 level;

check whether said present hematocrit level is within a heart function target range for the hematocrit level;

determine that a change in said SvO2 level is caused by a change of the heart function if said present hematocrit level is within said heart function target range; and

instruct said drug delivering device to adjust a delivery of said medication such that said SvO2 level is maintained within said heart function target range if said SvO2 level change is determined to be caused by a changed heart function.

29. The implantable medical device according to claim 1, wherein said patient status determining device is adapted to:

obtain at least one reference value for;

hematocrit, SvO2, body temperature;

heart rate;

the activity level, and/or minute ventilation; and

use said at least one reference value in said evaluation.

30. The implantable medical device according to claim 29, wherein said blood constituent determining device is configured to:

determine a reference hematocrit level, a reference SvO2 level;

a reference body temperature;

a reference heart rate;

a reference activity level, and/or a reference minute ventilation using at least one respective measured parameter value; and

store said determined respective reference values in a storage unit.

12. (canceled)

31. A method for monitoring a hematocrit level and a SvO2 level of a patient in an implantable medical device connectable to at least one medical lead including an optical sensor module adapted to measure at least one hematocrit value and at least one SvO2 value by means of at least first, second, and third light radiation wavelengths, comprising the steps of:

measuring hematocrit values and SvO2 values;

determining a present hematocrit level by means of said at least one hematocrit value and to determine a present SvO2 level by means of said at least one SvO2 value; and

determining a patient status based on an evaluating said present hematocrit level and said present SvO2 level, including deriving a change of said patient status.

32. The method according to claim 31, wherein said step of measuring hematocrit values and SvO2 values comprises the step of measuring hematocrit values and SvO2 values at predetermined intervals, wherein at least one sequence over time of hematocrit levels and SvO2 levels, respectively, is determined.

33. The method according to claim 31, further comprising the steps of:

obtaining a target range for said hematocrit level and said SvO2 level, respectively;

comparing said obtained target ranges with said present hematocrit level and said present SvO2 level, respectively; and

determining a therapy for said patient based on said comparison.

34. The method according to claim 31, further comprising the step of sensing a body temperature of said patient.

35. The method according to claim 34, wherein said step of determining a patient status comprises the steps of:

obtaining sensed body temperature values continuously or at predetermined intervals, wherein at least one sequence of body temperature values over time can be determined;

using said sensed body temperature values in said evaluation;

determining said patient status based on said evaluation, deriving a change of a condition of said patient.

36. The method according to any one of preceding claims 31, further comprising the step of sensing an activity level of said patient.

37. The method according to claim 36, wherein said step of determining a patient status comprises the steps of:

obtaining sensed activity level values continuously or at predetermined intervals, wherein at least one sequence of body temperature values over time can be determined;

using said sensed activity level values in said evaluation;

determining said patient status based on said evaluation, wherein a change of a condition of said patient can be derived.

38. The method according to claim 31, further comprising the steps of measuring a trans-thoracic impedance, including, during impedance measurement sessions,

generating electrical signals to be applied between at least a first electrode and at least a second electrode of electrodes of said at least one medical lead and/or said housing of said implantable medical device;

and

measuring the impedance in the tissue between said at least first electrode and said at least second electrode to the applied electrical signals.

39. The method according to claim 38, wherein said step of determining a patient status comprises the steps of:

obtaining sensed impedance values continuously or at predetermined intervals, wherein at least one sequence of impedance values overtime can be determined;

determining at least one sequence of a minute ventilation of said patient using said impedance values;

using said determined sequence of minute ventilation in said evaluation;

determining said patient status based on said evaluation, and deriving a change of a condition of said patient.

40. The method according to claim 31, further comprising the step of sensing a heart rate of said patient.

41. The method according to claim 40, wherein said step of determining a patient status comprises the steps of:

obtaining sensed heart rate values continuously or at predetermined intervals, wherein at least one sequence of heart rate values over time can be determined;

using said sensed heart rate values in said evaluation;

determining said patient status based on said evaluation, and deriving a change of a condition of said patient.

42. The method according to claim 33, wherein said step of determining a therapy comprises using at least one of, or all of the following parameters:

body temperature, heart rate, activity level, and minute ventilation.

43. The method according to claim 33, wherein said step of determining a therapy comprises determining a dosage of a drug based on said determined therapy.

44. The method according to claim 43, comprising connecting said implantable medical device to a drug delivering device said method further comprising controlling said drug delivering device to deliver a drug to said patient based on said determined dosage.

45. The method according to claim 31, wherein said implantable medical comprises a telemetry communication unit adapted for two-way communication with at least one extracorporeal device, said telemetry communication unit being connected to said patient status determining device and said therapy determining device, wherein said method further comprises transferring patient status related data and/or therapy related data from said communication device to said extracorporeal device or vice versa.

46. The method according to claim 45, further comprising transferring data including said determined dosage to said extracorporeal device via said telemetry communication unit, wherein said patient can be informed of said determined dosage.

47. The method according to claim 45 comprising employing a monitoring unit or a user equipment as said extracorporeal device.

48. The method according to claim 45, further comprising transferring said patient status related data and/or said therapy related data to said extracorporeal device at regular intervals.

49. The method according to claim 45, comprising connecting said extracorporeal unit to a communication network, and wherein said method further comprises said patient status related data and/or said therapy related data via said network to a monitoring device connected to said network, to inform a physician of a patient status and/or a determined therapy or dosage.

50. The method according to claim 31, wherein said step of determining a patient status further comprises the steps of:

monitoring at least one of the following parameters;

hematocrit level, SvO2 level, body temperature, heart rate, the activity level, and minute ventilation; and

determining whether said monitored parameter is within predetermined lower and upper limits.

51. The method according to claim 50, wherein said step of determining a patient status further comprises the step of:

providing said patient with a notification that a monitored parameter has exceeded or fallen below said predetermined limits, respectively, by sending an alert signal.

52. The method according to claim 50, further comprising sending said alert signal to said extracorporeal device or to a vibration unit of said implantable medical device causing it to vibrate.

53. The method according to claim 50, further comprising transferring said alert signal and/or information related to a development of said hematocrit level and said SvO2 level over time to said extracorporeal device via said telemetry communication unit, to inform said patient of said event.

54. The method according to claim 33, further comprising transferring said alert signal and/or information related to a development of said hematocrit level and said SvO2 level over time to said monitoring device via a network, to inform a physician of said event.

55. The method according to claim 33, further comprising the step of calibrating a level of medication by controlling said drug delivering device to adjust a delivery of a drug to said patient based on said comparison between said obtained target ranges with said present hematocrit level and said present SvO2 level, respectively.

56. The method according to claim 55, wherein said step of calibrating further comprises:

calibrating a level of medication by controlling said drug delivering device to adjust a delivery of a drug to said patient based on said measured parameters including any combination of;

the body temperature, the heart rate, the activity level, or the minute ventilation.

57. The method according to claim 33, wherein said drug delivering device is a device for delivering diuretics, and wherein said method further comprises the steps of:

checking whether said present hematocrit level is within said target range for the hematocrit level; and

instructing said drug delivering device to adjust a delivery of diuretics such that said hematocrit level is maintained within said target range.

58. The method according to claim 33, wherein said drug delivering device is a device for delivering a medication that affects the heart function of a patient, said method further comprising the steps of:

monitoring said SvO2 level and said hematocrit level;

checking whether said SvO2 level is within a heart function target range for the SvO2 level;

checking whether said present hematocrit level is within a heart function target range for the hematocrit level;

determining that a change in said SvO2 level is caused by a change of the heart function if said present hematocrit level is within said heart function target range; and

instructing said drug delivering device to adjust a delivery of said medication such that said SvO2 level is maintained within said heart function target range if said SvO2 level change is caused by a changed heart function.

59. The method according to claim 31, wherein said step of evaluating further comprises the steps of:

obtaining at least one reference value for the hematocrit, the SvO2, the body temperature, the heart rate, the activity level, and/or the minute ventilation; and

using said at least one reference value in said evaluation.

60. The method according to claim 59, further comprising the steps of:

determining a reference hematocrit level, a reference SvO2 level, a reference body temperature, a reference heart rate, a reference activity level, and/or a reference minute ventilation; and

storing said determined respective reference values.

61. (canceled)

62. A computer-readable medium encoded with programming instructions loadable into an internal memory of an implantable medical device that is connected to at least one medical lead that carries an optical sensor module that measures at least one hematocrit value and at least one SvO2 value using first, second and third light radiation wavelengths, said programming instructions causing said implantable medical device to monitor a hematocrit level and an SvO2 level, by causing said implantable medical device to:

measure hematocrit values and SvO2 values;

determine a present hematocrit value from at least one of said hematocrit values and to determine a present SvO2 value from at least one of said SvO2 values; and

determine a patient status by evaluating said present hematocrit value and said present SvO2 value, including derivation of a change of said patient status.