NON-INVASIVE MONITORING OF BLOOD METABOLITE LEVELS

• US 20120130212A1
• Filed: 06/04/2010
• Published: 05/24/2012
• Est. Priority Date: 10/27/2008
• Status: Active Grant

• Current Assignee: BioSensors, Inc.
• Original Assignee: BioSensors, Inc.
• Inventors: Pluta, Sarah E., Hewitt, John W.
• Granted Patent: US 9,307,935 B2
• Time in Patent Office: Days
• US Class Current: 600/345
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1468 using chemical or electrochemical methods, e.g. by polarographic means A61B5/1486 takes precedence
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

Solutions for non-invasively monitoring blood metabolite levels of a patient are disclosed. In one embodiment, the method includes: repeatedly measuring a plurality of electromagnetic impedance readings with a sensor array from: an epidermis layer of a patient and one of a dermis layer or a subcutaneous layer of the patient, until a difference between the readings exceeds a threshold; calculating an impedance value representing the difference using an equivalent circuit model and individual adjustment factor data representative of a physiological characteristic of the patient; and determining a blood metabolite level of the patient from the impedance value and a blood metabolite level algorithm, the blood metabolite level algorithm including blood metabolite level data versus electromagnetic impedance data value correspondence of the patient.

Claims

1. A method comprising:

repeatedly measuring a plurality of electromagnetic impedance readings with a sensor array from;

an epidermis layer of a patient and one of a dermis layer or a subcutaneous layer of the patient, until a difference between the readings exceeds a threshold;

calculating an impedance value representing the difference using an equivalent circuit model and individual adjustment factor data representative of a physiological characteristic of the patient; and

determining a blood metabolite level of the patient from the impedance value and a blood metabolite level algorithm, the blood metabolite level algorithm including blood metabolite level data versus electromagnetic impedance data value correspondence of the patient.

2. The method of claim 1, further comprising:

calibrating the sensor array based on the blood metabolite level of the patient and a known blood metabolite level of the patient.

3. The method of claim 1, wherein the blood metabolite level is a one of a glucose level, an electrolyte level or an analyte level.

4. The method of claim 1, wherein the individual adjustment factor data includes information about at least one of:

a weight of the patient, a sex of the patient, a body fat percentage of the patient, a heart rate of the patient, an age of a patient, and a race of a patient.

5. The method of claim 1, wherein the repeatedly measuring is performed within approximately one minute to approximately 6 minutes.

6. The method of claim 1, wherein the repeatedly measuring from the one of the dermis layer or the subcutaneous layer of the patient is performed within one glucose cycle of the patient.

7. The method of claim 1, wherein the repeatedly measuring includes measuring the plurality of electromagnetic impedance readings from the epidermis layer, the dermis layer and the subcutaneous layer of the patient.

8. The method of claim 1, wherein the sensor array contains a planar array of equally spaced electrodes.

10. The method of claim 1, wherein the equivalent circuit model includes an equivalent circuit equation including:

D=((ZK/(ZJ+ZK))−

(ZM/(ZL+ZM))

where ZJ is a first electromagnetic impedance reading from the epidermis layer, ZM is a second electromagnetic impedance reading from the epidermis layer, ZK is a first electromagnetic impedance reading from the one of the dermis layer or the subcutaneous layer, ZL is a second electromagnetic impedance reading from the one of the dermis layer or the subcutaneous layer, and D is the impedance value representing the difference.

9. (canceled)

11. A monitoring system for at least one of a glucose level, an electrolyte level or an analyte level, the monitoring system comprising:

a sensor array for repeatedly measuring a plurality of electromagnetic impedance readings from;

an epidermis layer of a patient and one of a dermis layer or a subcutaneous layer of the patient, until a difference between the readings exceeds a threshold;

a calculator for calculating an impedance value representing the difference, the calculating including using an equivalent circuit model and individual adjustment factor data representative of a physiological characteristic of the patient; and

a determinator for determining the at least one of the glucose level, the electrolyte level or the analyte level of the patient from the impedance value and at least one of a glucose algorithm, an electrolyte algorithm or an analyte algorithm.

12. The monitoring system of claim 11, further comprising a signal generator for generating electromagnetic signals and transmitting the electromagnetic signals to the sensor array.

13. The monitoring system of claim 12, further comprising a signal analyzer for analyzing the electromagnetic signals and generating the electromagnetic impedance readings.

18. The monitoring system of claim 11, wherein the electromagnetic impedance readings are obtained at a frequency between approximately 10 Hz and 10 MHz.

22. The monitoring system of claim 11, wherein the sensor array contains at least seven sensors.

23. The monitoring system of claim 22, wherein the at least seven sensors are arranged in a substantially linear arrangement.

27. The monitoring system of claim 11, wherein the sensor array includes a current transmitting electrode, a current sensing electrode, and two voltage sensing electrodes positioned on the epidermis layer of the patient in a linear arrangement.

82. The monitoring system of claim 27, wherein the current transmitting electrode, the current sensing electrode and the two voltage sensing electrodes are spaced equally from one another within the sensor array.

14-17. -17. (canceled)

19-21. -21. (canceled)

24-26. -26. (canceled)

28-55. -55. (canceled)

56. A program product stored on a computer readable medium, which when executed, performs the following:

determines a blood metabolite level of a patient based on a plurality of electromagnetic impedance readings collected from the patient within a single blood metabolite cycle of the patient,

wherein the plurality of electromagnetic impedance readings are non-invasively collected from the patient using a sensor array; and

provides instructions for calibrating the sensor array based on the blood metabolite level of the patient and a known blood metabolite level of the patient.

59. The program product of claim 56, which further provides instructions to a signal generator for transmitting an electromagnetic signal to the sensor array, the electromagnetic signal being used for the measuring of the plurality of electromagnetic impedance readings from the patient.

60. The program product of claim 56, wherein the electromagnetic impedance readings are collected from:

an epidermis layer of the patient and at least one of a dermis layer or a subcutaneous layer of the patient.

61. The program product of claim 56, which further performs the following:

calculates a complex impedance value from the plurality of electromagnetic impedance readings, and

determines the blood metabolite level of the patient based on the complex impedance value and a blood metabolite algorithm.

62. The program product of claim 61, wherein the calculating of the complex impedance value includes using an equivalent circuit model and individual adjustment factor data representative of a physiological characteristic of the patient.

65. The program product of claim 56, wherein the blood metabolite level is one of a glucose level of the patient, an electrolyte level of the patient or an analyte level of the patient.

57-58. -58. (canceled)

63-64. -64. (canceled)

66-81. -81. (canceled)