Systems and methods for detecting symptoms of hypoglycemia

• US 7,052,472 B1
• Filed: 12/18/2003
• Issued: 05/30/2006
• Est. Priority Date: 12/18/2002
• Status: Active Grant

• Current Assignee: DSP Diabetes Sentry Products, Inc.
• Original Assignee: DSP Diabetes Sentry Products, Inc.
• Inventors: Miller, Mark Edward, Evans, Ronald William
• Primary Examiner(s): SUNDARARAMAN, VIKRAM P
• Application Number:
  US10/740,695
• Time in Patent Office: 894 Days
• Field of Search: 600/549, 600/547, 600/365, 374/142, 374/185
• 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 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/4266 sweat secretion
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

A system for detecting symptoms of hypoglycemia in a diabetic individual. The system comprises a temperature sensing system, a conductance sensing system, a trending system, a threshold system, and an alarm system. The temperature sensing system produces a temperature signal representative of a skin temperature of the diabetic individual. The conductance sensing system produces a conductance signal representative of a level of perspiration of the diabetic individual. The trending system produces a slope estimate representative of a rate of change of the skin temperature over a predetermined interval in response to the temperature signal. The threshold system produces a slope threshold representative of a hypoglycemic decline in skin temperature observed over the predetermined interval in response to the conductance signal and to the temperature signal. The alarm system produces an indication of the presence of hypoglycemic symptoms in response to the slope estimate and the slope threshold.

Claims

1. A system for detecting symptoms of hypoglycemia in a diabetic individual, comprising:

a temperature sensing system for producing a temperature signal representative of a skin temperature of the diabetic individual;

a conductance sensing system for producing a conductance signal representative of a level of perspiration of the diabetic individual;

a trending system responsive to the temperature signal for producing a slope estimate representative of a rate of change of the skin temperature over a predetermined interval;

a threshold system responsive to the conductance signal and to the temperature signal for producing a slope threshold representative of a hypoglycemic decline in skin temperature observed over the predetermined interval; and

an alarm system responsive to the slope estimate and to the slope threshold for producing an indication of the presence of hypoglycemic symptoms.

2. A system as defined in claim 1, wherein the alarm system produces the indication when the slope estimate falls below the slope threshold.

3. A system as defined in claim 2, wherein the alarm means does not produce the indication when the slope estimate falls below an artifact rejection threshold, the artifact rejection threshold representing a rate of change of the skin temperature not indicative of hypoglycemic symptoms.

4. A system as defined in claim 3, wherein the artifact rejection threshold is less than the slope threshold.

5. A system as defined in claim 1, wherein the trending system produces the slope estimate through a linear regression analysis.

6. A system as defined in claim 1, wherein the threshold system decreases the slope threshold when the level of perspiration increases, and wherein the threshold system increases the slope threshold when the level of perspiration decreases.

7. A system as defined in claim 1, wherein the threshold system decreases the slope threshold when the skin temperature increases, and wherein the threshold means increases the slope threshold when the skin temperature decreases.

8. A system as defined in claim 1 wherein the alarm system produces an indication of the presence of hypoglycemic symptoms when the level of perspiration rises above a predetermined threshold representative of a hypoglycemic level of perspiration.

9. A system as defined in claim 8 wherein the alarm system produces an indication of a depleted battery when a battery potential falls below a predetermined battery alarm threshold.

10. A system as defined in claim 9 further comprising a strap formed of hypoallergenic and conformable elastomer and defining a stretchable recess, a hook fabric strip, and a loop fabric strip.

11. A system as defined in claim 9 further comprising an elastomeric cup defining a stretchable recess and a spring clip member.

12. A system for detecting symptoms of hypoglycemia in a diabetic individual, comprising:

a temperature sensing system for producing a temperature signal representative of a skin temperature of the diabetic individual;

a conductance sensing system for producing a conductance signal representative of a level of perspiration of the diabetic individual;

a signal estimation system responsive to the temperature signal and to the conductance signal for producing a basal conductance reference representative of a basal level of perspiration;

a threshold system responsive to the basal conductance reference and to the skin temperature signal for producing a conductance threshold representative of a hypoglycemic level of perspiration; and

an alarm system responsive to the conductance signal and to the conductance threshold for producing an indication of the presence of hypoglycemic symptoms.

13. A system as defined in claim 12, wherein the alarm system produces the indication when the conductance signal rises above the conductance threshold.

14. A system as defined in claim 13, wherein the alarm system produces the indication when the conductance signal rises above the conductance threshold for a predetermined length of time.

15. A system as defined in claim 12, wherein the signal estimation system produces the basal conductance reference by obtaining the mean of the conductance signal over a predetermined averaging interval.

16. A system as defined in claim 15, wherein the signal estimation system produces the basal conductance reference after a rate of change of the skin temperature signal falls below a predetermined slope threshold.

17. A system as defined in claim 12, wherein the threshold system increases the conductance threshold when the skin temperature increases, and wherein the threshold system decreases the conductance threshold when the skin temperature decreases.

18. A system as defined in claim 12 wherein the alarm system produces an indication of the presence of hypoglycemic symptoms when the skin temperature falls below a predetermined temperature threshold representative of a hypoglycemic skin temperature.

19. A system for detecting symptoms of hypoglycemia in a diabetic individual, comprising:

a temperature sensing system for producing a temperature signal representative of a skin temperature of the diabetic individual;

a conductance sensing system for producing a conductance signal representative of a level of perspiration of the diabetic individual;

a trending system responsive to the temperature signal for producing a slope estimate representative of a rate of change of the skin temperature over a predetermined interval;

a temperature threshold system responsive to the conductance signal and to the temperature signal for producing a slope threshold representative of a hypoglycemic decline in skin temperature observed over the predetermined interval;

a temperature alarm system responsive to the slope estimate and to the slope threshold for producing an indication of the presence of hypoglycemic symptoms;

a signal estimation system responsive to the temperature signal and to the conductance signal for producing a basal conductance reference representative of a basal level of perspiration;

a conductance threshold system responsive to the basal conductance reference and to the temperature signal for producing a conductance threshold representative of a hypoglycemic level of perspiration;

a conductance alarm system responsive to the conductance signal and to the conductance threshold for producing an indication of the presence of hypoglycemic symptoms; and

a selector system for selecting an operating mode from a plurality of operating modes.

20. A system as defined in claim 19, wherein one of the operating modes disables the conductance alarm means.

21. A system as defined in claim 19, wherein one of the operating modes disables the temperature alarm means.

22. A system as defined in claim 19, wherein the one of the operating modes prevents the temperature threshold means from responding to the conductance signal.

23. A system as defined in claim 19, wherein the one of the operating modes prevents the temperature threshold means from responding to the temperature signal.

24. A system as defined in claim 19, wherein one of the operating modes prevents the conductance threshold means from responding to the temperature signal.

25. A method of detecting symptoms of hypoglycemia in a diabetic individual, comprising:

producing a temperature signal representative of a skin temperature of the diabetic individual;

producing a conductance signal representative of a level of perspiration of the diabetic individual;

producing a slope estimate representative of a rate of change of the skin temperature over a predetermined interval in response to the temperature signal;

producing a slope threshold representative of a hypoglycemic decline in skin temperature observed over the predetermined interval in response to the conductance signal and the temperature signal; and

producing an indication of the presence of hypoglycemic symptoms in response to the slope estimate and the slope threshold.

26. A method of detecting symptoms of hypoglycemia in a diabetic individual, comprising:

producing a temperature signal representative of a skin temperature of the diabetic individual;

producing a conductance signal representative of a level of perspiration of the diabetic individual;

producing a basal conductance reference representative of a basal level of perspiration in response to the temperature signal and the conductance signal;

producing a conductance threshold representative of a hypoglycemic level of perspiration in response to the basal conductance reference and the skin temperature signal; and

producing an indication of the presence of hypoglycemic symptoms in response to the conductance signal and the conductance threshold.

27. A method of detecting symptoms of hypoglycemia in a diabetic individual, comprising:

producing a temperature signal representative of a skin temperature of the diabetic individual;

producing a conductance signal representative of a level of perspiration of the diabetic individual;

producing a slope estimate representative of a rate of change of the skin temperature over a predetermined interval in response to the temperature signal;

producing a slope threshold representative of a hypoglycemic decline in skin temperature observed over the predetermined interval in response to the conductance signal and the temperature signal;

producing an indication of the presence of hypoglycemic symptoms in response to the slope estimate and the slope threshold;

producing a basal conductance reference representative of a basal level of perspiration in response to the temperature signal and the conductance signal;

producing a conductance threshold representative of a hypoglycemic level of perspiration in response to the basal conductance reference and the temperature signal;

producing an indication of the presence of hypoglycemic symptoms in response to the conductance signal and the conductance threshold; and

selecting an operating mode from a plurality of operating modes.