Medical thermometer for determining body core temperature

• US 20070055171A1
• Filed: 12/08/2005
• Published: 03/08/2007
• Est. Priority Date: 08/19/2003
• Status: Active Grant

• Current Assignee: Helen of Troy Limited
• Original Assignee: Advanced Monitors Corporation
• Inventors: Fraden, Jacob
• Granted Patent: US 7,785,266 B2
• Time in Patent Office: Days
• US Class Current: 600/549
• CPC Class Codes: G01K 1/165 for application in zero heat flux sensors
• CPC Class Codes: G01K 13/20 Clinical contact thermometers for use with humans or animals
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A temperature sensing device including at least a first contact type temperature sensing element determines body core temperature of a warm blooded animal or human based on an estimated skin temperature of the patient which is computed based on temperature measurements obtained by the first sensing element.

Claims

1. A temperature sensing device for determining body core temperature comprising:

a housing;

a first contact type temperature sensing element coupled to the housing and including a first temperature sensor, wherein the first temperature sensor generates at least a first temperature data signal representative of a temperature measurement made at the sensor when the first contact type temperature sensing element is placed in contact with skin of a patient;

an electronic circuit electrically coupled with the first contact type temperature sensing element, wherein the electronic circuit uses the temperature data signal generated at the sensor to estimate a skin temperature and determines a body core temperature for the patient using the estimated skin temperature; and

an indicating means coupled to the electronic circuit and for at least one of audibly and visually indicating the body core temperature.

2. The device of claim 1 further comprising a thermal insulator positioned adjacent the first temperature sensor.

3. The device of claim 1, wherein the first temperature sensor generates a plurality of temperature data signals representative of temperature measurements made at the first sensor when the first contact type temperature sensing element is placed in contact with the skin of the patient, and wherein the electronic circuit uses the first temperature data signals to estimate the skin temperature.

4. The device of claim 3, wherein the first temperature sensor generates at least a second temperature data signal representative of a temperature measurement made at the first sensor before the first sensor is placed in contact with the skin.

5. The device of claim 2 further comprising:

a second temperature sensor coupled to the housing, wherein the thermal insulator is positioned generally between the first and second temperature sensors for thermally decoupling the first and second temperature sensors from each other, wherein the second temperature sensor is positioned to be thermally decoupled from the skin during measurement of the skin temperature by the first temperature sensor, wherein the second temperature sensor is operative to detect a reference temperature and generate at least one temperature measurement data signal representative of the reference temperature, and wherein the electronic circuit uses the temperature measurement data signals generated by the first and second sensors to determine the body core temperature.

6. The device of claim 1, further comprising a moveable element coupled to the first contact type temperature sensing element, wherein the moveable element is configured to move into at least first and second positions, wherein the first position is a position at which the first contact type temperature sensing element is not adapted for contact with the skin and the second position is a position at which the first contact type temperature sensing element is adapted for contact with the skin.

7. The device of claim 6, wherein the moveable element further comprises a shaft formed from a thermally insulating material.

8. The device of claim 7, wherein the shaft includes a resilient element normally biasing the first contact type temperature sensing element toward the first position.

9. The device of claim 1 further comprising:

a guard coupled to the housing and configured to surround and protect the first contact type temperature sensing element, wherein the guard is moveable relative to the first contact type temperature sensing element to allow the first contact type temperature sensing element to contact the skin.

10. The device of claim 1 further comprising:

a power supply coupled to the electronic circuit; and

a handling detector coupled to the electronic circuit and operative to detect handling of the device by the user, wherein the electronic circuit, upon detection of handling at the handling detector, provides for supply of electrical power from the power supply.

11. The device of claim 10, wherein the handling detector further comprises at least one of a motion sensor and a capacitive touch sensor.

12. The device of claim 6, wherein the housing comprises a switch mechanically coupled to the moveable element for detecting movement of the moveable element to the second position.

25. The device of claim 1 further comprising:

a guard means for protecting the first contact type temperature sensing means, wherein the guard means is moveable relative to the first contact type temperature sensing means to allow the first contact type temperature sensing element to contact the skin.

26. The device of claim 1 further comprising:

a power supply means coupled to the electronic circuit means; and

a handling detector means coupled to the electronic circuit means and for detecting handling of the device by the user, wherein the electronic circuit means, upon detection of handling at the handling detector means, provides for supply of electrical power from the power supply means.

13. A method of determining body core temperature of a warm blooded animal or human based on at least one measurement of temperature of skin of the warm blooded animal or human, the method comprising:

contacting the skin of the warm blooded animal or human with a first sensor of a first contact type temperature sensing element for generating at least a first temperature measurement data signal;

computing an estimated temperature of the skin based on the first data signal; and

determining body core temperature of the warm blooded animal or human based on the estimated skin temperature.

14. The method of claim 13 further comprising:

prior to contacting the skin with the first sensing element, generating at least a second temperature measurement data signal representative of the temperature of the first sensor; and

determining the body core temperature based on the first and second signals.

15. The method of claim 13, wherein the estimating of the skin temperature further comprises measuring a rate of change in skin temperature based on a plurality of the first data signals.

16. The method of claim 13 further comprising:

producing at least a second temperature measurement data signal representative of temperature measurements at a second temperature sensor thermally insulated from the first contact type temperature sensing element and the skin; and

determining the body core temperature from the first and second data signals.

17. The method of claim 13, wherein the body core temperature, T_c, is determined using the equation

T_c=AT_s²+(B+CT_r)T_s+DT_r+E

where:

T_S is the skin temperature,

T_R is a reference temperature, and

A, B, C, D and E are constants.

18. The method of claim 13 further comprising:

generating a plurality of the first data signals while the first contact type sensing element is contacting the skin.

19. The method of claim 18 further comprising:

determining a rate of heat flow using the plurality of the first data signals; and

determining the temperature of the skin using the rate of the heat flow.

20. The method of claim 13 further comprising:

generating at least a second temperature measurement data signal at the first sensor when handling of the sensor by a user is initially detected; and

determining the body core temperature based on the first and second data signals.

21. A temperature sensing device for determining body core temperature comprising:

a first contact type temperature sensing means including a first temperature sensor means, wherein the first temperature sensor means is for generating at least a first temperature data signal representative of a temperature measurement made at the first temperature sensor means when the first contact type temperature sensing means is placed in contact with skin of a patient;

an electronic circuit means electrically coupled with the first contact type temperature sensing element, wherein the electronic circuit means is for estimating a skin temperature based on the temperature data signal generated at the first sensor means and for determining a body core temperature for the patient using the estimated skin temperature; and

an indicating means coupled to the electronic circuit means and for at least one of audibly and visually indicating the body core temperature.

22. The device of claim 21 further comprising:

a second temperature sensor means thermally decoupled from the first temperature sensor means, wherein the second temperature sensor means is for generating at least one temperature measurement data signal representative of a reference temperature, and wherein the electronic circuit means is for determining the body core temperature based on the temperature measurement data signals generated by the first and second sensor means.

23. The device of claim 21 further comprising a moveable means coupled to the first contact type temperature sensing means and movable into at least first and second positions, wherein the first position is a position at which the first contact type temperature sensing means is not adapted for contact with the skin and the second position is a position at which the first contact type temperature sensing means is adapted for contact with the skin.

24. The device of claim 23, wherein the moveable means includes a resilient means normally biasing the first contact type temperature sensing means toward the first position.

27. A method of determining body core temperature of a warm blooded animal or human based on at least one measurement of temperature of skin of the warm blooded animal or human, the method comprising:

providing at least a first data signal representative of a thermal contact temperature measurement of the skin of the warm blooded animal or human;

computing an estimated temperature of the skin based on the at least first data signal; and

determining body core temperature of the warm blooded animal or human based on the estimated skin temperature.

28. The method of claim 27, wherein the computing the estimated skin temperature further comprises measuring a rate of change in skin temperature based a plurality of the first data signals.

29. The method of claim 27, wherein the body core temperature, Tc, is determined based on the at least first data signal and a reference temperature.

30. The method of claim 27 further comprising:

computing the estimated temperature based on a plurality of the first data signals.

31. The method of claim 30 further comprising:

determining a rate of heat flow using the plurality of the first data signals; and

computing the estimated skin temperature using the rate of the heat flow.