Method and apparatus for measuring temperature of a living body

• US 5,015,102 A
• Filed: 08/09/1989
• Issued: 05/14/1991
• Est. Priority Date: 12/24/1986
• Status: Expired due to Fees

• Current Assignee: Terumo Kabushiki Kaisha
• Original Assignee: Terumo Kabushiki Kaisha
• Inventors: Yamaguchi, Keiji
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Gutierrez, Diego F. F.
• Application Number:
  US07/378,186
• Time in Patent Office: 643 Days
• Field of Search: 374/102, 374/103, 374/107, 374/169, 364/557, 364/413.03, 128/736
• US Class Current: 374/107
• 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 method and apparatus for measuring the temperature of a living body, providing a predetermined predictive functional formula in which the value of a shape parameter for reflecting the shape of a sensed temperature curve and the value of coefficient parameters for superimposing said prediction function on said sensed temperature curve are unknown. The temperature of a living body is sensed to obtain temperature data for subsequent processing, and elapsed time from start of temperature measurement is measured to obtain elapsed time data. The value of shape parameter is set on the basis of prescribed temperature data, and the value of coefficient parameters are set by solving simultaneous equations composed of a plurality of said predictive functional formula which includes said set value of shape parameter, and in which temperature data at a plurality of different points in time serve as purposive variables and functions of time data at the plurality of points in time serve as explicative variables. Sensed temperature that will prevail at a future time is calculated through prediction processing in accordance with the functional formula specified by said set value of shape parameter and coefficient parameters.

Claims

1. A method of measuring temperature of a living body, wherein sensed temperature at a future time is capable of being predicted based on a predictive functional formula having elapsed time from the start of temperature measurement as variable, said method comprising the steps of:

providing a predictive functional formula having temperature data as independent variables and elapsed time data as dependent variables and including a shape parameter for reflecting the shape of a sensed temperature curve and coefficient parameters for superimposing said predictive functional formula on said sensed temperature curve, the value of said shape parameter and coefficient parameters being unknown;

a temperature sensing step of sensing temperature and generating temperature data indicative of the temperature sensed;

a time measuring step of measuring elapsed time from start of temperature measurement and generating time data indicative of the measured elapsed time;

setting a value of a shape parameter on the basis of said temperature data and said elapsed time data obtained early.

setting said value of coefficient parameters by solving a simultaneous equation comprising a plurality of said predictive functional formula, said plurality of predictive functional formulas being solved by substituting for said formula variables said value of shape parameter, temperature data, and elapsed time data at a plurality of different points in time; and

calculating sensed temperature at a future time in accordance with the predictive functional formula specified by said value of shape parameter and coefficient parameters.

2. The method according to claim 1, wherein said predictive functional formula is

3. The method of according to claim 2, wherein said value of shape parameter α

is set on the basis of temperature rise information obtained from a plurality of temperature data.

4. The method according to claim 3, wherein said value of shape parameter is set by detecting a point at which the sensed temperature curve exhibits a first predetermined slope, detecting a second slope S₁ preceding the detected point and a third slope S₂ following the detected point, and comparing said second and third slopes.

5. The method according to claim 4, wherein said value of shape parameter α

is set on the basis of said second slope S₁ and third slope S₂, in accordance with the following equation;

space="preserve" listing-type="equation">α

=Q.sub.1 (S.sub.1 /S.sub.2)+Q.sub.2 (S.sub.1 /S.sub.2).sup.n +Q.sub.3

where

n (a constant)<

1

Q₁ -Q₃ ;

constants

6. The method according to claim 2, wherein said value of shape parameter is set on the basis of plural items of temperature data at an early stage of temperature measurement following the start of measurement.

7. The method according to claim 6, wherein said value of shape parameter α

is set on the basis of information X_k based on plural items of temperature data T_k at respective predetermined points in time, in accordance with the following equation;

##EQU20## where D₀ -D₅ constants

X₀ -X₃ ;

T₀ -T₃

X₄ =(X₃ -X₀)/(X₁ -X₀)

8. The method according to claim 1, wherein said value of coefficient parameters A₀, A₁ are set by solving the following simultaneous equations with two unknowns:

space="preserve" listing-type="equation">T(t.sub.1)=A.sub.0 +A.sub.1 /t.sub.1.sup.α

space="preserve" listing-type="equation">T(t.sub.2)=A.sub.0 +A.sub.1 /t.sub.2.sup.α

on the basis of temperature data T(t₁), T(t₂) at two different points in time and time data t₁, t₂ respectively indicative of the points in time at which the temperature is sensed.

9. The method according to claim 8, wherein said temperature data at the two different points in time are temperature data in the vicinity of measurement starting time and temperature data at a present point in time.

10. The method according to claim 1, wherein said sensed temperature T_p (t_D) at a future time t_D is calculated in accordance with the following equation:

space="preserve" listing-type="equation">T.sub.p (t.sub.D)=A.sub.0 +A.sub.1 /t.sub.D.sup.α

based on a prediction function specified by the value of shape parameter α and

coefficient parameters A₀, A₁.

11. An apparatus for measuring the temperature of a living body, wherein sensed temperature at a future time is capable of being predicted, comprising:

memory means for storing a predictive functional formula having temperature data as independent variables and elapsed time data as dependent variable and including a shape parameter for reflecting the shape of a sensed temperature curve and coefficient parameters for superimposing said predictive functional formula on said sensed temperature curve, wherein said shape parameter and coefficient parameters are unknown;

temperature sensing means for sensing temperature and generating temperature data indicative of the temperature sensed;

time measuring means for measuring elapsed time from start of temperature measurement and generating time data indicative of the measured elapsed time;

shape parameter setting means for setting a value of shape parameter on the basis of said temperature data and elapsed time data;

coefficient parameter setting means for setting a value of coefficient parameters by solving a simultaneous equation comprising a plurality of said predictive functional formula, said plurality of predictive functional formulas being solved by substituting for said formula variables said value of shape parameter, and temperature data and elapsed time data at a plurality of different points in time; and

prediction processing means for calculating sensed temperature at a future time in accordance with the predictive functional formula specified by said value of shape parameter and coefficient parameters.

12. The apparatus according to claim 11, wherein said temperature sensing means includes peak holding means for successively detecting peak levels of sensed temperature and for holding and outputting the detected peak levels.

13. The apparatus according to claim 11, wherein said temperature sensing means includes peak holding means for successively detecting peak levels of temperature sensed at a predetermined period and for holding and outputting the detected peak levels, and averaging means for obtaining and outputting a running average value of plural peak levels held by said peak holding means.

14. The apparatus according to claim 11, wherein said shape parameter setting means sets the value of shape parameter on the basis of predetermined temperature rise slope information, which is based on plural items of temperature data.

15. The apparatus according to claim 11, wherein said shape parameter setting means sets the value of shape parameter on the basis of plural items of temperature data at an early stage of temperature measurement following start of measurement.

16. The apparatus according to claim 11, wherein said coefficient parameter setting means sets the value of coefficient parameters A₀, A₁ by solving the following simultaneous equations with two unknowns:

space="preserve" listing-type="equation">T(t.sub.1)=A.sub.0 +A.sub.1 /t.sub.1.sup.α

space="preserve" listing-type="equation">T(t.sub.2)=A.sub.0 +A.sub.1 /t.sub.2.sup.α

on the basis of temperature data T(t₁), T(t₂) at two different points in time and time data t₁, t₂ respectively indicative of the points in time at which temperature is sensed.

17. The apparatus according to claim 16, wherein said coefficient parameter setting means includes using, as the temperature data at the two different points in time, temperature data in the vicinity of measurement starting time and temperature data at a present point in time.

18. The apparatus according to claim 11, wherein said prediction processing means calculates a sensed temperature T_p (t_D), which will prevail at a future time t_D, in accordance with the following equation:

T_p (t_D)=A₀ +A₁ /t_D.sup.α

based on a prediction function specified by the value of shape parameter α and

coefficient parameters A₀, A₁.