IP Library › Granted Patent US 12,303,238
Granted Patent B2
US 12,303,238 · App. 18/100,361 · Granted May 20, 2025

System and method for determining an adaptive physiological strain index

Inventor: Mark J Buller (Douglas, MA)
Assignee: The Government of the United States, as represented by the Secretary of the Army
A61B5/02055A61B5/01A61B5/11A61B5/725A61B5/441A61B2503/20A61B2562/0219
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Quick Facts
Patent No.
US 12,303,238
App. No.
18/100,361
Granted
May 20, 2025
Kind
B2
Abstract

The invention in at least one embodiment includes a system and method for detecting and evaluating an adaptive physiological strain index (aPSI) of an individual with a processor and in a further embodiment taking into account the fitness, age and clothing of the individual based upon physiology. The invention in at least one embodiment includes a system and method to calculate the aPSI using physiological measures. In at least one embodiment, the method obtains an individual's skin temperature and heart rate in order to calculate the individual's aPSI.

Claims (189)

1. A system for generating an adaptive physiological strain index (aPSI) to reduce a likelihood of heat related illness (HRI) or treat for HRI of an individual based on the aPSI, the system comprising:

at least one heart rate sensor configured to measure a heart rate of the individual;

at least one temperature sensor configured to detect a skin temperature of the individual;

a processor in electrical communication with said at least one temperature sensor and said at least one heart rate sensor, said processor configured to produce the aPSI for the individual using the heart rate from said at least one heart rate sensor and an adaptive maximum body temperature based in part on a temperature gradient between the skin temperature and a body core temperature; and

a monitoring system in communication with said processor, said monitoring system configured to provide an alert identifying a treatment based on the aPSI to the individual or another individual when the aPSI is above a predetermined aPSI threshold for the individual, and

wherein the aPSI and the alert are used by the individual or the other individual to begin the treatment selected from having the individual adjust a level of activity or pace of the individual to lower the aPSI, drink fluids, submerse in water, and/or sit in a cooler environment to address physical strain;

wherein the at least one treatment identified by the alert updates as the aPSI for the individual changes; and

wherein when the aPSI is below the predetermined aPSI threshold, said system continues to monitor the individual.

2. The system of claim 1 , further comprising a housing containing said at least one heart rate sensor and said at least one temperature sensor, and

wherein said monitoring system includes a display configured to provide the alert as a visual alert.

3. The system of claim 1 , further comprising a memory in electrical communication with said processor, and

wherein said processor calculating the aPSI for the individual uses only

the heart rate from said at least one heart rate sensor,

the adaptive maximum body temperature based on

the temperature gradient between the skin temperature from said at least one temperature sensor and the body core temperature, the temperature gradient varies over time, and

a critical temperature,

the skin temperature from said at least one skin temperature sensor,

a resting body core temperature from said memory,

a resting heart rate from said memory,

a current heart rate from said at least one heart rate sensor, and the body core temperature from an internal temperature sensor or calculated from the current heart rate, and

a critical heart rate.

4. The system of claim 1 , further comprising a data storage configured to store a body core temperature at rest and a heart rate at rest; and

wherein said processor calculating the aPSI based on the following equation:

aPSI

=

5

⁢

(

CT

t

-

CT

rest

CT

critical

-

CT

rest

)

+

5

⁢

(

HR

t

-

HR

rest

HR

critical

-

HR

rest

)

CT

critical

=

39.5

°

⁢

C

.

+

(

CT

t

-

ST

t

)

-

4

4

where CT t is the body core temperature at a time t, CT rest is the body core temperature at rest, HR t is the heart rate at a time t, HR rest is the heart rate at rest, HR critical is a maximum heart rate, CT critical is the adaptive maximum body temperature, and ST is the skin temperature.

5. The system according to claim 1 , further comprising a timer circuit in communication with said processor, and

wherein said processor is configured to produce a new calculated aPSI based on calculating at least one first aPSI at an initial time designation of a timer circuit and calculating one new calculated aPSI at each predetermined time interval as provided by said timer circuit.

6. The system according to claim 1 , further comprising an accelerometer in communication with said processor; and

wherein said processor is configured to detect at least one of a resting heart rate and a resting skin temperature of the individual when a plurality of signals from said accelerometer remain below a predetermined threshold for a predetermined time period and/or substantially remain below the predetermined threshold for the predetermined time period, and

said processor is further configured to determine a resting body core temperature for the individual based on the resting heart rate.

7. The system according to claim 1 , wherein said processor is configured to calculate the body core temperature using a Kalman filter or an extended Kalman filter.

8. The system according to claim 1 , further comprising a display in communication with said processor to display the aPSI produced by the processor.

9. The system according to claim 1 , further comprising an alarm in communication with said processor,

wherein said processor is configured to produce an alert signal to said alarm when the aPSI exceeds the predetermined aPSI threshold.

10. The system according to claim 1 , further comprising:

a memory for storing at least a resting heart rate for the individual, and said memory is in electrical communication with said processor;

wherein said processor configured to produce an updated aPSI for the individual based on a current skin temperature, the resting heart rate, and a current heart rate where a current body core temperature is calculated based on the heart rate information and time since initiation of a monitoring session of the individual.

11. The system according to claim 1 , further comprising:

at least one internal temperature sensor configured to be internal to the individual to provide the body core temperature;

wherein said processor configured to produce an updated aPSI for the individual based on the skin temperature from said at least one skin temperature sensor, a resting heart rate from a memory, a current heart rate from said at least one heart rate sensor, and the body core temperature from said internal temperature sensor.

12. A method for generating an adaptive physiological strain index (aPSI) from at least one body core temperature and at least one heart rate for an individual to reduce a likelihood of heat related illness (HRI) or treat for HRI of an individual based on the aPSI, the method comprising:

receiving by a processor a heart rate signal or the heart rate from a heart rate sensor worn by the individual;

receiving by the processor a skin temperature reading from a temperature sensor detecting a skin temperature of the individual;

receiving, estimating, or calculating with the processor the body core temperature for the individual;

calculating with the processor an adaptive maximum body temperature based on a temperature gradient between the skin temperature reading and the body core temperature;

calculating with the processor the aPSI for the individual using the body core temperature, the adaptive maximum body temperature, and the heart rate signal or the heart rate; and

producing the aPSI from the processor;

repeating the method at predetermined intervals to calculate updated aPSI scores for the individual; and

if the aPSI is above a threshold, then

alerting the individual by identifying a treatment selected based on the aPSI from a group consisting of adjusting a level of activity or pace of the individual to lower the aPSI, drinking fluids, submersing in water, and/or sitting in a cooler environment to address physical strain preventing or treating the individual for HRI, and

continuing the method allowing the individual to monitor how effective the lowering of the aPSI is; and

if the aPSI is below the threshold, the method continues.

13. The method of claim 12 , wherein producing the aPSI includes sending the aPSI to an external device,

the method further comprising displaying a visual indicator of the received aPSI for the individual on the external device.

14. The method of claim 12 , further comprising

determining the heart rate from the heart rate signal; and

sending with a communications circuit the skin temperature and the heart rate to the processor located on an external system from the heart rate sensor and the temperature sensor.

15. The method of claim 12 , wherein calculating the aPSI for the individual uses only

the heart rate from said at least one heart rate sensor,

the adaptive maximum body temperature based on

the temperature gradient between the skin temperature from said at least one temperature sensor and the body core temperature, the temperature gradient varies over time, and

a critical temperature,

a current skin temperature from said at least one skin temperature sensor,

a resting body core temperature from a memory,

a resting heart rate from said memory,

a current heart rate from said at least one heart rate sensor, and the body core temperature from an internal temperature sensor, and

a critical heart rate.

16. The method of claim 12 , wherein calculating the aPSI is based on said processor calculating the aPSI based on the following equation:

aPSI

=

5

⁢

(

CT

t

-

CT

rest

CT

critical

-

CT

rest

)

+

5

⁢

(

HR

t

-

HR

rest

HR

critical

-

HR

rest

)

CT

critical

=

39.5

°

⁢

C

.

+

(

CT

t

-

ST

t

)

-

4

4

where CT t is the body core temperature at a time t, CT rest is the body core temperature at rest, HR t is the heart rate at a time t, HR rest is the heart rate at rest, HR critical IS a maximum heart rate, and CT critical is the adaptive maximum body temperature.

17. The method of claim 12 , wherein calculating with the processor the body core temperature uses a Kalman filter or an extended Kalman filter.

18. The method according to claim 12 , wherein for generating the aPSI from the skin temperature, the body core temperature and the heart rate, the method comprising:

when one of the skin temperature and the heart rate from the heart rate signal is unavailable, using a previously stored value or calculating a value for the unavailable skin temperature or the unavailable heart rate.

19. The method according to claim 12 , wherein calculating the aPSI for the individual is based on the skin temperature reading received from the temperature sensor, a resting heart rate, the heart rate signal received from the heart rate sensor, and the body core temperature calculated based on the heart rate signal.

20. A system for generating an adaptive physiological strain index (aPSI) to reduce a likelihood of heat related illness (HRI) or treat for HRI of an individual based on the aPSI, the system comprising:

at least one heart rate sensor configured to be worn by an individual;

at least one temperature sensor configured to detect a skin temperature of the individual;

a memory for storing at least a resting heart rate and a resting body core temperature for the individual; and

a processor in electrical communication with said at least one temperature sensor, said at least one heart rate sensor, and said memory, said processor configured to produce the aPSI for the individual using only

a heart rate from said at least one heart rate sensor,

an adaptive maximum body temperature based on

a temperature gradient between the skin temperature from said at least one temperature sensor and a body core temperature, the temperature gradient varies over time, and

a critical temperature,

a current skin temperature from said at least one skin temperature sensor,

a resting body core temperature from said memory,

a resting heart rate from said memory,

a current heart rate from said at least one heart rate sensor, and the body core temperature from an internal temperature sensor, and

a critical heart rate; and

a monitoring system in communication with said processor, said monitoring system includes a display configured to provide a visual alert to the individual or another individual of the aPSI for the individual, and

wherein the aPSI is used to select a treatment to be included in the alert, the treatment is selected from a group including having the individual adjust a level of activity or pace of the individual to lower the aPSI, drink fluids, submerse in water, and/or sit in a cooler environment to address physical strain when the aPSI is above a predetermined aPSI threshold to prevent or treat the individual for HRI, said system continues to monitor the individual and allows the individual or other individual to monitor an effectiveness of the treatment; and

when the aPSI is below the predetermined aPSI threshold, said system continues to monitor the individual.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Feb 13, 2025
From: BULLER, MARK J.
To: THE GOVERNMENT OF THE UNITED STATES, AS REPRESENTED BY THE SECRETARY OF THE ARMY
Reel/Frame 070210/0589 →
Continuity (3)
Continuation 16072815
Provisional Application 62323268 · Apr 15, 2016
Related Publication 20230148878A1 · May 18, 2023
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