Method and apparatus for early detection of worsening heart failure
This disclosure provides methods and devices for evaluating a patient's heath by assessing the patient's thermoregulatory response to heat. For example, methods include applying heat to patient skin and measuring rate of temperature change. If the rate of temperature change exceeds a pre-determined threshold, the patient can be identified as suffering from acute heart failure.
1 . A non-invasive method for providing detection of heart failure of a subject, the method comprising:
applying, via a mobile and wearable device, thermal energy to a portion of a subject's skin, the device being placed entirely around a portion of at least one of a torso, arm, and leg of the subject;
evaluating the subject's thermoregulatory response to the application of thermal energy, wherein said evaluating comprises:
performing, for about 2 to 3 minutes, an initial calibration step comprising raising the subject's skin temperature to approximately 33 degrees Celsius to calibrate baseline environmental conditions;
exposing the subject's skin to higher temperatures, via application of the thermal energy, of between about 38 degrees Celsius and 45 degrees Celsius;
measuring a rate of temperature change of the skin before the onset of sweating; and
comparing said rate of temperature change to a reference value to thereby assess a health status of the subject, wherein the reference value comprises a rate of change in temperature that was measured when the subject was in good health and not suffering from or experiencing heart failure.
2 . The method of claim 1 , wherein providing detection of heart failure of a subject comprises identifying that the subject has acute or worsening of a heart failure condition.
3 . The method of claim 1 , wherein, when the rate of temperature change exceeds the reference value, the subject is identified as having acute heart failure.
4 . The method of claim 1 , wherein the device further comprises one or more additional sensors for measuring at least one of heart rate or blood pressure.
5 . The method of claim 1 , wherein the device comprises a heater, the heater operable to heat an interior of the device to a temperature that is between 35 degrees Celsius and 45 degrees Celsius.
6 . The method of claim 1 , wherein the step of exposing the subject's skin to higher temperatures is performed for approximately 15 minutes or until sweating is detected with change in absolute humidity sensing.
7 . The method of claim 6 , wherein the step of exposing the subject's skin to higher temperatures and the step of measuring the rate of temperature change are performed at least partially coincident with each other.
8 . The method of claim 1 , wherein the step of comparing the rate of temperature change to the reference value is performed with a computer program.
9 . The method of claim 8 , wherein the computer program comprises a machine learning algorithm.
10 . The method of claim 9 , further comprising the step of providing training data to the machine learning algorithm, the training data comprising a plurality of rates of temperature changes with known patient health statuses.
11 . The method of claim 1 , further comprising reporting the health status to a physician or inputting the results into a treatment system and enabling change of treatment parameters.