Estimation of core body temperature from skin temperature, heat flux, and heart rate using a Kalman filter

Alexander P Welles; Xiaojiang Xu; William R Santee; David P Looney; Mark J Buller; Adam W Potter; Reed W Hoyt

doi:10.1016/j.compbiomed.2018.05.021

Estimation of core body temperature from skin temperature, heat flux, and heart rate using a Kalman filter

Comput Biol Med. 2018 Aug 1:99:1-6. doi: 10.1016/j.compbiomed.2018.05.021. Epub 2018 May 18.

Authors

Alexander P Welles¹, Xiaojiang Xu², William R Santee³, David P Looney⁴, Mark J Buller⁵, Adam W Potter⁶, Reed W Hoyt⁷

Affiliations

¹ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: alexander.p.welles.civ@mail.mil.
² Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: xiaojiang.xu.civ@mail.mil.
³ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: william.r.santee.ctr@mail.mil.
⁴ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: david.p.looney4.civ@mail.mil.
⁵ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: mark.j.buller.civ@mail.mil.
⁶ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: adam.w.potter.civ@mail.mil.
⁷ Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Natick, MA, 01760-5007, USA. Electronic address: reed.w.hoyt.civ@mail.mil.

PMID: 29803944
DOI: 10.1016/j.compbiomed.2018.05.021

Abstract

Core body temperature (T_C) is a key physiological metric of thermal heat-strain yet it remains difficult to measure non-invasively in the field. This work used combinations of observations of skin temperature (T_S), heat flux (HF), and heart rate (HR) to accurately estimate T_C using a Kalman Filter (KF). Data were collected from eight volunteers (age 22 ± 4 yr, height 1.75 ± 0.10 m, body mass 76.4 ± 10.7 kg, and body fat 23.4 ± 5.8%, mean ± standard deviation) while walking at two different metabolic rates (∼350 and ∼550 W) under three conditions (warm: 25 °C, 50% relative humidity (RH); hot-humid: 35 °C, 70% RH; and hot-dry: 40 °C, 20% RH). Skin temperature and HF data were collected from six locations: pectoralis, inner thigh, scapula, sternum, rib cage, and forehead. Kalman filter variables were learned via linear regression and covariance calculations between T_C and T_S, HF, and HR. Root mean square error (RMSE) and bias were calculated to identify the best performing models. The pectoralis (RMSE 0.18 ± 0.04 °C; bias -0.01 ± 0.09 °C), rib (RMSE 0.18 ± 0.09 °C; bias -0.03 ± 0.09 °C), and sternum (RMSE 0.20 ± 0.10 °C; bias -0.04 ± 0.13 °C) were found to have the lowest error values when using T_S, HF, and HR but, using only two of these measures provided similar accuracy.

Keywords: Computational physiology; Physiological modeling; Physiological status monitoring; Real-time estimation.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Adult
Body Temperature Regulation / physiology*
Heart Rate / physiology*
Humans
Male
Models, Biological*
Skin Temperature / physiology*