Bioheat modeling of elderly and young for prediction of physiological and thermal responses in heat-stressful conditions. (February 2020) - Itani, Mariam
Abstract: Exposure to hot and humid conditions results in physiological changes in metabolism, cardiac output and thermoregulation of the young adult and these changes deviate with elderly due to aging. The elderly population is more vulnerable than the healthy and young population due to age-weakened physiology and thermoregulatory functions. There are, however, limited bioheat models addressing such changes due to hot exposure in the young and the elderly. This paper develops robust bioheat models for young and elderly while incorporating the physiological changes under exposure to heat-stressful conditions for both age groups the age-related changes in physiology and thermoregulation to an elderly human. However, due to a large variability of thermoregulation among the elderly population, a sensitivity analysis revealed that the average elderly is characterized by metabolic rate and cardiac output, which are lower than those of the young by 21% and 14.4%, respectively. Moreover, the thresholds of the onset of vasodilation and sweating are delayed from those of young adults by 0.5 °C and 0.21 °C, respectively. The elderly and young bioheat models were validated with number of independent published experimental studies under hot exposures in steady and transient conditions. Model predictions of core and mean skin temperatures showed good agreement with published experimental data with a discrepancy of 0.1 °C and 0.5 °C, respectively. Highlights: Heat-stress causes changes in physiology and thermoregulation of young and elderly. Elderly are under higher risk with exposure to hot conditions. Characteristics of an average elder were selected based on a sensitivity analysis. Segmental multi-node elderly and young bioheat models are developed for hot exposure. Predicted core and mean skin temperatures agreed well with published data at error ≤ 0.1 °C and 0.5 °C, respectively.