Elderly bioheat modeling :changes in physiology, thermoregulation and blood flow circulatory -

Abstract

A bioheat model for elderly was developed while focusing on blood flow circulatory changes that influence their thermal response in warm and cold environments to predict skin and core temperatures for the different segments of the body especially for fingers. For this reason there was a need to improve the bioheat model by including the Cold induced vasodilation. Chapter I was an extend work on the bioheat model of the human to accurately predict the transient CIVD response in fingers after local exposure to cold conditions. Blood flow to the hand was determined by the segmental bioheat model of the human body which uses a modified Avolio multi-branched circulatory system. The CIVD response was modeled by constricting and dilating the blood flow through the AVA in the fingers periodically. Comparisons with several reported experimental data of controlled experiments on figure skin temperature showed good agreement with prediction of our model detecting the observed periodic CIVD reaction. In addition this model was used to study the effectiveness of the active cooling (AC) method of hand and forearm immersion in cold water to reduce core temperature following heavy physical activity as Chapter II show. The validity of the model was confirmed by comparison with published experimental data on core temperature change during and after immersion of forearms and hands in cold water. The validated model was used in a case study to enhance understanding of associated body thermal changes and arterial blood flow and AVA mechanisms during AC interventions that alleviate thermal stress in hot environment. The time needed for the core temperature to drop from 38ºC to 37ºC was found to be 33 minutes when subject was at rest and was exposed to air cooling at 21 ºC compared to 15 minutes when hands and forearms were immersed in water at 10ºC. The active cooling was found to be an effective method for accelerating reduction on core temperature and can be used with efficient, localized, and portable coo