Study on physiological response considering blood flow volume in transient and non-uniform bathing thermal environment using thermo-cardiovascular regulation model

Abstract

In transient and non-uniform thermal environments, such as bathing, the human thermal physiological response changes dramatically and accidents often occur owing to cardiovascular system diseases. Blood flow volume is a crucial index of the cardiovascular system; thus, studying the human thermal physiological response considering blood flow volume in a bathing thermal environment is essential. In this paper, we proposed a novel integrated thermo-cardiovascular regulation model that merged a human thermoregulation model (HTM) and a cardiovascular regulation model (CRM), to predict the human physiological response in a transient and non-uniform bathing environment considering blood flow volume and the thermal environment, metabolic rate, and heart rate changes. First, based on the Stolwijk model, more nodes representing different human body parts have been added to the HTM, and it takes into consideration metabolic rate changes. Second, based on the Windkessel model, the circulatory system of the CRM is divided into four parts. Meanwhile, the changes in heart rate over time is used to adjust the cardiac output of the CRM's circulation in real time. To assess the accuracy of the prediction model, we conducted a bathing experiment with a 50-year-old man. The results revealed that the proposed model could accurately predict the participant's thermal physiological response, including skin temperature, core temperature, blood pressure, and blood flow volume during bathing.