Cardiopulmonary values and organ blood flows before and during heat stress: data in nine subjects at rest in the upright position.

Abstract

Physiological changes associated with thermoregulation can influence the kinetics of chemicals in the human body such as alveolar ventilation (VA) and redistribution of blood flow to organs. In this study, the influence of heat stress on various physiological parameters was evaluated in nine male volunteers during sessions of exposure to wet-bulb globe temperatures (WBGT) of 21, 25, and 30°C for 4 h. Skin and core temperatures and more than 20 cardiopulmonary parameters were measured. Liver, kidneys, brain, skin, and muscles blood flows were also determined based on published measurements. Results show that most subjects (eight out of nine) have been affected by the inhalation of hot and dry air at the WBGT of 30°C. High respiratory rates, superficial tidal volumes, and low VA values were notably observed. The skin blood flow increased by 2.16-fold, whereas the renal blood flow and liver blood flow decreased by about by 11% and 18%, respectively. A complete set of key cardiopulmonary parameters in healthy male adults before and during heat stress was generated for use in physiologically based pharmacokinetic modeling. A toxicokinetic studies are ongoing to evaluate the impact of heat stress on the absorption, biotransformation and excretion rates of volatile xenobiotics.