After detection of a thermal stimulus, human beings initiate thermoregulatory behaviour in order to adjust the body\u2019s temperature. If detection of thermal stimuli is impaired or altered in any way, the behavioural thermoregulatory response can be altered to such an extent that it is no longer proportional to the thermal disturbance. Oxygen is essential for optimum functioning of the central nervous system. A lower partial pressure of oxygen in the breathing mixture (hypoxia) can be expected to affect the regulation of human body temperature. If autonomous mechanisms are also inhibited due to the expansion of the thermoregulatory nullzone, it is possible for a person at high altitude to be more prone to hypothermia, without being aware of it. A shift of the core temperature towards hypothermia may become critical in the absence of conscious detection, because the person will be unable to react appropriately in order to prevent further cooling of the body. Due to an inappropriate behavioural response to thermal disturbances in a hypoxic environment, the body may also be more prone to cold injury \u2013 e.g. freezing and non-freezing cold injury.<\/p>\n
A study was designed in which a gas mixture containing 11.5% O2 <\/sub>and 88.5% N2 <\/sub>was used as a hypoxic stimulus in order to establish the effects of a lower partial oxygen pressure on behavioural thermoregulation in humans. This gas mixture corresponds to the conditions at an altitude of 4.500 meters. Two successive experiments were performed at a minimum interval of one week. In the first experiment, volunteers breathed normal air, and in the second the gas mixture with a lower partial oxygen pressure. The sequence of the experiments was selected at random. During the experiments, the subjects sat in a bathtub filled with water at a temperature of 28\u00b0C. The preferential temperature, i.e. the temperature the subjects felt to be most comfortable at a certain moment, was monitored during the experiment in the following manner: at regular time intervals, the subjects selected the water temperature they considered most comfortable in a smaller vessel in which their left hand was immersed. Immersion in water caused slow cooling of the subjects\u2019 body core, changing their preferential temperature.<\/p>\n There were no significant differences between the results of the two experiments with regard to skin temperature, core temperature, heat flow or the preferential temperature of the subjects. However, minute ventilation was significantly different between the two trials. Assuming the selected preferential temperature is considered a component of behavioural thermoregulation, then a gas mixture containing 11.5% O2 <\/sub>and 88.5% N2 <\/sub>has no effect on behavioural thermoregulation in humans. Most probably, the degree of hypoxia used in the experiment was below the response threshold for human behavioural thermoregulation.<\/p>\n","protected":false},"excerpt":{"rendered":" After detection of a thermal stimulus, human beings initiate thermoregulatory behaviour in order to adjust the body\u2019s temperature. If detection of thermal stimuli is impaired or altered in any way, the behavioural thermoregulatory response can be altered to such an extent that it is no longer proportional to the thermal disturbance. Oxygen is essential for […]<\/p>\n","protected":false},"author":19,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[],"tags":[],"class_list":["post-1133","post","type-post","status-publish","format-standard","hentry"],"acf":[],"yoast_head":"\n