Effects of acute hypobaric hypoxia on thermoregulatory and circulatory responses during cold air exposure

Abstract

Background The thermoregulatory responses during simultaneous exposure to hypoxia and cold are not well understood owing to the opposite reactions of vasomotor tone in these two environments. Therefore, the purpose of this study was to investigate the influences of hypobaric hypoxia on various thermoregulatory responses, including skin blood flow (SkBF) during cold exposure. Methods Ten subjects participated in two experimental conditions: normobaric normoxia with cold (NC, barometric pressure (PB) = 760 mmHg) and hypobaric hypoxia with cold (HC, PB = 493 mmHg). The air temperature was maintained at 28 °C for 65 min and gradually decreased to 19 °C for both conditions. The total duration of the experiment was 135 min. Results The saturation of percutaneous oxygen (SpO2) was maintained at 98–99% in NC condition, but decreased to around 84% in HC condition. The rectal and mean skin temperatures showed no significant differences between the conditions; however, the forehead temperature was higher in HC condition than in NC condition. The pulse rate increased in HC condition, and there was a strong negative relationship between SpO2 and pulse rate (r = − 0.860, p = 0.013). SkBF and blood pressure showed no significant differences between the two conditions. Conclusion These results suggest that hypobaric hypoxia during cold exposure did not alter the overall thermoregulatory responses. However, hypobaric hypoxia did affect pulse rate regardless of cold exposure.

Endocrine, inflammatory and immune responses and individual differences in acute hypobaric hypoxia in lowlanders

“…This suggested individual differences in adaptability to HH. These results were consistent with previous studies of lowlanders 9,10,33 and even highlanders 4,5 . Although individual variations were seen in hemodynamic responses to HH, subjects were certainly exposed to HH and physiological changes were evoked.…”

Upregulation of cathepsin L gene under mild cold conditions in young Japanese male adults

“…In total, six young Japanese males aged > 20 years (mean age ± standard deviation, 21.8 ± 1.2 years) were recruited from the subject group that participated in our previous study on thermoregulatory and circulatory responses in hypobaric hypoxia and cold [ 32 ]. The anthropometric data of the study subjects are shown in Table 1 .…”