Short-term exposure effects of gradual and instantaneous indoor pressurization modes on people at initial stage of entering Xizang

To investigate the short-term exposure effects of different indoor pressurization oxygen supply modes on people at the initial stage of entering Xizang,the indoor physiologically equivalent altitudes in a range from 2 000 to 3 500 m are established in a pressurization building located in Lhasa through two modes of gradual pressurization and instantaneous pressurization.The changes of physiological parameters such as blood oxygen saturation,heart rate,and blood pressure of 9 young subjects who have just arrived at the plateau are monitored after short-term exposure for 30 min at various altitudes,and the symptoms of altitude sickness and the environmental subjective evaluation are investigated.The results show that with the increase of indoor air pressure,the indoor oxygen concentration increases from 0.186 kg/m3to 0.219 kg/m3,and the subjects gradually feel smooth breathing and stable heartbeat,while anxiety,mental sluggishness,dizziness,headache,and other uncomfortable symptoms are significantly alleviated,and when the physiological equivalent altitude drops to 2 000 m,33.3% of the subjects say that they do not need oxygen supply at all.The heart rates of the subjects gradually decrease,and the blood oxygen saturations increase significantly and return to the normal level (≥94%),both of which are related to the equivalent altitude as a power function,which could be used as sensitive indicators of human physiological response under the intervention of pressurization oxygen supply.Compared with the gradual pressurization mode,the instantaneous pressurization mode exhibits better subjective responses in alleviating shortness of breath but causes minor fluctuations in heart rate and headache.It can be seen that the pressurization building can significantly alleviate the subjective and physiological discomfort of people at the initial stage of entering Xizang,and the short-term exposure effect of the progressive gradual pressurization mode is better.