The influence of acute and chronic hypoxia on the electroencephalogram of human body.

Abstract

This report deals with the study of electroencephalograms of 36 subjects who inhaled hypoxic mixture at the sea level (PO2 is as that at 7000 m above sea level) or in a hypobaric chamber with rapid decompression (as that at 5000-7500 m above sea level) and of 46 subjects who reached high altitude area (5000-8600 m) under chronic hypoxia. The characters of the EEGs at rest during photic stimulation, hyperventilation and convalescence after hypoxia were compared in two experiments. The result of experiments shows that in the same individual, the severer the hypoxia, the more obvious the changes on the EEGs. At the same altitude, acute hypoxia causes more obvious changes on the EEGs than chronic one does, but its speed of recovery is faster than that of chronic hypoxia. Under chronic hypoxia, the changes on the EEGs caused by hyperventilation are slighter than those under acute hypoxia. When photic stimulation is given, there is temporary appearance of alpha waves on the EEGs featuring slow waves under acute and chronic hypoxia. The possible mechanism of changes on the EEGs under acute and chronic hypoxia is also analyzed in this report.