Acute Effects of Hypoxia
Some of the important acute effects of hypoxia in the
unacclimatized person breathing air, beginning at an altitude of about 12,000
feet, are drowsiness, lassitude, mental and muscle fatigue, sometimes headache,
occa-sionally nausea, and sometimes euphoria.These effects progress to a stage
of twitchings or seizures above 18,000 feet and end, above 23,000 feet in the
unaccli-matized person, in coma, followed shortly thereafter by death.
One of the most important effects of hypoxia is decreased mental
proficiency, which decreases judg-ment, memory, and performance of discrete
motor movements. For instance, if an unacclimatized aviator stays at 15,000
feet for 1 hour, mental proficiency ordi-narily falls to about 50 per cent of
normal, and after 18 hours at this level it falls to about 20 per cent of normal.