PATHOPHYSIOLOGIC EFFECTS ON THE ELECTROENCEPHALOGRAM
Hypoxia
Hypoxia may produce inadequate delivery of oxygen to the cerebral
cortex generating the EEG, and changes similar to those occurring with ischemia result.
Initially, hypoxemia may not result in any electroencephalographic changes because
the brain can increase blood flow to compensate. After the hypoxemia becomes severe
enough, further increases in flow are impossible, and electroencephalographic changes
occur. Slowing of the EEG during hypoxia is a nonspecific global effect.
Fast frequencies are lost, and low frequencies dominate. Eventually, the EEG is
abolished as the brain shuts down electrical activity and diverts all oxygen delivered
to the maintenance of cellular integrity.
