Update on anesthetic and metabolic effects during intraoperative neurophysiological monitoring (IONM).

Various agents are utilized in the operating room to produce anesthetic effects. These include barbiturates, halogenated inhalation agents, narcotics, non-barbiturate induction agents, and benzodiazepines. These agents have variable effects upon the EEG and EP (evoked potential) waveforms at different anesthetic levels. Metabolic changes such as body temperature and blood pressure can also elicit changes in the EEG and EPs.