The effect of nitrous oxide on cerebral electrical activity.

Recordings of cerebral electrical activity produced by the cerebral function analysing monitor ( CFAM ) were obtained from nine healthy volunteers breathing increasing concentrations of N2O in O2. Concentrations of 30 and 50% N2O produced significant reductions in CFAM trace amplitude. Withdrawal of N2O resulted in an increase in amplitude with an initial increase above the control level. There were no consistent changes in the frequency distribution of the weighted electroencephalographic signal with increasing concentrations of N2O.