(a) Cerebral electrical activity in a healthy volunteer, sitting in a quiet environment reading a magazine. Activity at normal sensitivity under 13 Hz to the left of the trend line. (b) A patient mildly sedated with lorazepam. The `monotony of sedation' pattern is illustrated. The spectral edge frequency (95% of brain wave activity occurring to the left of this line) demonstrates less variation between epochs.
Crippen Critical Care 1997 1:15 doi:10.1186/cc3