Figure 3

(a) Cerebral function tracing of an ICU patient who is alert, oriented, and aware but stimulated and anxious due to the frenetic ICU environment. There is progressively increased activity in the beta (> 13 Hz) ranges. (b) The same patient sedated with a continuous infusion of 2 mg/h midazolam. Narcotics and benzodiazepines in sedative doses generally induce a gradual reduction in activity at higher alpha (8-13 Hz) and beta (> 13 Hz) frequencies and increased activity at lower frequencies, especially theta (4-8 Hz) and delta (<4 Hz). The `activity line' shifts symmetrically to the left.