Effects of sedation with midazolam or propofol on cognition and psychomotor functions

The study compared the effects of midazolam and propofol on explicit and implicit memory, cognition, and psychomotor function in patients undergoing oral surgical procedures with local anesthesia and conscious sedation.

Twenty-eight patients were tested in a randomized, double-blind study. Patients were randomly allocated to one of two groups. One group received a bolus dose of midazolam, 0.1 mg/kg, followed by a continuous infusion of saline. The other group received a bolus dose of propofol, 1.0 mg/ kg, followed by a continuous infusion of propofol, 65 micrograms/kg/min. Subjective rating questionnaires and tapping, memory, and Digit Symbol Substitution tests were administered. Testing was done at baseline, 10 minutes after the drugs were given, 10 minutes after surgery ended and 10 minutes later.

The midazolam and propofol groups did not differ significantly on any demographic variables. Both drugs produced mental and physical sedation, which did not become substantially attenuated during the time studied. Both tranquilization and attitudes or other feelings showed smaller drug effects than mental and physical sedation. Tapping was decreased by both drugs 10 minutes after treatment, but not postsurgery. Performance on the Digit Symbol Substitution test was below baseline levels for both drugs at 10 minutes after treatment, but only for midazolam in the postsurgery assessment; at 10 minutes after treatment, propofol was associated with poorer performance than midazolam. Immediate and delayed explicit recall were impaired by both drugs 10 minutes after treatment. Immediate and delayed recall were lower for midazolam than propofol postsurgery, but only the difference on immediate recall was significant. Implicit memory was spared by both drugs.

Midazolam and propofol generally produced equivalent impairments, but the duration of the effects of propofol was shorter. Unlike explicit memory, implicit memory resisted impairment.