Evaluation of the sedative combination of nitrous oxide and orally administered diazepam

The effects of nitrous oxide/oxygen and oral diazepam, administered individually and in combination, on memory and psychomotor coordination were evaluated. Forty healthy adult volunteers (53% male) were randomly assigned to one of four conditions: (1) 100% oxygen and placebo, (2) 50% nitrous oxide/50% oxygen and placebo, (3) 100% oxygen and 20 mg diazepam, or (4) 50% nitrous oxide/50% oxygen and 20 mg diazepam. There was no significant difference between groups with respect to age or weight. Participants' performance was tested in two areas: (1) a visual recall and recognition task and (2) psychomotor coordination as indicated by performance on Trieger's modification of the Bender Gestalt Test. There was no significant difference between the effects of nitrous oxide or diazepam on memory given individually or in combination. Significant differences in psychomotor coordination were seen when comparing groups 2, 3, and 4 with group 1. However, no significant differences existed between groups 2, 3, and 4, indicating that nitrous oxide and diazepam both affect coordination but that their effects are not additive when combined in this manner. The trends in both the memory and psychomotor data suggest diazepam to have a greater effect than nitrous oxide, and the combination to have a greater effect than either agent individually. Further investigation in this area is needed.