Analgesic and physiological effects in conscious sedation with different nitrous oxide concentrations.

Objectives: to study the physiological changes, as well as the psychosedative and analgesic effects of nitrous oxide, in experimental conditions.

Study Design: 101 dental students volunteers participated in a single nitrous oxide sedation session without dental treatment. Signs and symptoms were registered during and after the procedure. Pulse rate and hemoglobin oxygen saturation were monitored at: 100 per cent O2, 30 per cent N2O, 50 per cent N2O and 5 minutes after 100 per cent O2. A Likert scale was used to evaluate pain perception. The analgesic effects of nitrous oxide were evaluated at: 30 per cent N2O, 50 per cent N2O, and five minutes postoperatively.

Results: Pulse rate and hemoglobin oxygen saturation decreased significantly through all the procedure and after recovery. However, oxygen saturation recovered after the final oxygenation. Only 8.2% of subjects reported the pain stimulus as being quite annoying when they inhaled 30 per cent N2O, while this percentage was of 15.8 % when inhaling 50 per cent N2O, and of 32.7 % during the recovery period. The most common effects of nitrous oxide sedation were bright eyes (99%), voice change (98%) and smiling (91%). Most of the subjects reported tingling (98%) and relax (91.1%)

Conclusions: nitrous oxide causes a significant decrease in heart rate and oxygen saturation, but always within safety limits. Maintaining an appropriate level of consciousness was confirmed as a feature in 50 per cent dose in this study. The analgesic effect of nitrous oxide was confirmed but a dose dependency could not be established. Key words:Nitrous oxide, conscious sedation, anxiolysis, safety, physiogical parameters, signs, symptoms, analgesia.