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 O
2
, 30 per cent N
2
O, 50 per cent N
2
O and 5 minutes after 100 per cent
O
2
. A Likert scale was used to evaluate pain perception. The analgesic effects of nitrous oxide were evaluated at:
30 per cent N
2
O, 50 per cent N
2
O, 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 N
2
O, while this percentage was of 15.8 %
when inhaling 50 per cent N
2
O, 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
