Nitrous Oxide is safe to use for long periods of time mixed with oxygen (O2). Hence, the “laughing gas” used now is called N2O-O2 and contains at least 30% oxygen as permitted. Usually, the mix is about 70% oxygen to 30% nitrous oxide.
Depending on the concentration and length of administration, four levels of sedation can be experienced after an initial feeling of light-headedness: a tingling sensation especially in the arms and legs, or a feeling of vibration, quickly followed by warm sensations, and a feeling of well-being, euphoria and/or floating. During heavier sedation, hearing may dissolve into a constant, electronic-like throbbing. At a deeper level of sedation again, sleepiness, difficulty to keep one’s eyes open or speak can occur.