An odourless gas : good analgesic, poor anaesthetic properties; can cause wild euphoria. Is used a lot with patients who are dental phobics. Known as relative analgesia (RA).
Discovered in nineteenth century USA, and used an intoxicant in "ether revels" ie parties. (The anaesthetic properties of ether were also discovered about the same time.)
Patients "on gas" feel less anxious, and are less bothered by what goes on around them. They feel light and floatly, or they can feel heavy and sleepy. I usually stop increasing the percentage of N20 to O2 when they fell tingles in their fingers and toes. Maximum is 70:30 (n2o:o2).
Despite being a good analgesic, local anaesthetic is still necessary in most dental procedures.
The prerequisite to using gas is that 1. the patient must be cooperative (will fail with severe dental phobics and uncooperative kids) and 2. must not have a blocked nose.