A new piece of medical equipment is being tested right now called the Pedisedate. Basically, it is a headset that is placed on a child before they are admitted to surgery. The device connects to a Game Boy or portable CD player (yup, not a Nintendo DS or iPod — apparently the Pedisedate also transports you to 1996) and a snorkel-like piece swings forward and is placed over the child’s nose. As the kid plays videogames or listens to music, nitrous oxide, an anesthetic gas, is emitted through the snorkel and puts the child to sleep.
Nitrous Oxide doesn’t knock you out, it just (deeply) sedates you and is a moderate pain killer.
With IV administered general anesthesia you’re knocked out in literal seconds, it’s wild if you’ve never experienced it. I’ve been “put under” three times: twice to have my 4 wisdom teeth removed and once for inguinal hernia surgery. It messes you up for a good hour or two post-surgery though.
The effects of Nitrous Oxide are reversed within a few minutes of cessation of exposure to the gas (I’ve done it recreationally numerous times, inhaling it while drunk is a wild experience everything is in slow motion like you’re looking into a strobe light).