Ketamine was used to sedate my then two-year-old daughter in the ER when she needed stitches near her lip. The doc didn't want to foul up her face if she thrashed. It was definitely odd. She was awake, but no reaction AT ALL.
Ketamine gets more use in kids than adults because they tend to react better to the dissociative effects. Adults can become combative.
To your point, when the first dissociative hit the market, phencyclidine (PCP), it was a bit of a miracle drug. No respiratory depression, actually makes the heart beat a little stronger. It wasn't until the dissociative effects became more known was it withdrawn from the market.
They do simulations and petri dish testing as well, what would a better method look like?