Re: Ketamine
I use it for procedural sedation for children routinely, safely and successfully.
Yes, it has risks: hypersalivation, tachycardia, increased ICP and IOP, emergence phenomena. They can be managed, usually by premedication, and are rare enough that the risks are less than the bigger risks of a typical anaesthetic like propofol or volatiles. Having, for example, an appendix removed under nothing but ketamine is not unheard of in remote areas or where access to hospital theatre standard is not available or impractical.
Its starring attributes are the protection of airway reflexes, its single agent achievement of the anaesthetic triad and its cardiostability. No other single agent comes close, even inhalation induction.
Personally I prefer IV over IM because the pharmacokinetics of IM is more like an infusion, so the redistribution phase is much more prolonged. However, the IV access itself can sometimes be more traumatising than the procedure itself - that's a judgement call.
Observing someone having it is peculiar. In particular the nystagmus and occasional vocalisation. Warn parents in advance and they won't freak out when it happens. It's not traumatic, except vicariously. The one advantage to that is you know for sure when dissociation has kicked in.
Some treatments, usually chronic pain related, involve gradually escalating an infusion until dissociation occurs, then stopping. The theory is that pain mediating neurotransmitters "wind up", and ketamine can wind them down again.
It can see how it would be easy to confuse recreational and therapeutic experiences (the "set and setting"). For recovery, dark, quiet rooms with familiar voices are good at preventing emergence phenomena - more of a happy dream than a scary nightmare. Take it out of the controlled surroundings of a critical care environment and it shows its mean streak.
As an NMDA antagonist it is an analgesic in subdissociative doses (up to 0.5mg/kg), and progressively becomes an anaesthetic at higher doses. It is also a horse tranquiliser, for the same reasons. Mammals share a lot of physiology. Who'd'a thunk it?