People taking ketamine in clubs usually use much less than k-hole or anaesthetic doses, because the effects are more conducive to partying. They generally take small bumps over the course of a night.

I really doubt the club kids to saw had taken anything like the equivelant of 300mg or 500mg taken IM (2x the bioavailability of intranasal), or even intranasally. If you are standing, 50-75mg taken intranasally can cause transient, trance-like states like you describe. 100mg taken intranasally (50g IM equivalent) is enough such that most people couldn't safely walk, and would have closed-eye visuals almost like a lucid dream. 150mg intranasally will guarantee a k-hole for most people, and 300mg plus would render all but those with extreme tolerances unconscious.

It's probably obvious, but the doses I mention are regarding pharmaceutical ketamine, straight from the vial, rather than for street ketamine.

Let’s say these particular kids had access to the good stuff. Cooked straight from the vial, albeit from Mexico or some further place. Done by the plateful and not in bumps.

I should also add that the ones whom I had to talk down were probably also on heaven-knows what other substances at the time.

Where can I learn de-escalatory calming techniques?

Social workers and ER nurses, in particular, have field-tested practices for dealing with people who are anxiously disoriented — or violently psychotic - in a manner which resolves the situation peacefully.

All I can say for what I did at the time was an intuition that I was confronted with a half-tranquilized, large confused ape and so acted as to prevent them from panicking and running amok with calm words, movements, and (most importantly I suspect in that state) caring touch.