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Comment by toomanybeersies | Hacker News Reader

Ketamine really was a miracle drug in this situation.

It's one of the few anaesthetics that doesn't cause respiratory depression, overdosing is practically impossible, and it's also injected intra-muscularly, rather than intravenously, making it easy to apply in the dark and underwater by an untrained person.

These factors are also why it was used extensively in the Vietnam war for battlefield surgery.

Interesting that, as usual, the media has labelled it as "horse tranquilliser". It's used more extensively on humans than on animals, and is used on all different mammals, not just horses.

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It's also used on dogs, but mentioning that it works on horses is more impressive since horses are known as very large strong animals. I think that's the reason it's often called a "horse tranquilizer", to emphasize that it's serious stuff.

I mean, the article makes clear that Dr. Harry is an anesthesiologist and that anesthesiology is a very serious discipline, so I don't think the author meant to suggest they were carelessly administering medication meant for animals instead of humans.

The irony is that it's actually one of the safest (and cheapest) tranquilizers and that's why it's used on large animals. It's hard to weigh a horse, so you want something that doesn't require a very precise dose.

They actually use a related chemical, tiletamine, on larger animals due to its increased potency:

http://wildpro.twycrosszoo.org/S/00Chem/ChComplex/Tiletamine...

Definitely true, though waking up from ketamine with your hands bound underwater in pitch black sounds absolutely hellish.

Nothing is hellish when you’re waking up from ketamine, dude. If it was, not all of the soccer players would have survived.

Ketamine doesn’t get more use due to the unpleasant effects when it wears off.

Apparently that’s less common in kids.

I would have thought they’d go with a benzodiazepine instead. It has all those benefits you mention without the post-emergence delirium.

Benzodiazepines have a depressant effect on the respiratory system, and have a risk of paradoxical reactions. In addition you’d need a heroic dose to cause total sedation, so a benzo is usually only a component of along with an opiate to induce “twilight” sleep. For the purposes of this dive obviously respiratory depression was unacceptable, and doubling down with an opiate would have been worse.

Ketamine is very safe, and some nasty side effects are preferable to death.

Benzodiazepines require heroic doses before they start to depress respiration. At low doses, like what you’d use to keep someone calm, it’s a non-issue.

Not sure why you’d want them so sedated that they are semiconscious.

It doesn’t take much to keep someone from freaking out.

It would take quite a large doze of benzos to keep someone calm enough to drag them underwater through a cave when they can't swim.

You'd also want to stop them from moving about and potentially causing trouble.

The whole point was to fully anesthetize them, not merely sedate them. The risk that they’d panic or become disoriented was too great.

Seems like overkill to me! I’ve seen people given reasonable doses of benzodiazepines be quite compliant!

Use of benzos in distressing situations is linked to PTSD.

What are the unpleasant effects?

A psychedelic experience basically, why people take it recreationally in doses that don't quite knock you out. It's really bizarre and something best not experienced submerged in a cave.

I was taught 20 years ago that it was still given to children as an anaesthetic because it's very safe and they tend to either not experience the "trip" or are not bothered by it, thinking it's a dream.

Compared to ketamine, benzodiazepines are far more likely to cause respiratory depression and arrest, as well as airway obstruction due to relaxation of muscles and soft tissues in the jaw and neck. I am a retired neurosurgical anesthesiologist (38 years experience) and used ketamine — both IV and IM — hundreds of times in the OR in children and adults.

Well you obviously know more than I do, but I guess my question is - were these kids anesthetized?

If so, I would agree ketamine is much safer. But if you’re just trying to keep them from freaking out, 5mg is diazepam will do the job and respiratory depression isn’t much of an issue.

Yes, the kids in the cave were anesthetized. Diazepam is NOT an anesthetic: it is an anxiolytic/hypnotic/sedative. 5mg of diazepam will calm some, put others to sleep, and not noticeably affect others. Variation in response is huge. With ketamine, a given mg/kg dose is far more predictable.

I don't like how this was articulated because giving someone enough drugs to 'knock them out' is extremely dangerous in any circumstance.

There are so many things that could have gone wrong during that time, my god man ... random diver dudes (i.e. non medical) giving needles putting people out - this was as dangerous as anything else.

It's not for nothing that it's not the WHO list of essential drugs. It's a miracle drug in more ways that one, with it now also being used with success against depression in treatment resistant patients, to treat alcoholism etc. And of course nothing beats a good old k-hole experience.

The horse tranquilliser thing needs to stop.

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