WKPP - Dealing with O2 tox protocols

db8us

@Andrew,
it is good to kepp our feet on the ground, so i really like your input, we just have to be careful about this thread going down the tube too fast.

@Cedric,
where can i find your protocol ?

abowie

Ahhh. I didn't realise that. In that case the protocol makes a lot more sense. Except the hand ventilation bit.

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Andrew Bowie

Rebreather-friendly Buddy

hchoat

In all honesty- this protocol was developed in my living room (really). Scott Hunsucker was the former medical guy for the WKPP. Scott and another Florida licensed EMT-P who was also a diver sat around and kicked ideas around in response to a request from George. They then ran the protocol past a friend who was a hyperbaric physician. The three of them decided that this *MAY* work under the conditions in place at Wakulla (troughs and habitats). The WKPP has never had a tox scenario, and this protocol has never (to my knowledge) been used "for real". It is and always has been a *best guess* of what to do in a tox situation, and, in my opinion, should never have been published as reference material- and certainly not as "fact".

Best,
Heather

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Jim Brown

I've seen a few O2 hits in hyperbaric chamber during PO2 testing for military divers. The seizures were variable. Some simply unresponsive, others were quite violent, like boulders rocking around in a rotating cement mixer (impression from outside). Blood, sweat and mucus everywhere. Grand mal seizure. Extended (30 minutes to over an hour) disorientation and uncoordinated, but eventual full recovery shortly thereafter.

Fact is, partners probably won't notice immediately, so from a practical standpoint assume the seizure is already in full swing. From there, treat as unconcious diver except don't change depth while body rigid. Can last a long time. Once relaxed, bring to surface at normal ascent rate, exercising pressure against abdomen to push expanding gasses via diaphragm. If breathing source in, leave it in, if out, leave it out.

As far as heads up, down, whatever, it somewhat depends how a flooded rebreather could wash caustic fluid into airway. For most that I've seen, a heads up attitude is best. Positions breathing loop lower than airway. Then the obvious, easier to burp diver during ascent if heads up. Then other considerations, bouyancy control devices, drysuits often have dumps at or near upper part of body. There are, of course, exceptions (various manufacturer wings with dumps up top and below), but feet-up blowup in drysuit is a consideration here.

Goal is to remove diver from water. DCS is secondary concern to drowning at this point. Barotrauma is of concern. Immediately notify EMS and chamber, start evac process. Support enroute with oxygen if needed.

If I recall (it's been awhile), O2 tox studies show no predisposition to continued or repeated seizure after an O2 hit. Very random datasets, only dealing with probabilities, but now getting into basics.

Regards, Jim Brown

Richard Lundgren

Jim I fully agree in general but bringing a diver up to the surface after a Wakulla dive is simply not an option. This is why the WKPP protocol is enforced but only relevant to these dives or diving under similar conditions.

Warm regards,
Richard Lundgren

Genesis

"Head down" (prone) is arguably good in that air rises, water sinks - so you're keeping the air in the mouth from ending up in the water, and vice-versa. This makes it POSSIBLE to keep a reg that is not-quite-tightly-sealed (kinda hard to seal when the victim is unconscious!) from ending up leaking a LOT of water into the mouth and then causing a spasm.

The rest is mere conjecture. A regulator's exhaust valve will not permit enough pressurization of the airway to ventilate someone (go ahead, try it with a conscious person who is relaxed and not attempting to "fight" with his diaphram and see how it works.) This is also why you can breathe a freeflowing reg, so for most situations its a feature rather than a bug.

DAN sells a MTV that WILL; it is basically a second state demand valve (that plugs into a DISS port on an O2 reg, not a reg port) that has a calibrated pop-off so that you don't explode the victim's lungs but have a decent crack at actually initiating respiration - kinda like using a bag-valve mask but under power. You press what would be the purge on a scuba reg to initiate powered ventilation. They're considered dangerous to use by untrained persons.

An O2 hit in the immediate vicinity of a habitat (vertically) can be managed by getting the victim out of the water (into the habitat), IF you can move them safely (e.g. they're not doing the full Grand-Mal watusi on you.) But most of us don't have habitats when we're diving....

IMHO the first priority needs to be preventing the O2 hit. I don't like the odds of surviving one - protocol or no protocol. What is known to be obviously bad is ascending during active convulsions or the tonic phase, as the airway will be locked shut and as such an ascent will probably kill the victim outright via an AGE.

Most of the reports from people who have survived an O2 hit include periods of complete lack of awareness that span quite a bit of time after regaining consciousness. Attempting to manage someone with a deco obligation under that circumstance is going to be quite some exercise - if you can pull it off without badly bending one or both of you, you're truly a hero. On the other hand, I'd rather be bent than dead!

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Jim Brown

Greetings Richard:

Agree that physical overheads impose constraints that are not present in virtual overhead that exists with deco obligation in open water. Cave diving not my field, so won't debate pros or cons of that environment.

Drowning is the primary cause of death here, so I guess bottom line is to get the diver out of the water. Deeper or shallower immaterial if result is (relatively) controlled environment that buys time to organize deliberate response. Deeper makes excellent sense if gas supplies and time on station not limiting factors to dealing with increased deco obligation. This gets into some very interesting scenarios. Risk stacking, orders of effect and all that.

Regards, Jim Brown

Jim Brown

Greetings:

Poseidon Odin at full flow, 1500 lpm, easily controlled with one hand occluding exhalation or impulsing purge. Very powerful reg. Anyway, not proposing any practical use for this, just a counterpoint. Goose it hard enough and I predict an unconscious diver's lips and jaw would just flap around it anyway.

Not sure airway locked shut during seizure. Probably best characterized as non-compliant, uncontrolled, unpredictable. Individuals make some funny (well, maybe not funny) noises inhaling and exhaling during seizures. Don't necessarily lock airway shut. In any case, we all agree not good time for depth changes.

You mention an interesting concept. Heroism. Do you crawl out into the ambush killzone to rescue your buddy? Or is s/he really your buddy? Choosing DCS to help your friend is similar concept.

Heads up v. down. Get diver out of water and prevent drowning (after relaxed). Heads up means bouyancy devices dumps up and also more ergonomic. Probably moot anyway because it's a lot easier to talk about over a beer than manage an unconscious diver's ascent in practice. I can tell you I'd be a real hard sell for anything but heads up ascent while rescuing unconscious diver. After diver relaxes, after all, they're just an unconscious diver. Possibly vomiting, coughing, talking/ moaning/ arguing uncontrollably, inspiring water, utterly helpless and (probably) actively drowning themselves until removed from water.

And one last thing... when you're deep it ain't that bad. Relative volume change per depth change much less than at shallower depths. Greatest risk for AGE or whatever would be from 20' (6m) or shallower. Very high risk from bottom of a pool. As significant for unconscious diver (hypoxia) as for O2 hit. So where's the greatest risk for barotrauma in a given population? At end of deep dive planned and conducted by trained divers or with inexperienced divers in 'rebreather experience' tooling around bottom of pool? Things start going into the sublime when considering too many details, same with overly complex emergency drills.

O2 tox drill -

Manage bouyancy for seizing diver, avoid depth changes if possible.
If breathing source in, leave it in, if out, leave it out.
When diver relaxes, heads up, normal ascent rate, burp expanding gasses during ascent with pressure on abdomen.
On surface, inflate bouyancy devices, signal for help, and establish airway. Rescue breathing if necessary.
Hand off to surface crew and immediately commence omitted deco procedures.

5 or 6 steps. Don't make it more than 7 because when things go from rosy red to shit brown you'll never remember it. Anything over 7 steps carry a little card to guide you. Been there and seen it. 9-line medevac, DAP/ little bird/ AC-130 call for fire, more than about 7 steps and even the best of them can turn into babbling fools until they are very seasoned. This would be after repetitive exposures to the situation, not the case with our population and O2 hits. Stress does that to you. (note that when I say 'you' I don't literally mean you, so don't take offense... just mean that's what happens to a person in that situation).

I'll leave cave procedures to someone else.

Regards, Jim Brown

Digger

Jim, I htink Richard means because of the time required decompressing. When you have 12 hours left to do, surfacing is basically a death sentence isn't it? Especially if you're at deeper stops, they will die pretty fast on the surface whatever you try. That's probably why the habitats are there, as well as other creature comforts.

After seeing the size of some of the habitats those guys are using it seems to be almost as good as getting them to the surface - once in the habitat you could work on airway and controlling convulsions and/or the reaction to it, and spend time waiting for them to come back. Once back you can work out a plan from there, or someone on the surface can I suppose. I remember one which had a deck chair in it from memory, and two other guys sat decompressing in there. Was that WKPP?

My best guesses, but that's what I'm thinking.

Digs.

dteubner

Re: Ventilating someone with a second stage.

It takes only 80 cmH2O to rupture an alveolus and create pulmonary barotrauma.

What's the IP of the first stage - 10ATA = 10,000 cmH2O. Purging the second stage potentially exposes the lungs to the IP. Sure some pressure is lost through the exhaust valve but how much?

Some basic maths - 10,000 is greater than 80.

It is a very bad idea. I have autopsy photos which show all the blood vessels on the outside of the brain full of air when ventialtion with a second stage was attempted.

Dave T