Oxtox: Seeing it 1st hand

[Duke Dive Medicine]

I have a bit of a theory that CNS deression from N2 reduces the likeihood of convulsions on air at high ppO2 compared to the same ppO2 on trimix without the CNS depression. Its not really provable due to the vagueries of convulsions in the first place. But does potentially explain the capacity to do pretty substantial air dives with sleepiness being the overriding symptom instead of excitability, twitching or convulsion type stuff.

Deep air probably makes O2 toxicity more likely d/t other risk factors: cold, and especially elevated blood pCO2 levels. The record-setters have a pretty high fatality rate - I think it's reasonable to assume that O2 toxicity is a factor.

 

[Cave Diver]

You've had IPE? Have we talked to you yet?

http://www.scubaboard.com/forums/ac...eniseggs-incident-near-miss-jackson-blue.html

 

[Slamfire]

To the Op:

If a diver is lost and in zero vis, he might think that there is no chance of getting out alive and the thought of death may creep into the mind. I have had a couple of close calls where I got a mental vision (of my cat) that snapped me back to reality and is the main reason that I survived. There is NO reason to ever give up and accept death during a dive. NEVER GIVE UP, is a golden rule that should not be taken lightly. Taking time to write a note to loved ones or some crap like that is burning valuable moments that can make the difference between getting out alive or dieing.

In with you on this. If I'm going to go I'd like to have the fortitude to go on my terms as much as possible. Not just because some difficult circumstances appeared before me and I decided not to face them. A few months ago I posted this thread about a guy who had to swim more than 10 hours to shore after being abandoned by his dive boat. I aspire to have that kind of fortitude if I ever have to face a difficult situation.

Now if you enter the water with the intention of suicide (I have a living will and understand this option) then why not just dive with a hypoxic mix. You will just drift into sleep and drown while you are asleep. There will be no pain or mental stress over the whole breathing of water ordeal.

But then I won't be able to go deep... I was envisioning this peaceful setting where I go deeper than I ever went before; without the stress and concerns of having to plan and execute a return trip. Just my last fun dive, totally relaxed, totally immersed in an entirely new environment I've never seen before. And then I slip out peacefully to eternity.

 

[diverdoug1]

Has anyone in this forum seen oxtox symptoms firsthand? I remember diving with a very experienced diver once who explained to me that he always planned his ppO2 (open circuit) for 1.6 at the bottom. His theory was that he had seen a lot of people bent, but he had never seen someone tox, and he had never known someone who had seen sometime tox.

I haven't either, and from his comment I assumed it must probably be a very, very rare event?

I have seen it over 20 times, but thankfully, all but two of these instances have been in chambers. The rarity of oxygen induced seizures is, ofcourse, inversely proportional to ppO2. I am supprised that the incidence of oxygen induced toxicity accidents is not higher in the general recreational diving community. I do a lot of liveaboards, and end up diving around OW divers with basic nitrox certification. The understanding of MOD is frighteningly poor for many of these divers in my opinon. The very experienced diver you mention did not seem to understand that planning to push your ppo2 to the limit on every dive is illadvised, just as pushing your deco schedule, or gas management. The consequence of an oxygen induced seizure at depth on OC is frequently death. I guess this goes back to the initial point of this whole thread, it is nice to have a forum where everyone participating already understands these concepts.( whoops, looks like this got moved to a different thread)

 

[diverdoug1]

slamfire, I've actually thought about the same thing. I have a bad family history for Alzheimer's, and don't want to end up in a nursing home drooling on myself. Taking a 40 of O2 for a swim doesn't sound like a bad end to things. If you seize, you are unaware of what's going on while you are seizing, and are usually not very responsive immediately afterwards. How aware you would be of taking that first breath of water, or of drowning, I don't know -- but you would certainly be less aware than you would be under normal circumstances. If you set the whole thing up to be pretty badly narced at the same time, you would definitely have some anesthesia for the whole drowning event.

If you decide to off yourself in this manner, please leave a number of notes detailing your intentions, so it does not get labled as a dive accident.

 

[Rhone Man]

If you decide to off yourself in this manner, please leave a number of notes detailing your intentions, so it does not get labled as a dive accident.

Not to hijack the thread, but I remember having a similar though to Lynne's once and deciding that was exactly what I would not do (leaving a note), although I was thinking more along the lines of "if I was diagnosed with terminal cancer". If you commit suicide it is a lot harder for your nearest and dearest to collect on your life insurance. On the other hand if you have an inexplicable diving accident, that is much simpler.

So, sorry in advance if one day I mess up the safety statistics...

 

[denisegg]

There is no reason ever that I would ever take my own life. There is no reason ever that I would ever give up under water. There is no reason ever that I would sit there letting my life flash before my eyes or thinking of my loved ones to encourage or motivate me to action.
When I had that moment happen to me, my thoughts focused on what I needed to be doing to safely exit the cave. As I swam toward the exit my mind was processing and evaluating the situation, going over the obvious like I have not had an equipment failure, I have plenty of gas left, I know the way out, there is nothing my buddy can do at this point, I have got to make it out of this cave.

 

[Trace Malinowski]

I received a PM from Marci (BabyDuck) asking me to contribute to this thread. I experienced what may have been oxtox diving the Duane when I worked as diving instructor in Key Largo. On a day off I went diving for fun with Lady Cyana Divers completing two morning dives followed by a bounce dive to recover what we thought was a set of car keys from our boat, but turned out to be some pocket change. I no longer remember the depths and times. But, I recall the afternoon dive very well.

Grace asked me if I wanted to go to the Duane when we reached the dock. Rather than go home, I decided to go diving. I had 31.5% oxygen in my nitrox. At the dive site the current was screaming. We were anchored into the stern. Because of the current many pelagics were drawn to the site including sharks. Every diver on board was an instructor. I was teamed with two instructors from our sister shop. We were all wearing BP/wings and long blade freediving fins. During the descent, masks were flooding as we descended the line due to the current. Swimming across the stern we were working a bit hard.

I don't recall every symptom now, but the two that I remember were feeling like I could hear a freight train pounding in my ears. I rested at that point. My maximum depth was 112 fsw. As I continued the dive, I had visual disturbances where my buddies looked like choppily edited video tape. At that point, I knew I needed to get out of there and thumbed the dive. Three bull sharks circled me like fighter jets before zipping away as I made my way back to the boat.

The visual disturbances may have been micro-seizures in the cerebral cortex according to one DAN physician which I believe would more likely be oxtox than CO2. Of course, CO2 would have played a huge role in this event had I been experiencing any form of oxtox. If that was the case, I was told that those micro-seizures placed me just a step behind grand mal.

 

[beanojones]

I have seen it over 20 times, but thankfully, all but two of these instances have been in chambers.

Tell me about the chambers you have been in. Were the patients/inside tenders on masks or was it the inside atmosphere high O2?

I only know about the one chamber I worked at and I am consistently confused by references to other chamber practices. The chamber was air, and we breathed high O2 on masks held to the face. If we seized the mask would fall off our faces and we would recover.

 

[ianr33]

Not to hijack the thread, but I remember having a similar though to Lynne's once and deciding that was exactly what I would not do (leaving a note), although I was thinking more along the lines of "if I was diagnosed with terminal cancer". If you commit suicide it is a lot harder for your nearest and dearest to collect on your life insurance. On the other hand if you have an inexplicable diving accident, that is much simpler.

So, sorry in advance if one day I mess up the safety statistics...

X2 on that.

I have always assumed if I were to plan a nice trimix dive to 400 feet or so then switch to 100% I would know nothing about it?