What's your PO2?

[PfcAJ]

Wookie, you do know that an immersed person is more susceptible to a toxic episode than a dry one, correct? I'm also sure that you know there is wild variation between subjects and within subjects in regards to exposure needed to cause a toxic episode, right?

 

[ScubaFeenD]

I get bored hanging on a rope at 30, 20, 10 feet. I learned from early divers. I've done a table 6. The table 6 has far far higher exposures than 2.0, and I wasn't affected by the exposure (well, except for this re-curring twitch ). I don't ever want to do another table 6 again. I'm not likely to spend more than 20 min on the bottom at those exposures anyway. I'm scared of rebreathers.

No offense, but when you get hyperbaric O2 in a medical setting, seizing isnt a big deal. When you seize at depth, you have a reasonably high likelihood of dying.

 

[LiteHedded]

I get bored hanging on a rope at 30, 20, 10 feet. I learned from early divers. I've done a table 6. The table 6 has far far higher exposures than 2.0, and I wasn't affected by the exposure (well, except for this re-curring twitch ). I don't ever want to do another table 6 again. I'm not likely to spend more than 20 min on the bottom at those exposures anyway. I'm scared of rebreathers.

you also weren't underwater. and your sample size is pretty low.

I disagree that information in and of itself causes people to die. It is the person's inability to apply critical thinking and assess the risk in relation to themselves in applying that information that causes people to die. Most call this Darwinism.

I do not have to agree with people's standard of safety or reason to learn about their thought processes. I just want to hear their side of the story.

well we circumvent natural selection every day don't we? a purely darwinian world is not a world I would want to live in.

 

[Wookie]

Obviously words alone do not cause deaths, Jax.

However, bad information can and does cause deaths. If no one says "hey, thats unsafe" and others read it and emulate it, they could get injured or killed.

I understand your way of thinking, and applaud it. I've come to understand, however, that everyone's physiology is different, and different exposures effect folks differently. For instance. One of my buddy's suffers from Nitrogen slam. I don't. My wife suffers during high exposures of oxygen. I don't. I am useless from narcosis at 100 feet. I'm so happy Billy Deans invented helium, I can't hardly stand it.

This is not a 'You should go out and do this" kind of thread, nor is it a "hold my beer and watch this" kind, either. This is a "what are your tolerances for risk" type of thread. I would hope every diver limits their exposure to whatever (cold, O2, He, N2, abusive DM's) to something within their comfort zone/experience level, and when they want to push the envelope, they get the proper training/mentoring to do so safely. I don't dive solo with a PO2 of 2.0, but I do make those dives. My buddy is well aware of my gas planning.

 

[Jax]

Um, guys, we're talking about Wookie, here.

I'm not sure, but he may have more hours underwater than y'all have on this Earth . . . .

 

[ScubaFeenD]

I'm not sure, but he may have more hours underwater than y'all have on this Earth . . . .

There are some things that you just cant get around with number of dives. Increasing age and definite human physiological susceptibility to ox tox are two of em. Just because it hasn't gotten you yet doesn't mean it wont, and in a world with gases that can decrease, significantly, the risk, why would you bother taking the risk? IJS

Also, i dont know wookie.

 

[Wookie]

Wookie, you do know that an immersed person is more susceptible to a toxic episode than a dry one, correct? I'm also sure that you know there is wild variation between subjects and within subjects in regards to exposure needed to cause a toxic episode, right?

There is also a wild variation between the same subject day to day and season to season as conditions change. And, yes, I understand that seizing in a chamber with a tech present to get your tongue out of your throat is different than spitting a regulator underwater.

Guys, I'm not advocating anyone else jump on out and determine your max tolerance to O2 for a given situation. At the point where anyone is worrying about O2 toxicity issues, they should have, however, a pretty fair knowledge of THEIR comfort level and response to physiological stimuli. I have gained the knowledge over a couple hundred dives that I'm not as susceptible UNDER PERFECT CONDITIONS to suffering from an O2 event as training standards are written for. I am, however more susceptible to DCS and narcosis than tables allow for. Frankly, I'm tired of being bent. All 3 were not deserved by table and dive computer. Obviously I deserved them, I got them. I don't have a PFO, I just seem to retain N2 more than most.

 

[wedivebc]

So it sounds like everyone keeps to the NOAA recommendations as a minimum, but lowers the PPO₂ for working, current, and/or time. Deco seems to be kept the same?

That is how divers tend to apply the limits now. It wasn't long ago the USN was recommending 2.0 as a practical limit to oxygen toxicity but have dialed it back in the last 10 years or so. If you notice from the above posts there have been (rare) cases of tox events below these limits and we may see some further dialing back as time goes on. Many tech divers are discovering the small decompression penalty they pay for lower PO2 may well offset the higher risk of higher PO2. But only time will tell just how great that risk is.

 

[Jax]

<sigh> Can we just reach for understanding here, instead of arguing someone's personal decision?

Look, we know NOAA recommends 1.4 or less, and 1.6 PPO₂ as an absolute max. Fine. It's the current accepted norm.

However, some people make a decision to do something else. That is okay. It is not our place to attack them or try to change their mind.

I would like to know why people do the things they do; in this case, they dive to a higher that accepted 'norm' of PPO₂. I am going to ACCEPT that the people that do this are not stupid, that they made the decision for themselves, and it's not my place to tell them they are wrong.

 

[Jax]

That is how divers tend to apply the limits now. It wasn't long ago the USN was recommending 2.0 as a practical limit to oxygen toxicity but have dialed it back in the last 10 years or so. If you notice from the above posts there have been (rare) cases of tox events below these limits and we may see some further dialing back as time goes on. Many tech divers are discovering the small decompression penalty they pay for lower PO2 may well offset the higher risk of higher PO2. But only time will tell just how great that risk is.

Super! Thank you!