Should we exercice during a diving trip, or sit on a beach and read a book ?

Well, I did 2.7 in controlled underwater environment for kicks and lived to tell the tale. Went to about 2.4 in very uncontrolled circumstances (down current in Komodo which made me swear off diving EAN at many sites).

Sounds like a couple of interesting stories there....on the 2.7 were others around who were there in case things went south? Sounds like it. Though I am not sure I would try that one myself.

As for drowning in the chamber, that may be true of water, but one can still drown in the bad BO of the chamber nurse!

So perhaps the Oxygen Toxicity was not actually Oxygen Toxicity in these reports

Well, I did 2.7 in controlled underwater environment for kicks and lived to tell the tale. Went to about 2.4 in very uncontrolled circumstances (down current in Komodo which made me swear off diving EAN at many sites).

As for drowning in the chamber, that may be true of water, but one can still drown in the bad BO of the chamber nurse!

Yeah, BO in multiplaces can be a problem, chambers can get pretty hot. How about the chambers out on the rigs in the gulf, where the guys live and use the toilet for a week. Then there's the true story where a guy had his intestines sucked out due to a malfunctioning toilet flush valve - and lived, with surgery done on the chamber bunk. (I've heard Keith Van Meter from New Orleans give this talk)

I think the problem with EAN and O2 toxicity is the upredictability with 1.4 - 1.6 being considered safe within a significant margin. There have however been reports of seizures and even death within normal 1.4-1.6 ranges. I'm not sure it's clear why this discrepancy exists, but I imagine it has to do with higher levels of physical exertion, hypothermia etc.

Sounds like a couple of interesting stories there....on the 2.7 were others around who were there in case things went south? Sounds like it.

yes 4 guys on a rebreather dive at 15m sandy bottom and bored. One ex Navy guy in the group says they regularly went to 2.5 in combat training exercises. NOT ADVOCATING TRY THIS AT ALL! 1.2 people 1.2pp!

Then there's the true story where a guy had his intestines sucked out due to a malfunctioning toilet flush valve - and lived, with surgery done on the chamber bunk.

Ok you win for most gross story of the day! Which brings up the warning for those using toilets in pressurized environments (planes, chambers etc)... Don't sit on the toilet when flushing!

There actually is a huge range of O2 toxicity reported in the literature, in this summary table linked below, you can see it varies fron 1 in 48 to 1 in 40,000. Depends on multiple factors. Monoplace, multiplace, air breaks, treatment protocols etc. Either way, in my own experience in a monoplace setting for wound management, treatments at 2.8ATA for 90 minutes, without air breaks, greater than 2000 treatments over about 3 years, I never saw a single seizure.

http://books.google.com/books?id=6hEfU-YbW...esult#PPA750,M1

The reality is that our tolerance for O2 toxicity while diving is clearly much lower than in a dry chamber. Added to this of course is that one cannot drown in a chamber.

That's good news for your patients, but I am a bit surprised. Our diabetic foot ulcer guys used to say it was nearly 1 in 100. As you say though a lot depends on lots of factors.

Bill

Come on, guys (it seems to be mostly guys on this thread)...

It is plausible that O2-toxicity is normally distributed against PO2 when factors such as CO2 retention are controlled. If the incidence of O2-toxicity is negligible at 1.4 bar and almost negligible at 1.6 bar, the implication is that some divers will tolerate much higher partial pressures of O2, particularly at rest and breathing with minimal dead space or resistance.

I have always thought it more interesting to look at the factors that increase sensitivity to O2-toxicity, which may affect diving practices.

It isn't surprising, and not all that useful, to hear of circumstances where a high PO2 has been tolerated. It would be instructive to hear of situations in which a low PO2 has been associated with apparent toxicity.

Shallow-water nitrogen narcosis is a case in point: having had a narcotic hit at 60' (dark water, strong current, high stress, high workload), I looked into narcosis and learned far more to influence my own diving than in reading about deep divers who haven't been narcosed.

Tim

As an actual lab rat case for you I do 30 minutes of medium paced circuit training and/or swimming (if I can) every morning while on a dive vacation - first thing before any diving. So far I've not gotten bent from it after more than 10 years. We often do a night dive and finish around 9pm, mostly four dives a day. I get up around 6am so there's about a 9hr surface interval between diving and exercising. Everything I have read about exercise suggests waiting a few hours after diving, but they are not usually talking about multiple days and multiple dives. I figure 9 hours ought to be enough surface time, heck isn't PADI now advocating flying after 12hrs? (I think I read that somewhere). I say enough of a workout to help maintain is fine (not a medical expert, don't claim ot be one), I'm not about to be sending my system to peak heart rate levels and 2hrs of aerobic training (that's to remove the stress of sitting in front of a computer all day) - after all there's diving to be done!

Yeah, BO in multiplaces can be a problem, chambers can get pretty hot. How about the chambers out on the rigs in the gulf, where the guys live and use the toilet for a week. Then there's the true story where a guy had his intestines sucked out due to a malfunctioning toilet flush valve - and lived, with surgery done on the chamber bunk. (I've heard Keith Van Meter from New Orleans give this talk)

I think the problem with EAN and O2 toxicity is the upredictability with 1.4 - 1.6 being considered safe within a significant margin. There have however been reports of seizures and even death within normal 1.4-1.6 ranges. I'm not sure it's clear why this discrepancy exists, but I imagine it has to do with higher levels of physical exertion, hypothermia etc.

Hypothermia/water temperature is an interesting point, are there any studies which take into consideration (water) temperature? I get cold easy hence the question. Also not sure if that's the case for everyone but im definately a lot more comfortable and at ease in warm water, this could also affect stress levels to some degree.