Can medication increase or decrease oxtox susceptibility??

[BillP]

The Iceni once bubbled...
yes Bill, and aspirin is poisonous to cats!

Aspirin is "poisonous" to people too- if you take a large enough dose over long enough period of time. Cats don't metabolize aspirin well, but they can safely take small doses infrequently if prescribed by a vet.

To suggest that aspirin is always absolutely contraindicted in cats because it is "poisonous" would be incorrect- just as to suggest that there is "no evidence either way" on the oxygen toxicity moderating effects of caffeine would be incorrect- so I'm sure that you would never intentionally do either.

Just my 2¢,

Bill

 

[The Iceni]

BillP once bubbled...
Aspirin is "poisonous" to people too-
Bill

Hi Bill,

My point is that animal models are not very good for extrapolation to the human diving scenario. For example, rats can be killed very effectively with helium as they behave very differently from humans, at least when it comes to isobaric counterdiffusion and the offgassing helium.

We know so little about the mechanism involved in the generation of CNS oxtox I would even aver that Wetvet's suggestion that antioxidants "cannot hurt" may be an extrapolation too far.

In all honesty, we really do not know for sure.

For example, when using Nitrox I find the benefits of piping-hot post-dive coffee far outweigh any purely theoretical risks.

 

[BillP]

The Iceni once bubbled...


My point is that animal models are not very good for extrapolation to the human diving scenario. For example, rats can be killed very effectively with helium as they behave very differently from humans, at least when it comes to isobaric counterdiffusion and the offgassing helium.

Counterdiffusion of helium? I must be confused. I thought that we were discussing oxygen toxicity. Do you have evidence to suggest that the rat is an inappropriate model for CNS oxygen toxicity? Animal studies have been used for many years in diving research.

I grant you that the study that I referred to is indeed not "hard-and-fast" evidence, and, as I also said in my original post, it is in rats. It is hardly proof that caffeine is beneficial, or even safe in human divers. But to dismiss the study out-of-hand (and even ridicule it?) simply because it is an animal study is uncalled for, IMHO.

As you said, the mechanism by which oxygen causes CNS toxicity is not completely understood, but it is possibly by a diffferent mechanism than by which caffeine causes CNS stimulation, and the effects of the two aren't necessarily additive. While it may be premature to recommend caffeine as a preventative for CNS O2 toxicity, the rat study suggests that it may be unnecessary to vilify caffeine in diving as some people do.

Just more of my 2¢,

Bill

 

[The Iceni]

pipedope once bubbled...
Many drugs are suspected of increasing the likelyhood of oxtox.

Best is no drugs if possible.

If you need the medication then maybe you should not be doing dives where oxtox is a significant possibility.

So keep pp O2 below 1.4 bar!

 

[beche de mer]

The Iceni once bubbled...


So keep pp O2 below 1.4 bar!

Sound advice. But interesting to note that, in the "1996 tech diving fatality" thread, the deceased was happily swanning around at a pp02 of 2.9 for 19 minutes before the inevitable happened.

 

[Charlie99]

beche de mer once bubbled...
But interesting to note that, in the "1996 tech diving fatality" thread, the deceased was happily swanning around at a pp02 of 2.9 for 19 minutes before the inevitable happened.

Another datapoint is the oxtox incident during a GUE trimix class in Croatia. The tox occurred at 19 minutes into the dive, at 36 meters, breathing from tanks that were later analyzed as 50.1% --- ppO2 of 2.3ata.

GUE class oxtox

The common thread is virtually every oxtox incident I've seen is that the diver was accidently breathing something other than what he intended -- either breathing deco gas at depth, tanks got inadvertantly swapped around, or tanks that weren't analyzed.

Charlie

 

[WheelerDealer]

The Iceni said...
Theoretically ANY STIMULANT will increase the risk of CNS oxtox and sudafed (pseudoefedrin) is a stimulant closely related to epinefrin.

So then, theoretically do depressants decrease risk of oxtox??

 

[Charlie99]

WheelerDealer once bubbled...
So then, theoretically do depressants decrease risk of oxtox??

Nope. They increase the real risk, which is that you get sloppy and breathe the wrong gas.

Smart*ss comments aside, the increased danger from the side effects of depressants are probably more dangerous than any benefit from a possible reduction oxtox susceptibility, as long as you are diving within recognized ppO2 + time limits.

Charlie

 

[WheelerDealer]

Charlie once bubbled...
Smart*ss comments aside, the increased danger from the side effects of depressants are probably more dangerous than any benefit from a possible reduction oxtox susceptibility, as long as you are diving within recognized ppO2 + time limits.

I hope you understand my previous post was not meant to be a smart*ss comment but instead an honest question.

 

[beche de mer]

WheelerDealer once bubbled...

So then, theoretically do depressants decrease risk of oxtox??

Theoretically that may well be the case. The most serious symptom of acute oxygen toxicity is convulsions, so any drug which increases the threshold for neural activation (e.g. anti-epileptic drugs, sedatives) might reduce the risk of convulsing on high oxygen pp's.

All very theoretical of course, and I don't know of any data to support this.