medical o2 on deck

[monkeymustpull]

Dr. Decompression

Is there any benifit or danger in using 100% o2 after diving is done for the day or between multi. dives?

 

[Lost Yooper]

Short answer is there is no danger.

Mike

 

[TexasMike]

As you will learn in your RescueDiver clas (one I highly recommend all divers take), there is no physical harm in applying 100% 02 to a diver on the surface who is in trouble.

 

[The Iceni]

I would hazard a bit more than this.

Not only is post-dive oxygen totally harmless it is actually beneficial.

If you think about it, high concentrations of oxygen are used to accelerate decompression underwater because it increases the Nitrogen off-gassing gradient. As you know it is also used as the first-line treatment in DCI for the same reason.

So using 100% Oxygen as your surface gas will increase your margains of safety between dives and after the days diving it will reduce the incidence of those unexpected (delayed) episodes of DCI.

Hope that helps.

Paul

 

[large_diver]

I am not a doctor.......

I've read a few comments from tech divers using 100% O^2 for deco at their shallowest stop or at the surface that they sometimes experience lung/breathing irritation if they use it for too long. Some of these have come from George Irvine, where he has discussed using oxygen for short periods with breaks in between because it reduced the "asthma-like" irritation of breathing 100% oxygen. Others have used 80% O^2 in their deco bottles to reduce this irrtation.

I think oxygen is eventually toxic to EVERYONE if breathed long enough even at the surface.....but I assume this would take a LONG time and the benefits of quicker off-gassing outweigh the toxicity risks given the short time a person will be breathing the oxygen....???

I would be interested in hearing some comments on this from Dr. Deco and other medical types.

 

[Lost Yooper]

LD,

There's a lot more involved in using O2 at 20' than most divers know about -- surprise, surprise. Extended periods on O2 at 20' will give you a congested feeling in the chest/lungs, but this is easily dealt with by taking back gas breaks (use the lowest PPO2 mix available). However, there is more to it than congestion -- extended periods of O2 will actually restrict offgassing. The best way is to go on O2 for 12mins (not 20mins) and break for 6mins on backgas.

Why 12mins on and 6 mins off? Here's the science/reasoning as I understand it:

In 12 mins, O2 will reach its most effective and useful saturation level. Beyond that, O2 is actually detrimental to gas transfer. Longer exposures to O2 will constrict blood vessels in order to protect the lungs. This adds cells and mucous excretion which restricts gas transfer and causes lung tissue to swell and may possibly cause scarring and long term problems.

Why the break?

Going to a low PPO2 will prevent (or keeps to a minimum) and/or reverse all this gas restriction going on in the lungs. You want to avoid reversing the condition by preventing it from occurring in the first place (i.e. 12 mins on -- max). So, by going on a low PPO2 mix, you will reverse what ever restriction has occured and "reopen" the capilaries and thus allow gas to enter the blood (better offgassing). The deco programs out there cannot take these breaks into account -- they see them as being a bad thing. By going back and forth between O2 and backgas you are maximizing off gassing in the most efficient way possible.

This is the gist of it.

Mike

 

[The Iceni]

Mike,

I fear you may be confusing our simian aquanaut!

There is the world of difference between the post-dive Oxygen he proposes - at atmospheric pressure - and the well recognised production of toxicity (either whole body/pulmonary or CNS toxicity) when Oxygen is breathed at pressures greater than 1 bar.

I am no great expert but understood that adults could tolerate 100% Oxygen at 1 bar for at least 24 hours before developing significant pulmonary toxicity, which you so elegantly describe.

Is that not so?

 

[Lost Yooper]

Hey doc,

I was referring to Large Diver's post regarding deco on O2, not O2 on the surface. My post was only relavant to O2 used for deco at 20' (1.6 PPO2). Going on O2 after a dive will do wonders for you and breaks aren't needed -- as far as I've heard. I guess I wasn't 100% clear.

Take care.

Mike

 

[sky50960]

well some patients are under 100% o2 in intensive care units for no longer than 12 to 24 hours without any problems

Post dive o2 ( with no DCS symptomes ) is efficient in reducing residual nitrogen and reduces the potential DCS.

If diving the same day as flying ( if you have to take the plane the same day for an urgent reason ) there is a ' protocole' for o2 breathing before flying.
But always dive safe within the tables

 

[Dr Deco]

Dear Readers:

Using oxygen at the surface poses no medical problem and defintely aids in the elimination of inert gas. The toxic effects of oxygen do not occur until one is at about 30 fsw or deeper. Then there is a time factor that must be added in.

It is true that oxygen will cause some vasoconstriction (= causing the arterioles to constrict), but this is not a factor at the surface. It will not interfere with off gassing.

Oxygen is just one of those thing that gives a scuba diver a little edge.

Dr Deco :doctor: