Breathing a High P02 Gas Post Dive

[PfcAJ]

I think the instructor was going along the lines of you may have DCS and not know it. You pushed the boundry too far. Since you are curing the DCS without knowing you had it, that may be the issue they have.

If you think you pushed the limits too far, yes take the surface O2. Physically it can only help. Mentally, you may have had DCS and not known it?

That’s exactly what I’d like to do. It’s why I do deco stops. It’s why I breath oxygen on deco. That’s literally the point.

You didn’t get bent. Mission accomplished! Deco = successful.

If you don’t get bent, you’re not bent. Wild idea.

 

[broncobowsher]

That’s exactly what I’d like to do. It’s why I do deco stops. It’s why I breath oxygen on deco. That’s literally the point.

You didn’t get bent. Mission accomplished! Deco = successful.

If you don’t get bent, you’re not bent. Wild idea.

That is not what I was saying. What I am saying is you did get bent, you pushed the limits too far. But fixed it with surface O2.

Fixing it is good. Not knowing you were bent, not good.

I'm not advising against surface O2. Just trying to figure a reason someone would say to not use it.
The key point is not ignore the fact you might have a mild case of DCS on the surface and you brushed it off with surface O2. You still had a DCS hit. You pushed the limits too far. Maybe you don't know you pushed them too far. Maybe you go to push a little further later, not knowing you have already found your limit.

 

[Wibble]

No he doesn't. He has only convinced you he does. Get a new instructor.

"He" might be taking the instructor's "cover your arse" approach. By the book, etc.

"We" all know somewhat different -- we know that breathing oxygen doesn't hurt and it could help, especially after a long or arduous dive. Just sitting in your space for 10 or 15 mins whilst you chill out post dive whilst breathing from the loop or even your high PPO2 deco gas is good; especially if the weather's crap.

However, the best thing is to ensure you follow your computer's advice and possibly, if it's been a tough dive, spend longer at 6m/20ft to surface with a lower GF High.

 

[Akimbo]

Not knowing you were bent, not good.

For all practical purposes, perceptible symptoms are the only means of diagnosing DCS. Therefore, if you have no symptoms you don't meet the current clinical definition for DCS. There is a vast gray area but "no harm no foul" applies.

Prophylactic Oxygen has value because it also reduces your residual diluent load, which reduces your DCS risk for repetitive dives in addition to post dive. Obviously, breathing pure oxygen at 15-20' (4-6M) would be more effective as long as you are symptom free. I frequently use this technique. For other readers, I believe that most agencies require Advanced Nitrox training for pure O2 underwater.

You only have to look at Sur-D-O2 (Surface Decompression using Oxygen) for a precedent. The practice has been in common use at least since the 1930s in military and commercial diving. Divers are intentionally brought to the surface and recompressed in a chamber to complete decompression. They are allowed 5 minutes from leaving their last stop to be at their next stop in the chamber, typically 40-60' (12-18M) on pure oxygen. The chamber run is considered "normal decompression" instead of treatment even though they would absolutely get bent if they did not complete decompression in the chamber.

See these threads for more information:

Info - Oxygen Toxicity Limits & Symptoms

Oxygen Toxicity Limits & Symptoms Oxygen toxicity limits can be very confusing, especially for PPO2 (Partial Pressure of Oxygen) levels above 1.6 ATA used in chamber-based hyperbaric treatment (recompression) and decompression tables. For example, here is a chart of one of the most common DCS...

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Info - Decompression & Treatment Simplified

1: Introduction Everything should be made as simple as possible, but not simpler — Albert Einstein (paraphrased) I probably violated the "But Not Simpler" part, but I tried to include enough Hyperlinks to make amends. Clicking on them should allow any interested diver to "drill-down" as far...

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