O2 prior to fly/alltitude for short SI?

[Rick Inman]

I made 4 dives between Sunday night and Tuesday morning in the Puget Sound, with max depths of 105', 103' 75' and 94' (on the last dive, we did about 30 mins at 15' at the end of the dive). I did a 3 hour SI before driving over the 3000' pass - as usual - and was thinking that some 100% O2 might be nice.
Wouldn't breathing straight O2 before flying or driving to altitude allow you to off gas faster and shorten the necessary surface interval ? Or, even with the required SI, decrease the risk of DCS? What about sucking down a tank of EAN32 on the surface? Waste of time?

 

[H2Andy]

Wouldn't breathing straight O2 before flying or driving to altitude allow you to off gas faster and shorten the necessary surface interval ?

from what little i know of the subject, yes. you accelerate offgasing by
reducing the amount of nitrogen you inhale and thus facilitating gas exchange
(i.e. more nitrogen comes out of your system).

but i don't know that anyone has worked out exactly how much time you save
per X volume of O2 used.

i would say play it safe and wait.

 

[BigJetDriver]

Wouldn't breathing straight O2 before flying or driving to altitude allow you to off gas faster and shorten the necessary surface interval ? Or, even with the required SI, decrease the risk of DCS?

Rick,

Simple answer, yes it would. Unfortunately, as Andy pointed out, we don't really have the tables for it, although there are empirical methods for working it out.

At this point, it's best to take the SI and know where you stand, even though that will not remove ALL risk.

Cheers!

Rob Davie

 

[cmalinowski]

I was thinking about this last night, and low and behold I find that it's here. Interesting thought. I was picturing myself on the dive boat breathing pure o2 while everyone stares at me...

 

[rmediver2002]

I believe this subject is currently being studied at Duke.

I know that the Navy is investigating this subject as well (NEDU)

Perhaps at some point we will have a basic set of surface O2 tables for surface interval before flying

 

[wedivebc]

This seems like an easy problem , but I'm no expert. If your tables allow you to decompress to sea level why not just adjust the altitude to whatever you're flying and consider it an altitude dive. I know v-planner allows you to adjust altitude
comments?

 

[Narcoleptic]

This seems like an easy problem , but I'm no expert. If your tables allow you to decompress to sea level why not just adjust the altitude to whatever you're flying and consider it an altitude dive. I know v-planner allows you to adjust altitude
comments?

I am a noob to this site but as a pilot and a diver, I can say that both are 90% risk management. So what altitude will you decompress to? 8000 ft which is the typical cabin altitude of an airliner at 35,000 ft? What happens if the cabin decompresses and you find yourself instantly at 35,000 ft?

There could be subtle problems like a malfunctioning cabin pressure controller which I had a few months ago. The cabin doesn't decompress but the rate of pressure change is excessive. Remember that the rate of pressure change is most important, just like ascents from the bottom. How do you plan for that? With airfares at record low prices, often cheaper than taking a bus, due to low cost operators, don't think for a second that you are immune to a faulty pressure system onboard an aircraft. You may not even know it is happening until your joints start seizing up after you get home.

Why do we always feel the need to push the envelope? Heaven forbid you have something happen and try to make a claim with an insurance company. If there is any way out of paying a claim, they will find it.

It's all about managing risk to an acceptable level. Everyone has a different threshold.

My 2 cents, for what it's worth.

 

[DandyDon]

I don't think using Nitrox on surface would do very much, but using Nitrox on the dives to obtain shallower adjusted air depths can enable the use of Navy tables for altitude ascents after diving. See NOAA Dive Manul.

 

[Dr Deco]

Hello readers:

Breathing oxygen following a dive (or a mixture with reduced nitrogen content) would allow one to washout dissolved tissue nitrogen at a faster rate. I am not aware of any tables to which you could refer to find where you are in a “partial pressure map” of your body. Yes, you would be protected, but you would not the degree of washout. Naturally, one could calculate this, if they knew how.

Oxygen prebreathing, as a “countermeasure” against decompression sickness is employed by aviators and astronauts. Creating useful schemes for this was a large part of my job while I was with NASA.

As a practical adjunct for recreational divers at the current time, I suspect that its day has not yet arrived.:06:

Dr Deco :doctor:

 

[Rick Murchison]

Wouldn't breathing straight O2 before flying or driving to altitude allow you to off gas faster and shorten the necessary surface interval ?

I know that the Navy is investigating this subject as well (NEDU)

NAMI (Naval Aviation Medical Institute) did studies decades ago and decided to make pre-breathing pure oxygen SOP (Standard Operating Procedure) for us before high altitude post-maintenance check flights (where we'd be turning the pressurization off at high altitude).
I'd call that a "yes."
Rick