Geezer Gas

[agilis]

At 72 I have a few years to go before any rational person would regard me as a geezer, but I've used nitrox on most of my dives for years, not so much for additional bottom time as for the extra safety factor. I follow air tables and a computer set for air calculations while using 25% to 35% Nitrox. I no longer dive deep enough for O2 toxicity to be an issue.

I have noticed less fatigue and headaches with Nitrox, especially when doing repetitive dives or dives during which I expend a lot of energy chasing aquarium fish or fighting currents. The futility of skip breathing or shallow breathing was something I figured out when I was in my teens, long before I was certified.

I remember bringing up the topic myself during one of the class discussions we had in what was, way back then, a weeks long basic certification course. The instructor concurred, and the discussion continued into areas like helicopter flights for DCS hits and the ways in which body processes are affected by external factors.

 

[Akimbo]

Headaches after diving are caused by skip breathing or taking short breaths underwater. Try breathing slowly and slow your ascent and the headaches will disappear, even on air.

Probably true in many cases. Nitrox increases an already elevated level of blood O2 but has no effect on CO2. It is also unlikely that Nitrox would be a factor in sinus related headaches.

 

[Lorenzoid]

Related to the placebo effect, I can see how someone who believes Nitrox is beneficial for them might dive in a more relaxed manner on Nitrox than when they dive on air, leading to less CO2 retention, fewer headaches, etc. Maybe the major contributor to feeling good is not Nitrox per se but just relaxing and breathing properly on whatever gas it may be.

 

[victorzamora]

I know it's anecdotal and as far from science as you can get, but I've never felt better after a dive than after I started doing O2 stops and padding my safety stop on oxygen for a few minutes beyond recommended

 

[Aquavelvet]

Anecdotal here as well, but I've felt better after using EAN50 to accelerate decompression during simple deco dives. It happens often enough that I think there's probably something more at work than the placebo effect.


Sent from my iPhone using Tapatalk

 

[victorzamora]

It happens often enough that I think there's probably something more at work than the placebo effect.

Yeah, same here. When I'm cold on deco or don't pad my last stop quite as much I don't feel as good coming out of the water. I know people claim there's no direct fatigue reduction, but a reduction in sub clinical dcs. My assumption has been that I don't feel better with nitrox but that I feel worse without it.... so it might be fatigue due to stress on tissues of off gassing.

My point is I don't think aggressive nitrox diving is any better than aggressive air dives, but it's easier to be more conservative with nitrox and safety stops are more effective.

 

[Storker]

I don't think aggressive nitrox diving is any better than aggressive air dives, but it's easier to be more conservative with nitrox

I think we have a winner here.

safety stops are more effective.

I have a hard time believing that the offgassing you get during a 3 to 5 min safety stop is significantly affected by the slight decrease in pPN2 you get from normal rec nitrox mixes.

 

[victorzamora]

I think we have a winner here.

I think this is the majority of it. In glad you agree.

I have a hard time believing that the offgassing you get during a 3 to 5 min safety stop is significantly affected by the slight decrease in pPN2 you get from normal rec nitrox mixes.

I think it helps. Especially if you're diving a really rich mix, like 36-40%. Either way, it certainly doesn't hurt.

 

[Akimbo]

… There are two studies I know of, the first was a joke, and as I remember, the second noted divers feeling slightly (but not scientifically significant) better but the researchers said it was not from fatigue but from less sub clinical DCS….

This theory is very plausible, especially since Nitrox users are less likely to push limits since terminally boring and sometimes bone-chilling stops are shorter. It doesn’t explain the hangover cure though (Post #14).

Minute for minute in the water, I do find that deeper dives are more fatiguing than significantly shallower dives. Gas density (respiratory workloads), stress due to narcosis management (higher levels of concentration), and getting cold during decompression stops no doubt contributes though.

An interesting question is do eCCR divers running a constant PPO2 at 1.4 ATA find a difference than when diving Nitrox? The point being that Nitrox will only be at 1.4 ATA at the max planned depth of the dive as opposed to the entire dive including stops.

 

[Storker]

Either way, it certainly doesn't hurt.

That's for certain, at least.

---------- Post added February 2nd, 2015 at 10:11 PM ----------

...getting cold during decompression stops no doubt contributes though.

That last point isn't particularly relevant for rec divers (the majority of SCUBA divers), particularly if they're diving dry.

---------- Post added February 2nd, 2015 at 10:13 PM ----------

I think it helps. Especially if you're diving a really rich mix, like 36-40%. Either way, it certainly doesn't hurt.

I'd love to hear from someone more knowledgeable about deco theory than I am whether or not normal rec mixes (32-36%) significantly affect your offgassing during a normal rec safety stop.