crazy headache and nitrox?

[lv2dive]

Yes, of course the oxygen percentage is impacted by depth/pressure... but I didn't think it was necessary to state the obvious because

A) I was clearly referring to the fO2 -fraction of oxygen, as opposed to the ppO2 - partial pressure of oxygen
And
B) I wasn't trying to 'splain EANx 101 here in Basic Scuba

32% times pressure, but I agree: its unlikely. From the stuff I read it seems equally unlikely that nitrox would make one feel better, yet plenty of people swear to it. In this very thread too.

 

[GJC]

So last weekend we went to Vancouver island and dove some wrecks, even though I did my nitrox class last year these were my first dives with nitrox, and I surfaced with a massive headache every time which subsided in 10 min completely on the boat. no deco dives and not even close by surface
dive 1 Saturday we did the Capilano on 28% 122ft max depth, 24 min run time it was super bad vis 3-5 ft from surface to 80 feet where it opened right up. perdix said I had 85 min of NDL left by the time i reached 15' for a 5 min stop this was the first wreck Id done without a line and was a free descent and ascent in whale snot. lowest NDL got to was 5 min
dive 2 saturday 1 hr 51min surface int. 28% we did a wall near the ship 117 feet 39 min total time lowest NDL got to was 4 min

dive 3 sunday- HMSC Saskatchewan totally fantastic dive worst headache from the 3 dives
101 feet 37 min total time on 32% lowest NDL got to was 11 min . I opted not to do dive 2 on it.

the more experienced divers said they figured it was CO2 retention.
the same guy filled all the tanks for the 5 of us at same time for the 5 of us diving OC the 6th member was diving a rebreather

I didn't notice if i was skipping breathes or anything my air consumption was right where it normally is unless I unconsciously do this with air and its just not as noticeable on air as nitrox.
Ive been to those depths before on air as well quite a few times but not quite as long.
I was also stressed out at work so im sure this may have played a factor.

anybody have any thoughts or insights?

As your headache seemed to come and go pretty quickly, could it have been a reverse sinus block?

 

[dmaziuk]

Yes, of course the oxygen percentage is impacted by depth/pressure... but I didn't think it was necessary to state the obvious because

A) I was clearly referring to the fO2 -fraction of oxygen, as opposed to the ppO2 - partial pressure of oxygen

I did briefly glance at the abstracts when posting the links: both articles cite arterial partial pressure of oxygen as being the guilty party, or at least as important as oxygen content. Hence the nitpick.

I expect there's enough nitrox divers out there that, if it was really an issue, we'd've heard of crazy headaches already. Still, it's interesting that the possible mechanism for headaches actually exists: cerebral vasoconstriction. Fascinating, as Mr. Spock would say.

 

[Rred]

"but if higher 02 produced more co2"
In my limited understanding, it just doesn't work that way. The amount of CO2 that you produce us a result of how much metabolic activity you have. It will be LIMITED by the amount of oxygen in your system, but given that your body should be "fully" oxygenated (i.e. more than enough for your metabolic needs) under all conditions and even with a plain air fill...You shouldn't be having any metabolic issues caused by a higher percent of oxygen in your tank. Climbing Mt. Everest in the death zone, sure, that's different.
I don't think there are any references to anyone having a CO2 problem or headache problem from nitrox, but CO poisoning is relatively common, headaches are a symptom, and the first way to eliminate that would be to test the remaining air in the tanks. If the tanks have since been refilled, that may not be possible. In which case, you'd be left with needing to CO test your next round of fills, to figure it out.

 

[dmaziuk]

... CO poisoning is relatively common, headaches are a symptom ...

... but as @compressor pointed out is rather unlikely to resolve itself in 10 minutes because when CO sticks to hemoglobin, it really sticks. Which is what makes CO poisoning so bad.

 

[Gareth J]

... but as @compressor pointed out is rather unlikely to resolve itself in 10 minutes because when CO sticks to hemoglobin, it really sticks. Which is what makes CO poisoning so bad.

I know that and didn't think about it, let alone mentioning it in the thread ... Duhhh

 

[Rred]

Ah, I missed the resolve in ten minutes. I'll throw in with the "sinus" crowd then, if they'll have me.

 

[Compressor]

Correct. The affinity of CO to Hb is very high (~100x that of O2). For the scientists in us, it shifts the Oxygen-Hb dissociation curve to the left meaning that not only does the C) binds to the Hb molecule with great affinity but also at the tissue level, the oxygen that "is" bound to Hb does not unload well to allow consumption there. From enclosed curve, you can see that for the same oxyhemoglobon level (O2 Saturation), the patient/diver with CO poisoning will lower tissue PO2.

Treatment is easy: oxygen. For example when I worked at a hyperbaric chamber, we used to put folks who had CO poisoning from house fires into the hyperbaric chamber to hasten unloading of CO from Hb.

Hope that helps.

Source for diagram.

 

[leadduck]

I expect there's enough nitrox divers out there that, if it was really an issue, we'd've heard of crazy headaches already. Still, it's interesting that the possible mechanism for headaches actually exists: cerebral vasoconstriction.

If you search for it you'll find quite a few diving forum posts where people report headaches after diving with Nitrox that they didn't have with air. And usually the replies all say it can't be the Nitrox, it has to be something else, listing numerous other things that could cause headaches. But yes, cerebral vasoconstriction is a mechanism that links Nitrox with headaches. Maybe it's just not strong enough by itself to affect many divers, but only when amplified by other factors such as hypertension and dehydration.

 

[dmaziuk]

Maybe it's just not strong enough by itself to affect many divers, but only when amplified by other factors such as hypertension and dehydration.

:shrug: I sometimes get headaches when there's a storm brewing half a continent away, there's all kinds of "other factors" that won't surprise me at all. What does is the stock "it can't possibly be nitrox" reply -- and when it's a lightning strike in Alberta, that it can be?