Ahh.. Dreamdive/Claudia.. thanks for that. That read like something Ebersole wold have written and it looked like it hinted around his PFO study but never came right out and mentioned such.
The paper also mentioned that the headaches were correlated to the profile, but for the small shunt group I guess. I remember listing to Ebersole's speeches but I don't think I remember him mentioning headaches as he was all about the doppler data.
Every now and then this forum proves to me its value.. thanks for that. Now, in light of my previous statements it sounds like a persistent headaches has me taking a tangent. IMO if I was the gent with these headaches I'd be careful with my profile and pay better attention to it and the symptoms searching for correlation, and at the same time perhaps check the shops air analysis to check for CO2 and practice good breathing habits.
Here is a cool one on PP CO2 and relates CO2 to density as well which lends me to think trimix is good no matter for the CO2 displacement (my theory), and the potential sensitivity due to density ... which explains to me why I can dive deep on OC, but at 135-138ft on CCR with air I hold back less I become a stumbling fool. Is it from density, higher loop PP CO2, or perhaps my PO2 setting.. not sure, but its what happens to me at 138ft on CCR with air diluent around 1.2po2. If I hover at 130-135ft I'm fine because I know at 138 I become stupid which has me on the fence because on OC I'd be ~1.1'ish, and when on mix I'm clear as can be... so density/displacement/retention.. ...just go with mix I figure.
https://www.globalunderwaterexplorers.org/carbon-dioxide-narcosis-and-diving
Here is the scenario I play in my head:
assuming my gas is 550ppm like in Cozumel:
I'm assuming that 0.055% is treated just like O2 so at 1ata lets call it ppCO2=.055
That number is telling me that I'm breathing 0.055% CO2 at ~1ATA and if pressure increases I'll have an increasing ppCO2, like we do with everything else.
Now, at 5ATA I'm breathing a ppCO2 of 0.23 which is logical as its the same with every other gas.
Just a brain-fart here: I'll wager if the air to the compressor was scrubbed of CO2 so that whatever CO2 existed was the result of monoxycon conversion if it would be less narcotic, and without the helium penalty at moderate depths. I'll wager its the argon and CO2 in the gas that is more narcotic than the N2. At moderate depths say 130-160 I wonder how much more "clear" a diver would be if just air was scrubbed of CO2 & argon. My gotcha is that we constantly scrub on CCR, so I'm not sure how this plays into the equation but that there is some magical ppCO2 that affects us just as there is with N2, and the saving grace woud be that lowering the ppCO2 would extends the PN2 narcotic depth.
Now if you are on 10/50, and you have 40% of that .055 then you are at .022 1ATA, then you can negate the ppCO2 effect as no sane person wold go much deeper to worry about it. I bet you don't feel narked at 300' on 10/50 with a ppCO2 0.22 and you dont blackoutt from CO2 poisoning. As long as the ratios work out it seems ppCO2 is always negated on deep dives.
This all flys in the face of EAN of course because the point is to lessen the deco obligation at moderate depths... what to do...my whole point is I'd like to hear if anybody has ever tried to lower the PPCO2 as combining that with EAN would be the best bet for extending the narcotic depth as well as maintaining shallow recreational NDL obligation. Thus, we could see if its the CO2 sensitivity, assuming good breathing habits, as lowering the PPCO2 to surface level at max MOD would negate the density/sensitivity factor of CO2. Then if dude gets headache... close the PFO.
