CNS %

[njdiverjoe]

That's exactly how I felt when Kazbor's shut down.

So, too much oxygen and too little hot wings produces the same effect.

Okay guys so all we should need to do to increase CNS tolerance is add a bucket of hot wings to our deco stops! rjack321 this can also help clear out the snotty...


In all seriousness I'm really glad to see this topic discussed -- it's something I've discussed with several local CCR divers and gotten some interesting responses.

In the paper that Trace linked they state that "In humans, no oxygen induced convulsions have been described with a PO2 lower than 1.3 ...", this was actually a factor in my decision to use a high setpoint of 1.2 instead of the normal 1.3 . This morning I read through the proceedings linked by Dr. Mitchell and found that "the NOAA limits apply not just to CNS oxygen toxicity but also to pulmonary toxicity" -- which explains why we have CNS limits for the lower PO2s. This is something I have heard and suspected but never heard confirmation from an authority on the topic.

 

[Doppler]

The other point is that risk is very sensitive to the inspired PO2, and so I would counsel against breathing high-ish PO2s when your exposure has been very long. For example, I generally keep my inspired PO2 1.3 or less during long decompressions. I don't do 100% oxygen at 6m (inspired PO2 1.6) on dives like that.


Simon M

As always, Simon, thanks for your input. Hope all is well. And hope to see you in Singapore next April.