Posted by John Walker on May 12, 2001 at 09:20:30:
In Reply to: N2 tolerance... posted by Bob3 on May 12, 2001 at 04:18:24:
You canot build up a resistance to either. Its a physiolocical issue, not a psycological.
In order to resist O2 toxicity (CNS) your bodies metebolic rate would have to decline. Good luck!
It is believed that CO2 production is a major contributor to both O2 toxicity as well as Narcosis. Dr. Edward Lanphier noted that CO2 retainers were highest candidates for hyperoxic seizures over 40 years ago, and todays studies would coincide with that.
Other issues such as adrenaline also appear to convert to a highly toxic chemical in the brain, that predisposes a diver to a hyperoxic seizure. This is noted in a study I once posted on the BBS by Dr. Johnny Brian. Adrenaline is a hard one to control for divers. Increases in adrenaline take place the moment a diver jumps in the water, and sometime before they jump in the water.
Histamines are also a problem that create the vascular constriction from O2 and the vascular dialation from CO2. These can also be coverted into that toxic chemical (hydrogen peroxide).
I also have done deep air dive, and pulled them off. I can honestly say that had a problem arose, the outcome of the dive most likely would have been much different. Although I could monitor my guages and swim, my motor skills were declined as well as my thinking process (known as cognative function).
On a dive with such responsibilities where buddy awareness, gas selection, buoyancy and trim control, stress management, and responsive actions are critical, it would be a bad idea to except anything less than diving with the highest fiteness, highest level of dexterity, and the highest level of thought processing.
Anyone who can truly adapt to these issues of Narcosis and O2 toxicity are super humans. In my opinion they are fooloing themselves. But they might actually belive that they have developed a resistance , but thats probably due to the deteriorating features of the narcosis.
JOhn Walker