Narcosis

[Freedive WI]

I was always taught the 02 was twice as narcotic as N2, but because it get's metabolized by the body the narcotic efffect is basically a wash, which goes back to nitrox having the same narcotic properties as air.

Adding in varying amounts of helium can change your narcotic depth to whatever you want it to be- 80', 100', 130', ect. This is why trimix is sometimes called "dial-a-mix" since you can "dial" in the buzz you get by how much helium you add.

On a totally unrelated topic of narcosis theory the coolest research that I have been reading about is going on with some deep freedivers off of Australia and PNG.

Freedivers can get narked just like scuba divers, and this can happen on a sled or freeswimming. Freedivers can also get bent, and I have met at least one who did. This group of divers in Australia are getting around the narcosis and the DCS by using something called FRC diving. FRC stands for: Functional Resdiual Capacity- or, how much air you have left in your lungs after a full exhale. This is the same way that Seals and whales dive- they exhale and drop. All of the 02 is stored in the blood and there is no gas that gets pushed in and out of solution by compressing the lungs at depth. No gas exchange = no narcosis/DCS.

Of course, these people have VERY flexible rib cages and they work up to deeper dives over a period of time so that they can work into it slowly- just like you don't decide to get off the couch one day and run a marathon, they don't just drop down to 300' on the first plunge.

They are hitting depths of well over 300' in this manner and can dive again, and again, to these depths all day long. If the were to do a full inhale breathhold dive they would need to put plenty of surface interval inbetween dives or run the risk of getting bent. By doing FRC dives they can drop again as soon as the catch their breath.

Jon