Posted by John Walker on January 19, 2002 at 23:03:26:
In Reply to: Helium & deco... posted by Bob3 on January 18, 2002 at 13:26:58:
Quit looking at just one tree. Look at the whole forest.
Helium clearly does have deco benefits. This may not show up as clearly looking at an arcaic decompression model. We have known this for some time now but the recreational diving community finds that acually teaching students something about current thoughts on decompression theory takes up to much time in the class room.
The benefits show up by paying close attention to any reduction in vital capacity. We can do this ourselves by noting our physical condition up to several days after a big dive.
Also as we did last night following a deep dive is by doppler study. This is only a tool as to how your deco and body have delt with a profile but generally gives us an idea as to how well we are going to feel later.
Other testing has been and is still going on with the USN, Hamilton research, WKPP and Florida State University on chemical changes in the blood following helium based dives. They can look at markers in the blood to see if the auto immmune system is activated post dive. The can also see marker from inflamation cause by perfusion.
Helium is a good gas of choice to reduce narcosis. Narcosis is thought to be related to gas solubility properties. These solubility properties are the same ones which create difficulty in tracking decompression obligations in the body. Since He is so much less retentive in the body than N2 it become much easier for us to track it.
Expect to make significant changes in slow tissue areas of your profile and remember since He offgasses fast the fast tissues need to be controlled a little more. When done right, less inflamation and a quicker deco is to be exspected.