schford

I have heard discussed that there is a theory that although helium is a lighter gas than nitrogen and on gasses and off gases quicker than it, that fatty tissues off gass it slower than nitrogen - this being the case then some dive profiles would result in a deco schedule where off gassing of helium from fatty tissue would be the controlling factor as the M value and half time for that theoretical compartment would control the dive.

Present-day dissolved gas models employ a concept for multiple inert gases (in a mix such as tri mix) which states that the total inert gas pressure in a hypothetical "tissue" compartment (eg the fatty tissue compartment) is the sum of the partial pressures of the inert gases present in the compartment, even though the various inert gases each have a different half-time for that compartment.

With deco models either having the same M value for Nitrogen and Helium or a higher (this is better) M value for Helium than Nitrogen and then calculating an intermediate M-value(which is an adjustment between the separate M-values for nitrogen and helium based on the proportion of these inert gases present in the compartment) and with Helium having a much shorter half time this should mean that on a typical deep trimix dive Helium either does not affect the deco schedule or shortens it.

I wondered if any one had any comments on this, could explain it to me or had a link to some web based research I could gander at - as obviously if this theory is correct any thing that off gasses slowly from fatty tissue would affect little *coughs* old me....