Decompression Strategies: Part One

Here is a little information on Decompression Strategies for those of you who cannot get enough of this stuff. I am planning on planning on making 5 entries in the weeks:

1. Micronuclei
2. Bad Assumptions
3. Conditioning
4. Decompression Tactics
5. Putting it Togerther

MICRONUCLEI

The starting point is to understand more about what causes DCS.  Everyone understands that excessive bubbles will cause DCS.  But what a lot of divers don't realize is how these bubbles start ... which will help a diver to understand how to decrease their risk.  When a diver goes underwater, the diver's tissues start taking in inert gas due to the pressure.  So when the diver surfaces, the tissues have an excess of inert gas in them.  But, contrary to what divers believe, this is not the problem.  A diver could take up a very large amount of inert gas and never get DCS if it wasn't for one thing ... the presence of micronuclei ... or bubble seeds.  In other words, a diver could dive to very deep depths for very long times without ever needing to decompress if it wasn't for the micronuclei.  These micronuclei act as a source for bubbles to start occurring.  They may be viewed as very tiny bubbles themselves.  What happens while ascending is that the gas built up in the tissues from the dive are now in a supersaturated and high pressure state.  This gas wants to start leaving the tissue and escaping.  This gas will go wherever possible.  One route is for it to enter the blood and exit that way.  Another possible route is that the gas leaving randomly bumps into and enters a nuclei.  This nuclei will continue to grow as more gas enters it and/or the diver ascends towards the surface causing it to expand according to Boyle's law.  If this nuclei gets too big, a bubble results.  So why is this being mentioned?  In addition to the obvious point of slowly ascending/decompressing through the water column towards the surface, the control of nuclei is a topic that should be discussed.  It has been shown that activity increases resulting bubbling from a decompression.  Since micronuclei can't be seen, they are postulated due to the known increase in bubbling from activity.  Most activity generates micronuclei, but the activity performed by divers are especially bad for generating micronuclei such as hauling gear to and from the water or climbing up the ladder onto a boat.  The greater the activity, the more nucleation that will occur.  It doesn't matter when the nucleation occurs.  It can occur from pre-dive activity or post-dive activity.  As long as there is an excess of gas in the tissues from the dive, nucleation will generate more places for gas to enter while trying to leave the tissues ... and the more places gas has to enter, the greater the number of resulting bubbles ... and the greater the risk of decompression sickness.  So the moral of the story is not to believe that a model is responsible for your safety, but instead understand that your own activity can be too and be aware that pre and post dive activity (as well as that during the dive itself) can substantially increase the risk of getting decompression sickness.