Lessening the risks of a hit...

[SSIdiver02]

I am a relatively new diver, Im only 19, in good shape and dont smoke or drink :boozer:.
Ive done 25 dives and never been bent. I realise that theres no way to make yourself "immune" to developing DCS, but is there anything that you can do, before/during/after the dive, that would significantly reduce the risk of developing DCS? We all know that drinking water before a dive and being well hydrated aids in the removal of nitrogen....what about other stuff that you can do? The fact that i might not be able to dive again from developing DCS makes me sick, and wish to prevent DCS at all costs! Thanks for your time.

 

[The Iceni]

SSIdiver02 once bubbled...
We all know that drinking water before a dive and being well hydrated aids in the removal of nitrogen....

I think the whole of this forum is dedicated to answering your main question, SSdiverO2. The incidence of DCI in recreational divers is very low indeed so you may be worrying unduly. I confidently predict that provided you dive accoring to your teaching you are unlikely ever to suffer DCI and would be very surprised indeed if you had suffered a hit after only 25 dives.

However, can I hijack your thread and ask Dr Deco one of my usual posers?

I accept that rapid rehydration after diving helps offgassing and also helps in treatment of DCI by ensuring adequate perfusion. (In addition, perhaps, the bolus of fluid post dive acts as a liquid sponge to soak up some of the excessive nitrogen load.)

However, although this is readily accepted, I am not sure of the mechanism by which dehydration itself predisposes to DCI.

Does it?

If so, is this determined by a reduction in the surface tension of plasma when dehydrated due perhaps to an increased concentration of surfactants?

(This is a genuine question as I do not know the answer.)

 

[Dr Deco]

Surface Tension and DCS - - -

Dear Paul:

Hydration

I favor the idea first expressed by Dennis Walder in his MD thesis of 1948, that is, that hydration dilutes surfactants and increases the dissolved nitrogen pressure needed to allow nuclei to grow. This would probably be more important than the perfusion issue; IV fluids produce quick results.

Walder

In the ATTACHMENT [first figure] are the surface tension measurements from Walder’s thesis. Unfortunately, this has not been found to be repeatable. I never heard Dr Walder ever repudiate his findings, however, and ascribe them to an artifact. The biophysics of the situation appears to be valid.

In this paradigm, it is necessary to view the body as a gas-in-water emulsion for purposes of discussion of DCS. There is a spectrum of gas micronuclei [ATTACHMENT, figure 2 is data from ocean water] and surface tension is one determinant for nuclei growth [along with radius, physical activity (= pressure reductions in microvolumes), and gas partial pressure.] All determine the Laplace radius for nuclei conversion to decompression bubbles.

Dr Deco :doctor:

 

[Dr Deco]

Dear SSIdiverO2:

Avoiding the Bends

As Dr Thomas indicated, this is the general focus of this FORUM. There are probably many postulates out there as to how to accomplish this.

Tables or Meters?

My first answer would be to not seek the solution in tables and meters. All of these devices produce DCS incidences that are so low as to be virtually unable to explain a “hit.” When meters first came out, it was feared that DCS incidence would increase. It did not even though many if not most deco meter dives are to the limit. That is the nature of how meters are used. One does not go to the next deepest depth and next longest interval. However, there is not an increased risk of DCS found to be occurring.

Physical activity

This then comes down to micronuclei rather than supersaturation as the only determinant factor. Here we find that lifting, hauling, climbing activities are ones that really cause an increase in DCS when tests are performed. :boom:

In fact, sedentary individuals are relatively useless when it come to observing cases of decompression sickness. Test subjects must be active, standing, and lifting things for DCS to occur in a chamber.

Do yourself a favor and do not climb up the ladder into the boat with all of your equipment on (weight belts and tanks), don’t lug tanks around during the surface interval, do not play beach volleyball, etc.:lifter:

Dr Deco :doctor:

 

[The Iceni]

It would be nice to confirm Dr Walder's findings using modern equipment.