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I tried sending this out last week but as we all know, something
has been amiss...  In any case, here goes...

>It is worth remembering that the divers on whom the tables were tested
>originally were never investigated for the presence of PFOs, and probably
>as many of them had PFOs as the general population (or as the technical
>diving community, for that matter). Two sets of tables is an interesting
>idea, but of course would be extremely difficult (if not unethical) to
>formulate.

Everyone has seemed to come out against two sets of tables.  Dr. Pitkin
raises the "ethics" issue.  I respect the work that he has done and
thank him for taking the time to post to this group.

After considering this isue for some time, let me change my original 
viewpoint on this issue and take a stand that it is unethical *NOT* to have 
two sets of tables.  I agree entirely with Dr. Pitkin's assumption that the 
tables were developed with a cross section of people with and without PFO.  
By continuing along our current path (i.e. one set of tables), we are 
unnecesarily exposing people with PFO to an abnormally high incidence of DCS.
Simply telling all divers to dive "within the tables" has proven to be
insufficient.

Until such time that all divers are screened for PFO, we are treating the 
diving population with a distribution of DCS as one single group when indeed, 
it appears we have a bimodal distribution.

So, what I believe should be done is:

#1)  All divers should be screened for PFO.  I'm not sure if this should be
	mandatory, left up to the potential diver (with the knowledge of
	the percentages and risks involved), or left up to the certifying
	agencies (I personally don't like this last one because I would
	like a little more uniformity among what can be expected).  Perhaps
	a little discussion on this issue would be good.
#2)  Tables for divers with PFO should be developed.
	This may be more difficult than it sounds since, as someone already
	pointed out there is both chronic and acute PFO (and probably
	many degrees in between).

If we had two sets of tables, then all divers that go untested could
choose to dive within the "pfo" tables, thereby reducing their risk.
Having two tables with untested divers diving on the "pfo" table seems
to be analagous to divers diving air tables while using Nitrox.

I'll pose another question. If people with PFOs were removed from the current
distribution, what would *that* do to the current tables.  It seems to me 
that they might actually be now considered very conservative!  Would they be
reformulated, perhaps with longer times???  Perhaps this is the reason why
many people dive near or over the edge of the tables consistently with
no ill effects!!!

-Carl-

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