David Strike wrote:

> I've got a bit of pain in my elbow and numbness in a
> > couple fingers on my left hand as a result of not using mine the one
time
> I really should have.

> Is that a cautionary tale that you might care to share?  :-)

At the risk of being told I was as foolish as I know I was, I suppose I
should.  Maybe somebody else will avoid the discomfort.  It's not like I
didn't konw better, or hadn't preached better to others.  While it took an
odd combination of factors to cause a problem, it's still a case of I should
have listened to my own good advice.

It was my August Tortugas trip, the 7 dive a day spearfishing trip 70 +
miles from shore, one of the several factors.  The boat offers air or 32%
from a membrane system, another factor.  On this trip, the captain's young
son, in his early teens, was acting as mate.  It later turned out that he
had little understanding of at least some of the risks of using a gas other
than air, still more factors.  My own complacency was the final and most
critical factor.

As those that pay attention here know, I got an O2 analyzer shortly after I
was trained for nitrox.  I'm on my second unit.  At home, I have a very
specific process for testing and marking my gas and have been a pretty
consistent advocate of the rule that every diver should test his own gas,
every time.  Of those who opted for nitrox on the liveaboard, I was the only
one that had an analyzer, let alone used it, and I did use it.  Membrane
systems are pretty reliable.  Once they're set up for a particular mix, they
tend to provide it consistently.  My buddy and I both have low gas
consumption.  It's low enough that have to monitor our nitrogen, and oxygen,
status pretty carefully, adjusting our depth to stay in a reasonable comfort
zone rather than the time of our dives.  We both like to hug the bottom, so
we keep a pretty close eye on our depth and nitrogen load.  Even on 32%, we
come as close to our limits as we think safe.  We stay out of the computer's
caution zone, but not far out of it.  Knowing this, I did what I've done in
years past.  I tested the first few fills to confirm the mix and, quit
worrying about it.  The membrane system didn't fail me, but the human system
did.

Late in the second day, I noticed that air tanks and nitrox tanks were
hooked to the fill system at the same time.  A look at the boat's in line
analyzer showed that air was being pumped at the time.  Being a bit
uncomfortable with that, I got out my analyzer.  Both my tanks had just been
filled, so I tested both of them.  The one I had used last was 29% rather
than the 32% it should have been.  The other tank was correct.  I reported
the problem to the captain, adjusted my computer accordingly, and continue
my diving.  Two dives later, I got the first hint that something was wrong.
Two days later, I knew what I'd done to myself for sure.

Hindsight tends to be pretty good.  An analysis of everything that went
before convinced me of what had happened.  The tank I had used on the dive
before I tested my gas was filled with air.  I dove it as nitrox.  The fill
I tested was nitrox on top of the air remaining in the tank, hence the
somewhat, but not seriously low reading on one tank and the correct mix in
the other.  By the time I knew I had messed up, I had alreay done the
damage.  I made several mistakes.  Some I'd probably make again, others I
probably won't:
1. I let the hurried diving pace and confidence in the mechanical system
influence my decision on following my own standards for diving gas other
than air.
2. Having been on the same boat, but with different mates, I became
complacent.  I failed to take the human factor into account.
3. While I reported the problem, I didn't do enough to compensate for it.  I
adjusted my computer, but not my subsequent dives.  The "safe enough for me"
that my computer was reporting was not, in fact, safe enough at all.
Perhaps I should have stopped diving.  Perhaps I should have been more
conservative on subsequent dives.  Perhaps I should have been breathing O2
as a precaution or even arranging to be evacuated.  Perhaps I should have
stopped off at the local hospital on my way home.  Instead, I did nothing.

So, once again, I learned that if you're going to be foolish, you have to be
tough.  I think my arm is getting better, but it's a slow enough process
that I can't be sure.  I didn't and don't have the level of pain normally
associated with DCS.  Rather I have an relatively constant  ache, just
enough to remind me of my mistakes.  The numbness seems to be circulation
related.  It's not constant, but is recurring.  Fortunately, it does not
seem to occur as often as it did shortly after my incident.

The only bright parts of this are:
1. When I tested my tank, I tested a friend's tank as well.  His too had
been filled with air.  His consumption is such that he could not and did not
have the nitrogen load I managed to accumulate and he's about 10 years
younger.  Adjusting his computer for the actual mix was enough for him.
Lucky him.
2. I now have another experience which others can learn from.

Interestingly, I spoke with a now retired commercial diver friend.  His
question "You screwed up?"  My response "yes."  His question "How old are
you?"  My response "54."  His statement "That's how old I was the first time
I got bent."  Maybe age was a significant factor.  Lord knows, I got away
with doing things that should have bent me like a pretzel when I was
younger.  The only thing I can say for sure is that if I want to avoid
additional pain, I'm going to have to be a bit more careful in the future.
FWIW, I've already decided I'll use nitrox as air on next year's trip . . .
AND test my gas before every dive.

Regarding my analyzer.  It has a cap that goes over the sensor that forms
both a test chamber and a flow restrictor.  The cap has a hose barb out the
side and a pin hole restricter on the top.  With only a little practice, you
can place the pin hole against the valve and moderate the flow to get a
reading as accurate as the unit can provide.  This has been my practice in
the past.  It's effective, but you have to take your time and you have to do
it right.  It's time consuming enough to be inconvenient when you're in a
hurry.  My local dive shop, which is closely affiliated with Halcyon, sells
an inflator connection/hose barb with a flow restrictor designed for
standard intermediate pressures.  It's considerably easier to get consistent
results with a system like this and, for me, easier and quicker translates
to "more likely to be used."  I may have gotten an education from this
experience, but I'm still the same person that got himself into this
situation in the first place.

Lee