Hello to all, sorry I've been so scarce lately, however I've been
keeping track of the postings.

Disregarding most of Christian's missive that Bob has effectively
dismembered, :-) there is one area mentioned that is of great interest
to me and I recently came across an interesting medical description of
the physiological effects of the valsalva maneuver written by Dr. Ernie
Campbell.

------------
Question:
What happens with the valsalva maneuver and why can it be dangerous?

Answer:
Many things can happen with the 'valsalva maneuver'. This includes
holding the breath while straining at stool, doing leg lifts or push
ups, lifting a heavy anchor at depth and also is an intensive care trick
to alter the electrical impulse in the heart. The same procedure can
inflate the middle ears while equalizing.

There is increased blood flow into the thorax, with elevation of the
blood pressure and heart rate. The blood pressure become actually
supraphysiologic and can cause strokes and epidural hematomas. At the
same time there are increased intra cardiac pressures on the venous side
and this can cause a reversal of blood flow across a shunt (read PFO)
and if this blood has bubbles - can cause a stroke like picture. This
would indeed be dangerous to the individual with incipient heart failure
and an already heavy preload from simple immersion effects.

The maneuver can cause a decrease in ocular blood flow and can cause
maculopathy and retinopathy in the eye. There is decreased skin blood
flow, and there are changes in the p wave during electrical condiction
of the hear during paroxysmal auricular tachycardia. It can increase the
incidence of cluster headaches  and cause bladder leakage.

In diving the technique can also cause rupture of the round and oval
windows, resulting in inner ear damage and perilymph fistula. Excessive
valsalva maneuvers on ascent might result in pulmonary barotrauma with
gas embolism.

You can see why it would be better if a diver learned another clearing
technique.
---------------

Personally, I have found the Toynbee maneuver to be much more effective,
reliable, and 'easy on the ears' way of clearing than valsalva.  Since I
make my living with my ears (acoustical design), I've been very careful
to preserve my hearing by finding ways to gently clear and compensate
for pressure at depth.

A good read in this matter is a comprehensive work, Underwater Ear &
Nose Care by Noel Roydhouse V.R.D.,Ch.M(U.Otago),F.R.C.S.(Eng),F.R.A.C.S
[whatever all that bit of braid on the chest means] from Auckland, New
Zealand.  Virtually every method to equalize pressure in your ears is
described and illustrated with graphic (Ewuuuu!) pictures.  I found
several new methods that work well for me, especially the Toynbee.

In any case, it can't hurt to repeat Bob's excellent suggestion:
 > Whatever you read, cycle them through the computer between your ears!

Best regards,
Russ


Reef Fish wrote:
> On Sun, 1 Dec 2002 20:20:07 +1100, Christian Gerzner
> <[log in to unmask]> wrote:

**snip**

>>There is another advantage to this method of compensation. There is no
>>potential (cannot be) brute force involved, unlike the Valsalva.
>
>
> Okay, your method (whatever it is) has a less potential for THIS
> particular kind of "abuse".
>
>
>>Disadvantage? You don't know that you're performing it, it becomes
>>automatic. Therefore it does not "warn" you if you are going deeper as
>>the "physical", hand to nose, Valsalva tends to do.
>
>
> That's YOUR abuse of Valsalva, if you use it to gauge depth.  :-)
> That's what your depth gauge or computer are for!
>
>
>>I make *very* sure
>>that I set my Aqualand to the maximum depth that I intend to go to,
>>especially on walls. Been there, made that mistake also.
>
>
> That particular use of the alarm in the Aqualand IS an abuse itself!!!
>
> Don't you MONITOR your depth and air CONSTANTLY?  You not only will
> NEVER be too deep unknowlngly, but you should NEVER be unknowingly
> OOA because you failed to monitor your air supply.  You rely on
> your AI-computer to beep you?  ;-)
>

**snip**

> Whatever you read, cycle them through the computer between your ears!
>
> -- Bob.
>