[chrisch]

Valsalva

The nose pinch or valsalva method causes a pressure change in the heart between the right and left atrium.  If you have a hole between these vessels this causes bubbles to move from one side to the other.  This hole is a Patent Foramen Ovale (PFO) and about 30 percent of us have it.

If bubbles are present this can shift them into the arterial system where they can give arterial gas embolism (AGE) which can be very nasty if it is in the brain or spinal column.

There are a lot of ifs here so it is more of a hypothetical risk than a problem.  The key thing is to avoid equalising by this method at the end of a dive, for example if you accidentaly descend due to other divers pulling the shot line down as they ascend while you safety stop or deco.

To avoid this get in the habit of using a jaw wiggle or swallowing with the tongue pressed against the top of the mouth.

As gblades does this then no hassle - good for you.

I got interested in this as my partner is a migraine sufferer - a sign of possible PFO.  I had dived for ten years before that without having heard of this.  I am embarassed to admit having equalised at the dive end just as described above in the past.

I have now sort of got to where I can equalise without valsalva - sometimes I still have to resort to it on the descent.  However I am aware of the danger and so make more effort to maintain good depth control on the stops - which is just good diving really after all.

Better safe than sorry and at no cost or loss of pleasure...

Chris.