Flying, diving, DCS and Diversions

[Diver_Dave]

Changing Pressures

Rainboe.

Normally the pressur increases by (roughly) 1ata pre 10m of depth.

Sport diving tends to teach no-stop diving so that decompression
isn't required. However, finishing any dive there is still residual
nitrogen dissolved in the blood, how much is a factor dependant on
the relationship between Depth and Time (although not straight line) and
also for repeat dives cumulative.

this leads to teh tissue loading I was talking about earler, in that whilst the residual nitrogen won't form bubbles as it liberates at 1ata (sea level) it will
as the ambient pressure reduces.

Given that the total tissue desaturation times can be up to 24hrs therefore in your example the drop to 60-55% ata could induce bubbles.

As luck would have it bends come in 3 sorts, with type 1 being by
far the most common.

Type1 skin (Looks like nettle rash and itches like hell! Caused by small
nitrogen bubbles under the skin.

Type2 Joints. Pain and immobility in joints caused by larger gas
bubbles in Joint soft tissue, relieved by contracting joint,
elbows and knees most comon hence 'Bends'. Can lead to paralysis

Type3 Nuro. Bubbles liberated in brain causing pressure, Symptoms vary
from mild imparement (appears intoxicated) to the symptoms of a sever stroke.

In all 3 cases O2 administration as soon as possible. Type 1 *should* be
OK but the others require recompression.

This essentially is in controlled conditions taking the diver back to depth
(in air / O2) and carefully managing the ascent.

I'm actually glad there hasn't been a chorus of 'Oh yes we do that'
so maybe the problem isn't that bad, although I may ask the DDRC (Deep Diving Research Centre) who deal with a lot of UK incidents if they've got any
figures.

Thanks to everyone who's contribute, please keep it coming if anyone has
anything else to add.

thanks again for yor time.

DaveA