Bend Types (Cause, effect, recovery)

[Janos]

Originally Posted by Martin Burnard

BUT how is the bend TYPE determined or is it just random?

Originally Posted by Janos

Whether you get a type 1 or a type 2 depends on the dive profile. If your profile pushes the limits on the brain / CNS tissues then you're more likely to have a type hit then if your profile is limited by the type 1 hit.

[MattS]

IANAD

Briefly.

Type 1 DCS - was a term used to describe pain only bends symptoms - commonly at or near a joint.

Type 2 DCS - was a term used to describe CNS bends symptoms - such as paralysis and visual disturbance etc.

DCI is the term currently used to describe any bends symptoms on account that CNS damage is implicated even in pain only bends.

A bend results when your body can not adequately deal with the volume of inert coming out of solution. Hydration, diet, water temperature, physical fitness all affect your body's ability to deal with hyperbaric inert gas. Depth and time affects the volume of inert gas your body has to deal with. The ascent procedure affects how the inert comes out of solution.

Although there are no hard and fast rules, symptom trends are apparent due to the non linear nature of gas absorption and expulsion throughout the body. CNS symptoms are often associated with bubbles forming in the relatively 'fast' tissues. Pain only bends (if there is such a thing) are often associated with 'long' bottom times. Scuba divers need to take care when interpreting 'fast', 'slow', 'short', and 'long' as time periods are relative to the gas supply which can by physically carried. Generally, in the 25m+ dives which cause the majority of scuba bends the bottom times are relatively short - a saturation diver will quantify that statement.

Understanding how different profiles and ascent procedures relate to bends symptoms requires an understanding of the physiology and gas transport that underly it. Unfortunately it is beyond my capability to simplify it to the point I can explain it in a 10 minute forum post.

[Hickdive]

The Institute of Naval Medicine has a slightly different method of classifying DCI. You may find this link interesting.

http://www.rnreference.mod.uk/09/inm...n/contents.htm

[Nick Kay]

Heres my 2EuroCents worth...

1. As far as BSAC are concerned, theres "no difference" between Type1 and Type2 as far as basic treatment is concerned - shove them on O2 and its then up to DDRC etc to sort it out

2. Things likely to aggravate/bring on DCS/DCI:
- poor hydration
- cold
- tiredness
- overexertion
- skip breathing
- being overweight / unfit / a smoker
- PFO
- overexertion AFTER the dive, eg climbing the ladder
- fast acsent
- missed deco
- pushing the "no stop" envelope
- I'm led to believe that sites of previous injuries are more prone to DCS/DCI - healing scar tissue etc

3. Two real examples (no names - to protect the guilty/innocent)
a) shallowish dive, no overexertion, no deco, safety stops, classic "safe" profile according to the computer. Yet, diver got (pretty seriously) bent
b) diver eating curry & drinking the night before, dehydrated on the boat - drinks coffee to alleviate, seasick, hot weather. Diver gets "minor" bend

[Martin Burnard]

Thank you all concerned
The info provided has been great... the links excellent.
Verbal feeb back from Brian at Aquanauts also superb.
Any more info is welcome.
I hope many more of you have found the info as interesting and helpful as I have.

Once again

THANKS ALL

[Boat Elf]

www.londondivingchamber.co.uk also has some useful info on DCI