Tissue Half Times

[Ben Panter]

Hi Folks,

A group of us are prepping for the FCD theory exam at the moment, and a question we went over last night wanted you to match certain tissues to their halftimes. While I understand the hand wavy version of this, does anyone have a list of tissues and half times that we could have? Be it Haldane's, Buhlmann's or whatever. Tried Lippmann and the rest and not had much luck, and web searches never result in a table linking actual tissues to halftimes. I appreciate that decompression algorithms use combinations of theoretical compartments rather than real tissues - but these estimates must be based on some measures, however crude?

cheers,

Ben

[richard scarsbrook]

Ben

I've attached a pdf of a presentation Bulhmann himself gave at DOC86 (after lunch, in a thick Swiss accent, very technical, sending the majority of the audience to sleep :) ). I think it contains just what you are looking for, though you will have to trawl through it since there is no table as such.

I've never posted an attachment to a forum post before so I hope this works. If not PM me with an email address and I'll send it the traditional way.

Good luck with the exam.

[Ben Panter]

Thanks for that Richard - the attachment works fine, and I can see what you mean about trawling! Not quite what I was after, but it certainly helps me along the way.

cheers,

Ben

[Ben Panter]

One of the other chaps found this:

http://jacquet.stephan.free.fr/MT92_plongee.pdf

in which there is a table (page 3).

Ben

[paul_c]

oddly enough this stuff is very usefull for me as well.

try contacting the london hyperbaric medice centre as well

02085391222

as for lee

[Nigel Hewitt]

I thought one of the key aspects of the compartment model was that if you calculate the effects of a ppInert change on a chain of linked compartments the total effect at the end of the chain is of just one compartment with a different time constant. Hence in a real body the model applies with gases feeding through avioli, blood and then layers of tissues. You cannot say that one tissue has one time-constant just that it is on the end of a chain.

Then the 'compartments' tcs are chosen so that the effects overlap and you are effectively managing all possible 'compartments' to within an acceptable error.

[AndrewA]

I think the information you want is in Bob Coles book "The Decompression Matrix" (specifically fig.2.7 on page 2-9).
This is a super little book and when I saw the question you were working on I remember thinking it might have come from here!
Sorry I am not clever enough to reproduce it here but in order from fastest to slowest the tissues are: Blood, Brain,Spina lCord, Skin Muscle,Joints

[paul_c]

also have a gander at

http://www.lizardland.co.uk/DIYDeco.html