Hypercapnia test. Is this normal?

[finbar.taylor]

Just searching through the interweb and stumbled across this link

http://www.beyondmagazine.co.uk/general/trmod1.htm

This is the point of interest

Hypercapnia test
Remove the sofnalime from the unit and reassemble and one at a time breathe from the unit. The idea is to get an idea of what CO2 poisoning feels like in a safe situation, do not do this test in water!! Observe the reaction in the student - it is interesting that even after observing this test a student is visibly being affected before he realises it. Remember that underwater the effects occur sooner. Keep an accurate log of the scrubber duration remembering to include dry drill time. If in doubt change it.


Did any one else do this? I'm aware of instructors recomending against it but could see the benefit I'm just wary that this could introduce other problems that may not be a good idea.


Any thoughts apreciated


Fin

[Janos]

When I did my MOD1, my instructor told me that there was evidence to show that early signs of hypercapnia were not present if the subject was breathing a high ppO2 (above 0.8 IIRC).

So I think the current internet consensus [1] is that it's a bad idea.

I think Digger had a go on his homebuild. There's a report somewhere.

I must admit to being curious though.

Janos

[1] - For what that's worth!

[Juz]

I think Padowan might have done a similar test - not 100% sure tho..........

Juz

[DaveB]

My understanding is that some of the effects may be more than temporary, and the lessons learnt not worth the risk.

Fairly vague I know, but it was enough to put me of trying!

[Freeflow]

I tried it on my Dolph, while leaning over a chair face downwards after reading a report on the Drager site on Smartgroups about the bloke who couldn't move his arms to get the loop out of his mouth.

I felt a pressure behind the eyes adn a slight greying out as my breathing rate increased, and the headache lasted 10 hours.

I also did a low O2 expreiment, visual narrowing and a dull pain behind the forehead are the result.

I'm a lab rat, don't try this at home.

[zepp]

Originally Posted by Freeflow

.
I felt a pressure behind the eyes adn a slight greying out as my breathing rate increased, and the headache lasted 10 hours.

I also did a low O2 expreiment, visual narrowing and a dull pain behind the forehead are the result.
.

I have tried it and had similar symptoms. Headache lasted only half hour though. Hypoxic test made me feel tired and slightly dizzy. I believe that this is not a true test as under pressure symptoms would be more serious and come on much quicker.
Here is a pic of me trying it out on the "Dyson with Death"

[Freeflow]

Looks like you are trying for a date with newly single PV with that pose!

C'mon ladies, get him while he's hot!

[zepp]

Originally Posted by Freeflow

Looks like you are trying for a date with newly single PV with that pose!

C'mon ladies, get him while he's hot!

OK, is this better????

[Janos]

Since you're so kind enough to be guinea pigs

What ppO2 did you use? O2 or air? I'm curious about the 'fact' that I heard that short term symptoms are non-existant for a ppO2 above 0.8. I belive it, but more evidence is always welcome.

Janos

[nigelH]

Originally Posted by finbar.taylor

Did any one else do this? I'm aware of instructors recomending against it but could see the benefit I'm just wary that this could introduce other problems that may not be a good idea.

It's a total waste of time. The effects of CO2 vary hugely with ambient pressure.

My hit had no warning symptoms that I can remember. I just realised that my breathing rate had crept up and was now getting difficult to manage. Deeper than I was it is reputed to be a sudden blackout as in an oxygen hit.