What setpoint for 100m+ diving do you use?

Mixaddict · 13th February 2008, 05:12

Quote: (Originally Posted by Drmike)

I believe its the instantaneous ppo2 and the situation at that time that is far more critical. I can imagine a circumstance where someone with a CNS of 50% toxes because they are swimming hard with high ppHe and high setpoint, where as someone with a CNS of 200% sat on deco doing nothing with same setpoint is safer.

My point is I don't really worry about the CNS (as its traditionally measured) I concern myself with what my ppo2 is at a given time and given circumstance. There may well be a cumulative effect - but I suspect this is masked by the fact we are usually well into restful deco by the time the CNS creeps that high.

Mike, is there any point at which you personally start to worry about the CNS cumulative time clock, or is it only your current pO2 and work load that is your concern?

Drmike · 13th February 2008, 05:23

Quote: (Originally Posted by Mixaddict)

Mike, is there any point at which you personally start to worry about the CNS cumulative time clock, or is it only your current pO2 and work load that is your concern?

Personally I worry much more about the latter than the former.

Ive done many dives with CNS off the clock. Its hard to do anything big withouit having CNS over 200%, but on those dives (and in general when the CNS is high) I tend to keep my setpoint low where possible especially during high risk (working) parts of dive

Air breaks are well proven to reduce risk of toxing even when exposed to very high PPO2s,

Mixaddict · 13th February 2008, 05:34

Quote: (Originally Posted by Drmike)

Personally I worry much more about the latter than the former.

Ive done many dives with CNS off the clock. Its hard to do anything big withouit having CNS over 200%, but on those dives (and in general when the CNS is high) I tend to keep my setpoint low where possible especially during high risk (working) parts of dive

Air breaks are well proven to reduce risk of toxing even when exposed to very high PPO2s,

What about OTUs over multiple days?

Gobfish1 · 13th February 2008, 06:46

Quote: (Originally Posted by Gilles)

My sincere apologies to those who feel I polluted this thread!

Ha Ha .. tuff shit Gilles

it was a 50/50 split which one of us would got the kick in the bollox ...

no need to apologies looks like you did me a good turn

,,

ps good morning Mike ,, good post ,,, by the way ,,, you're a bad boy sleeping on deck with out your underwear ,, have you a photo ...

(edit that ) should read i hope you ant going to post a photo

***EBT*** · 13th February 2008, 09:27

Mike,

Quote: (Originally Posted by Drmike)

High inspired ppHe and high retained CO2 are contributors to O2 tox

Thats not the first time someones referred to He/Tox relationships, but I've not been able to track down any basis for it, do you have any evidence for this one (research or anecdotal).

Cheers...

ps. "someone" includes me, glad to see its not just me who has to re-evaluate beliefs

pps... Well done on the Hogarthian approach Steve, I guess you dont need to drag the closet around anymore :P

Quote: (Originally Posted by gobfish)

by the way ,,, you're a bad boy sleeping on deck with out your underwear ,, have you a photo ...

dave t · 13th February 2008, 09:42

Rich Pyle reported that he found HPNS would be more evident shallower on a rebreather than on OC. the fact that helium in high concentrations will "excite" the nervous system, will be a contributing factor to what Mike suggests

Dave

jhaaja · 13th February 2008, 10:24

Quote: (Originally Posted by EBT)

Mike,

Thats not the first time someones referred to He/Tox relationships, but I've not been able to track down any basis for it, do you have any evidence for this one (research or anecdotal).

Cheers...

ps... Well done on the Hogarthian approach Steve, I guess you dont need to drag the closet around anymore :P

Some studies around the issue have been done:
Effects of nitrogen and helium on CNS oxygen toxicity in the rat -- Arieli et al. 98 (1): 144 -- Journal of Applied Physiology

Effects of nitrogen and helium on CNS oxygen toxicity in the rat -- Arieli et al. 98 (1): 144 -- Journal of Applied Physiology

JH

Drmike · 13th February 2008, 11:48

Quote: (Originally Posted by Mixaddict)

What about OTUs over multiple days?

absolutely not bothered about that. for one thing on a big dive the last thing i want to do day before or day after it is much of a dive. on multi-dive days such as on a lob or holiday diving i never bother worry at all about cumulative otus

Richard Harris · 13th February 2008, 12:09

Hi Mike. i also was going to ask you about the high [He] and oxtox?? Where does that come from.?..any info appreciated.

Cheers
Harry

Drmike · 13th February 2008, 13:24

Quote: (Originally Posted by Richard Harris)

Hi Mike. i also was going to ask you about the high [He] and oxtox?? Where does that come from.?..any info appreciated.

Cheers
Harry

Hey Harry,

Well Ive been busy digging through my papers trying to find where this came from with no sucess - indeed quite the contrary as Ive found I have lots of referances to exactly the opposite being the case! (He as an inert gas reduces time to tox compared to N2 as inert gas!) lol. Frankly Im starting to think I was talking bollock5

re: ppHE contribution to toxing - however it doesnt change my overall position on unecessarily high ppo2s on deep dives

Damn I got something wrong!! - guess theres a 1st time for everything

13th February 2008, 05:12	#31 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 426	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Drmike) I believe its the instantaneous ppo2 and the situation at that time that is far more critical. I can imagine a circumstance where someone with a CNS of 50% toxes because they are swimming hard with high ppHe and high setpoint, where as someone with a CNS of 200% sat on deco doing nothing with same setpoint is safer. My point is I don't really worry about the CNS (as its traditionally measured) I concern myself with what my ppo2 is at a given time and given circumstance. There may well be a cumulative effect - but I suspect this is masked by the fact we are usually well into restful deco by the time the CNS creeps that high. Mike, is there any point at which you personally start to worry about the CNS cumulative time clock, or is it only your current pO2 and work load that is your concern? __________________ Randy Thornton (MixAddict) Inspiration, Evolution,Hammerhead & Sentinel CCR Instructor
(Offline)

13th February 2008, 05:23	#32 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,128	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Mixaddict) Mike, is there any point at which you personally start to worry about the CNS cumulative time clock, or is it only your current pO2 and work load that is your concern? Personally I worry much more about the latter than the former. Ive done many dives with CNS off the clock. Its hard to do anything big withouit having CNS over 200%, but on those dives (and in general when the CNS is high) I tend to keep my setpoint low where possible especially during high risk (working) parts of dive Air breaks are well proven to reduce risk of toxing even when exposed to very high PPO2s, __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 13th February 2008 at 05:28.
(Offline)

13th February 2008, 05:34	#33 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 426	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Drmike) Personally I worry much more about the latter than the former. Ive done many dives with CNS off the clock. Its hard to do anything big withouit having CNS over 200%, but on those dives (and in general when the CNS is high) I tend to keep my setpoint low where possible especially during high risk (working) parts of dive Air breaks are well proven to reduce risk of toxing even when exposed to very high PPO2s, What about OTUs over multiple days? __________________ Randy Thornton (MixAddict) Inspiration, Evolution,Hammerhead & Sentinel CCR Instructor
(Offline)

13th February 2008, 06:46	#34 (permalink)
Gobfish1 Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Join Date: Apr 2005 Location: Manchester UK Posts: 352	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Gilles) My sincere apologies to those who feel I polluted this thread! Ha Ha .. tuff shit Gilles it was a 50/50 split which one of us would got the kick in the bollox ... no need to apologies looks like you did me a good turn ,, ps good morning Mike ,, good post ,,, by the way ,,, you're a bad boy sleeping on deck with out your underwear ,, have you a photo ... (edit that ) should read i hope you ant going to post a photo __________________ Steve G Apparently not the only gay diver in the village http://drinkingliberally.org/blogs/o...nzee-glock.gif http://www.scubatunes.com/audio/vol01/mp3/HiTech.mp3 Last edited by Gobfish1 : 13th February 2008 at 07:54.
(Offline)

13th February 2008, 09:27	#35 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,855	Re: What setpoint for 100m+ diving do you use? Mike, Quote: (Originally Posted by Drmike) High inspired ppHe and high retained CO2 are contributors to O2 tox Thats not the first time someones referred to He/Tox relationships, but I've not been able to track down any basis for it, do you have any evidence for this one (research or anecdotal). Cheers... ps. "someone" includes me, glad to see its not just me who has to re-evaluate beliefs pps... Well done on the Hogarthian approach Steve, I guess you dont need to drag the closet around anymore :P Quote: (Originally Posted by gobfish) by the way ,,, you're a bad boy sleeping on deck with out your underwear ,, have you a photo ... __________________ Eagles May Soar, but weasels don't get sucked into jet engines! Rebreather World Terms of service Real diving t-shirts for real divers Last edited by EBT : 16th February 2008 at 10:17.
(Offline)

13th February 2008, 09:42	#36 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 621	Re: What setpoint for 100m+ diving do you use? Rich Pyle reported that he found HPNS would be more evident shallower on a rebreather than on OC. the fact that helium in high concentrations will "excite" the nervous system, will be a contributing factor to what Mike suggests Dave
(Online)

13th February 2008, 10:24	#37 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 867	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by EBT) Mike, Thats not the first time someones referred to He/Tox relationships, but I've not been able to track down any basis for it, do you have any evidence for this one (research or anecdotal). Cheers... ps... Well done on the Hogarthian approach Steve, I guess you dont need to drag the closet around anymore :P Some studies around the issue have been done: Effects of nitrogen and helium on CNS oxygen toxicity in the rat -- Arieli et al. 98 (1): 144 -- Journal of Applied Physiology Effects of nitrogen and helium on CNS oxygen toxicity in the rat -- Arieli et al. 98 (1): 144 -- Journal of Applied Physiology JH
(Offline)

13th February 2008, 11:48	#38 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,128	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Mixaddict) What about OTUs over multiple days? absolutely not bothered about that. for one thing on a big dive the last thing i want to do day before or day after it is much of a dive. on multi-dive days such as on a lob or holiday diving i never bother worry at all about cumulative otus __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 13th February 2008 at 11:52.
(Offline)

13th February 2008, 12:09	#39 (permalink)
Richard Harris Dr Harry Current Rebreather/s: Classic Kiss MK 15.X Other Rebreather/s: Join Date: Jul 2005 Location: Adelaide, South Australia Posts: 118	Re: What setpoint for 100m+ diving do you use? Hi Mike. i also was going to ask you about the high [He] and oxtox?? Where does that come from.?..any info appreciated. Cheers Harry __________________ "Harry" www.divedoc.net
(Offline)

13th February 2008, 13:24	#40 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,128	Re: What setpoint for 100m+ diving do you use? Quote: (Originally Posted by Richard Harris) Hi Mike. i also was going to ask you about the high [He] and oxtox?? Where does that come from.?..any info appreciated. Cheers Harry Hey Harry, Well Ive been busy digging through my papers trying to find where this came from with no sucess - indeed quite the contrary as Ive found I have lots of referances to exactly the opposite being the case! (He as an inert gas reduces time to tox compared to N2 as inert gas!) lol. Frankly Im starting to think I was talking bollock5 re: ppHE contribution to toxing - however it doesnt change my overall position on unecessarily high ppo2s on deep dives Damn I got something wrong!! - guess theres a 1st time for everything __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode