+ Reply to Thread
Page 1 of 4 1 2 3 4 LastLast
Results 1 to 10 of 35

Thread: Effect of in-water oxygen pre-breathing at different depth on decompression-induced b

  1. #1
    RBW Member gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas's Avatar
    Join Date
    Jan 2006
    Location
    Athens,Greece
    Posts
    506
    Megalodon

    RB80 Clone, CastoroC96, RGU

    Effect of in-water oxygen pre-breathing at different depth on decompression-induced b

    http://www.ncbi.nlm.nih.gov/pubmed/20185629?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsP anel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=3&log$=relatedarticles&logdbfrom=pubmed


    interesting read , and very feasible to do (breathing O2 for 20 mins before the dive) while kitting up, attaching stages, fins etc, then doing bubble check , sensor check at 6m.

  2. #2
    RBW Member nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh has much to be proud of nigelh's Avatar
    Join Date
    Mar 2005
    Posts
    1,382

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by gtzavelas  View Original Post
    http://www.ncbi.nlm.nih.gov/pubmed/20185629?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsP anel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=3&log$=relatedarticles&logdbfrom=pubmed


    interesting read , and very feasible to do (breathing O2 for 20 mins before the dive) while kitting up, attaching stages, fins etc, then doing bubble check , sensor check at 6m.
    If I decided to breath 100% O2 for 20 minutes at 12 meters before the main dive half this group would take away my rebreather, grab the VHF and call PAN-PAN-MEDICO-diver-gone-mad.

  3. #3
    RBW Member Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy has much to be proud of Dutchy's Avatar
    Join Date
    Apr 2006
    Posts
    1,064

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    It *sounds* like kicking in an open door. You lower the N2 content in the body prior to a dive.
    I'd like to see the comparison of diving with enriched air creating an identical CNS (or OTU) load and then compare results.
    Obviously for us mere mortal amateurs 100%/12m isn't an option but who knows...

  4. #4
    RebreatherWorld Sponsor tdzao has a spectacular aura about tdzao has a spectacular aura about tdzao has a spectacular aura about tdzao has a spectacular aura about tdzao has a spectacular aura about tdzao has a spectacular aura about tdzao's Avatar
    Join Date
    Sep 2006
    Location
    Vancouver, BC
    Posts
    136

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    I also had the idea of breathing O2 at the surface for a while, pre-dive, to denitrogenate and decrease decompression times. I kind of thought it was obvious, but since people didn't do it, I figured it must be either impractical or ineffective. Now reading this study, maybe it could be worthwhile, especially for extreme deep dives.

    I wonder if you could plug a profile like that into V-Planner and see how much the deco time is reduced? Technically the software should calculate the denitrogenation even of surface O2 breathing pre-dive.

    Eric Fattah
    Liquivision Products

  5. #5
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
    Join Date
    Jun 2005
    Location
    Stockholm Sweden
    Posts
    634

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by Dutchy  View Original Post
    It *sounds* like kicking in an open door. You lower the N2 content in the body prior to a dive.
    I'd like to see the comparison of diving with enriched air creating an identical CNS (or OTU) load and then compare results.
    Obviously for us mere mortal amateurs 100%/12m isn't an option but who knows...
    I agree fully.

    Quote Originally Posted by tdzao  View Original Post
    Now reading this study, maybe it could be worthwhile, especially for extreme deep dives.
    I would say the opposite, it could give some benefit for very limited decompression dives but likely gives a completely insignificant increase in safety or reduction of deco obligation for a big dive with deco in the hours range.

    After all what is it that this O2 prebreathing for a some minutes does, it simply helps by giving you a little "nitrogen loading credit", but only for comparatively fast tissues. A high pN2 gradient during the dive will easily "catch up" with this small advantage and give a much greater N2-loading within minutes. Besides extreme deep diving and N2 being the limiting offgasser deco wise, does that sound right? Of course this is just me speculating.

    Or are you takling about free diving?

    In that case I agree, although I think you might want to at least purge the lungs with a last breath of air again. Doing an extremely deep freedive with 100% oxygen in your lungs does feel rather wrong O2-toxwise...
    Last edited by jaap; 9th March 2010 at 18:02. Reason: Added some more rambling

  6. #6
    RBW Member gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas's Avatar
    Join Date
    Jan 2006
    Location
    Athens,Greece
    Posts
    506
    Megalodon

    RB80 Clone, CastoroC96, RGU

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by tdzao  View Original Post
    I also had the idea of breathing O2 at the surface for a while, pre-dive, to denitrogenate and decrease decompression times. I kind of thought it was obvious, but since people didn't do it, I figured it must be either impractical or ineffective. Now reading this study, maybe it could be worthwhile, especially for extreme deep dives.

    I wonder if you could plug a profile like that into V-Planner and see how much the deco time is reduced? Technically the software should calculate the denitrogenation even of surface O2 breathing pre-dive.

    Eric Fattah
    Liquivision Products

    I have also thought for long time its kind of obvious... so when I read the title I found it very interesting ....

    Tried Vplanner and indeed you "save" 10 mins deco (that's for my last dive (3hrs).

    My intention is to do it as an additional margin of safety , not really to shave deco...

  7. #7
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
    Join Date
    Jun 2005
    Location
    Stockholm Sweden
    Posts
    634

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by gtzavelas  View Original Post
    Tried Vplanner and indeed you "save" 10 mins deco (that's for my last dive (3hrs).

    My intention is to do it as an additional margin of safety , not really to shave deco...
    Interesting, care to share details on the gas, depth and bottom time of your simulation/dive?

    My V-planner is on a laptop that I don't have with me, but will also play with it when I get around to it.

  8. #8
    RBW Member gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas is a glorious beacon of light gtzavelas's Avatar
    Join Date
    Jan 2006
    Location
    Athens,Greece
    Posts
    506
    Megalodon

    RB80 Clone, CastoroC96, RGU

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by jaap  View Original Post
    Interesting, care to share details on the gas, depth and bottom time of your simulation/dive?

    My V-planner is on a laptop that I don't have with me, but will also play with it when I get around to it.
    Dive: 40 mins @ 66m with 15/55 @ SP 1,1 (and SP 1,3 from 30m up).
    VPM BE+3
    Total time 167 mins

    Now if you add before the dive 20mins @ at 0.01m at SP1 (100%)
    you get total time 173m - 20mins (pre breathing) = 153 or 14 mins less deco....

  9. #9
    Normal people worry me jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap is a name known to all jaap's Avatar
    Join Date
    Jun 2005
    Location
    Stockholm Sweden
    Posts
    634

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Quote Originally Posted by gtzavelas  View Original Post
    Dive: 40 mins @ 66m with 15/55 @ SP 1,1 (and SP 1,3 from 30m up).
    VPM BE+3
    Total time 167 mins

    Now if you add before the dive 20mins @ at 0.01m at SP1 (100%)
    you get total time 173m - 20mins (pre breathing) = 153 or 14 mins less deco....
    Very interesting, I'm baffled that the effect is so substantial for such a dive.

    That 20 min of offgassing N2 at gradient of 0,79 bar can give you 14 min less deco after a dive with a bottom pN2 of ~2,3 and pH2 ~4,2 for 40 min?

    Unless VPM is seriously off target with this sort of odd profiles...I know it is for some profiles, like the approach to saturation.

    Does it also give you less deco if you do the same prebreathing thing and then dive on heliox dil? If it does I think its very likely off target here.

    Definately have to play with this when I get back to my "deco"-laptop

  10. #10
    RBW Member SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL is just really nice SteveL's Avatar
    Join Date
    Nov 2005
    Location
    Sydney Australia
    Posts
    252

    Re: Effect of in-water oxygen pre-breathing at different depth on decompression-induc

    Certainly must be something to it - don't astronauts get on a bike and breathe 100% before doing a space walk?

    Inside the capsule is like doing a "higher" pressure pre breathe before going outside in a lower pressure environment. I've heard it assistis in preventing decompression sickness

    better get googling to check this out some more ...

    Steve

+ Reply to Thread
Page 1 of 4 1 2 3 4 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts