syncope ??

**Dave Sutton** · 11th August 2007, 07:50

[quote=AD_ward9;130623]IAlso, put your head in cold water for the test: it extends your breath holding range by slowing your metabolism./quote]

By triggering the mammalian diving reflex, just a note for those who don't know it exists. We exploit it deliberately by removing mask and breathing wet-face in the water for a few minutes before freediving... it's *amazing* what happens.

Alex, thanks for the good stuff. Green coming.

Dave

**Dave Sutton** · 11th August 2007, 07:53

Quote: (Originally Posted by tibby)

I have no idea if this is a valid test but I've got nothing more interesting to do at the moment. How's that for anecdotal data?
Tibby

It's as valid as any, thanks! I'll replicate here in the pool this afternoon. It's an interesting avenue of experimentation.

What Alex mentions (instantly lowering PP02 on exhale) has cost more than one freediver his life.

Best,

Dave

jasondrake · 11th August 2007, 08:34

Quote: (Originally Posted by AD_ward9)

Jason take note: your PPO2 in post 36 was 0.42 when you started your experiment, but what you did was hazardous because you hit the surface with a PPO2 of around 0.09 - with falling PPO2 you do not know how close you are to simply passing out. Rebreathers can be one breath from death machines. Read CeeBee's "Always Know your PPO2 Thread" before you go diving again - it may well save your life. The attachment to post 64 is the consequence so divers might want to think more carefully before new experiments, and the events are on the rest of the thread. CeeBee's husband died last year died doing effectively, just what you did Jason. Just like learning to drive gives a person a weighty responsibility, so does learning to dive.Alex

Thanks for your concerns but they are unfounded. While I imagine my expertise falls far short of yours in this area, I think my 15 years of commercial, trimix and freediving experience qualify me to hold my breath under water for a couple of minutes. The pp02 in my blood when I hit the surface is dependant on more variables than you or anyone else can calculate, which is why I did what freedivers have done for maybe 10,000 years and used my instincts.

AD_ward9 · 11th August 2007, 09:55

Quote: (Originally Posted by jasondrake)

Thanks for your concerns but they are unfounded. While I imagine my expertise falls far short of yours in this area, I think my 15 years of commercial, trimix and freediving experience qualify me to hold my breath under water for a couple of minutes. The pp02 in my blood when I hit the surface is dependant on more variables than you or anyone else can calculate, which is why I did what freedivers have done for maybe 10,000 years and used my instincts.

Nothing personal in my comment, except that I wanted to make the point strongly in the hope that other divers do not repeat your experiment. As you say there are a lot of parameters involved, but your PPO2 was in the range 0.085 to 0.12 when you hit the surface. Where exactly neither you or I know.

Incidentally, it took you more than 3 seconds to go from 10m to the surface. If you drop your weight belt and inflate your BCD at 100m, you will hit 100m/min ascent rate (taken from a fatal accident post mortem where the diver did just that: see Bennett and Elliott's Physiologic and Medicine of Diving, 5th Ed), and it takes a little bit to accelerate and get to terminal velocity. No pun intended. So probably about 9s from 10m to the surface. Shows how risky underwater experiments are unless we sit down and plan them carefully before hand, just like a stuntman would plan any stunt.

I would also point out the diver I mentioned who passed away in very similar circumstances, except he did not hold his breath deliberately, was also a very experienced diver holding an Advanced Trimix Cert and widely regarded as a careful diver.

Anyhow, again there is no personal issue here just that what you did worked for you that time, but if other divers try and copy some will not make it back.

Alex

Silent · 11th August 2007, 10:00

I'm in the camp that believes that if you exhale on the ascent you'll pass out and probably die.

BUT, in the interim while the various people with the brain power try to prove their respective viewpoints, shouldn't the MOST IMPORTANT message that can be given is "If in doubt bailout!" (to a normoxic mix of course)

At least that way there are no physiological variables and you are assured of getting to the surface alive.
It's the same as PO2 exposure, you may get away with high exposure on some occassions but you may not when it really matters.

Why take the risk?

That's why I always carry bailout.

**Dave Sutton** · 11th August 2007, 11:12

All good stuff.

Alex, this is an interesting area, and ought to bring forth the following: A person who wishes to master his/her knowlage of this area needs to understand the three different reference systems that are possible: Freedivers physics, F02 referenced physiology (open circuit SCUBA), and PP02 referenced physiology (CCR). If a diver can express himself in these three "languages" then he's mastered the art.

Comments?

Dave

CeeBee · 11th August 2007, 15:09

I don't know much, but I know this thread scares the hell out of me. Read the link posted by Alex...and then go away and brush up on some basics or sort out some training. If still convinced that you have it right despite what you've read here, then please feel free to use my Skype or Msn contacts...I'll willingly tell you what its like to live with the consequences.

Christine

brandonmc · 11th August 2007, 15:57

Quote: (Originally Posted by Dave Sutton)

All good stuff.

Alex, this is an interesting area, and ought to bring forth the following: A person who wishes to master his/her knowlage of this area needs to understand the three different reference systems that are possible: Freedivers physics, F02 referenced physiology (open circuit SCUBA), and PP02 referenced physiology (CCR). If a diver can express himself in these three "languages" then he's mastered the art.

Comments?

Dave

I'm not diving a rebreather yet but I just wanted to thank you guys for this discussion. Definitely pointed out some things I hadnt consider but now seem disturbingly obvious in hindsight.

Dave (or others),

In the spirit of your post can you recommend any good references for further education?

Thanks,
Brandon

Depth-junkie · 11th August 2007, 18:50

5 pages of bollocks, if you were at 10m with a PP02 of 0.21 pump some o2 into the loop and get it to rise to a decent level and take a few good breaths before going up, and flood the loop at 6m with 02 whilst still pumping 02 into the loop all the way up.

Or if no 02 were available, go on your OC of air and give it a good few breaths to get your lungs up to the current PP02 of the OC air before accendng.

Stop being knob jockeys, with stupid what if's. Common sense peeps

ATB
Gareth

**Dave Sutton** · 11th August 2007, 20:21

Quote: (Originally Posted by brandonmc)

disturbingly obvious in hindsight.

Dave (or others),

In the spirit of your post can you recommend any good references for further education?

Freedive, by Terry Mass, for that area of discussion. Dunno the others, all of my stuff is old handwritten college notes and physiology texts. Alex?

Dave

11th August 2007, 07:50	#41 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: syncope ?? [quote=AD_ward9;130623]IAlso, put your head in cold water for the test: it extends your breath holding range by slowing your metabolism./quote] By triggering the mammalian diving reflex, just a note for those who don't know it exists. We exploit it deliberately by removing mask and breathing wet-face in the water for a few minutes before freediving... it's amazing what happens. Alex, thanks for the good stuff. Green coming. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Online)

11th August 2007, 07:53	#42 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: syncope ?? Quote: (Originally Posted by tibby) I have no idea if this is a valid test but I've got nothing more interesting to do at the moment. How's that for anecdotal data? Tibby It's as valid as any, thanks! I'll replicate here in the pool this afternoon. It's an interesting avenue of experimentation. What Alex mentions (instantly lowering PP02 on exhale) has cost more than one freediver his life. Best, Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Online)

11th August 2007, 08:34	#43 (permalink)
jasondrake New Member Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Nov 2005 Location: Completely homeless Posts: 76	Re: syncope ?? Quote: (Originally Posted by AD_ward9) Jason take note: your PPO2 in post 36 was 0.42 when you started your experiment, but what you did was hazardous because you hit the surface with a PPO2 of around 0.09 - with falling PPO2 you do not know how close you are to simply passing out. Rebreathers can be one breath from death machines. Read CeeBee's "Always Know your PPO2 Thread" before you go diving again - it may well save your life. The attachment to post 64 is the consequence so divers might want to think more carefully before new experiments, and the events are on the rest of the thread. CeeBee's husband died last year died doing effectively, just what you did Jason. Just like learning to drive gives a person a weighty responsibility, so does learning to dive.Alex Thanks for your concerns but they are unfounded. While I imagine my expertise falls far short of yours in this area, I think my 15 years of commercial, trimix and freediving experience qualify me to hold my breath under water for a couple of minutes. The pp02 in my blood when I hit the surface is dependant on more variables than you or anyone else can calculate, which is why I did what freedivers have done for maybe 10,000 years and used my instincts.
(Offline)

11th August 2007, 09:55	#44 (permalink)
AD_ward9 So much more to learn Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jun 2005 Location: Scotland Posts: 1,868	Re: syncope ?? Quote: (Originally Posted by jasondrake) Thanks for your concerns but they are unfounded. While I imagine my expertise falls far short of yours in this area, I think my 15 years of commercial, trimix and freediving experience qualify me to hold my breath under water for a couple of minutes. The pp02 in my blood when I hit the surface is dependant on more variables than you or anyone else can calculate, which is why I did what freedivers have done for maybe 10,000 years and used my instincts. Nothing personal in my comment, except that I wanted to make the point strongly in the hope that other divers do not repeat your experiment. As you say there are a lot of parameters involved, but your PPO2 was in the range 0.085 to 0.12 when you hit the surface. Where exactly neither you or I know. Incidentally, it took you more than 3 seconds to go from 10m to the surface. If you drop your weight belt and inflate your BCD at 100m, you will hit 100m/min ascent rate (taken from a fatal accident post mortem where the diver did just that: see Bennett and Elliott's Physiologic and Medicine of Diving, 5th Ed), and it takes a little bit to accelerate and get to terminal velocity. No pun intended. So probably about 9s from 10m to the surface. Shows how risky underwater experiments are unless we sit down and plan them carefully before hand, just like a stuntman would plan any stunt. I would also point out the diver I mentioned who passed away in very similar circumstances, except he did not hold his breath deliberately, was also a very experienced diver holding an Advanced Trimix Cert and widely regarded as a careful diver. Anyhow, again there is no personal issue here just that what you did worked for you that time, but if other divers try and copy some will not make it back. Alex Last edited by AD_ward9 : 11th August 2007 at 14:37.
(Offline)

11th August 2007, 10:00	#45 (permalink)
Silent Staying Silent! Mostly... Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Ouroboros Other CCR Join Date: Jun 2005 Location: Northants, UK Posts: 383	Re: syncope ?? I'm in the camp that believes that if you exhale on the ascent you'll pass out and probably die. BUT, in the interim while the various people with the brain power try to prove their respective viewpoints, shouldn't the MOST IMPORTANT message that can be given is "If in doubt bailout!" (to a normoxic mix of course) At least that way there are no physiological variables and you are assured of getting to the surface alive. It's the same as PO2 exposure, you may get away with high exposure on some occassions but you may not when it really matters. Why take the risk? That's why I always carry bailout.
(Offline)

11th August 2007, 11:12	#46 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: syncope ?? All good stuff. Alex, this is an interesting area, and ought to bring forth the following: A person who wishes to master his/her knowlage of this area needs to understand the three different reference systems that are possible: Freedivers physics, F02 referenced physiology (open circuit SCUBA), and PP02 referenced physiology (CCR). If a diver can express himself in these three "languages" then he's mastered the art. Comments? Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Online)

11th August 2007, 15:09	#47 (permalink)
CeeBee Found pills and ate them. Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Sep 2006 Location: Liverpool Posts: 1,019	Re: syncope ?? I don't know much, but I know this thread scares the hell out of me. Read the link posted by Alex...and then go away and brush up on some basics or sort out some training. If still convinced that you have it right despite what you've read here, then please feel free to use my Skype or Msn contacts...I'll willingly tell you what its like to live with the consequences. Christine __________________ "In Ceebs We Trust. All others pay cash." Denz 1973-2007 King of the One-Liners www.justgiving.com/markginsberg1
(Offline)

11th August 2007, 15:57	#48 (permalink)
brandonmc Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Oct 2006 Location: Maryland Posts: 102	Re: syncope ?? Quote: (Originally Posted by Dave Sutton) All good stuff. Alex, this is an interesting area, and ought to bring forth the following: A person who wishes to master his/her knowlage of this area needs to understand the three different reference systems that are possible: Freedivers physics, F02 referenced physiology (open circuit SCUBA), and PP02 referenced physiology (CCR). If a diver can express himself in these three "languages" then he's mastered the art. Comments? Dave I'm not diving a rebreather yet but I just wanted to thank you guys for this discussion. Definitely pointed out some things I hadnt consider but now seem disturbingly obvious in hindsight. Dave (or others), In the spirit of your post can you recommend any good references for further education? Thanks, Brandon __________________ http://www.downtoolong.com/
(Online)

11th August 2007, 18:50	#49 (permalink)
Depth-junkie 10/52 Psycho Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Aug 2005 Location: Wrexham Posts: 298	Re: syncope ?? 5 pages of bollocks, if you were at 10m with a PP02 of 0.21 pump some o2 into the loop and get it to rise to a decent level and take a few good breaths before going up, and flood the loop at 6m with 02 whilst still pumping 02 into the loop all the way up. Or if no 02 were available, go on your OC of air and give it a good few breaths to get your lungs up to the current PP02 of the OC air before accendng. Stop being knob jockeys, with stupid what if's. Common sense peeps ATB Gareth
(Offline)

11th August 2007, 20:21	#50 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: syncope ?? Quote: (Originally Posted by brandonmc) disturbingly obvious in hindsight. Dave (or others), In the spirit of your post can you recommend any good references for further education? Freedive, by Terry Mass, for that area of discussion. Dunno the others, all of my stuff is old handwritten college notes and physiology texts. Alex? Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
(Online)

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