Training Improves Divers Ability to Detect Increased C02

iain-hsm · 7th November 2007, 15:31

Training Improves Divers Ability to Detect Increased C02.
From Aviation Space and Environmental Medicine Vol 74 No5 May 2003

This is a significant document and worth downloading below

Abstract:
Eynan M, Daskalovic YI, Arieli Y, Arieli R, Shupak A, Eilender E, Kerem DH.

A total of 213 Navy divers were tested for CO2 retention and the ability to detect CO2 in novice divers who were either CO2-recognition-trained subjects (TS) or untrained subjects (UTS).

Results: The minimal mean inspired Pco2 that could be detected was 4.8 ± 1.6 kPa (36 ± 12 mm Hg) in UTS and 2.9 ± 0.7 kPa (22 ± 5 mm Hg) in TS (p < 0.0001).
There were 46 TS who were found to be CO2 retainers and 19 were classified as poor detectors.

Seven subjects exhibited both traits.
During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects

Conclusions: that CO2 recognition training improves the diver’s capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity.

tibby · 7th November 2007, 15:58

Wow, very interesting.
Thanks you for posting it.
Tibby

JCdesign97 · 7th November 2007, 16:30

Very significant document, Iain - many thanks from me, as well.

***caveseeker7*** · 7th November 2007, 17:24

Thanks Iain, and blob for you.

bgpartri · 7th November 2007, 19:57

If I am doing the conversions right, they are exercising at very low levels around 4 METS. That sounds about right for typical diving.

While this information is interesting, unless someone has data to the contrary, no one can detect CO2 at high levels of exertion like swimming hard against a current. (10 METS)

I believe that you can learn to detect CO2 at low levels of exertion. I used to induce CO2 detection in students in the classroom by getting them to breath into a plastic bag while I was maintaining PPO2 manually. It was interesting to see the different ways they would describe the feeling. Of course I have no idea whether they were experiencing what I experience, but one student on a course did correctly detect and signal a CO2 hit. The scrubber was in fact flooded on examination after the event.

I think it is very useful to detect CO2 during normal diving and take early aggressive actions to handle it.

But pushing your scrubber because you think you can detect CO2 in all situations is a very different thing.

Bruce

***ScubaDadMiami*** · 7th November 2007, 20:13

Have some green for providing the great information.

***jradomski*** · 7th November 2007, 20:15

Quote: (Originally Posted by iain-hsm)

Training Improves Divers Ability to Detect Increased C02.
From Aviation Space and Environmental Medicine Vol 74 No5 May 2003

This is a significant document and worth downloading below

Abstract:
Eynan M, Daskalovic YI, Arieli Y, Arieli R, Shupak A, Eilender E, Kerem DH.

A total of 213 Navy divers were tested for CO2 retention and the ability to detect CO2 in novice divers who were either CO2-recognition-trained subjects (TS) or untrained subjects (UTS).

Results: The minimal mean inspired Pco2 that could be detected was 4.8 ± 1.6 kPa (36 ± 12 mm Hg) in UTS and 2.9 ± 0.7 kPa (22 ± 5 mm Hg) in TS (p < 0.0001).
There were 46 TS who were found to be CO2 retainers and 19 were classified as poor detectors.

Seven subjects exhibited both traits.
During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects

Conclusions: that CO2 recognition training improves the diver’s capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity.

Interesting study.. I have always felt this was the case but had no data other than personal experience to back it up. A hypercapnia excercise has been part of the ANDI Rebreather curriculum since the original classes back ~1991.. Now I can point to a study that shows its a useful excercise..

Drmike · 8th November 2007, 10:37

Quote: (Originally Posted by bgpartri)

no one can detect CO2 at high levels of exertion like swimming hard against a current. (10 METS)

This in my opinion is totaly untrue.

In my experience the symptoms of retained CO2 are the same shallow or deep mild exersion or high - its a matter of being sensitive to recogise those symtoms. We 'feel' retained CO2 on most dives where we have to swim a bit. We pull back automatically if we feel we are exerting too hard (that feeling is recognising retained CO2) I had to stop after 35mins fighting flow mainline Ginnie few months back. I was swimming my ass off against the flow non stop flat out for 35mins dragging all my stages and boris with me - but I still recognised the symptoms of rising CO2 and took action to fix it. On many wreck dives fighting current pulling down lines etc Ive had the same recognition and have taken same action to fix and continue the dive. Had strong feelings of rising CO2 during descent around 170m depth in a cave and took action to solve it (and once recovered continue my descent)

Am I the only diver who continuously listens to his body on a dive???? Im sure not.

I mean its hardly rocket science. You start to feel increasingly anxious, feel increasingly uncomfortable, increasingly stressed, maybe panicy, your RMV is increasing....these are not IMO easy symptoms to miss.....and the more times you experience them the earlier you recognise them the next time. - hence the training observation.

Quote:

But pushing your scrubber because you think you can detect CO2 in all situations is a very different thing.

I agree but we are talking about retained co2 which has nothing to do with the scrubber

bletso · 8th November 2007, 11:41

Quote: (Originally Posted by Drmike)

This in my opinion is totaly untrue.
I mean its hardly rocket science. You start to feel increasingly anxious, feel increasingly uncomfortable, increasingly stressed, maybe panicy, your RMV is increasing....these are not IMO easy symptoms to miss.....and the more times you experience them the earlier you recognise them the next time. - hence the training observation.

I agree but we are talking about retained co2 which has nothing to do with the scrubber

My obsevations dead spot on. BTW, Isn't that a response we were taught in basic open water traing. Why do so many forget or ignore it?

Dale

JCdesign97 · 8th November 2007, 12:46

Quote: (Originally Posted by iain-hsm)

Results: The minimal mean inspired Pco2 that could be detected was 4.8 ± 1.6 kPa (36 ± 12 mm Hg) in UTS and 2.9 ± 0.7 kPa (22 ± 5 mm Hg) in TS (p < 0.0001).
There were 46 TS who were found to be CO2 retainers and 19 were classified as poor detectors.

Seven subjects exhibited both traits.
During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects

Conclusions: that CO2 recognition training improves the diver’s capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity.

Stepping away from CO2 recognition for a moment (not to say that it isn't equally or more important) but Iain, is there any way for the unwashed masses of us to determine whether or not we are CO2 retainers? Short of joining the Israeli navy, of course ...

7th November 2007, 15:58	#2 (permalink)
tibby untitled Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2007 Location: Salt Lake City, UT Posts: 336	Re: Training Improves Divers Ability to Detect Increased C02 Wow, very interesting. Thanks you for posting it. Tibby __________________ Does the voice of reason change when you add helium to the mix?...hmm
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7th November 2007, 16:30	#3 (permalink)
JCdesign97 My unit can beat up yours Current Rebreather/s: Optima Other Rebreather/s: Join Date: Mar 2007 Location: PA, USA Posts: 350	Re: Training Improves Divers Ability to Detect Increased C02 Very significant document, Iain - many thanks from me, as well. __________________ Cheers, John
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7th November 2007, 17:24	#4 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,325	Re: Training Improves Divers Ability to Detect Increased C02 Thanks Iain, and blob for you. __________________ Cheers Stefan "It is still a good day if you are on the green side of the grass! Su amigo Roberto!" Sponsor Lou in Race For Life!
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7th November 2007, 19:57	#5 (permalink)
bgpartri Rebreather Zealot Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Sport Kiss Classic Kiss Titan Join Date: Apr 2005 Location: Vancouver, Canada Posts: 379	Re: Training Improves Divers Ability to Detect Increased C02 If I am doing the conversions right, they are exercising at very low levels around 4 METS. That sounds about right for typical diving. While this information is interesting, unless someone has data to the contrary, no one can detect CO2 at high levels of exertion like swimming hard against a current. (10 METS) I believe that you can learn to detect CO2 at low levels of exertion. I used to induce CO2 detection in students in the classroom by getting them to breath into a plastic bag while I was maintaining PPO2 manually. It was interesting to see the different ways they would describe the feeling. Of course I have no idea whether they were experiencing what I experience, but one student on a course did correctly detect and signal a CO2 hit. The scrubber was in fact flooded on examination after the event. I think it is very useful to detect CO2 during normal diving and take early aggressive actions to handle it. But pushing your scrubber because you think you can detect CO2 in all situations is a very different thing. Bruce __________________ http://www.rebreather.ca Good judgement comes from experience, and experience comes from bad judgement.
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7th November 2007, 20:13	#6 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 1,937	Re: Training Improves Divers Ability to Detect Increased C02 Have some green for providing the great information. __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
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7th November 2007, 20:15	#7 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,817	Re: Training Improves Divers Ability to Detect Increased C02 Quote: (Originally Posted by iain-hsm) Training Improves Divers Ability to Detect Increased C02. From Aviation Space and Environmental Medicine Vol 74 No5 May 2003 This is a significant document and worth downloading below Abstract: Eynan M, Daskalovic YI, Arieli Y, Arieli R, Shupak A, Eilender E, Kerem DH. A total of 213 Navy divers were tested for CO2 retention and the ability to detect CO2 in novice divers who were either CO2-recognition-trained subjects (TS) or untrained subjects (UTS). *Results:* The minimal mean inspired Pco2 that could be detected was 4.8 ± 1.6 kPa (36 ± 12 mm Hg) in UTS and 2.9 ± 0.7 kPa (22 ± 5 mm Hg) in TS (p < 0.0001). There were 46 TS who were found to be CO2 retainers and 19 were classified as poor detectors. Seven subjects exhibited both traits. During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects *Conclusions:* that CO2 recognition training improves the diver’s capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity. Interesting study.. I have always felt this was the case but had no data other than personal experience to back it up. A hypercapnia excercise has been part of the ANDI Rebreather curriculum since the original classes back ~1991.. Now I can point to a study that shows its a useful excercise.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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8th November 2007, 10:37	#8 (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: Training Improves Divers Ability to Detect Increased C02 Quote: (Originally Posted by bgpartri) no one can detect CO2 at high levels of exertion like swimming hard against a current. (10 METS) This in my opinion is totaly untrue. In my experience the symptoms of retained CO2 are the same shallow or deep mild exersion or high - its a matter of being sensitive to recogise those symtoms. We 'feel' retained CO2 on most dives where we have to swim a bit. We pull back automatically if we feel we are exerting too hard (that feeling is recognising retained CO2) I had to stop after 35mins fighting flow mainline Ginnie few months back. I was swimming my ass off against the flow non stop flat out for 35mins dragging all my stages and boris with me - but I still recognised the symptoms of rising CO2 and took action to fix it. On many wreck dives fighting current pulling down lines etc Ive had the same recognition and have taken same action to fix and continue the dive. Had strong feelings of rising CO2 during descent around 170m depth in a cave and took action to solve it (and once recovered continue my descent) Am I the only diver who continuously listens to his body on a dive???? Im sure not. I mean its hardly rocket science. You start to feel increasingly anxious, feel increasingly uncomfortable, increasingly stressed, maybe panicy, your RMV is increasing....these are not IMO easy symptoms to miss.....and the more times you experience them the earlier you recognise them the next time. - hence the training observation. Quote: But pushing your scrubber because you think you can detect CO2 in all situations is a very different thing. I agree but we are talking about retained co2 which has nothing to do with the scrubber __________________ 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 : 8th November 2007 at 10:51.
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8th November 2007, 11:41	#9 (permalink)
bletso An independent diver. Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: May 2006 Location: Louisville, KY, USA Posts: 221	Re: Training Improves Divers Ability to Detect Increased C02 Quote: (Originally Posted by Drmike) This in my opinion is totaly untrue. I mean its hardly rocket science. You start to feel increasingly anxious, feel increasingly uncomfortable, increasingly stressed, maybe panicy, your RMV is increasing....these are not IMO easy symptoms to miss.....and the more times you experience them the earlier you recognise them the next time. - hence the training observation. I agree but we are talking about retained co2 which has nothing to do with the scrubber My obsevations dead spot on. BTW, Isn't that a response we were taught in basic open water traing. Why do so many forget or ignore it? Dale Last edited by bletso : 8th November 2007 at 11:43.
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8th November 2007, 12:46	#10 (permalink)
JCdesign97 My unit can beat up yours Current Rebreather/s: Optima Other Rebreather/s: Join Date: Mar 2007 Location: PA, USA Posts: 350	Re: Training Improves Divers Ability to Detect Increased C02 Quote: (Originally Posted by iain-hsm) *Results:* The minimal mean inspired Pco2 that could be detected was 4.8 ± 1.6 kPa (36 ± 12 mm Hg) in UTS and 2.9 ± 0.7 kPa (22 ± 5 mm Hg) in TS (p < 0.0001). There were 46 TS who were found to be CO2 retainers and 19 were classified as poor detectors. Seven subjects exhibited both traits. During actual oxygen diving performed later by this group, the only four cases of CNS-oxygen toxicity were among those seven subjects *Conclusions:* that CO2 recognition training improves the diver’s capability to detect CO2. We suggest that a diver who is both a poor CO2 detector and a CO2 retainer will be prone to CNS-oxygen toxicity. Stepping away from CO2 recognition for a moment (not to say that it isn't equally or more important) but Iain, is there any way for the unwashed masses of us to determine whether or not we are CO2 retainers? Short of joining the Israeli navy, of course ... __________________ Cheers, John
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