Article and flowchart about OxTox Convulsion

cedricverdier · 28th April 2006, 23:20

Hi all,

After written an article about how to keep the oxygen exposure low during a deep rebreather dive, a nice discussion about how to deal with a convulsing diver took place:
http://www.rebreatherworld.com/gener...onvulsion.html

Based on this discussion and with the help of Jon Swarbrick and Cathy Riley, I just publish the following article:
http://www.rebreatherworld.com/gener...html#post45702

Feel free to use the flowchart and give me your comments to improve it.

Cheers

Tino de Rijk · 29th April 2006, 07:10

Hi, Cedric.

Remember me maybe? You were our (=my wife Rita & me) co-trainer during a intro-to-cave training in Mexico, together with Mike.

I really like your flowchart: it is clear & simple. And I fully agree with the procedure.

There was a similar sequence description somewhere else on this forum, and on top of what you describe, it also recommended at least trying to do your deep stops, in order to at least try to reduce the risk at type II (=severe) deco.

Now, I realise that adds significantly to the taskload, as a rescue of an oxtox diver is already not a trivial task, and that's an understatement.
However, IF (and I stress IF) you have a solid ascent line, either an anchor, or a pre-shot SMB, would you think making the deep stops is worth the added trouble...?

I am tempted to cautiously say "yes", but it depends. E.g., if the victim doesn't breath, it adds to his time without oxygen, and he might die due to the added time in/under the water. Then again: it might help the rescuer to avoid serious bends, and deep stops are usually short (1-2 minutes), and as such sort of manageable.

I haven't taken a position yet. What is your idea, Cedric?

I would like to use the schema though in an uopcoming textbook of the NOB on advanced Nitrox (NOB = dutch divers socieity = CMAS member; 17000 members in Holland; non-commercial). Off course using it always with full reference to the source - you.

Ciao,

Tino.

dave t · 29th April 2006, 09:02

Cedric

Whilst I agree with most of your flow chart there are a few points to consider. Having first hand experience of two o2 convulsion rescues (both sucsessfull)I feel I have some insight as to what goes on.

The diver is very likely to convulse more than once.
there needs to be some awareness of the "off-effect"
removing the diver from high o2 may not stop the convulsions, it may trigger more
It is highly likely that the diver will stop breathing
it is POSSIBLE that the heart may stop of stutter
the diver will become uncounsious for at least 30-50mins (in my experience)
some haulcinations may take place whilst in a semi concoius state
the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending
the second phase of the convulsoin is very difficult to spot.

hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!!

Dave

cedricverdier · 29th April 2006, 15:57

Quote: (Originally Posted by Tino de Rijk)

Hi, Cedric.

Remember me maybe? You were our (=my wife Rita & me) co-trainer during a intro-to-cave training in Mexico, together with Mike.

I really like your flowchart: it is clear & simple. And I fully agree with the procedure.

However, IF (and I stress IF) you have a solid ascent line, either an anchor, or a pre-shot SMB, would you think making the deep stops is worth the added trouble...?

I am tempted to cautiously say "yes", but it depends. E.g., if the victim doesn't breath, it adds to his time without oxygen, and he might die due to the added time in/under the water. Then again: it might help the rescuer to avoid serious bends, and deep stops are usually short (1-2 minutes), and as such sort of manageable.

I would like to use the schema though in an uopcoming textbook of the NOB on advanced Nitrox (NOB = dutch divers socieity = CMAS member; 17000 members in Holland; non-commercial). Off course using it always with full reference to the source - you.

Tino.

Hi Tino,

Nice to hear from you again! No problem to use the flowchart. It's designed for that!

An ascent line can help to maintain the depth and better control the buoyancy.

About the deep stop, it's a matter of personal preference.
- If the victim breathes, the rescuer has all the time he needs.
- If the victim does't breathe, time is crucial and the victim should be carried to the surface ASAP...

Cheers

cedricverdier · 29th April 2006, 16:04

Quote: (Originally Posted by dave t)

Cedric
The diver is very likely to convulse more than once.
there needs to be some awareness of the "off-effect"
removing the diver from high o2 may not stop the convulsions, it may trigger more
It is highly likely that the diver will stop breathing
it is POSSIBLE that the heart may stop of stutter
the diver will become uncounsious for at least 30-50mins (in my experience)
some haulcinations may take place whilst in a semi concoius state
the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending
the second phase of the convulsoin is very difficult to spot.

hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!!

Dave

Hi Dave,

Your first-hand experience is highly valuable. I guess everything is also a matter of circumstances. For a deep trimix dive with a "heavy" decompression requirement, I personaly would prefer to take my time to ascend - if the victim is breathing. If the victim doesn't breathe, I fully agree with you and will bring the victim to the surface ASAP.

Quote: (Originally Posted by dave t)

the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending
the second phase of the convulsoin is very difficult to spot.

hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!!

Dave

As you mentionned, a second convulsion may occur and would be difficult to spot.But it also can happen during a fast ascent... So what is the solution?

Cheers

dave t · 29th April 2006, 16:58

I am not sure there is any one solution, you have to do what you think is best on the day and under the circumstances. You as a rescuer put yourself in grave danger, when I did my rescue I blew off 30 mins of deco, I didnt even think about it until I hit the surface! The other rescue, there was no deco obligation for the vitim or rescueing diver.

Cedric well done for your article and well done for bringing this subject into perspective, Its very important to make people realise that this kind of rescue has a VERY likely bad outcome and o2 convulsions in them selves are an extreme hazard not something one will "just recover from in a few moments"

I think it was Genesis who said "we should concentrate on making sure the o2 hit doesnt happen in the first place" (or words to that effect)

Dave

Sutty · 29th April 2006, 18:03

On the whole I like the flowchart, you have obviously put a lot of thought into it.

I still have a problem following the "mouthpiece out" side of the chart - having sealed the mouth, ascended punching out gas, if the convulsion subsides you are then asking for an assessment whether the victim is breathing, but you are sealing the mouth, expelled most of the lung content, and no reg is in place, so the victim can't breathe, and you will always go to the "ascend direct to surface" pathway, in which case you could simplify the chart.

However I would suggest that if the convulsion subsides it would be reasonable to continues to ascend (so lung gas is expanding and flooding the airway is less likely) and make 1 attempt to insert a reg at that stage before entering the 2nd half of the chart. This gives you a chance of entering the "victim is breathing" pathway which is likely to have the best chance of survival.

Punching out gas every 10m may be excessive - if the victim has a reasonably high FO2 in the lungs they at least have some O2 "reserve" to delay the onset of hypoxia - it would be a shame to remove all of this. I'd suggest expelling gas initially and then each time you halve the depth until 5m, this correlates better with the gas expansion in the lungs.

With seizures on land (epileptic, metabolic, head trauma, etc - I have no experience of O2 seizure) many patients can be very confused, agitated or aggressive as consciousness returns. So a breathing victim still doesn't mean you neccesarily have lots of time as an agitated victim may pull out a mouthpiece or reg and mask and tragically drown just as they are recovering.

Neil

P.S. 2nd box down on left has a typo "moutpiece" instead of "mouthpiece"

cedricverdier · 30th April 2006, 05:44

Quote: (Originally Posted by Sutty)

Punching out gas every 10m may be excessive - if the victim has a reasonably high FO2 in the lungs they at least have some O2 "reserve" to delay the onset of hypoxia - it would be a shame to remove all of this. I'd suggest expelling gas initially and then each time you halve the depth until 5m, this correlates better with the gas expansion in the lungs.

Neil

Hi Neil,

Thanks for the comments.

"Every 10m" is to simplify the procedures as much as possible. For some people it's too often, for some others not often enough.
Expelling gas each time you halve the depth is maybe slightly too complex for a highly stressed rescuer who has to remember and perform everything...

Cheers

Drmike · 30th April 2006, 07:05

None of the research Ive found suggests a toxing patient doesnt start breathing again afterwards. Many here suggest otherwise. Can I ask Sutty or any of the other learned fellows here for their take on this.

Seams to me if breathing starts automatically in all or even in just the majority of cases then the use of a ffm is clearly beneficial. With the airway protected there is no need to ascend imediately there is no need to ascend during convulsion phase and risk lung injury and deep stops, possibly more stops, can be completed.

Im sure bringing up an unresponsive or possibly agressive/confused diver up will be difficult - but at least a ffm gives you time to do so.

The OC diver that saw fred convulsing couldnt stop fred from drowning and couldnt get him to take an OC reg. I cant help but think the outcome could have been very different had he been able to just turn a BOV on a ffm, wait for the convulsion to end and then begin ascending.

With or without a ffm extending the kneck would aid in keeping the airway open during ascent

Sutty · 30th April 2006, 08:28

Cedric, I understand that you are trying to keep it simple. My concern is that over-zealous "punching out" of gas may drown a victim who might have made it otherwise. How about only expelling gas if there isn't significant bubbling from mouth or mask on ascent (if there is then victims airway is at least partially open), if little/no bubbling then expel gas each time you have to dump air from your wing - keeps it easy and matches the physical volume changes.

Mike, unless there is something special about O2 convulsions compared to "ordinary" seizures I can't see why the victim would not re-start breathing (may be a pause), or at least attempting to. Whether they can breathe depends on whether the airway is open of course, and whether they have anything to breathe from.

One advantage of some FFMs could be that the victim could breathe through the nose, the nasal airway is easier to keep open than the oral one (ironically the oral airway may be easier to keep open if some form of mouthpiece is in the mouth). This is also why I would not remove a mask to hold the nose closed, you'll have to let go at some point and there's not too much water in a mask.

28th April 2006, 23:20	#1 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 488	Article and flowchart about OxTox Convulsion Hi all, After written an article about how to keep the oxygen exposure low during a deep rebreather dive, a nice discussion about how to deal with a convulsing diver took place: http://www.rebreatherworld.com/gener...onvulsion.html Based on this discussion and with the help of Jon Swarbrick and Cathy Riley, I just publish the following article: http://www.rebreatherworld.com/gener...html#post45702 Feel free to use the flowchart and give me your comments to improve it. Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
(Offline)

29th April 2006, 07:10	#2 (permalink)
Tino de Rijk Old, maybe one day wise Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Evolution Join Date: Mar 2006 Location: Amsterdam Posts: 309	Re: Article and flowchart about OxTox Convulsion Hi, Cedric. Remember me maybe? You were our (=my wife Rita & me) co-trainer during a intro-to-cave training in Mexico, together with Mike. I really like your flowchart: it is clear & simple. And I fully agree with the procedure. There was a similar sequence description somewhere else on this forum, and on top of what you describe, it also recommended at least trying to do your deep stops, in order to at least try to reduce the risk at type II (=severe) deco. Now, I realise that adds significantly to the taskload, as a rescue of an oxtox diver is already not a trivial task, and that's an understatement. However, IF (and I stress IF) you have a solid ascent line, either an anchor, or a pre-shot SMB, would you think making the deep stops is worth the added trouble...? I am tempted to cautiously say "yes", but it depends. E.g., if the victim doesn't breath, it adds to his time without oxygen, and he might die due to the added time in/under the water. Then again: it might help the rescuer to avoid serious bends, and deep stops are usually short (1-2 minutes), and as such sort of manageable. I haven't taken a position yet. What is your idea, Cedric? I would like to use the schema though in an uopcoming textbook of the NOB on advanced Nitrox (NOB = dutch divers socieity = CMAS member; 17000 members in Holland; non-commercial). Off course using it always with full reference to the source - you. Ciao, Tino.
(Online)

29th April 2006, 09:02	#3 (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: Article and flowchart about OxTox Convulsion Cedric Whilst I agree with most of your flow chart there are a few points to consider. Having first hand experience of two o2 convulsion rescues (both sucsessfull)I feel I have some insight as to what goes on. The diver is very likely to convulse more than once. there needs to be some awareness of the "off-effect" removing the diver from high o2 may not stop the convulsions, it may trigger more It is highly likely that the diver will stop breathing it is POSSIBLE that the heart may stop of stutter the diver will become uncounsious for at least 30-50mins (in my experience) some haulcinations may take place whilst in a semi concoius state the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending the second phase of the convulsoin is very difficult to spot. hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!! Dave
(Offline)

29th April 2006, 15:57	#4 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 488	Re: Article and flowchart about OxTox Convulsion Quote: (Originally Posted by Tino de Rijk) Hi, Cedric. Remember me maybe? You were our (=my wife Rita & me) co-trainer during a intro-to-cave training in Mexico, together with Mike. I really like your flowchart: it is clear & simple. And I fully agree with the procedure. However, IF (and I stress IF) you have a solid ascent line, either an anchor, or a pre-shot SMB, would you think making the deep stops is worth the added trouble...? I am tempted to cautiously say "yes", but it depends. E.g., if the victim doesn't breath, it adds to his time without oxygen, and he might die due to the added time in/under the water. Then again: it might help the rescuer to avoid serious bends, and deep stops are usually short (1-2 minutes), and as such sort of manageable. I would like to use the schema though in an uopcoming textbook of the NOB on advanced Nitrox (NOB = dutch divers socieity = CMAS member; 17000 members in Holland; non-commercial). Off course using it always with full reference to the source - you. Tino. Hi Tino, Nice to hear from you again! No problem to use the flowchart. It's designed for that! An ascent line can help to maintain the depth and better control the buoyancy. About the deep stop, it's a matter of personal preference. - If the victim breathes, the rescuer has all the time he needs. - If the victim does't breathe, time is crucial and the victim should be carried to the surface ASAP... Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
(Offline)

29th April 2006, 16:04	#5 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 488	Re: Article and flowchart about OxTox Convulsion Quote: (Originally Posted by dave t) Cedric The diver is very likely to convulse more than once. there needs to be some awareness of the "off-effect" removing the diver from high o2 may not stop the convulsions, it may trigger more It is highly likely that the diver will stop breathing it is POSSIBLE that the heart may stop of stutter the diver will become uncounsious for at least 30-50mins (in my experience) some haulcinations may take place whilst in a semi concoius state the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending the second phase of the convulsoin is very difficult to spot. hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!! Dave Hi Dave, Your first-hand experience is highly valuable. I guess everything is also a matter of circumstances. For a deep trimix dive with a "heavy" decompression requirement, I personaly would prefer to take my time to ascend - if the victim is breathing. If the victim doesn't breathe, I fully agree with you and will bring the victim to the surface ASAP. Quote: (Originally Posted by dave t) the risk of embolism is VERY high especially if the diver convulses a second (or third time whilst ascending the second phase of the convulsoin is very difficult to spot. hope this helps. my opinion is you should get the victim to the surface ASAP you can unbend a diver but you cant undead one!! Dave As you mentionned, a second convulsion may occur and would be difficult to spot.But it also can happen during a fast ascent... So what is the solution? Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
(Offline)

29th April 2006, 16:58	#6 (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: Article and flowchart about OxTox Convulsion I am not sure there is any one solution, you have to do what you think is best on the day and under the circumstances. You as a rescuer put yourself in grave danger, when I did my rescue I blew off 30 mins of deco, I didnt even think about it until I hit the surface! The other rescue, there was no deco obligation for the vitim or rescueing diver. Cedric well done for your article and well done for bringing this subject into perspective, Its very important to make people realise that this kind of rescue has a VERY likely bad outcome and o2 convulsions in them selves are an extreme hazard not something one will "just recover from in a few moments" I think it was Genesis who said "we should concentrate on making sure the o2 hit doesnt happen in the first place" (or words to that effect) Dave
(Offline)

29th April 2006, 18:03	#7 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 775	Re: Article and flowchart about OxTox Convulsion On the whole I like the flowchart, you have obviously put a lot of thought into it. I still have a problem following the "mouthpiece out" side of the chart - having sealed the mouth, ascended punching out gas, if the convulsion subsides you are then asking for an assessment whether the victim is breathing, but you are sealing the mouth, expelled most of the lung content, and no reg is in place, so the victim can't breathe, and you will always go to the "ascend direct to surface" pathway, in which case you could simplify the chart. However I would suggest that if the convulsion subsides it would be reasonable to continues to ascend (so lung gas is expanding and flooding the airway is less likely) and make 1 attempt to insert a reg at that stage before entering the 2nd half of the chart. This gives you a chance of entering the "victim is breathing" pathway which is likely to have the best chance of survival. Punching out gas every 10m may be excessive - if the victim has a reasonably high FO2 in the lungs they at least have some O2 "reserve" to delay the onset of hypoxia - it would be a shame to remove all of this. I'd suggest expelling gas initially and then each time you halve the depth until 5m, this correlates better with the gas expansion in the lungs. With seizures on land (epileptic, metabolic, head trauma, etc - I have no experience of O2 seizure) many patients can be very confused, agitated or aggressive as consciousness returns. So a breathing victim still doesn't mean you neccesarily have lots of time as an agitated victim may pull out a mouthpiece or reg and mask and tragically drown just as they are recovering. Neil P.S. 2nd box down on left has a typo "moutpiece" instead of "mouthpiece" __________________ Never forget that life is a finite resource.
(Offline)

30th April 2006, 05:44	#8 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 488	Re: Article and flowchart about OxTox Convulsion Quote: (Originally Posted by Sutty) Punching out gas every 10m may be excessive - if the victim has a reasonably high FO2 in the lungs they at least have some O2 "reserve" to delay the onset of hypoxia - it would be a shame to remove all of this. I'd suggest expelling gas initially and then each time you halve the depth until 5m, this correlates better with the gas expansion in the lungs. Neil Hi Neil, Thanks for the comments. "Every 10m" is to simplify the procedures as much as possible. For some people it's too often, for some others not often enough. Expelling gas each time you halve the depth is maybe slightly too complex for a highly stressed rescuer who has to remember and perform everything... Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
(Offline)

30th April 2006, 07:05	#9 (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: Article and flowchart about OxTox Convulsion None of the research Ive found suggests a toxing patient doesnt start breathing again afterwards. Many here suggest otherwise. Can I ask Sutty or any of the other learned fellows here for their take on this. Seams to me if breathing starts automatically in all or even in just the majority of cases then the use of a ffm is clearly beneficial. With the airway protected there is no need to ascend imediately there is no need to ascend during convulsion phase and risk lung injury and deep stops, possibly more stops, can be completed. Im sure bringing up an unresponsive or possibly agressive/confused diver up will be difficult - but at least a ffm gives you time to do so. The OC diver that saw fred convulsing couldnt stop fred from drowning and couldnt get him to take an OC reg. I cant help but think the outcome could have been very different had he been able to just turn a BOV on a ffm, wait for the convulsion to end and then begin ascending. With or without a ffm extending the kneck would aid in keeping the airway open during ascent __________________ 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
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30th April 2006, 08:28	#10 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 775	Re: Article and flowchart about OxTox Convulsion Cedric, I understand that you are trying to keep it simple. My concern is that over-zealous "punching out" of gas may drown a victim who might have made it otherwise. How about only expelling gas if there isn't significant bubbling from mouth or mask on ascent (if there is then victims airway is at least partially open), if little/no bubbling then expel gas each time you have to dump air from your wing - keeps it easy and matches the physical volume changes. Mike, unless there is something special about O2 convulsions compared to "ordinary" seizures I can't see why the victim would not re-start breathing (may be a pause), or at least attempting to. Whether they can breathe depends on whether the airway is open of course, and whether they have anything to breathe from. One advantage of some FFMs could be that the victim could breathe through the nose, the nasal airway is easier to keep open than the oral one (ironically the oral airway may be easier to keep open if some form of mouthpiece is in the mouth). This is also why I would not remove a mask to hold the nose closed, you'll have to let go at some point and there's not too much water in a mask. __________________ Never forget that life is a finite resource. Last edited by Sutty : 30th April 2006 at 08:30.
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