Accident in Finland
- Thread starter Igor
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Lancer4545
Member
Hi Baz, could you point out what additional failure points there are with a FFM compared to a conventional 1/2 mask?? I've been diving the same mask for years and have never had a failure.
There are many causes which can lead to a diver becoming unconscious not just a Hyperoxic breathing loop. It could be caused by a Heart Attack, Hypoxic loop or a CO2 induced CNS event where the loop PO2 is quite within an acceptable PO2 level and others. Not everyone dives a bottomless abyss and many fatalities have occurred in relatively shallow water where rescuers were able to raise the unconscious diver but were unable to revive him because they had drowned after dropping the mouthpiece.
Add to that if the victim had ingested water in his lungs and flooded the unit the majority of CCR divers don't have sufficient additional lift to raise them from the bottom.
I don't think the issue here is Self Rescue and Bolting for the surface and is simply not an option for a lot of divers who have accumulated a hefty deco commitment. Bolting would almost certainly seriously bend or possibly embolize and kill them.
As for raising a diver and have both the rescuer and the victim in an uncontrollable ascent that would depend a lot on the skill of the rescuer and each individual case. Rescuing another diver is a skill rarely practiced other than once during their initial rebreather course and very few divers take it seriously enough to keep current with this skill. If as you stated, both divers ended up in an uncontrollable ascent then the rescuer has not taken all the necessary steps before leaving the bottom to enable him to control the ascent.
I accept diving with a FFM is not for everyone as it requires a more disciplined approach to diving and is another skill set the diver needs to learn. They are not a self rescue item and were never intended to be, but in some circumstances will give the victim a much better chance of surviving had they been wearing a 1/2 mask and will make the task for the rescuer much easier than if they weren't wearing one.
There is a much better chance of reviving a diver who has not ingested water than one who has been lying on the bottom with his lungs full of water.
Regards,
Lance
Ben Field
All IMVHO obviously...
I think the answer to your problem is in the question there.
Lastly I take exception to your suggestion "most" CCR is solo, in my experience (In the UK) there is little solo diving.
I know people do dive solo, I've done it myself but IMO its less fun and much less safe, another hand (or pair of) can solve almost all problems underwater that you can't on your own- plus, who else's bailout gas will you steal to fill your lift bag when bagging swag otherwise? Only a fool would use their own!
GLOC
real name: Gareth Lock!
Lastly I take exception to your suggestion "most" CCR is solo, in my experience (In the UK) there is little solo diving.
I know people do dive solo, I've done it myself but IMO its less fun and much less safe, another hand (or pair of) can solve almost all problems underwater that you can't on your own- plus, who else's bailout gas will you steal to fill your lift bag when bagging swag otherwise? Only a fool would use their own!
Solo, same ocean or team diving?
The problem is we don't have the stats to back up either side of the argument. However, I personally think that a large number of fatalities could be prevented if divers stayed together.
At least one from last year would have been, and I have a video of a very close call which would have been prevented if the diver hadn't been solo diving. When I reviewed the video with the diver I commented about solo diving when their buddy shot off down the shot leaving the diver around 10m on their own to resolve an issue, their reply was 'that is how we dive'. The issue initiated at 68m, they bailed (probably C2 narcosis), ascended, had real issues, then nearly switched to 50% at 34-38m after they thought their bottom/bailout stage was empty. (It wasn't and the only reason they didn't switch is because the 50% was off).
One of the consensus pieces from RF3.0 was the use of mouthpiece retaining straps (gag-straps) and also to look at the merits and negatives of using FFMs in sport CCR diving (not Mil or Commercial) - do the benefits outweigh the negatives which needs to include initial cost and maintenance. If money wasn't an option, I am sure that many things would be different.
Regards
Ben Field
All IMVHO obviously...
IMO its Buddy diving if you are in regular touch and one diver can reach the other when summoned in no more than a single held breath, anything else is Solo.
Team and Same ocean is b*ll*x said by Solo divers justifiying themselves to those who discourage it
I think the price of FFM is a big barrier, I know a few people who're interested. I understand economies of scale obviously but find it hard to rationalise a mask at £20 and FFM at £1000 (by the time you've sorted adapters and additional regs etc)
A Gag-strap has got to be worth everyone (here) trying given the cost and potential IMO
Simon Mitchell
Well-Known Member
Gidday Baz,
I think that is a fair stance to take, as is Lance's advocacy. You are both coming at a complex issue from completely opposite perspectives: a skeptical non-user vs an enthusiastic and highly experienced user respectively.
This question came up during discussion of the recent accidents at Oztek. It is probably not as big a problem as it intuitively seems it should be. Seizures will terminate even if the diver continues to be exposed to the hyperoxic PO2 that initiated them, and they won't necessarily reoccur (not immediately anyway) if the diver resumes breathing hyperoxic gas. This is seen in monoplace chamber seizures where there is no easy option to quickly change the diver to a lower PO2 breathing gas. Usually the operators wait until the seizure terminates, and then decompress the chamber (which takes time) once the patient starts breathing after the seizure.
As I see it, there are several key issues that need to be resolved in this debate (and both were raised at RF3).
The first is whether or not a FFM really does reliably protect the airway in an unconscious diver, including one who has seizures (with the associated twitching and facial contortions etc). If it does, then this makes a strong safety case for their use because preventing aspiration of water increases the chance of survival. It might seem intuitively obvious that it would, but I don't think this issue has been "formally" addressed (which is why it was "returned to the community" as a research question at RF3). It would be difficult to approach this issue experimentally for obvious reasons, and probably the only way we can dig into it would be to compile a series of known cases of unconsciousness in divers wearing FFMs and try to discern whether the airway was protected. I know of one where it was not, but in that case the accident was caused by unfamiliarity with the FFM itself.... and that leads to the second key issue:
The second is whether the principal potential safety benefit of FFMs (airway protection in an unconscious diver) is offset by an increase in risk accruing from various things like the complexity of the devices, failure points, and risk during training and acquisition of experience with FFMs. Obviously, at least some of these issues could be mitigated by thorough training.
At some point it was my intention to ask the UHMS Diving Committee members to start trying to accumulate case histories and outcomes for divers who have been unconscious with an FFM. The tricky bit will be identifying any effect of "reporting bias" eg divers who survive are more likely to talk about their story whereas divers who don't make it obviously won't.
The FFM or not debate is a discussion worth having, but we need more data to inform the direction we take.
Simon M
I think that is a fair stance to take, as is Lance's advocacy. You are both coming at a complex issue from completely opposite perspectives: a skeptical non-user vs an enthusiastic and highly experienced user respectively.
This question came up during discussion of the recent accidents at Oztek. It is probably not as big a problem as it intuitively seems it should be. Seizures will terminate even if the diver continues to be exposed to the hyperoxic PO2 that initiated them, and they won't necessarily reoccur (not immediately anyway) if the diver resumes breathing hyperoxic gas. This is seen in monoplace chamber seizures where there is no easy option to quickly change the diver to a lower PO2 breathing gas. Usually the operators wait until the seizure terminates, and then decompress the chamber (which takes time) once the patient starts breathing after the seizure.
As I see it, there are several key issues that need to be resolved in this debate (and both were raised at RF3).
The first is whether or not a FFM really does reliably protect the airway in an unconscious diver, including one who has seizures (with the associated twitching and facial contortions etc). If it does, then this makes a strong safety case for their use because preventing aspiration of water increases the chance of survival. It might seem intuitively obvious that it would, but I don't think this issue has been "formally" addressed (which is why it was "returned to the community" as a research question at RF3). It would be difficult to approach this issue experimentally for obvious reasons, and probably the only way we can dig into it would be to compile a series of known cases of unconsciousness in divers wearing FFMs and try to discern whether the airway was protected. I know of one where it was not, but in that case the accident was caused by unfamiliarity with the FFM itself.... and that leads to the second key issue:
The second is whether the principal potential safety benefit of FFMs (airway protection in an unconscious diver) is offset by an increase in risk accruing from various things like the complexity of the devices, failure points, and risk during training and acquisition of experience with FFMs. Obviously, at least some of these issues could be mitigated by thorough training.
At some point it was my intention to ask the UHMS Diving Committee members to start trying to accumulate case histories and outcomes for divers who have been unconscious with an FFM. The tricky bit will be identifying any effect of "reporting bias" eg divers who survive are more likely to talk about their story whereas divers who don't make it obviously won't.
The FFM or not debate is a discussion worth having, but we need more data to inform the direction we take.
Simon M
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bazSXD
Member
Thanks Simon, all good stuff but as you said sadly inconclusive at this point. In regards to Lances points:
Failure points: ... Every single extra o-ring, hose or strap you introduce increases the risk factor.
Then you should, its called getting your config correct. Enough lift for worst case situations
Better bent than dead In the case of an incapacitating hit of whatever type the surface is the place to be. Every diver should aim for self rescue. One its only fair on your buddy and two it is a very very good practise not to rely on anyone else to resolve your stuff ups.
If anyone has actually had to raise a stricken diver for real you will know that it is not easy at all, even given the best training in the world .... remember we are talking real life here not a training exercise. It is hard to maintain control all the way when you are pumped and fighting to save some guys life.
I accept diving with a FFM is not for everyone as it requires a more disciplined approach to diving and is another skill set the diver needs to learn. They are not a self rescue item and were never intended to be, but in some circumstances will give the victim a much better chance of surviving had they been wearing a 1/2 mask and
I guess we need to agree to disagree on what is easier ... as Simon indicated its early days.The jury is still out on this one
There is a much better chance of reviving a diver who has not ingested water than one who has been lying on the bottom with his lungs full of water.
Regards,
Lance[/QUOTE]
So until we have some concrete guidelines I for one would like to see more research done here. I tend to fall on the side of bugger the rescue bit and look after yourself. If you dive with someone then do the risk analysis and make your peace with each other and your families, better one dead than two.
My two bobs worth .... regards Baz
Failure points: ... Every single extra o-ring, hose or strap you introduce increases the risk factor.
Then you should, its called getting your config correct. Enough lift for worst case situations
Better bent than dead In the case of an incapacitating hit of whatever type the surface is the place to be. Every diver should aim for self rescue. One its only fair on your buddy and two it is a very very good practise not to rely on anyone else to resolve your stuff ups.
If anyone has actually had to raise a stricken diver for real you will know that it is not easy at all, even given the best training in the world .... remember we are talking real life here not a training exercise. It is hard to maintain control all the way when you are pumped and fighting to save some guys life.
I accept diving with a FFM is not for everyone as it requires a more disciplined approach to diving and is another skill set the diver needs to learn. They are not a self rescue item and were never intended to be, but in some circumstances will give the victim a much better chance of surviving had they been wearing a 1/2 mask and
I guess we need to agree to disagree on what is easier ... as Simon indicated its early days.The jury is still out on this one
There is a much better chance of reviving a diver who has not ingested water than one who has been lying on the bottom with his lungs full of water.
Regards,
Lance[/QUOTE]
So until we have some concrete guidelines I for one would like to see more research done here. I tend to fall on the side of bugger the rescue bit and look after yourself. If you dive with someone then do the risk analysis and make your peace with each other and your families, better one dead than two.
My two bobs worth .... regards Baz
Wow, this thread has certainly taken some twists and turns. That said, it is some of the most interesting discussion I have read in a long time.
I'm curious if there is anyone on this board who has actually had a CNS hit while on a CCR FFM? If so, it would be very interesting to hear about it from their perspective, especially to hear if they were able to keep from ingesting water.
I'm curious if there is anyone on this board who has actually had a CNS hit while on a CCR FFM? If so, it would be very interesting to hear about it from their perspective, especially to hear if they were able to keep from ingesting water.
MeRodent
New Member
Also interesting to hear the same with a gag strap.
Lancer4545
Member
bazSXD
Member
For the sake of the thread I'm bowing out now, comments like those in the last post are just beyond it. I'm lost for words and trust me that doesn't happen too often, get this example ????
"Most FFMs use no more straps, o'rings or anything else than a 1/2 mask"
A FFM is not as complex as a normal mask Jesssus give us a break, no o-rings in my mask ???
A last throw way for you Lance ... snow is white, go on now argue its black.
Shame this could have lead some place good, but all too hard.
regards Baz
"Most FFMs use no more straps, o'rings or anything else than a 1/2 mask"
A FFM is not as complex as a normal mask Jesssus give us a break, no o-rings in my mask ???
A last throw way for you Lance ... snow is white, go on now argue its black.
Shame this could have lead some place good, but all too hard.
regards Baz
kwinter
PITA
I have looked high and low at my FFM/BOV. I counted exactly one extra o-ring. It is where the BOV connects to the FFM. The mask itself has no o-rings at all, and I defy you to find any. Post a photo of the o-rings in your FFM. And the BOV is exactly the same as if I use it without the FFM.
So please get over yourself.
GLOC
real name: Gareth Lock!
I am not sure how well people know each other personally, but there certainly appears to a significant amount of negative emotion in posts which then winds others up, who respond and the cycle continues.
This maybe your way of communicating but it certainly doesn't help with the community spirit.
Regards
This maybe your way of communicating but it certainly doesn't help with the community spirit.
Regards
The FFM mask is very interesting.
I bought and tried a FFM some time ago in preparation of a very big dive where I would be pushing the PO2 and would have a higher risk of oxtox.
I would definitely agree that there are some clear advantages in it and also the comfort level is much better in very long dives.
However we ended up setting up a habitat (that covers much much better the oxtox risk plus has many more advantages).
I ended up selling the FMM as i didn't like it for "every day diving"
Would be very interested however to hear of incidents of unconscious divers with FFM beeing rescued ....
I bought and tried a FFM some time ago in preparation of a very big dive where I would be pushing the PO2 and would have a higher risk of oxtox.
I would definitely agree that there are some clear advantages in it and also the comfort level is much better in very long dives.
However we ended up setting up a habitat (that covers much much better the oxtox risk plus has many more advantages).
I ended up selling the FMM as i didn't like it for "every day diving"
Would be very interested however to hear of incidents of unconscious divers with FFM beeing rescued ....
Paul Haynes
CCRX Supporter
As many of you will know from previous posts (refer to General Diving Thread), I have been a strong advocate of the use of a rebreather mouthpiece retaining strap having used one for nearly 25 years on a range of rebreathers where a full face mask is not used. I believe that when worn correctly, its use increases the likelihood of surviving a loss of consciousness event. I have witnessed a CNS oxtox event where the diver did not inhale water due to his airway being protected by a mouthpiece retaining strap, he was recovered and survived the incident without any long term detrimental effect to health or diving.
As I repeatedly state, there are no guarantees when using a retaining strap, however a rational conclusion can be made that if the airway and loop is protected wholly or partially from flooding, the likelihood of a positive outcome is increased. In contrast, what is guaranteed is that in event of loss of consciousness, if not using a retaining strap or full face mask, the next inhalation will be water and you quickly loose buoyancy as your loop and lungs flood. As a consequence, if a rescue is not immediately implemented taking you directly to the surface, your demise in less than 200 seconds is a highly probable outcome. The use of retaining strap might just buy you back that time enabling either self or buddy rescue. Why there is resistance to the use of retaining straps by many within the rebreather diving and manufacturing community is beyond me - it in no way prevents or restricts the use of an alternative source of breathing gas such as an off board bailout demand valve. However the very same type of resistance was in place 30 years ago from drivers and automobile manufacturers regarding seat belts. Thankfully those charged with the responsibility of protecting the public from unnecessary risk, implemented laws to ensure that vehicles were built with seat belts and their use by drivers on public highways became mandatory. Driving fatality figures dropped by a significant amount immediately following the implementation of these laws. A change of driving culture has now occurred such that how many of us these days would consider driving without wearing a seatbelt? It would be great to see the same change of culture within the rebreather community as I believe future lives would likely be saved.
The next level of protection up from a retaining strap is the full face mask. These however do come with their disadvantages, which for many might offset their advantages. However many hundreds of thousands of rebreather dives are safely conducted using full face masks by the world's militaries every year and their reliability and safety record is extremely high.
To conclude then, for those who do not use one, go and buy yourselves a Drager mouthpiece retaining strap and wear it correctly; that simple piece of rubber just might be the last line of self preservation that enables you one day to return home to your family. A worthy investment if ever there was one eh.
Rgds Paul
MeRodent
New Member
Paul, I'm interested in examples such as the one you have given.
I dive a rEvo with a shrimp and have moved the gag strap to the shrimp precisely as I believe it is a safer option (despite the fact that it tastes like sucking air from a car tyre). It feels as though I won't ingest water though I have to admit I haven't lost consciousness whilst diving so can't categorically state this as fact.
Even though I believe it is a safer option it would be good to have this confirmed.
I dive a rEvo with a shrimp and have moved the gag strap to the shrimp precisely as I believe it is a safer option (despite the fact that it tastes like sucking air from a car tyre). It feels as though I won't ingest water though I have to admit I haven't lost consciousness whilst diving so can't categorically state this as fact.
Even though I believe it is a safer option it would be good to have this confirmed.
Ben Field
All IMVHO obviously...
Is it worth expanding on this? Might negate some of the resistance if people knew more about it...
FWIW, I think more people would use them if they came as standard and where taught with them.
paulraymaekers
Active Member
As all know, this is one of my XXX I have been pushing on for years: they come as standard on rEvo, for at least the last 5 years
'correctly':
- tighten the strap so that when in the water, the mouthpiece stays in your mouth, and seals off, without the need to bite
- if your upper lip hurts, or is 'cut' into the upper part of the bite piece, it's because your mask is tightened to hard, and pushes your upper lip onto the 'ridge' of the bite piece: just loosen your mask, and you'll notice it works perfect