Rebreather Diver dies in Pool in Oregon

[BigJetDriver]

In the case of Dr. Kendall, if his diving partners had noticed erratic behaviour in him on earlier dives, they'd be obligated to report it. Just like the case with this incident.

There was no erratic behaviour on the part of Dr. Kendall to report, but you are quite correct, however, see my comment above. (Post #60)

 

[DivingCRNA]

I don't dive a rebreather yet, and it's very likely that my guess could be wrong. However, if a scrubber goes past it's usefull limit, and starts a slow build up of CO2, would you still see it coming and experience the buildup of CO2 as rapid? (honestly asking a question here) Or am I out to lunch on how a scrubber failure due to overuse would manifest itself?

I deliver anesthesia for a living. The machine we use to deliver anesthesia gas is semiclosed rebreather with a ventilator that allows us to introduce anesthesia gasses. We have continuous CO2 monitoring of the gasses in the circuit.

I have had the CO2 absorber totally fail once in my career. The CO2 level did slowly creep up, but they it suddenly jumped very high when total failure occured. This should not happen though.

I was a student and had just been moved into that room. A step in readying a anesthesia machine (I imagine it is also true for a rebreather) is to check the CO2 absorber. I did not take the time to look at the absorber before the case. Once we figured it out, I could change the absorber during the case. You can't during a dive.

I surely hope he checked the absorber before his dive.

I have been reading a bunch of this thread. If he was a little bit different from most people, has anyone considered he did this on purpose? And he did not do it in open water for fear of not being found? I didn't know the guy AT ALL. I have just been reading this thread, so it is just a thought.

 

[Uncle Pug]

Stand By

Thread temorarily closed while I review it for forum specific TOS violations. This should not take long.

 

[Uncle Pug]

After complete review I have determined that there are no TOS violations in this thread.

While the TOS for this forum indicate it is not for casting blame neither is it for covering up problems that contributed to the incident. This is not a condolences forum.

If you have specific issues please feel free to PM me directly but do not introduce a *discussion of the thread* within the thread.

 

[wedivebc]

I deliver anesthesia for a living. The machine we use to deliver anesthesia gas is semiclosed rebreather with a ventilator that allows us to introduce anesthesia gasses. We have continuous CO2 monitoring of the gasses in the circuit.

I have had the CO2 absorber totally fail once in my career. The CO2 level did slowly creep up, but they it suddenly jumped very high when total failure occured. This should not happen though.

I was a student and had just been moved into that room. A step in readying a anesthesia machine (I imagine it is also true for a rebreather) is to check the CO2 absorber. I did not take the time to look at the absorber before the case. Once we figured it out, I could change the absorber during the case. You can't during a dive.

I surely hope he checked the absorber before his dive.

I have been reading a bunch of this thread. If he was a little bit different from most people, has anyone considered he did this on purpose? And he did not do it in open water for fear of not being found? I didn't know the guy AT ALL. I have just been reading this thread, so it is just a thought.

Here is a question for you, what effect does increase CO2 have on an unconcious patient? Does his breathing rate increase rapidly? What amount of CO2 do you start to see symptoms.
Pt40fathoms was referring to the fact (and I think most rebreather divers will concur) that very little CO2 buildup will cause a very uncomfortable experience for a consious diver. This discomfort will be felt (I believe) at levels much below those that cause unconsiousness.
I also believe this accident has nothing to do with hypercapnia and everything to do with hypoxia. Whether training as a contributor played a major role is still to be debated but it is sure looking that way to me.

 

[DivingCRNA]

Here is a question for you, what effect does increase CO2 have on an unconcious patient? Does his breathing rate increase rapidly? What amount of CO2 do you start to see symptoms.
Pt40fathoms was referring to the fact (and I think most rebreather divers will concur) that very little CO2 buildup will cause a very uncomfortable experience for a consious diver. This discomfort will be felt (I believe) at levels much below those that cause unconsiousness.
I also believe this accident has nothing to do with hypercapnia and everything to do with hypoxia. Whether training as a contributor played a major role is still to be debated but it is sure looking that way to me.

The increase in CO2 level's effects depends. If the patient is paralyzed, it takes can be difficult to detect without monitors. If the patient is breathing on their own, they do breath faster and deeper. But this is a generality. One thing that is going on under anesthesia that is not while using a rebreather is surgery. The stimulation from surgery can also increase respiratory rate.

I agree 100% that hypercapnia and hypoxia cause discomfort and anxiety. I have seen it hundreds of times. I am still trying to reason out how these folks on rebreathers die and do not look like they knew it was coming. I would love to hear from anyone who knows how this happens. Maybe you black out really fast from breathing the nitrogen and CO2 that is left after your body uses up the oxygen in the rebreather system?

 

[wedivebc]

I agree 100% that hypercapnia and hypoxia cause discomfort and anxiety. I have seen it hundreds of times. I am still trying to reason out how these folks on rebreathers die and do not look like they knew it was coming. I would love to hear from anyone who knows how this happens. Maybe you black out really fast from breathing the nitrogen and CO2 that is left after your body uses up the oxygen in the rebreather system?

As a medical professional I am sure you are aware that breathing response is triggered by CO2 and not O2. The increase in CO2 causes a feeling of air starvation that is very uncomfortable. If you don't believe me fill a bag with pure O2 and breathe from it. You will feel very air starved even though the bag will still contain almost pure O2 and some smalll amount of Co2 .
Hypoxia in an atmosphere where the CO2 is removed provides very little discomfort amd can easily go unnoticed by the diver. This is the primary danger of rebreathers and the reason "Alwys know your PO2" is the mantra of us who choose to dive them.

 

[caveseeker7]

I am still trying to reason out how these folks on rebreathers die and do not look like they knew it was coming. I would love to hear from anyone who knows how this happens.

Luckily I have never encountered either hypoxia nor hypercapnia.

I don't recall anyone experiencing hypoxia and giving an account of it.
It's very sneeky and fast, probably because you're using O2 at a higher rate whe diving than when at rest. Also, from all accounts (of fatalities) it seems that the symptoms are either less to the point of being unperceptable or so fast that the body, much less the mind have much time to react.

There are plenty of accounts of hypercapnia, DrMike on the boards posted his at TDS and RBW. Maybe here, too, I'm not sure. He was perfectly aware that something was wrong, and that he needed to switch to OC, but entirely uncapable of closing the BOV and thereby switching to his bailout gas. The onset of hypercapnia is slower, the loss of conciousness too, but it can be incapacitating quite quickly. Jason Mc Hatten posted his chilling account of a Co2 hit Dive-Oz, he lost conciousness and spend a good time in the chamber.

 

[DivingCRNA]

As a medical professional I am sure you are aware that breathing response is triggered by CO2 and not O2. The increase in CO2 causes a feeling of air starvation that is very uncomfortable. If you don't believe me fill a bag with pure O2 and breathe from it. You will feel very air starved even though the bag will still contain almost pure O2 and some smalll amount of Co2 .
Hypoxia in an atmosphere where the CO2 is removed provides very little discomfort amd can easily go unnoticed by the diver. This is the primary danger of rebreathers and the reason "Alwys know your PO2" is the mantra of us who choose to dive them.

Now that you put it that way...I can see that. This is exactly why I talk about anesthesia machine experience and not rebreather experience. The anesthesia machine has an alarm that will go off when pO2 is under 0.21. Rebreathers cannot do this because 21% O2 is toxic at deep enough depths (and you pO2 has to be less than .21 to dive it), but this alarm is why I seldom, if ever see hypoxia without hypercapnea. Anesthesia machine do a lot of other things too. That is why they are $50-$100 THOUSAND!

Thanks for the info. BTW-While rebreathers seem like a great way to go, it will probably be a long time before I would think about paying for one. Plus-it would seem a lot like being at work, only it is MY life at risk

Thanks again.

 

[DivingCRNA]

As a medical professional I am sure you are aware that breathing response is triggered by CO2 and not O2. The increase in CO2 causes a feeling of air starvation that is very uncomfortable. If you don't believe me fill a bag with pure O2 and breathe from it. You will feel very air starved even though the bag will still contain almost pure O2 and some smalll amount of Co2 .
Hypoxia in an atmosphere where the CO2 is removed provides very little discomfort amd can easily go unnoticed by the diver. This is the primary danger of rebreathers and the reason "Alwys know your PO2" is the mantra of us who choose to dive them.

I forgot to add this-

CO2 is the PRIMARY drive for breathing. It is the only one that healthy people really use. O2 can be a seconday breathing trigger, but it is many in patients with bad lung disease who become used to high CO2 levels due to their disease. If you put a patient with bad emphysema on 100% O2 they could easily stop breathing due to no hypoxic drive. But someone in this condition would have no business SCUBA diving, so the fall outside the usefull realm of this thread