Wesley Skiles' widow suing over rebreather

[Chris Brown Tech]

Now that you understand where I am coming from, would you be so kind as to explain to me why the sports divers don't use these concepts or procedures? It seems to be to be the simplest and most straightforward approach to emergencies and just plain good sense when it comes to procedures. So why the chortles?


Also, with respect to Wes, I don't believe that was his first CCR dive, in fact, I believe that he had a fair amount of experience with a number of other units, more than I have. Also, I don't know what led you to jump into the pit of "OC doesn't translate to CCR," nobody said that it did, or did not, that was a strawman of your own creation.

Well, to answer your questions, I guess I first need to forgive you for suggesting that Im a self styled "guru" and that Ken is a "power user" Neither was ever suggested or claimed by either of us

However, the differences are based on needs. The military isnt concerned about how informed the diver is. Take for example a navy guy who called me this week that wants to learn CCR from me because the Navy wont even let him build his unit. They arent allowed to dive a computer or any form of mix and are often tethered.

As you know, its a "need to know" environment where consistency, reliability and easability rules. I suspect the F02 approach came about prior to current oxygen management technology. Its a great way to know your MAX po2 based on a KNOWN diluent should you flush the loop. Therefore if your dil is normoxic, you can reduce the risk of hypoxia on ascent.

A sport CCR diver on the other hand, has no surface support, no mission objective, government department or anyone else that can help him. The need for self sufficiency has created an environment of 'must haves' such as CO2 monitors, temp sticks, decompression software etc. Although admittedly woefully inadequate at times and often years too late and not cutting edge, I think we've done OK based on the limited resources the industry has. The military admitted they were years behind sport diving rebreathing at RF3 in terms of technology, understanding and training. The other 'must have' for the current sport diver is a good understanding of what is in his loop and the physics of rebreather diving, plus the limitations and inadequacies of 02 sensors and electronics and IN PARTICULAR, the limitations of his own unit.

You suggested that you doubted Wes would have died due to a lack of training or familiarity on that particular unit. Im saying quite the opposite.

The modern eCCR such as the Optima is designed to maintain set point the whole dive. A trained and prudent user wouldnt flush prior to ascent as theres simply no need. The Po2 would have been 1.2 or thereabouts. Based on the depth, Wes' dil would have been around .6 or .7 if he had flushed the entire unit. All that would have happened would have been an immediate replacement of that gas with oxygen from the solenoid as the machine attempted to regain setpoint. An untrained and unfamiliar diver wouldnt neccessarily know how to maintain P02 or be aware of hypoxia on ascent due to low P02

An 02 flush at 20' or shallower is more effective than a dil flush prior to ascent. This is often employed in sport diving.

Hope this helps

 

[padiscubapro]

To add to Chris's post in regards to a diluent flush...

The original MK-15 electronics are analog electronics that have been designed to maintain a set-poit of approximately 0.7 ata... So in the case of the Navy a diluent flush makes 100% sense when using a normoxic mix(if your deeper than ~70fsw, then you will have a po2 higer than the sp, AND you can verify your po2) ... You insure that your loop is where the SP was designed to be (in the above example from Chris)... The civilian market uses a 1.3sp as normal, the higher po2 is much better for asecents physiologically, if we did a flush without changing set-point to around a 0.7 (not all units allow a manual switch) as chris pointed out o2 would be continually injected until the sp reaches 1.3 (or whatever the diver set it at).. This is a big waste of o2 and adds to potential buoyancy issues.. We only flush the loop when we doubt the loops content like a sensor being voted out or "feeeling funny"

Since the MK-15 was an analog controller, and really had no way to vote on the accuracy of the sensors, the system operates on a continual average.. so a dead cell would bring the average loop po2 measured down to about 0.46, the electronics would inject until it averaged out to about a 0.7 (which would be an actual po2 of about 1.1) .. Using the same type system in the civilain market doesn't work well (although civilian MK15 divers use a calibration trick to alow them to use an approximate sp of 1.3, byt they risk hyperoxia with a failed cell) since we generally run higher po2s to reduce deco obligation...

 

[Thalassamania]

Chris: yes it helps, however, let's (for the moment) assume that the problem Wes encountered was hypoxia on ascent that rendered him unconscious. Were he to have performed a diluent flush at the start of his ascent what advantages would have been gained at what costs? The advantage would have been that his loop fO2 would have quickly approached his diluent's fO2, causing his ceiling to have gone to the surface ... and he'd still be alive. The disadvantage would be that there would be a, "big waste of O2" and a need to manage the same kind of buoyancy issues that divers, especially OC divers, handle on almost every dive.

Chris says that, "The modern eCCR such as the Optima is designed to maintain set point the whole dive. A trained and prudent user wouldnt flush prior to ascent as theres simply no need. The Po2 would have been 1.2 or thereabouts. Based on the depth, Wes' dil would have been around .6 or .7 if he had flushed the entire unit. All that would have happened would have been an immediate replacement of that gas with oxygen from the solenoid as the machine attempted to regain setpoint. An untrained and unfamiliar diver wouldnt neccessarily know how to maintain P02 or be aware of hypoxia on ascent due to low P02."

The issue at hand is that the modern eCCR that Wes was using appears, for whatever reason, to NOT HAVE maintained the set point it was supposed to for the whole dive. Because of the effects of dropping ambient pressure on ppO2, failure to maintain the set point (at least on the hypoxic side) tends to present as an issue on ascent. Had Wes flushed his loop with diluent prior to ascent (as I routinely do), his ppO2 would have been 0.6, or higher, and his ascent would have been without incident.

Granted, the reason for how (and why) his loop had such a low ppO2 is unknown. The reason why Wes failed to properly react to the data presented, or was not presented with the data or alarm that he should have been, is also unknown. But ... the reality is that if he'd done a diluent flush just prior to ascent, we'd not be having this discussion. It seems to me that the reasons that have been presented for not doing one (that he'd have "wasted" a few bucks worth of oxygen or that he'd have had buoyancy control issues), especially since he was making a solo ascent (which is significantly more dangerous than having a competent buddy there with you), pale to insignificance.

 

[wedivebc]

Chris: yes it helps, however, let's (for the moment) assume that the problem Wes encountered was hypoxia on ascent that rendered him unconscious. Were he to have performed a diluent flush at the start of his ascent what advantages would have been gained at what costs? The advantage would have been that his loop fO2 would have quickly approached his diluent's fO2, causing his ceiling to have gone to the surface ... and he'd still be alive. The disadvantage would be that there would be a, "big waste of O2" and a need to manage the same kind of buoyancy issues that divers, especially OC divers, handle on almost every dive.

Chris says that, "The modern eCCR such as the Optima is designed to maintain set point the whole dive. A trained and prudent user wouldnt flush prior to ascent as theres simply no need. The Po2 would have been 1.2 or thereabouts. Based on the depth, Wes' dil would have been around .6 or .7 if he had flushed the entire unit. All that would have happened would have been an immediate replacement of that gas with oxygen from the solenoid as the machine attempted to regain setpoint. An untrained and unfamiliar diver wouldnt neccessarily know how to maintain P02 or be aware of hypoxia on ascent due to low P02."

The issue at hand is that the modern eCCR that Wes was using appears, for whatever reason, to NOT HAVE maintained the set point it was supposed to for the whole dive. Because of the effects of dropping ambient pressure on ppO2, failure to maintain the set point (at least on the hypoxic side) tends to present as an issue on ascent. Had Wes flushed his loop with diluent prior to ascent (as I routinely do), his ppO2 would have been 0.6, or higher, and his ascent would have been without incident.

Granted, the reason for how (and why) his loop had such a low ppO2 is unknown. The reason why Wes failed to properly react to the data presented, or was not presented with the data or alarm that he should have been, is also unknown. But ... the reality is that if he'd done a diluent flush just prior to ascent, we'd not be having this discussion. It seems to me that the reasons that have been presented for not doing one (that he'd have "wasted" a few bucks worth of oxygen or that he'd have had buoyancy control issues), especially since he was making a solo ascent (which is significantly more dangerous than having a competent buddy there with you), pale to insignificance.

Flushing the loop with air diluent is not only unnessasary it is dangerous. Assuming there was an interruption of O2 supply flushing with air would put you in a worse situation.
Flushing prior to ascent is a SCR practice where the carry gas is nitrox not air.

 

[Chris Brown Tech]

let's (for the moment) assume that the problem Wes encountered was hypoxia on ascent that rendered him unconscious. Were he to have performed a diluent flush at the start of his ascent what advantages would have been gained at what costs? The advantage would have been that his loop fO2 would have quickly approached his diluent's fO2, causing his ceiling to have gone to the surface ... and he'd still be alive. The disadvantage would be that there would be a, "big waste of O2" and a need to manage the same kind of buoyancy issues that divers, especially OC divers, handle on almost every dive.

Id rather not assume. You have made the assumption that it was hypoxia on ascent for some reason.

Nevertheless, flushing his loop with air dil prior to ascent (if indeed he had air in his dil tank) would not have necessarily meant he would still be alive today.

The issue at hand is that the modern eCCR that Wes was using appears, for whatever reason, to NOT HAVE maintained the set point it was supposed to for the whole dive.

Theres simply no evidence to support this claim. Do you know he died of Hypoxia on ascent? Did I miss something? What exactly was wrong with the rebreather?

Had Wes flushed his loop with diluent prior to ascent (as I routinely do), his ppO2 would have been 0.6, or higher, and his ascent would have been without incident.

Sorry, you are incorrect. PO2 would only have been .6 if he managed to flush THE ENTIRE LOOP of low p02 gas and started his ascent at around 60 fsw. As he ascended the loop P02 would have dropped, possibly to hypoxic levels. He would not have been at .6 at the surface.

Granted, the reason for how (and why) his loop had such a low ppO2 is unknown.

How do we know he had a low p02 in his loop at the time he died?

But ... the reality is that if he'd done a diluent flush just prior to ascent, we'd not be having this discussion.

Alas, I suspect we would

 

[TSandM]

Did I miss something? Do we know he was hypoxic?

 

[HIGHwing]

I would say, we don't know. My theory considering the length of dive, water temp, reported condition of the sensors, reported gas available - Wes was hyperoxic. I think there's not a chance he was hypoxic as there was available oxygen and the HH electronics just won't let you make that mistake (unless you modify the unit with an EZ Solenoid inline shutoff).

I suspect the old and lazy cells were reading lower than actual PO2 and Wes was breathing a much hotter PO2 that he thought. In the absence of diluient (onboard or offboard) he had no (practical/meaningful) way to flush anything prior other than by going to a fill station. (I concede he could have flooded the loop with 100% O2, but who's going to do that at ~70-feet, and why?)

He's been breathing God know's what for however long and as he ascends the old lazy sensors tell the HH to do what it's supposed to do - pound in O2 and keep doing it as the PO2 is "dropping" away from the SP.

I'm a real fan of the idea the unit would not have been able to pass the Post-Assembly Check (specifically minimum milivolt test and/or calibration). I think this set the chain of events in motion, compliemented by the decisions of 1) No bailout 2) No training 3) Solo diving 4) Continuation of the dive beyond available diluient.

I think what makes the absolute most sense (based on my understanding) is that Wes slowly and actively converted the machine into an oxygen rebreather and the old sensors didn't give him enough information to put the pieces of the puzzle together.

I'd be *extremely* interested to know... Would the unit have calibrated if he tried to calibrate it? I seriously doubt it, and I also think that had he done a MV check and calibration the accident is likely avoided.

I wasn't there, but I'm sure someone knows what really happened. Until such release of information is available, my money is on an OxTox event.

 

[Thalassamania]

WebdiveBC: Flushing with air prior to ascent is SOP in some communities, especially the military. Wes was at 80ft, if he flushed at the start of his ascent he'd have finished and squared his buoyancy away at about 60 feet (correct me if wrong, I've never dove an Optima). He's now two minutes to the surface and could flush again with diluent if his ppO2 was falling too low and his oxygen supply failed, I suspect that you might remember that that is why you use air or nitrox as diluent in most cases?

Chris: If you'd rather not assume, then please hypothesize and help falsify, that is how it is done. I make the assumption that it was hypoxia on ascent for rather obvious reasons, that is, given the evidence at hand, that is the most likely event (see my answer to Lynne below).

I'd be interested in your explanation as to why flushing his loop with air diluent prior to ascent, if indeed he was using air as his diluent, would not have prevented a hypoxic ascent.

Sorry, but no one ever suggested this, you are again presenting your own straw-man: "you are incorrect. PO2 would only have been .6 if he managed to flush THE ENTIRE LOOP of low p02 gas and started his ascent at around 60 fsw. As he ascended the loop P02 would have dropped, possibly to hypoxic levels. He would not have been at .6 at the surface." Please model how Wes' ppO2 would have gone hypoxic on his ascent after a diluent flush.

If you do not think that Wes had a low pp02 in his loop at the time he died, please suggest a scenario that fits what is known, we'd all love to hear anything that is anywhere near as likely. That is the process, rather than simple pontification without hypothesis or falsification. You see, no one really cares what you think, or for that matter what I think, these discussion are not ruled by such appeals to authority, they are conducted on the basis of event likelihood, supported by evidence, and falsification of a proposed hypothesis.

Lynne: Occam's razor makes it the most likely cause of unconsciousness on ascent with a CCR. I welcome other entries in the hunt for an explanation, but I've not read any, just snide asides concerning his possible use of drugs and "we'll just have to wait for the report," a phrase that anyone with even a modicum of diving accident investigation experience is not worth the time I took to type it. People who die on ascent tend to do so for one of three reasons, hypoxia as the ppO2 drops, AGE as gas in the lungs expands during a panicked claw for the surface or collision with a vessel. There was no vessel collision, the likelihood of an AGE is inversely proportional to diving experience, for a number of reasons, leaving ... hypoxia. Is that proof? No. Is that sufficient for a hypotheses? Yes. So as a "highest likelihood" hypothesis yet to be advanced, it becomes incumbent upon those interested in the question to falsify (or just cast doubt on) the hypothesis, something that no one has done, either deductively or inductively.

I would say, we don't know. My theory considering the length of dive, water temp, reported condition of the sensors, reported gas available - Wes was hyperoxic.

...

I wasn't there, but I'm sure someone knows what really happened. Until such release of information is available, my money is on an OxTox event.

Thanks, its nice to have another idea on the table.

 

[HIGHwing]

Thanks, its nice to have another idea on the table.

You're welcome. While I admit that a low PO2 fits the profile, I don't think it's the most likely scenario. I can reasonably conclude the desire to use the rebreathers was to get closer to the aquatic life (goliath grouper). The other reason for their use was to stay calm, still, and remain down for a considerable bit of time. In fact, we know that Wes ascended not because he was low on gas, but because he ran short on film/storage media.

I'm going to insert some numbers just to create my scenario, they're not based on any inside information, just my understanding of how my unit works. You assemble the unit, skip the post assembly, complete a full and valid pre-breathe and jump in the water. Upon arriving at 70-feet, you spray a little diluient, do a quick bubble check, and establish the SP at 1.2 PO2.

Imagine while you're down there the sensors are "current-limited" in that they can't really read much above an unknown high-value mark. Perhaps sensor x and xx are limited near 1.2 and the HH is commanding the solenoid (to do what's it's supposed to do) to apply O2. This goes on for :30 minutes, an hour, all the while the actual P02 is continually creeping past the current limit. The cells are still putting out a 1.2 PO2 or approximate equivalent milivoltage but what's really happening is the cells are increasingly becoming less and less accurate and the O2 solenoid continues to gently fire O2 as it has been set to do by the user.

I genuniely think it's a real possibility that the cells were so old and tired they couldn't give an accurate reading of the PO2. The bad cells gave bad information and all the while the user is laying quietly during the dive. It occurred to me that in the discussion of breathing high PO2's we always hear about Seals breathing crazy high PO2s under very still and calm conditions. Perhaps those conditions are similar to stalking a 300lb fish? It's interesting that he gets into trouble during a period of activity during an ascent where we know the sensors are going to detect a decaying PO2 and inject even more oxygen.

In my opinoin Wes put himself in a box and had absolutely nothing breathable. Alpinist diving is cute and admirable, but it's just not fair to my family. I wish people would stop promoting Aplinist diving. If you want to do it, I guess that's fine, free country...but it's so unfair to those who care.

Regarding the lawsuit, I see no element of the lawsuit where Terri's cause should prevail. It's reasonably clear the unit was functioning as it was designed. In fact, that same design successfully supported the rebreather's owner (who was trained) before Wes used it and the unit was functioning as designed after the fatality. For the record, if I have an accident on my O2ptima, Mark Derrick is free to look at it and my wife knows my wishes. I don't feel Terri has the right to profit at Lamar, or Mark's expense as Wes made very grave decisions and choices in an area of expertise and knowledge. He knew the limitations of rebreathers, he knew the dangers, he clearly displayed disregard for these dangers by the lack of bailout, and if he willfully put his wife's financial security in jeopardy (as many of us probably do) when taking on these adventures that was also a choice he made.

I don't begrudge Wes. I would be dead on the inside if my wife didn't let me do crazy stuff. What I dislike here is Terri is changing Wes' legacy. Wes' legacy shouldn't end up as the guy married to a woman who financially devistated the SCUBA industry. I think Wes had a story to share and Terri is taking that away from him.

 

[wedivebc]

WebdiveBC: Flushing with air prior to ascent is SOP in some communities, especially the military.

Since our military uses SCR I can't comment on that but unless the US military has their own exception to the laws of physics that makes no sense.
In the absence of any external source of oxygen an air dil flush regardless of depth it is conducted at will result in a PO2 of something less than 0.21 at the surface depending on how much the diver metabolized on the way up. Not a very safe situation to be in and I rather skeptical of your claim that it is SOP for any CCR diver.