DCS cure using pure02 or Nitrox mix

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Dr Deco

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I would be in favor of using your air in the water and surface to use the oxygen on board. The tables allow a degree of safety and DCS should not result.:shakehead:

Motion in water builds CO2 and increases risks of a convulsion.:no:
 

doctormike

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Mike, it has been suggested that there is a difference between "explosive decompression", which is driven by pressure gradients and other forms of DCS. BTW, I am not the one suggesting this but follow what others are saying in the literature. Honestly, I don't like discussions on DCS on forums because the topic is so difficult. As you might agree, even among 'experts' there is divergence of opinion. This is overall beneficial because the issue of DCS is unsolved. Just because one can measure something, does not mean that it is causal to the phenomena. (I believe it was either Mollerlokken or Bruback who stated this in regards to bubble studies). The best tool we currently have at our disposition is a dive computer who manages 'real time' tissue loading. Tables are out. A continued argument appears to be how that loading information is being managed by various algorithms. Some argue that shorter decompression times are better over longer ones. The idea being that by going shallower more quickly rather than doing 'deeper stops', you ongas less which you have to offgas later. The other side is WHERE we should do our decompression, ie deeper vs shallower.

What actually constitutes decompression stress? Bubble loads? Current research is looking into biomarkers as a way to qualify this. But, it looks like we don't have enough information, yet.

"while this all means that you can't accurately predict the overpressure threshold that will cause DCS", I stopped thinking of DCS as an overpressure threshold issue unless it is AGE or "explosive deco" because I have seen complete white out in the left side of the heart with NO symptoms whatsoever. We see divers with PFO's doing He dives for years before getting hit - that raises the question "Why Now??".

OK, at this point I'm not actually clear on what we are debating! :D

I don't know about you, but I'm not a hyperbaric doc or other decompression science professional. Just an interested amateur. I do agree that a discussion of the nuances of decompression science is beyond the scope of this thread. I guess the only reason that we are still discussing it is that we at some point gave different opinions to the OP, right?

I would summarize my position here like this:

(1) We don't know all of the variables that contribute to the clinical entity know as DCS.

(2) Bubbles are neither proven to be the direct cause of symptoms / injury in DCS or a totally reliable biomarker for decompression stress.

(3) However, greater degrees of decompression stress (whether or not this correlates precisely with bubble formation) are associated with a greater risk of symptoms and injury. And when I say decompression stress, I'm not talking about any secondary measurement, bubbles or biomarkers, I'm just talking about physics - the profile and the gas composition. While there is a lot of controversy in this field, I don't think that is controversial.

So as far as I can reconstruct (from your post #13), I said that his diver should do as much deco before surfacing as was operationally possible (including the possibility of extra gas). You said that it would be better to get out of the water earlier, watch for symptoms and breath 100% O2 on the boat, because it wasn't that important to stay further from the M-value line, just do pure Buhlmann and get out.

Isn't that what you were saying? I still think that the diver should do the deco on the line in the water, nuances of decompression science, biomarkers, and the limits of the bubble hypothesis notwithstanding.
 

dreamdive

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OK, at this point I'm not actually clear on what we are debating! :D

I don't know about you, but I'm not a hyperbaric doc or other decompression science professional. Just an interested amateur. I do agree that a discussion of the nuances of decompression science is beyond the scope of this thread. I guess the only reason that we are still discussing it is that we at some point gave different opinions to the OP, right?

I would summarize my position here like this:

(1) We don't know all of the variables that contribute to the clinical entity know as DCS.

(2) Bubbles are neither proven to be the direct cause of symptoms / injury in DCS or a totally reliable biomarker for decompression stress.

(3) However, greater degrees of decompression stress (whether or not this correlates precisely with bubble formation) are associated with a greater risk of symptoms and injury. And when I say decompression stress, I'm not talking about any secondary measurement, bubbles or biomarkers, I'm just talking about physics - the profile and the gas composition. While there is a lot of controversy in this field, I don't think that is controversial.

So as far as I can reconstruct (from your post #13), I said that his diver should do as much deco before surfacing as was operationally possible (including the possibility of extra gas). You said that it would be better to get out of the water earlier, watch for symptoms and breath 100% O2 on the boat, because it wasn't that important to stay further from the M-value line, just do pure Buhlmann and get out.

Isn't that what you were saying? I still think that the diver should do the deco on the line in the water, nuances of decompression science, biomarkers, and the limits of the bubble hypothesis notwithstanding.


I agree, guess we got a bit off topic from the original post :D.

However, I did not say "You said that it would be better to get out of the water earlier, watch for symptoms and breath 100% O2 on the boat, because it wasn't that important to stay further from the M-value line, just do pure Buhlmann and get out."

I said that:

1. Another OPTION is to get out of the water (before running out of gas) and (if NDL's have been violated) breath oxygen on the boat (instead of in the water), to observe and act accordingly.

2. In post 13, I was taking exception to your implying that "riding the M value line" puts you at "high likelihood of DCS".
 

doctormike

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1. Another OPTION is to get out of the water (before running out of gas)

I totally agree that he should get out of the water before running out of gas! :D


and (if NDL's have been violated) breath oxygen on the boat (instead of in the water), to observe and act accordingly.

OK, so you are saying that for missed deco, an option is surface O2 and observation. That's not what I learned in my tech training. We learned to go back and do the deco.

I suppose you are modifying the recommendation since this diver isn't tech trained, and would need to have extra gas brought to him (as per the OP's question). I still think that he should do the deco, or as much of it as possible.

2. In post 13, I was taking exception to your implying that "riding the M value line" puts you at "high likelihood of DCS".

Fair enough, I can't really back that up with research, even if I did have a number for "high likelihood". But I will say that pure Buhlmann, especially in this scenario, puts you at increased risk of DCS when compared to more conservative ascent profiles.
 

dreamdive

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I totally agree that he should get out of the water before running out of gas! :D




OK, so you are saying that for missed deco, an option is surface O2 and observation. That's not what I learned in my tech training. We learned to go back and do the deco.

I suppose you are modifying the recommendation since this diver isn't tech trained, and would need to have extra gas brought to him (as per the OP's question). I still think that he should do the deco, or as much of it as possible.



Fair enough, I can't really back that up with research, even if I did have a number for "high likelihood". But I will say that pure Buhlmann, especially in this scenario, puts you at increased risk of DCS when compared to more conservative ascent profiles.


Enough Said. Thanks Mike :D
 

Bob DBF

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If your dive plan is that close to the edge, read up on deco and take more air. Perhaps hang a bottle on your upline. I don't know about the OP, but my computer does not switch gasses so having O2 may be faster, but you still wouldn't know how long faster is. The emergency O2 onboard is usually for surface use only, different connectors and hardware, so you wouldn't be taking them for a swim. To have O2 for scuba diving you would be trained and would be careful to avoid a deco dive without proper planning and gas. In the OP's spot, I'd grab, or have sent down, another bottle of air, and be bored for as long as it takes whilst kicking myself in the a** the whole time.




Bob
 
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