DCS hit during final stop? Has it ever happened?

[kekenned]

Just curious if the PFO closure's positively affected you out of the water? For example do you feel as if you've more stamina, less fatigue, etc. when you're just walking around?

I do feel generally better! However, I have a pretty major additional variable -- I was getting regular IV iron infusions to correct an iron deficiency at the same time I got my PFO closed. It's hard to separate out which factor has caused my improvement in energy/stamina/etc, since they both ultimately should result in more oxygen reaching my tissues. I'm assuming both helped.

I guess I'm just I'm a medical... not a miracle. What's the opposite of a medical miracle? A medical mess?

 

[Wibble]

Living life and getting on with it. So many people I know just give up.

 

[kekenned]

I'm just happy to be able to breathe underwater again! Plus not being totally exhausted after dives... it's a revelation.

 

[Duke Dive Medicine]

I think so, too. I imagine the vast majority of successful cases do not get reported.

It all depends, too, on how liberal you are with the definition. If you go to the Wikipedia page on this topic, you will see a nice list of the different formal protocols that can be used. Scroll to the bottom of the page and you will find this paragraph:

Although in-water recompression is widely regarded as risky, and to be avoided, there is increasing evidence that technical divers who surface and demonstrate mild DCS symptoms may often get back into the water and breathe pure oxygen at a depth 20 feet/6 meters for a period of time to seek to alleviate the symptoms. This trend is noted in paragraph 3.6.5 of DAN's 2008 accident report.[18] The report also notes that whilst the reported incidents showed very little success, "[w]e must recognize that these calls were mostly because the attempted IWR failed. In case the IWR were successful, [the] diver would not have called to report the event. Thus we do not know how often IWR may have been used successfully."
​

I have seen that done first hand, with great success. In such a case, if it were not successful, the diver would have headed off to a chamber, and we would know about it. As that quote from DAN indicates, you really only find out about an IWR case when it doesn't work, and so the success rate is poor. Even if it doesn't work, you can't really be sure it didn't work. If someone shows up at a chamber and gets treatment for mild DCS after IWR, how are we to know how serious the case might have been had there been no IWR?

@boulderjohn all very good points.

 

[boulderjohn]

We used Deco Planner to plan the dives, set for Buhlmann with a gradient factor of 20/85. (I did go back after the fact and re-run the numbers with a gradient factor of 30/70 instead, and honestly it didn't make much of a difference.)

I am not sure that you realize that both of those are considered very deep first stops in the current trend of thinking on decompression.

Evolving Thought on Deep Decompression Stops - ElBuceoNuestroDeCadaDia.com

EDIT: I just realized that this link went to a website that copied the original article, and they did a really bad job of formatting it. I tried to make the link to the original site, but Chrome would not let me link to it.

 

[kekenned]

I am not sure that you realize that both of those are considered very deep first stops in the current trend of thinking on decompression.

Evolving Thought on Deep Decompression Stops - ElBuceoNuestroDeCadaDia.com

I was aware 20/85 was considered to be a deep stop, it's a discussion I've been having with my GUE instructor. Dr. Holm recommended 30/70 in the future, which is why I re-ran my deco calcs with that to see if it would have made a difference (it didn't, for these particular profiles). Is there a different gradient factor you'd use?

Also, can you elaborate on how changing the gradient factor would affect these specific dives, where almost all of the deco was conducted at 20'? Would you go faster than 10 ft/min up to 20' after the gas switch at 70'?

 

[ginti]

@kekenned @boulderjohn
In the GUE tec1 course, max depth is 171ft/51m, and the maximum total deco time is 30minutes, resulting in 20 somethings at the last stops. Basically, the first stops account only for few minutes, the time required to switch to deco bottles and a little bit more. At this level, more modern gradient factors wouldn't result in a drastic change of the deco stops as far as I remember, and as far as @kekenned calculation with 30/70 shows (I also did my math, and I had similar results). At higher depth, the situation is quite different.

 

[boulderjohn]

I was aware 20/85 was considered to be a deep stop, it's a discussion I've been having with my GUE instructor. Dr. Holm recommended 30/70 in the future, which is why I re-ran my deco calcs with that to see if it would have made a difference (it didn't, for these particular profiles). Is there a different gradient factor you'd use?

Also, can you elaborate on how changing the gradient factor would affect these specific dives, where almost all of the deco was conducted at 20'? Would you go faster than 10 ft/min up to 20' after the gas switch at 70'?

A lot of people like Simon Mitchell and David Doolette, who are as up on things as you can get, are doing at least 50 for a GF Low. As long as you are referencing GUE, here is a GUE blog by David Doolette in which he mentions using a GF Low of 70: Gradient Factors in a Post-Deep Stops World

As for your actual dives, your GF Low was largely irrelevant. My comments were more generic about deco diving than to your specific dives.

I do 30 FPM throughout my ascent.

 

[kekenned]

A lot of people like Simon Mitchell and David Doolette, who are as up on things as you can get, are doing at least 50 for a GF Low. As long as you are referencing GUE, here is a GUE blog by David Doolette in which he mentions using a GF Low of 70: Gradient Factors in a Post-Deep Stops World

As for your actual dives, your GF Low was largely irrelevant. My comments were more generic about deco diving than to your specific dives.

I do 30 FPM throughout my ascent.

Cool, thanks! I definitely have been planning to do a deeper dive into current thinking on gradient factors before returning to tech (even if it wouldn't have made a difference in this particular case).

 

[rjack321]

Cool, thanks! I definitely have been planning to do a deeper dive into current thinking on gradient factors before returning to tech (even if it wouldn't have made a difference in this particular case).

GF low is irrelevant for NDL dives. It also still won't really affect any plausible profile with ~20-30mins of deco and EAN50 as the deco gas. 10/20/30/50/60 GFlow is still irrelevant as your first stop is dictated by the gas switch anyway. If you end up doing long "shallow" dives (eg 100ft for 60mins) with O2 for deco then it starts to matter a little bit while still within the T1/intro deco level max 30mins deco paradigm.

Only >30mins deco and 2 deco gases is where different GFlow choices have an ever increasing influence. Once you're counting TTS in hours your GFlow choice now going to make a big, potentially measurable, difference.