my DCS Hit

nicolite

This is along the same lines of thought that I have. I think most dive computers have ascent rate warnings but leave the surface interval at the diver's discretion. Perhaps what would be good is if dive computers include some sort of algorithm that computes the duration and depth of the last dive(nitorgen loading) and then warns the diver if he is starting on another dive with insufficient surface interval.

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jepuskar

Yes, but wouldnt insufficient surface interval be based on what the next planned dive is??

jhaaja

The saw tooth on the first dive was not good for the deco and neither was the second dive after 1 hour. I would have rested the rest of the day. It is more OK if you do a shallow dive before a deeper one. The deco from the deeper dive will clear any residual inerts from the first shallow one.

Glad you are OK!

JH

gtzavelas

Guys, the fact that the hit was probably caused by the bad profiles is obvious, please read the conclusion of my post:
in fact at the end of the first day I said to my buddy:"if i dont get bent today,i will never be" (big mouth eee?), and was almost "surprised" that I didn’t have any symptoms….

What is surprising (and a possible lesson) is that after 48 hours, when I thought I was clear I did the dive and got bent…

the point that z is making is interesting , as indeed maybe if there was a portable dopler (and someone that could use it!) and I was tested at the end of the first day (or even the next one?) it could be seen (maybe) that I was not clear at all…

It would seem reasonable now after the incident that I would have some (even mild) symptoms at the end of the first day that I just didn’t register..

SteveJ

Sorry, but have to clarify this. Standard teaching is that there is an increased risk of DCI by doing reverse profile dives. I don't think that the evidence for this is particularly robust ( and I've just traced the conclusion from the DAN symposium of 1999) but I'm pretty sure that there is no evidence for the contrary arguement that it is safer to dive shallow than deep. If you have such evidence, please share with me.

A symposium on reverse dive profiles was held in October 1999 in Washington DC, at the Smithsonian Institute, co-sponsored by DAN, DEMA and others. The Reason was to substantiate with scientifically sound findings the current statement by many Training Agencies that reverse dive profiles are not recommended due to an increased risk of DCI. The conclusions of the workshop are the following:
"The Findings
1)Historically neither the US Navy nor the commercial sector have prohibited reverse dive profiles
2)Reverse dive profiles are being performed in recreational, scientific, commercial and military diving
3)The prohibition of reverse dive profiles by reacreational training organizations cannot be traced to any definite experience that indicates and increased risk of DCS
4)No convincing evidence was presented that reverse dive profiles within the no-decompression limits lead to a measurable increase in the risk of DCS
The Conclusions
We find no reason for the diving community to prohibit reverse dive profiles for no-decompression dives less than 40 msw (130 fsw) and depth differentials less than 12 msw(40fsw)."

In simpler words, if diving is performed within the no-d limits and the different dives are done within a maximum difference of 12 meters, the current evidence does not show any demonstrable increase in risk of DCI.

But this doesn't infer that reverse profile is safer.

Janos

I agree that the profiles of the first, unsymptomatic dive are 'more-dodgy' [1] than the symptomatic dive. But this doesn't mean that they necessarily caused the bend. You could have just been 'lucky' on the first dive and 'unlucky' on the second.

You also have a large spike in the symtompatic dive, as you ascend from 100m to 60m, then back down again. This would worry me if I were doing this dive.

Janos


[1]- Obviously no-one really knows what a perfect profile looks like.

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sasmedic

HI there!!

I must say that I admire your courage to share this experience on the site. I think a couple of divers will definately learn from your experience. I also want to congratulate you on complying to go to a chamber and VERY important also is your actions of in water recompression (IWR), O2 admin and rehydration BEFORE going to the chamber!!! I think your actions is what caused your recovery to be so successful (the Dr may think otherwise) after the hyperbaric therapy?

It is interesting that you still displayed denial even after a dive to such a significant depth!! I your case it seemed that you where given good advice from fellow divers??

Just a few questions and comments if I may???

Based on the diagnosis of mild type 2 in the knees, I doubt that the 1st dive was the cause because of the long interval between the wednesday and the monday. If you bent due to the monday dives I am fairly certain that you would have bent sooner. Especially if you look at the presentation of the symptoms after the wednesday dives. The profile of the monday's first dive (referring to the 50m bounce late in the dive) almost resembles a technique in IWR called a deep-spike if I remember correctly. Not sure about the gasses before such a procedure and so on but at least that is what it look like??

You second but shallow dive may have served as further recompression therapy but could also cause more ongas of nitrogen which raises the question (or answers it wrt IWR) on why you did not show symptoms earlier than that wednesday dive?!

The why or what question (that someone asked) wrt to your dive is important to determine what kind of exertion you where exposed to during your dive! If you think back and compare the two deep dives what was the difference between the two ito what you did at depth (and I agree that the depth is very significant in your case!!). If I can fathom a conclusion to this question I guess it is evident when you look at the saw profile on your second dive? It seems that there was hard swimming involved (with stages) which could be responsible for the onset in your knees???? Maybe you could elaborate more on that in retrospect, if you do not mind?

Based on these comments I am not sure about the conclusion that you mentioned? Did you or the Dr make the probable conclusion?
Are there any reason why you did not do deep stops??

Which recompression profile did you do follow in the chamber?? (Duration and O2 versus air breaks intervals)

Regards and well done once again on your after symptom actions!!!

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jhaaja

Is there any evidence that forward profiles are better? Thinking the physiological events during diving I would think that reverse profiles are better. The difference is not big if you are diving say max 40m depth and sort dives. But it is bad if you do a serious decodive and after that for example a small dip to 10m or so. There is evidence of DCI after that kind of dives.

JH

PaulTG2

Hello,

Where do they believe the bubble that caused the problem ended up? Was it still in the knee/vienious systems of did it migrate and become an AGE? If the latter did they recommend a check for a PFO?

-p

gtzavelas

Sasmedic an the rest thanks for the feedback, that’s exactly the reason i did the post, so everybody (including myself can learn something).
I ll try to answer the questions:


The advise I got from my fellow divers was great: to go to the habitat, although I was inclining not to go, so the credit should go to them for pushing me.


The second deep dive was much more strenuous than the first: more hard swimming with stages. Also on the second dive I was more stressed and much more tired.
I guess a knee bent could be correlated with hard swimming, so you may have a point here…

Actually the conclusion came from the doc

I did all the deep stops (RGBM+2 produces really deep stops), maybe the resolution of the profile is not good but my 1st stop was around 80 meters


The first ride was around 3 hours 100% starting at 9 meters for 100 minutes maybe and going up at 8 and 6 , (no air breaks at all !!!). The doc examined me after the 100m at 9 meters and was surpised to see i was recovering very fast. Actually he said that my good physical condition helped a lot as the response they see from fit individuals is much much better
The 2 others were standard 100 minutes at 100% if I recall at 8 meters (no breaks)
That’s very approximate as I don’t recall exactly


the doc said that this spike by it self should not be considered a problem (of could one could argue that there was not 1 main reason for the hit but many additive small reasons…