Do you think this could be DCS?

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scubadada

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I gave examples of suunto which uses rgbm as well, depending on user setting, it gives up to 22 minutes less ndl for his average depth. He stated that his mares was set to minimum conservatism. Had he used more conservative setting, which would be more suitable for his personal fitness and diving conditions, this would be probably a decompression dive.
It's all relative. There is little data on the performance of deco algorithms for repetitive dives. The ScubaLab chamber testing is among the little available. DSAT and Buhlmann 45/95 would be considered liberal. Suunto RGBM, Buhlmann 45/85, and PZ+ would be considered moderate/middle of the road, Mares and Cressi RGBM would be considered conservative. Algorithms with adjustments were tested at their most liberal setting.

Not to belabor the point, these were not aggressive profiles
 

Ucarkus

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It's all relative. There is little data on the performance of deco algorithms for repetitive dives. The ScubaLab chamber testing is among the little available. DSAT and Buhlmann 45/95 would be considered liberal. Suunto RGBM, Buhlmann 45/85, and PZ+ would be considered moderate/middle of the road, Mares and Cressi RGBM would be considered conservative. Algorithms with adjustments were tested at their most liberal setting.

Not to belabor the point, these were not aggressive profiles

What do you reckon DAN would tell him, had he took your advice and called them? Like many of us, I too, did way more aggressive dives without any problems and I do not find his profile particularly aggressive. But there is enough insult in that profile for a dive doc to worry given he complained muscle weakness (that is something testable to a certain degree) developing after the dive.
About a year ago, I was on raja ampat explorer, 6 of us did a night dive (4th dive of the day), due to current we went down as deep as 25m. I was diving with a big housing, so it was pretty cumbersome to check my computer (need to press a button to turn the light on), which I did not do so often, but we were diving in a loose group, so, I was not so much bothered by it either. Suddenly I heard the beep from my computer telling me that I am out of ndl. I signaled my buddy and we ascended slowly, rest of the group also gradually followed. Rest of the dive went normal. Most of the others were diving with Aladdin/Bühlmann so they were well within ndl. 1 diver was 75+ years old, 2 of them 65+ but all 3 fit. We all dove more or less the same profile, only difference I can think of is she was slightly overweight.
In the morning I found out that one of the divers, shown signs of dcs and went on land, escorted by another diver. She was on the phone diagnosed as dcs but her condition was not severe enough (skin rush) to fly her to Manado.

Moral of the story is dcs is something very individual. In below links there are other stories most of them with benign dive profiles:
It Happened to Me: Decompression Sickness / The Bends
DAN Europe - Decompression Illness
 

scubadada

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Hi @Ucarkus

I don't think we disagree. Despite being a physician myself, I would call DAN if I suspected I might have DCS, and I suggest that others should do the same. I would not hesitate to go on oxygen therapy in that situation, the response can also be useful in helping make a diagnosis.

What I am saying, is that statistics are useful. All else being equal, who would be at greater risk for DCS, a diver who does not come close to NDL with a conservative computer, a diver who pushes NDL to the limit with a liberal computer, or a diver who skips a significant deco stop with that same liberal computer?

Of course, statistics apply to populations and individuals may be outlier. Individual factors such as exertion, thermal stress, fitness, dehydration, PFO, ..., may alter the equation. In the OP's case, the dives were not aggressive, one factor in analyzing the situation.

I assume you were diving your Suunto in Raja Ampat, Scubapro's version of Buhlmann is also considered conservative to moderate, even without their additional conservative factors in play.

Good diving, Craig
 

Ucarkus

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Hi Craig,
Any diver coming out of "any" dive and showing sign and symptoms of dcs, "has" dcs until otherwise is proven. PADI considers any dive exceeding 18m as deep dive, that makes it a significant dive. I will also quote DAN directly:
"Since DCI is a random event, almost any dive profile can result in DCI, no matter how safe it seems. The reason is that the risk factors, both known and unknown, can influence the probability of DCI in myriad ways. Because of this, evaluation of a diver for possible decompression illness must be made on a case-by-case basis by evaluating the diver's signs and symptoms and not just based on the dive profile."
Decompression Illness: What Is It and What Is The Treatment? — DAN | Divers Alert Network — Medical Dive Article

When we discuss the profile whether it is aggressive or not, we are not helping boiling frog to jump out of the boiling pot. Contrary we are telling the frog it might not be too hot, yet. This is the wrong message I think because it will delay divers to seek advice and get diagnosed properly.

As humans we are peculiar in how we deal with risk and probability. Fact is, dcs is random, all tables and computers have a hit rate, which means that if you do enough diving, you will get bent.
 

scubadada

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Hi @Ucarkus

You would enjoy a look at the SAUL recreational dive planner if you are not already aware of it, a probablistic decompression algorithm SAUL Recreational Dive Planner | Modern Decompression

For example, a dive to 60 feet on air to the NDL of GF high 95, 85, and 75 would have the following risk of DCS:

GF high 95, NDL 51 min, probability of DCS 0.27%, 1/370
GF high 85, NDL 41 min, probability of DCS 0.15%, 1/667
GF high 75, NDL 32 min, probability of DCS 0.06%, 1/1,667

These probabilities include a 3 min safety stop in the profile
 

boulderjohn

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As humans we are peculiar in how we deal with risk and probability. Fact is, dcs is random, all tables and computers have a hit rate, which means that if you do enough diving, you will get bent.
Speaking as someone who did in fact get DCS on a day of diving that was well within normal limits, I concur that there does seem to be some randomness to it, but not to the degree that your sentence implies. Recent research indicates that in the majority of DCS cases, the victims were within normal limits, but there is a statistical quirk to that which should be considered. Saying that the majority of DCS cases happen to divers diving within normal limits is like saying the majority of people dying in Germany are Germans and trying to draw a conclusion from that.The overwhelming majoirty of divers stay within normal limits, and only a very small minority of divers get DCS.

The study (which I am having trouble finding right now and am struggling to remember exactly) indicated that some people are more prone to DCS through their own biology, and it also suggests that there might be a problem in the normal limits in regard to the clearing of mid-range tissues, so even that degree of randomness might not be true. The problem is that doing further study to further refine decompression profiles for NDL diving would be very expensive and hard to do--the gold standard for such a study would be the percentage of divers who get bent, and getting divers bent in a study is frowned upon. I think in general people believe current norms are "close enough."
 

Duke Dive Medicine

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The OP seems to have answered his own question in post #19.

@boulderjohn , was it this article you were thinking about? It's not a study so much as a synopsis of information, but it's a good one as is always the case with Neal Pollock's work.

Updates in Decompression Illness - PubMed

Best regards,
DDM
 
https://www.shearwater.com/products/perdix-ai/

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