"Undeserved" DCI

[DandyDon]

Don,

It's true that PFO has never been named as a proximate cause of decompression illness, but it is definitely correlated with a few things, some of which are sudden-onset severe neurological decompression illness after dives that were mildly provocative but within the no-stop limits. This description appears to fit these dives. Maybe I'm assuming too much, but if these had been square profiles, I'd think that the original title of the post would have been something like, "We blew our decompression and my husband got bent." I agree that it would be interesting to see the dive profiles, though.

At any rate, I would not categorize the test for PFO as "invasive". In the lectures and presentations given by our own Dr. Richard Moon, he states that a transthoracic echocardiogram with bubble contrast is sufficient to detect a clinically significant PFO. This involves an IV line and an ultrasound probe on the chest. Some cardiologists choose to do a transesophageal echo, which is entirely appropriate and only mildly uncomfortable.

PFO repair is another matter. Depending on where it's done and what type of device is used, the risk of complications can exceed the risk of DCS. For divers with a PFO, the decision to have it repaired should be a well-educated one and should be made in careful consultation with a diving medical specialist and an interventional cardiologist.

Thanks for another well stated post. I guess the PFO test is less invasive than I'd thought. Discussing the possibility with an appropriate physician would seem like a prudent idea, even better - two opinions - and still, be careful what you believe.

Looking at the dives described in post 1 tho, we just do not have enough info for a good answer. Without seeing the dives downloaded from a computer, or even knowing if they had computers, there are just too many possibilities. If square profiles, those dives are well beyond NDLs. Just sounds too much like follow the DM diving without dive planning, charts, etc.

I don't agree with this statement. There are a number of medications that are used to control blood pressure. And among risk factors for which the jury's still out, dehydration is up near the top of the list.

I appreciate that there different meds for BP, but diuretics are common - and discounting dehydration risks surprises me. I've seen that suggested by professionals before here on SB, and that confuses me - as I have always thought that dehydration was a contributing factor for DCS.

 

[boulderjohn]

Thanks for another well stated post. I guess the PFO test is less invasive than I'd thought. Discussing the possibility with an appropriate physician would seem like a prudent idea, even better - two opinions - and still, be careful what you believe.

Unfortunately, the PFO test is for most people invasive of the wallet. It is by itself often not covered by insurance. I have a friend who had a bad DCS hit suggestive of PFO, and he was hesitant to have the test for that reason. I myself had to have the same test for a totally different reason, a reason covered by my insurance. The test itself is not even remotely invasive. The worst part is getting the IV needle.

 

[DandyDon]

Unfortunately, the PFO test is for most people invasive of the wallet. It is by itself often not covered by insurance. I have a friend who had a bad DCS hit suggestive of PFO, and he was hesitant to have the test for that reason.

And most divers with PFOs never end up in a chamber. Additionally, what are you going to do if you find one? Repairs are riskier than DCS, costly - and no guarantee. Most are just going to dive more conservatively either way. Yeah, I'd be nervous regardless after a hit, fearful of another - but this is a hypothetical discussion without closely looking at the 2 - 45 min, 60 ft dives.

 

[Duke Dive Medicine]

If square profiles, those dives are well beyond NDLs.

Concur.

I appreciate that there different meds for BP, but diuretics are common - and discounting dehydration risks surprises me. I've seen that suggested by professionals before here on SB, and that confuses me - as I have always thought that dehydration was a contributing factor for DCS.

Diuretics are commonly prescribed as first-line meds for mild hypertension, but stopping them prior to diving may not be advisable. Re dehydration: I'm not discounting it as a risk factor, in fact it makes good physiological sense, but like PFO, causality hasn't been demonstrated; in fact, I'm not aware of any study that even demonstrate correlation. You can certainly see dehydration post-dive, especially in a diver with a bad case of DCS, but DCS itself can lead to dehydration because of the inflammatory process. So which came first, the dehydration or the DCS?

The statement, "I got DCS because I was dehydrated" gets tossed around a lot, but is nearly impossible to prove. Consider how subjective the phrase "I'm dehydrated" is. To truly demonstrate causality you'd have to come up with a way to quantify dehydration, like an increase in hematocrit of a certain percentage; then, because DCS is so rare in the first place, get an enormous sample of divers with pre and post-dive hematocrit levels and show that divers with an increase of "X"% in hematocrit are at a higher risk of DCS.

Best,
DDM

 

[Hatul]

It would be good if you could post the dive profiles from your husband's computer. The rate of ascent can also be a factor. Though since presumably the two of you were diving together and only he got bent it suggests something peculiar to him.

 

[flots am]

For What it's Worth:

When run as a square profile, vPlanner says you blew off a 5 minute decompression stop on the first dive, and a 14 minute and a two minute decompression stop on the second dive, so if you actually did a mostly square profile, the DCS hit isn't entirely unexpected.

flots.

 

[eelnoraa]

didn't read the entire thread, so not sure if this was mentioned before. Ascent profile can play a role here especially on 2nd dive.

 

[Quero]

Looking at the dives described in post 1 tho, we just do not have enough info for a good answer. Without seeing the dives downloaded from a computer, or even knowing if they had computers, there are just too many possibilities. If square profiles, those dives are well beyond NDLs. Just sounds too much like follow the DM diving without dive planning, charts, etc.

It just doesn't matter, Don, whether the victim followed the DM, planned the dive, used a chart or whatever. Yes, it would be nice to see the computer graphic of the profile, but at this point the injury has been suffered, and from a differential diagnosis perspective, it makes sense to consider PFO as a possibility.

It's also not necessarily true that for every patient with a PFO

Repairs are riskier than DCS, costly - and no guarantee.

I mentioned two divers of mine who both had PFOs repaired recently. One was a stroke victim after diving, and the PFO was repaired as a hedge against future strokes. The other had a bend after only two dives on a liveaboard (rather aggressive dives but within computer NDLs), chamber treatments, and then home to investigate further. His PFO repair was undertaken because according to his doctors he was at a much higher risk for stroke. Keep in mind that stroke kills one third of victims, so the potential complications associated with PFO repair versus the mortality rates of stroke victims makes for an entirely different argument than repairing a PFO only to be able to continue diving. For my two divers, the repair did allow them to continue diving, but more importantly, it was seen to help stave off a stroke. It's a mistake to oversimplify the PFO issue. If a dive accident medical investigation reveals the presence of a PFO, all sorts of factors need to be taken into account in the decision to repair or not to repair, and those factors may have little to do with scuba diving beyond a coincidental relationship.

 

[Mr Carcharodon]

Exercise does increase the number of seed bubbles which could increase the risk of DCS. But the bubbles are thought to decay over the course of a few hours. There may not be specific guidelines for this. But I suspect an afternoon dive after a two hour morning workout would be fine but a morning work plus a dive might not be.

 

[socaljohn]

As someone who hits the iron pretty hard a 3 times a week at my gym I really appreciate this info. I have worked out on a Friday and then dove Sat but I will probably not in the future. I can tell myself lugging my stuff up and down a cliff or to the boat and back count as my workout...
Thanks!