Diving after DCS

[therookie]

He also has a lifelong history of migraines, with occasional aura, which is often associated with PFOs.

Hello @hiker11. I can't comment based on experience with DCS and PFOs, but I also have a lifelong history of migraines with occasional aura. Like the two of you now, I'm also a two-tank-per-day-max kind of "older diver".

No-one has touched on this so far so I just wanted to add that my personal rule is to scrub a dive morning if I have a headache, no matter how slight, because for me they can quickly escalate without warning, which causes all kinds of stress on my system that I just don't need underwater and could possibly contribute to DCI.

Roatan is just far enough away from where I live that I can't dive there as often as I would like, but it has the advantage of an on-island chamber with a good reputation, which only adds to its appeal for me as a dive destination. You didn't specify what you meant by "not too far from a chamber" but for me personally I would be uncomfortable with anything over an hour away from the dive site. Which yes, limits my choice of dive destinations considerably, especially when combined with my above rule about scrubbing a planned dive if I am suffering from something as simple as a minor headache.

I believe there are other dive destinations in the Caribbean with similar easy, quick access to a chamber. Unfortunately it probably no longer compares to the Pacific in terms of underwater beauty (and perhaps never did), but I will take what I can get...

 

[kinoons]

The test my husband had was a Transthoracic Echocardiogram. Quoted from the report: "An agitated saline study (bubble study) was performed with and without Valsalva, and was inconclusive in determining if a small shunt (PFO) is present."

You're most welcome, and thanks for clarifying what type of PFO test he had. TTE with agitated saline aka bubble contrast is what we normally recommend for PFO testing for divers, though some cardiologists prefer transesophageal echo. An inconclusive result isn't the same as not having a PFO, and it sounds like you all are proceeding as if he does have one, which seems reasonable.

I’m only passingly familiar with reading echo reports, and mainly for ventricular function when I do in the ER.

How often do you see Echo reports for PFO with clinical fence sitting from the radiologist like hiker’s husband report? Cannot exclude if a small PFO is present? So you can exclude if a large one is present? How small of PFO can the radiologist not exclude? Is there any size that, from a diving perspective, becomes non-clinically significant?

Is the result “inconclusive if small shunt (PFO) is present” a common result? Is it a technical limitation of the echo procedure itself, the skill of the person performing the echo, or is finding a small PFO that technically difficult?

I guess the short question to my long post is how likely is a small, but clinically significant PFO, to be present when you are handed a read like that by radiology?

 

[Maolli]

the term "O2 exposure" is usually reserved for long periods of moderate PPO2.

This is news. At least to me.

I was unaware that O2 exposure due to prolonged periods of breathing EANx within appropriate depths is given considerably more importance than O2 exposure from exceeding the MOD and thus the PO2 for the particular gas blend.

Do you have a source for this?

 

[davehicks]

This is news. At least to me.

I was unaware that O2 exposure due to prolonged periods of breathing EANx within appropriate depths is given considerably more importance than O2 exposure from exceeding the MOD and thus the PO2 for the particular gas blend.

Do you have a source for this?

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Honestly trying to help here. You should read this book to get a better understanding of the science instead of blaming others for your misunderstandings.

 

[GiraffeMarineSalvage]

In addition to following individualized medical advice from the right doctors knowledgeable of dive medicine and striving to be very conservative one's dive computer settings + near a chamber, adequate hydration is a practically free and potentially priceless consideration for helping to reduce risks of developing DCS... (Effect of Water Amount Intake before Scuba Diving on the Risk of Decompression Sickness - PMC)

 

[Duke Dive Medicine]

I’m only passingly familiar with reading echo reports, and mainly for ventricular function when I do in the ER.

How often do you see Echo reports for PFO with clinical fence sitting from the radiologist like hiker’s husband report? Cannot exclude if a small PFO is present? So you can exclude if a large one is present? How small of PFO can the radiologist not exclude? Is there any size that, from a diving perspective, becomes non-clinically significant?

Is the result “inconclusive if small shunt (PFO) is present” a common result? Is it a technical limitation of the echo procedure itself, the skill of the person performing the echo, or is finding a small PFO that technically difficult?

I guess the short question to my long post is how likely is a small, but clinically significant PFO, to be present when you are handed a read like that by radiology?

I've seen it before but not frequently. With the disclaimer that I'm not a provider but channeling one here: if I wanted more specifics I'd probably contact the reading radiologist. Depending on exactly why it was inconclusive we may give the patient the option of either assuming a PFO was present, re-doing the test, or possibly moving to TEE.

Best regards,
DDM

 

[Duke Dive Medicine]

Me? I don't eat gummy bears. This isn't about me or how I plan my dives. I was quoting another diver who said O2 exposure doesn't matter with single tank rec divers. He didn't specify that only certain types of O2 exposure don't matter and that what he said only applies if they breathe at a faster rate. If he did we wouldn't be having this conversation about the different ways that divers can possibly be exposed to excess O2.

Please stop arguing semantics. It's derailing the thread. From your posts it doesn't appear as if you misunderstand O2 toxicity, but I think it's being interpreted that way because you're clinging to a particular phrase. What was said about O2 exposure in this thread is related specifically to the OP's situation. If she and her husband are making recreational, no-stop nitrox dives to 60 feet and shallower, then their exposure to the potentially toxic effects of oxygen is next to nil. That does not apply to every diver everywhere and I think we can all agree on that.

Best regards,
DDM

 

[dmaziuk]

No, that is incorrect. What was said about O2 exposure was directed at all recreational divers.

Which is why I take issue with it.

I have placed the offending part of that post in bold typeface to clear up the apparent confusion.

Interestingly enough, ChatGPT says the most commonly used blend is EAN32. I wonder where it got the data, but assuming it's true: at 1.4 it has MOD of 34 msw so you could overshoot your MOD if you go down to 40 msw. Of course if you live dangerously and set your PPO2 at 1.6 you have nothing to worry about. Same goes for EAN36 at 1.6: you can overshoot your MOD, but you have to go down to the RSTC depth limit too -- e.g. on a typical Caribbean reef dive this is not going to happen often since most of the stuff to see there is in the 25-ish msw range anyway.

Figuring out whether you can rake up significant pulmonary toxicity during an average 7-10 days diving trip is left as an exercise to the reader. (And I hear there are questions on how they count that, too.)

 

[lizardland]

[EDIT] Deleted as it was not helping but I enjoyed saying it

 

[Brett Hatch]

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A ScubaBoard Staff Message...

Hello. This thread is about a specific diver with a specific issue. Some off-topic posts regarding the definition of O2 exposure vs O2 MOD have been removed. Please stick to the topic at hand. And, keep in mind that the Diving Medicine Q&A enjoys special rules, in particular, this is a friendly and flame-free environment

If you would like to discuss the difference between O2 MOD (related to short durations of high O2) versus CNS O2 exposure (related to long durations of less O2), start a new thread for that. The Advanced Scuba forum or the Technical Diving forum might be more appropriate

Thanks

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