Blood Pressure Under Water

[MidOH]

None of the ones I've seen, treated, evaluated, studied or reviewed over nearly 35 years in Navy diving, diving medicine, and accident analysis were related to stupidity. This is the type of thinking and judgemental talk that (a) has no place in a learning zone and (b) actually detracts from diving safety. If you'd truly reviewed accidents from a human factors perspective, you would understand this. Kindly review the rules of the learning zone.

Best regards,
DDM

Lol. Not much of a teacher, are you.

Right. The smart, educated, expert diver, who forgot to exhale on a CESA......Really drives home the point.

That's so much easier to imprint onto anothers mind.

Maybe, for learning purposes, we should also reduce the injury to a nosebleed. Not death. Because it's so scary. Don't want to be a mean bad scary doctor. My mistake.




That being said, air embolism, seems the most likely "heart seizure", type thing.

Nobody looked at the two elderly men that died of plain old regular heart attacks, and assumed it was anything other than natural.

I don't think it's fair to say "scuba causes more heart attacks". But a heart attack underwater isn't survivable like it might be on land. Or in the case of embolism 's, just be smart, pull it together, and say "ah".

 

[boulderjohn]

What happens when you have a heart seizure?


In about 80 percent of cases with seizures where the heart is affected, the heart speeds up after a seizure. This heart rhythm is known as sinus tachycardia and can cause heart palpitations.

I didn't know the exact terminology in my original post. This is what I found on Google.

I still do not understand the question. If you have a seizure under water and your heart develops palpitations, then I have never heard of it being called a heart seizure. If you have a seizure under water, heart palpitations are not an issue, because you are likely drowning.

I googled the phrase "Heart seizure" and got nothing. Could you provide the link you found?

 

[Duke Dive Medicine]

Not much of a teacher, are you.

Are you teachable? <edit: That is to say, are you open-minded enough to consider breaking your mental model of this? >

I don't know you and I realize this may be an oversimplification, but I wonder if your thought process originates in an understanding that an AGE is a serious injury and you really don't want one (not that anyone does), so your mind goes, only stupid people get AGEs, I'm not stupid, therefore I won't get an AGE. You adhere to this viewpoint because you think it keeps you safe. If your dive count is accurate, you may have also been taught this and it's still stuck there. This is an understandable thought process, and it's not uncommon.

The rub is that it actually keeps you less safe. Human error that leads to injury to oneselve or someone else is not equivalent to stupidity. At this point in the conversation you may not believe me. If that's the case, please at least pick up Gareth Locke's book, "Under Pressure", and give it a read.

FWIW the individual who asked the question about "heart seizures" clarified, and it was not a question about gas embolism.

Best regards,
DDM

 

[Duke Dive Medicine]

What happens when you have a heart seizure?


In about 80 percent of cases with seizures where the heart is affected, the heart speeds up after a seizure. This heart rhythm is known as sinus tachycardia and can cause heart palpitations.

I didn't know the exact terminology in my original post. This is what I found on Google.

I'm struggling to tie this in with the original poster's question and the topic of the thread. That said, sinus tachycardia is an adaptive heart rhythm. When the body is under stress, the heart speeds up. If you've done vigorous physical exercise, you've experienced sinus tachycardia.

A seizure could result in sinus tachycardia, but "heart seizure" would not be the right way to characterize this. Seizure could also result in sinus bradycardia (slow heart rate). Of more concern under water would be the seizure itself - seizures while diving typically end in severe injury or death.

Best regards,
DDM

 

[MidOH]

Are you teachable? <edit: That is to say, are you open-minded enough to consider breaking your mental model of this? >

I don't know you and I realize this may be an oversimplification, but I wonder if your thought process originates in an understanding that an AGE is a serious injury and you really don't want one (not that anyone does), so your mind goes, only stupid people get AGEs, I'm not stupid, therefore I won't get an AGE. You adhere to this viewpoint because you think it keeps you safe. If your dive count is accurate, you may have also been taught this and it's still stuck there. This is an understandable thought process, and it's not uncommon.

The rub is that it actually keeps you less safe. Human error that leads to injury to oneselve or someone else is not equivalent to stupidity. At this point in the conversation you may not believe me. If that's the case, please at least pick up Gareth Locke's book, "Under Pressure", and give it a read.

FWIW the individual who asked the question about "heart seizures" clarified, and it was not a question about gas embolism.

Best regards,
DDM

All I'm saying is that someone that holds their breath and races to the surface, ruining everybody's diving for weeks, isn't a brainiac. That's very very very stupid.

And should be used as an example to teach others.

But every week, the current status quo of "experts" fails to teach this.

 

[Duke Dive Medicine]

All I'm saying is that someone that holds their breath and races to the surface, ruining everybody's diving for weeks, isn't a brainiac. That's very very very stupid.

And should be used as an example to teach others.

But every week, the current status quo of "experts" fails to teach this.

That sounds like the voice of experience. If so, I'm sorry that happened.

I'm not married to changing your thinking here, but I do have a vested interest in enhancing divers' safety mindsets, including yours. If this is interesting to you as well, please read on.

Diving accidents are used for teaching all the time. So are medical errors. We break them down into their components, look at all the external and internal factors, and understand that sometimes human beings act like human beings and make errors, and also that those human beings function within systems that are designed by human beings. Your example of the diver who has a panic ascent and experiences an AGE could mean that the diver wasn't adequately trained or prepared for the dive, lost situational awareness because of excess task loading, and forgot to check his/her gas supply.

There are countless analogous medical errors. The RaDonda Vaught case is one. The route that was taken was to blame the single offender, which is what you're suggesting; as I said, your viewpoint is not uncommon. The reality was much more complex.

Again, please consider picking up Gareth's book, if for nobody but yourself. Enjoy the rest of your weekend.

Best regards,
DDM

 

[boulderjohn]

When a diver is not getting air for whatever reason and the carbon dioxide builds up, the diver will begin to panic. (When someone is smothering you and you feel horrendous panic, the panic is the result of CO2 buildup.) When you panic, you will not necessarily make the best choices. I know of cases where very highly experienced CCR divers felt panic because they were overbreathing their scrubbers in a difficult situation, and they had the sense to wait motionless until their CO2 levels dropped. Open circuit divers do not have that luxury, and they have to make instant decisions. That is the importance of training. When something goes wrong, you need the proper training to make the correct choice under pressure.

When the joint PADI/DAN project identified rapid, panicked ascents (usually in OOA situations) as a major cause of fatalities, PADI instituted training changes to try to help. They greatly improved the buddy training during the pool sessions, and they included emphasis on awareness of gas levels. That should help, but I strongly suspect that a lot of instructors are not fully following those procedures in class, since they require spending ample time swimming around the pool area to ingrain the habits.

As I have written countless times in threads like this, the biggest training problem leading to bad decisions is the way we teach the CESA in the pool sessions. We require students to swim horizontally for 30 feet "at a normal ascent rate" wile exhaling all the way. When I was certified as an instructor, I was told not to use the phrase "normal ascent rate" too literally--it can and should be faster. Taken literally, a normal ascent rate means students must exhale for at least 30 seconds while not getting the benefit of expanding air as they would in a normal open water CESA. Even when it is done diagonally from the deep end to the shallow end, it is very difficult to do it, and instructors rely on artificial means to get the students to pass (hyperventilating, exhaling so little that it is close to holding the breath).

So what is the lesson students get from this? I could never do it in a real case unless I hold my breath. For proof, just go to the countless threads on this topic ScubaBoard over the entire time of its existence and see how many of them focus on the impossibility of doing a CESA from anything deeper then 20-30 feet. In every thread you will see people suggesting taking freediving lessons to improve their ability to hold their breath so they can do a CESA from deeper depths.

It is clear to me that the way we train students for the CESA increases the likelihood they will not do it right and will hold their breath during an OOA ascent. No matter what we may say in the classroom, our instructional technique teaches them to do it incorrectly.

 

[dmaziuk]

I didn't know the exact terminology in my original post. This is what I found on Google.

Perhaps you are thinking of a core BP spike from getting into cold water after thoroughly heating up topside?

 

[dmaziuk]

... In every thread you will see people suggesting taking freediving lessons to improve their ability to hold their breath so they can do a CESA from deeper depths.

That would be dumb, to put it charitably. Suggesting that people take freediving lessons to improve their comfort underwater without gas blowing into their mouth, so that they are less likely to panic when OOG, OTOH ...

 

[boulderjohn]

That would be dumb, to put it charitably. Suggesting that people take freediving lessons to improve their comfort underwater without gas blowing into their mouth, so that they are less likely to panic when OOG, OTOH ...

It may seem dumb to you, but for a very large number of people responding to threads about how deep you can do a CESA, the primary factor is your ability to hold your breath. It does not seem dumb to them. That's the problem.