Shallow- and Deep-Water Blackouts

[Arubandi07]

I agree, but then we're not all as blood thirsty as some.

No need for blood, I've experienced what Hank described, pursuing the totally 'benign' activity of UW-photography ...

Love the 'Zone' ...

 

[Hank49]

No need for blood, I've experienced what Hank described, pursuing the totally 'benign' activity of UW-photography ...

Love the 'Zone' ...

I have two stepsons, 9 and 12 years old. Both are really getting into spearfishing. Their bio father was a real hunter who disappeared on a week long trip back near Victoria's Peak, so it's in their blood. But in training them, I don't want to carry a gun so I can focus on them and what's there. But I DO want to carry my GoPro.
You're absolutely right. Getting close is getting close. It's the same skill whether camera or gun.

 

[TSandM]

No, what I was saying is that pulse ox measures the saturation of hemoglobin . . . and hemoglobin is essentially fully saturated at .21ATA in a person with normal lungs. There is very little additional oxygen CONTENT in the blood at higher ATAs. If you are using a pulse ox to tell you when to begin to ascend, the saturation is not going to begin to decrease meaningfully until you hit the upper bend of the sigmoid curve, and at that point, saturation is dropping very fast. Because of the long plateau at the top of the curve, pulse ox just wouldn't be very useful in the application you're envisioning.

 

[FPDocMatt]

No, what I was saying is that pulse ox measures the saturation of hemoglobin . . . and hemoglobin is essentially fully saturated at .21ATA in a person with normal lungs. There is very little additional oxygen CONTENT in the blood at higher ATAs. If you are using a pulse ox to tell you when to begin to ascend, the saturation is not going to begin to decrease meaningfully until you hit the upper bend of the sigmoid curve, and at that point, saturation is dropping very fast. Because of the long plateau at the top of the curve, pulse ox just wouldn't be very useful in the application you're envisioning.

So what you're saying is that if I put a pulse ox on my finger and hold my breath, it won't drop appreciably for two minutes? I gotta try this out. ===>

Okay, I was able to hold my breath for 1 minute, and the pulse ox dropped from 99 to 98, which means it didn't drop at all.

Okay, I'm going to try this every day, see how long I can learn to hold my breath, and see when it starts dropping.

Despite the shape of the curve, I suspect it will still drop enough that you can figure out the right time to surface. But I could be wrong.

 

[TSandM]

In my difficult airway course, they told us that a preoxygenated young, healthy person can be apneic for about four to six minutes before they'll begin to desaturate. It'll be a little shorter for someone who isn't prebreathing 100% oxygen, but not a whole lot. The fact that you CAN maintain saturation for that long is the whole reason that freediving is possible. You can't fight physiology, and if the ppO2 falls much below .16, you are going to black out. So the essence of apnea diving is that, if you can learn to tolerate the elevated pCO2, you have quite a bit of time to remain conscious and functional before the ppO2 drops to dangerous levels.

 

[ImmersionFreediving]

Matt a much safer method is to take a freediving class, and ALWAYS dive with a trained buddy

You can probably hold into the 1:30 -2:00 range before you see any drop. Here is why it doesn't drop for a while. Hemoglobin comes to the lungs loads up on O2 and then makes a trip through your body dropping of the O2. Once it makes it back to the lungs there is still enough O2 in the lungs to fill up. This happens over and over again. While the O2 level in the lungs are dropping there is still enough for the hemoglobin to get fully saturated. At some point when there is less and less O2 in the lungs, the hemoglobin can't "fill up" so it can't carry all the 02 that it could. With most people once it starts to drop it will drop quickly.

 

[Arubandi07]

I have two stepsons, 9 and 12 years old. Both are really getting into spearfishing. Their bio father was a real hunter who disappeared on a week long trip back near Victoria's Peak, so it's in their blood. But in training them, I don't want to carry a gun so I can focus on them and what's there. But I DO want to carry my GoPro.
You're absolutely right. Getting close is getting close. It's the same skill whether camera or gun.

Guess, the one big difference is, that you still gotta handle that fish after getting the shot, pretty physical affair, I imagine ...

On the upside, you get to eat what you shot ... Not, that digital memories don't make for a nice dessert ...

 

[Doppler]

No, what I was saying is that pulse ox measures the saturation of hemoglobin . . . and hemoglobin is essentially fully saturated at .21ATA in a person with normal lungs. There is very little additional oxygen CONTENT in the blood at higher ATAs. If you are using a pulse ox to tell you when to begin to ascend, the saturation is not going to begin to decrease meaningfully until you hit the upper bend of the sigmoid curve, and at that point, saturation is dropping very fast. Because of the long plateau at the top of the curve, pulse ox just wouldn't be very useful in the application you're envisioning.

Lynne: fascinating stuff... as a wanna-be free-diver when I was a bit younger, this topic was the seasoning for a few rum-fired evenings.

HOWEVER, is there an Pulse/Ox device that one can use underwater? Surely not...

 

[TSandM]

No, to my knowledge, there isn't -- and where I dive, it would be pretty darned hard to make one, because your fingers and toes are so cold, it would be hard to get any kind of reading, even if you could waterproof the probe!

 

[Arubandi07]

So what you're saying is that if I put a pulse ox on my finger and hold my breath, it won't drop appreciably for two minutes? I gotta try this out. ===>

Okay, I was able to hold my breath for 1 minute, and the pulse ox dropped from 99 to 98, which means it didn't drop at all.

Okay, I'm going to try this every day, see how long I can learn to hold my breath, and see when it starts dropping.

Despite the shape of the curve, I suspect it will still drop enough that you can figure out the right time to surface. But I could be wrong.

Are you conducting your experiment under varying conditions, in terms of physical stress? Talking about 'static' vs various levels of physical activity.