Human Survival at Extreme Pressures

[paradichloroawesome]

I was just pondering about pressure and it's effects on the body when a thought struck me: Would it be possible to very gradually increase the atmospheric pressure on a human so that they could survive in an extreme pressure environment.

 

I imagined a situation like this:

A deep sea laboratory where the pressure started at normal atmospheric levels and increased over time (weeks, months, years?) until the air pressure inside was equivalent to the water pressure outside and the subject would be able to swim in the water without a bulky dive suit.

 

Would this be possible or does the human body have a limit to the pressure it can withstand no matter the rate of pressure change.

[Cap'n Refsmmat]

What you describe exists; it's called a diving bell. Similarly, there are underwater habitats like Aquarius which can be kept at high pressure.

 

One has to change the air mixture breathed at depth; you don't want to breathe pure nitrogen and oxygen at high pressures, so they often use a blend of helium, nitrogen and oxygen in various proportions.

[paradichloroawesome]

What you describe exists; it's called a diving bell. Similarly, there are underwater habitats like Aquarius which can be kept at high pressure.

 

One has to change the air mixture breathed at depth; you don't want to breathe pure nitrogen and oxygen at high pressures, so they often use a blend of helium, nitrogen and oxygen in various proportions.

 

Aha, that's cool. I knew of the diving bell but wasn't aware that it functioned at high pressures.

 

I wonder if that principle holds true at all depths of water and pressures.

Edited February 15, 2012 by paradichloroawesome

[Externet]

The human blood absorbs more nitrogen at higher air pressures causing several adverse effects.

 

The high andean natives's blood captures triple oxigen amounts breathing, it is something they developed trough generations to counteract the thinner atmosphere.

 

As a guess, would take a loooong time to evolve in a similar way to battle the effects of nitrogen narcosis in the situation you describe, and to limited amount. Your "extreme environment" depth speculation would likely be impossible even for several generations.

Diving tables tell to avoid beyond 1 hour at 20 metres depth.

[Moontanman]

Aha, that's cool. I knew of the diving bell but wasn't aware that it functioned at high pressures.

 

I wonder if that principle holds true at all depths of water and pressures.

 

No, there are real limits to depth and pressure tolerance but the limits are very extreme, at some point the gases you would be breathing would be so dense your lungs couldn't physically handle them.

 

The human blood absorbs more nitrogen at higher air pressures causing several adverse effects.

 

The high andean natives's blood captures triple oxigen amounts breathing, it is something they developed trough generations to counteract the thinner atmosphere.

 

As a guess, would take a loooong time to evolve in a similar way to battle the effects of nitrogen narcosis in the situation you describe, and to limited amount. Your "extreme environment" depth speculation would likely be impossible even for several generations.

Diving tables tell to avoid beyond 1 hour at 20 metres depth.

 

This time limit has more to do with the decompression needed and the toxicity of nitrogen than a physical intolerance to the pressure. Mixed gasses like helium oxygen mixtures avoid this toxicity of nitrogen and make decompression easier.

[GamerColyn117]

I feel like this is a very good question. I see what you are trying to say here. Like a frog in boiling water. You increase the heat a little bit over time so they get used to it, or like in the shower when you gradually increase the temperature because your body adjusts to it.

 

I think that it may be possible to do this, but like the others have said, I think there would be a point where the pressure would be TOO high and your lungs would most likely stop working. This is a very good question though.

[John Cuthber]

gas viscosity is independent of pressure to a good approximation.

You don't need 20% O2 in breathing mixtures.

If the lungs are a bit less efficient then you can raise the O2 concn to compensate. I suspect other problems would limit the pressure people can survice. I think there's a direct effect of pressure on the nerve synapses

[CaptainPanic]

No, there are real limits to depth and pressure tolerance but the limits are very extreme, at some point the gases you would be breathing would be so dense your lungs couldn't physically handle them.

I think I read somewhere that, if sufficiently oxygenated, you could theoretically breathe liquid. The reason you drown in water is not because the water is too dense... it's simply because your lungs cannot extract oxygen from water efficiently.

 

Here's a wikipedia page about liquid breathing.

And here's an article about a mouse who was breathing liquid.

[Leader Bee]

You actually beat me to it Captain, just as I was about to mention perflurocarbons I see your post!

 

From what I understand though, the technology isn't fully developed; While you can breathe the stuff it's the fact were still struggling to come up with a mixture we can just as efficiently extract oxygen from as we can air. The main reason liquid breathing exists however is to lower the differences between the densities in your body and the densities in your body cavities (I.E your lungs) for high pressure diving because liquids are much more difficult to compress than gas, giving the liquid breather better tolerances to depth and pressure.

[John Cuthber]

My body seems to work just fine with a difference in density between the contents of my lungs (about 1.2 g/ litre) and the stuff the rest of me is made of (roughly 1000 g/litre).

If you double the pressure that difference gets smaller.

If air strictly followed the ideal gas laws the air would have the same density as my lungs at about 800 atmospheres pressure.

 

Filling them with a fluorocarbon (density about 1900 g/litre) would be rather pointless: the difference in density would be worse than with air at well over a thousand atmospheres. The liquid is also probably something like 100 or 1000 times more viscous than air.

The deepest dives are about 1000 feet

At that depth the pressure is something like 30 atmospheres.

 

The bottom of the Mariana trench is about 11,000 metres so, at the bottom the pressure would be something like 1,100 atmospheres.

So, if you were scuba diving at the deepest part of the earth's oceans the air would be less dense than the fluorocarbon liquid.

 

For very deep diving there might be advantages to using liquid breathing, but there would also be massive problems.

[alan2here]

Can low presures be achieved in the same way? How long does it take for all the air caught in enclosed spaces inside the body to make it's way out? Do all of a persons cells for example need to be alloud to devide?