What are the limits for saturation diving?

[JT2]

After watching a program last night about an underwater study lab that rests in 63fsw in which scientists will spend 10 days at a time living in and working outside of the habitat using SCUBA, it got me thinking about saturation diving operations. I was wondering what the limitations were as far as how long it is safe to stay saturated before we as humans start having any type of side effects, and what types of side effects are there, also would I be correct in assuming that these side effects would depend on the depth at which the saturated subject was living? Have there been any studies done on the effects of people living in a pressurized environment for prolonged periods of time, and if so what were some of the things found that were considered most harmful, and were there any physical benefits to living in this type of environment? I know this isn't really a diving specific question, but it has really got me curius. Thanks!

 

[Bob3]

Cousteau also had his CONSHELF project, the USN had their SEALAB projects, & there have been several other interesting studies/projects involving extended saturation living. Depths ranged from 33 feet to over 600.
NASA and NOAA got on the bandwagon as well with the TEKTITE projects.
There don't seem to be any serious drawbacks to staying saturated for long periods of time.
The main physical benefit is that you only have to decompress once.

 

[Dr Deco]

Dear Readers:

Human Deep Saturation

When the dives become very deep, that is, beyond several hundred feet, they will all end with a saturation-type decompression schedule. This means that the decompression ascent rate will be on the order of 100 feet per day. Thus we are really looking at how deep have divers gone. As far as I am aware, the current record is by the French diving company Comex in a chamber dive. During a portion of the bottom time, they went down to 2278 feet.

Animal Studies

The French also dove a pig to 5,000 feet and returned him safely to the surface, if memory serves me correctly. Monkeys have also gone to 5,000 feet but were euthanized and not returned alive.

Dr Deco :doctor:

 

[JT2]

Hey Doc, do you know where I might be able to find some good reading on this topic?
I guess the test with the monkey was considered a failure huh?

 

[Dr Deco]

I am not aware of anything in the literature. On the www, one might find something under "comex."

The monkey was alive and well at 5,000 feet. The scientist considered it a success - the monkey thought it was a flop.

Dr Deco=-)

 

[joens]

ther is a bookstore on the web with a HUGE selection of books on the topics of saturation diving ,commercial diving undersea habitats etc. www.bestpub.com

 

[Alban]

Hello all

It would seem all manner of creatures are used for testing , from crabs to the famous goats . As I understand it pigs are genetically very close to humans ,theoretically the major organs could be transplanted to humans and infact some parts which can be cleaned from cross contamination are . I would assume if the organs are similar then blood flow would be also and therefore any results could be comparable to humans ?

I was considering the difficulties in compressing animals such as equalising , pigs are intelligent but I am not sure they could perform a valsalva manuava , so I guess they are compressed slowly to prevent stress , something which they are subseptical to . Living bodies seem totally dynamic with so many variables , actions and interactions that it must be impossible to control such tests and reach conclusive results .

The smaller creatures used in testing would also be subject to the formation of micronuclie , would this be proportionately smaller than the 0.1 - 1 microns found in humans or is it relative to the total volume ? One last question if I may, do different biomolecules which form surfactants have differing properties such as applying more or less surface tension ?

This is probably all way over my head and is a result of a few days holiday , unfortunatly the rest of my holday has been mapped out for me and involves much DIY work :bonk:

Thanking you Alban

 

[Alban]

On a lighter note perhaps this will amuse and interest you

http://news.bbc.co.uk/1/hi/health/330807.stm

Best wishes Alban

 

[Dr Deco]

Dear Alban:

Similarities - - -

Pigs are similar in their circulatory system to humans in terms of response to stress. They have been used for research in barophysiology, especially the small breeds. Clearly we are not talking about a huge 500-pound barrow. One advantage of pigs is that they will do anything for food - throw down some to eat and they will follow you anywhere. They are somewhat like the animal version of Shaggy in Scooby Doo.

Equalizing

Mammals have an inner ear and do have equalization problems. Taking them on an initial “familiarization dive” with a slow compression easily treats this. You can see them shaking their head which apparently is the trick in the animal world. After this initial chamber experience, they can be dived at sixty feet per minute. It is necessary to watch them, however, as sometimes they can have a problem, just as do human divers.

Micronuclei

Smaller animals are more resistant to decompression sickness. Probably this is the result of a high perfusion (= faster blood flow) in their organs. It could also be the result of smaller tissue micronuclei than humans. The answer is to known (but perfusion is the better guess).

Do different biomolecules which form surfactants have differing properties such as applying more or less surface tension ?

It is known that biomacromolecules in the body differ with respect to their surfactant properties. The surfactants of the lung alveoli will produce a surface tension as low as 0.5 dynes/cm. This helps to keep the small air sacks from collapsing. Such surfactants are not found in the blood, however. The surface tension of blood does vary from individual to individual to some degree. It might be that this difference along with the number and size distribution of nuclei accounts for part of the difference individuals display toward decompression.

Dr Deco :doctor: