Breathing Fluid?

One question that has been bugging me for a while came from that movie, ‘The Abyss’. If I were a diver, and I had to dive that far beneath the ocean, would It
even be possible to breath a ‘Highly Oxygenated Fluid’?

Yes. At least this addresses the “Breathing Fluid” part. The pressure part is another story.

Here is one thread from a few months ago. Comment #3 has links to two other threads on the subject. (As a guest you can’t do a search.)

But as charizard indicated, the breathing fluid is real. In the movie, the mouse was really submerged in it, although the actor wasn’t.

The “oxygenated fluorocarbon emulsion” depicted in the movie The Abyss actually exists, but would not actually be useful for diving as depicted in the movie. Such fluids, while theoretically capable of delivering sufficient oxygen to the lungs, are not capable of offgassing waste carbon dioxide at a rate fast enough to keep up with metabolic demand. IIRC, actual applications of these fluids are in treatment of premature babies or other lung complications where in practice, only one lung at a time is flooded.

To further address the diving at ambient pressure application - oxygen becomes toxic at increased partial pressures. To deal with this problem, divers decrease the amount of oxygen in their breathing mixtures as depth increases. The non-oxygen component of a breathing mixture is not metabolized, but does get dissolved in the bloodstream and body tissues according to exposure (partial pressure of inert components and time). Another complication - just as oxygen becomes toxic at increased partial pressure, nitrogen becomes narcotic. This is why helium is used in deep diving gas mixtures - the helium is truly inert and does not cause the narcosis that diving on air or a higher nitrogen content gas would. Other effects such as high pressure nervous syndrome (HPNS) are related to gas composition, as well as descent rate.

What does this have to do with breathing liquid? First off, the amount of oxygen in the fluid would need to be varied with depth, which presents a tough practical problem - how do you dissolve and/or extract oxygen in a volume of fluid greater than a human lung capacity at a rate sufficient to keep up with ascent/descent? Second, if supposedly “inert” components of gas mixtures can be problematic at increased pressures, who knows what sort of effect the non-oxygen component of this fluid would have? I don’t know what the stuff is made of, but it is reasonable to assume it has larger molecules than N2 or He, and as such probably has narcotic or toxic potential worse than the gas mixtures we currently use. Finally, there is the CO2 problem, as well as all the practical issues associated with breathing liquid - what works in a lab in a patient on a gurney might not be so useful for a diver trying to accomplish useful work.

IIRC, the rat shown in the movie was actually breathing the stuff. No word on whether they got the shot in one take (or one rat).

Imdb.com is a good spot for information as well. There are two references to the effect in the trivia section.

Click here

Another problem with nitrogen at high partial pressures is that it is absorbed more rapidly into the cells. It can only outgas at a certain rate, and absorbing too much will cause prohibitively long decompression stop times or risk decompression illness (DCI). (Here’s a site that explains the issues involved in more details.) The nitrogen does also have a narcotic effect which is not thouroughly understood.

Neither of these are an issue with helium; however, one problem with helium (in addition to the extreme cost) is that it is very thermally conductive and will leach heat from the diver, requiring that it be preheated for long duration dives. Also, the diver has to carry another gas source (usually argon) to pressurize the drysuit, though given the expense of heliox this would typically be done anyway.

For the most part, technical divers will use trimix (O[sub]2[/sub]-N[sub]2[/sub]-He), calculating the propotions for the plan depth to prevent excessive nitrogen absorption, oxygen toxicity, and bankbook decimation. Usually in diving regimes where this is required, you’ll have two or more mixes you’ll have to switch to depending on the stage of the dive, usually ending in breathing a high O[sub]2[/sub] mix (50% or thereabouts) for a while from a hang bottle at 5 or 7 meters below the boat to help purge some of the “deeper” nitrogen absorbing tissues. This is, naturally, way beyond normal recreational diving, though in recent years “tec-rec” diving has become a popular niche activity within the non-commercial diving community.

I don’t know any specifics about LiquiVent, but here and here are a couple of citations I haven’t seen in past threads. I’d just as soon climb in a capsule or send a tethered robot down that try to breathe fluid; that sounds just crazy to me, unless your only option is to get smooshed flat by a nuclear warhead.

You know, of course, that man has visited the deepest part of the ocean, the Marianas Trench, for twenty minutes, once, in 1960.

Not many people know that.

Stranger

Helium causes even longer decompression times than nitrogen. This, along with cost, is the reason that trimix is typically employed for open circuit technical diving (non saturation) as opposed to heliox - a tradeoff between reducing narcosis and not incurring unreasonable decompression times. Heliox is better for you physiologically though, and for commercial operations at extremely deep depths, these dives are almost without exception saturation dives, often using gas-reclaim gear that doesn’t waste huge amounts of helium, so heliox is more common. At saturation, any increase in exposure time does not result in a further decompression obligation, so typically, the commercial guys are blown down to depth in the deck decompression chamber (where they can be monitored for any ill effects), and once saturated, transferred in a personnel transfer capsule to the working depth, where they work their shift, and are brought back to the deck decompression chamber under pressure to relax, sleep, etc., for as many days as are required to complete the job. Once finished, the divers can decompress slowly in the relative safety of the dry chamber and be monitored by a supervisor or medical personnel. Such operations are immensely expensive compared to one-atmosphere solutions like submersibles and hardsuits.

This is a rather informative site I often refer to when I have a question.

More than one take, according to an account I’ve seen - the rat kept panicking and defecating in the fluid, which wasn’t exactly the effect they wanted.