would vacuum damage a corpse?

May 6, 2007 4:35 PM

Would vacuum damage a corpse? This is actually a scientific research question (at the end of the explanations).

US Army is looking for innovative solutions for human remains transfer. Current practice is aluminum boxes with lots of ice. Obviously it is not working. The main goal for the new transfer case is to reduce the temperature of the body initially down to a temperature between 34-37 F and sustain it for a minimum of 10 hrs. Also, it should be self-powered in the event that there is no access to external power. There are many other constraints and requirements, but above is the gist of the problem.

I was thinking, after bringing the temperature of the body down to 34-37 F, we can create a vacuum inside the chamber to reduce the heat transfer mode to mostly radiation; add good insulation and seals, then your power requirements are much less than an active cooling system. Obviously there are many challenges one has to address in this plan. But my question is to biology/medical members of the ask.metafilter community. I don't know if the body (corpse rather) would be damaged due to vacuum. I would worry about eyes and circulatory system.

We have internal pressure in our eyes. What happens to that pressure when we die?

Same question applies to circulatory system.

Or anything else that might be adversely affected by vacuum?

Thanks.

posted by eebs to science & nature (20 comments total)

Umm, wouldn't it be better to have a double-walled box with a vacuum between the walls, like a Thermos bottle? You could pack ice around the body inside the inner chamber and not have to worry about any effects of vacuum exposure.
posted by Quietgal at 4:41 PM on May 6, 2007

Thanks. What you're suggesting is already part of the "good insulation." The problem with packing ice is that they make the body go down below 34 F, which I believe is a problem for the skin and other tissues. Part of the goal is to preserve the body.
posted by eebs at 4:47 PM on May 6, 2007

related
posted by LobsterMitten at 4:52 PM on May 6, 2007

also
posted by LobsterMitten at 4:54 PM on May 6, 2007

Why not try nitrogen packing instead of a vacuum.
posted by Osmanthus at 4:59 PM on May 6, 2007

Well, I would suggest some actual experimentation. Start with pig carcasses, work your way up to bodies donated to medical science. You can theorize all you want, but until you've got yourself a corpse, you won't know.

I suspect that you will have issues due to the wounds on the corpse, especially any kind of abdominal wound.

Also, you will need to suspend the body in some kind of hammock/cocoon, so heat doesn't conduct.
posted by adipocere at 5:48 PM on May 6, 2007

Could you explain why ice or dry ice don't work?

To address the vacuum question, though: the chamber would likely need to be strengthened to withstand the 15 psi differential. The cost and additional weight may be a disadvantage.

My first thought is that the the solids and liquids inside the chamber will evaporate, precluding a complete vacuum and permitting some heat conduction. This is true to some extent, but the vapor pressure of water, for example, is less than 1% atmospheric pressure at 0°C, so it doesn't appear that that would be a problem.
posted by Mapes at 7:05 PM on May 6, 2007

@adipocere:
Point taken on the experimentation. I thought these things would be trivial knowledge for the medical/biology people. As for the wounds, from what I understand, usually they do not do any kind of cleaning before it reaches home or friendly territory (Germany or Turkey). Finally, my thoughts for the heat conduction issue you justly raised was strapping the body to a platform that is separated from the walls/floor of the case by low conducting legs. As I have indicated in the original text above, there are many other considerations that needs to be addressed, however my specific question is about response of a corpse to vacuum.

@Mapes:
Re: Ice/dry ice: This method works by direct contact with the body or another solid material surrounding the body (hence conduction). The goal is to sustain the body at a specific temperature range, which happens to be greater than freezing temperature. Ice is by definition at or below freezing temp. It will directly contact the body and presumably reduce the temperature of the body near the contact surfaces (skin) to near freezing. Why this situation is undesirable is not clear to me either, but I can only speculate that frost might yield permanent marks on the body that stay when it is thawed (?). What's clear is that the new solution requires the temperature range 34-37 F.

Strengthening the chamber is sound advice. That will be achieved using stiffeners much like the ones used in aerospace shell structures.

Thanks for answers - much appreciated.
posted by eebs at 9:02 PM on May 6, 2007

How about the equivalent of a giant FoodSaver? Food seems to survive, and bodies are just large lumps of meat, after all.

I've just been rereading The Loved One, brought on by a trip to The Museum of Funeral Customs, where I learned that modern american embalming got its start on Civil War battlefields, so this question has a strange fascination for me.
posted by Quinbus Flestrin at 9:15 PM on May 6, 2007

Vacuum will play havok with the corpse should there be any trapped gases in the GI tract or lungs. Trapped gases at a sufficiently higher pressure than the surrounding space = potential for ugliness.
posted by frogan at 11:45 PM on May 6, 2007

Vacuum will play havok with the corpse should there be any trapped gases in the GI tract or lungs. Trapped gases at a sufficiently higher pressure than the surrounding space = potential for ugliness.

The live human body can support pressure differences of order 1 atmosphere, as demonstrated by people not bursting at the top of Everest (1/3 atm), or when they take their gloves off on spacewalks (~0 atm). Assuming the trapped gas is at a pressure of order 1 atmosphere, the body has no trouble holding it all in, and my guess is this wouldn't be too different for a corpse. What happens on the surface of Mars at the end of Total Recall is pure fiction.
posted by caek at 1:23 AM on May 7, 2007

I think you will first have to define what is acceptable damage to the corpse. Vacuum will likely result in dehydration of the corpse, and eventual mummification. This can also result in cell damage/protein denaturation, but I'm not sure what the cosmetic effects are likely to be.

Question: Does it have to be one body/one device? The cost involved in creating a structure strong enough to withstand a pressure differential might be alleviated if you used this unit for multiple bodies. (Size/weight? Transportable by air? By commercial air? C-141?)

I think Thermos style vacuum walls would still be a safer bet. Heat transfer would still have to proceed through a vacuum space.
posted by Comrade_robot at 5:22 AM on May 7, 2007

How about some sort of self-powered refrigerator? Something with a thermostat that can be set to a specific range and then left to it's own devices?
posted by LunaticFringe at 6:04 AM on May 7, 2007

Correct me if I'm wrong, but I believe the only things that exert pressure are gasses — liquids like blood and aqueous/vitreous humor shouldn't. Air in the lungs or digestive tract would have pressure, however, and if the gas was unable to escape it could rupture the organ.
posted by panic at 6:13 AM on May 7, 2007

Oh, and this is somewhat related:

http://www.straightdope.com/classics/a3_147.html

But the medical literature suggests this view is exaggerated. For one thing, I have never seen anything indicating your eyeballs would explode (although your eardrumms might burst). It's true that in the absence of ambient pressure your blood and other bodily fluids would boil, in the sense that they would turn to vapor. But that's not as drastic as it sounds. Your soft tissues would swell markedly, but they'd return to normal if you were recompressed within a short time.

It's conceivable your lungs might rupture, since in a vacuum the air in them would greatly expand. But experience suggests this is rare even if decompression is extremely rapid. The chances are much greater if your windpipe is closed, making it impossible for the expanding air to escape.
posted by Comrade_robot at 6:27 AM on May 7, 2007

How about the equivalent of a giant FoodSaver? Food seems to survive, and bodies are just large lumps of meat, after all.

The problem with this is the ongoing activity of bacteria within the body that will produce gases. Yuck.
posted by scblackman at 8:00 AM on May 7, 2007

Why expose the body to vacuum at all? Your idea is a big thermos bottle in essence. Wrap the corpse in a body bag, evacuate to remove oxygen, forming the plastic around the corpse like a vacuum pack, and bung it in a big vacuum bottle. The bottle/cffin can be made of any convenient material. Glass is best, but aluminum should work just fine.

You will need additional cooling. To avoid the freezing problems associated with ice (or dry ice! Corpses shouldn't have freezer burns!), I'd suggest a zeolite hydration cycle, but there are lots of endothermic salt phase transitions solutions out there. Medical rapid cooling packs are made of these things.
posted by bonehead at 8:04 AM on May 7, 2007

Alternatively look at liquid nitrogen flash-freezing technology, though I doubt it could be done to a full-size body. Human sushi!
posted by bonehead at 8:06 AM on May 7, 2007

@Comrade_robot:
It has to be one body/one device per request.

@LunaticFringe:
Thought about the refrigerator. The problem is the compressor and its power requirements.

@bonehead:
I'll have read on the zeolite hydration cycle. Thx.

Based on the links you guys provided, creating vacuum in the chamber seems like it might cause cosmetic damage to the corpse. However, the FoodSaver idea is intriguing. Air could be sucked out by a human powered mechanical device (pump). I'll have to think about this a little more. Hmmm.

Thanks for the answers. Keep 'em coming.
posted by eebs at 8:52 AM on May 7, 2007

when they take their gloves off on spacewalks (~0 atm)

No, they don't.
posted by musicinmybrain at 6:48 PM on May 7, 2007