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Would it be possible, in a small and controlled environment, to create an artificial atmospheric pressure that could potentially stop, or significantly slow, bleeding from a clean wound?

I know that if the pressure was too high it would collapse the blood vessels, but on a relatively small scale that could be beneficial to the wound.

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It is a cool idea. Obviously pressure on a wound with my hands or with a tight bandage will slow bleeding. You are thinking of some sort of cup with an occlusive seal which you then place over the wound and inflate to greater than atmospheric pressure. You would need to have some sort of strap to keep it in place or it will blow itself off of the wound.

I think a device like this would be less good than a dressing which directly contacted the wound with a solid (like a cloth). The solid will push tissues together and damaged tissues give off factors that encourage clotting. The cloth itself will encourage clotting. A gas will not have either of those procoagulant effects.

You could slow bleeding with your gas device if the pressure within exceeded the pressure driving the blood out. That balance depends on whether it is arterial or venous blood, the latter being at low pressure one could easily exceed. If you have a strap holding on a cup with pressure equal or greater than arterial pressure then that strap will be at the same pressure and will effectively be a tourniquet. If you are going to do that, do it proximal to the wound!

An interesting thing is that people use hyperbaric chambers and high pressures of oxygen to help treat dirty / anaerobic wounds. This is down the road, recovery wise from where you are but I wonder if one could apply the pressure directly to the wound. I worry that it would compromise venous return.

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  • $\begingroup$ wow awesome answer, it was very adviceful I appreciate your knowledge! $\endgroup$ – Hunter Mitchell Apr 12 '17 at 18:55
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If your goal is sealing the wound then low pressure may also help work. A pressure lower than 6.25 kpa or .9 psi also known as the Armstrong Limit is when the boiling point of blood is equivalent to body temperature. As the blood in the wound boils it's temperature will rapidly drop causing it to freeze, sealing the wound. Probably not the safest option, but it ought to work.

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  • $\begingroup$ Why do you think the "temperature will rapidly drop" $\endgroup$ – Seeds Apr 12 '17 at 17:41
  • $\begingroup$ How does the blood boiling cause its temperature to drop below freezing? $\endgroup$ – Nuclear Wang Apr 12 '17 at 17:41
  • $\begingroup$ I don't think, I know. When water is boiled what is actually occurring is the water molecules with the greatest energy are escaping, resulting in the overall temp going down because the average kinetic energy is dropping. Additionally, that phase change requires a great deal of energy which it gets from the surrounding liquid adding to the cooling. That's why sweating cools you off. $\endgroup$ – Joe Kissling Apr 12 '17 at 17:48
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    $\begingroup$ @Seeds That is exactly what happens. Here is a video of water freezing from boiling under low pressure. $\endgroup$ – Joe Kissling Apr 12 '17 at 17:56
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    $\begingroup$ There exist low pressure devices for wounds: the Wound-Vac. It keeps juices / seepage from building up. If you put that on a bleeding wound it will suck the blood out. That can happen if a wound is too fresh or breaks down with the wound vac. Vacuum adequate to cause the blood to boil will cause a lot of associated tissue damage; imagine the worst hickey in the world, right on your wound. $\endgroup$ – Willk Apr 12 '17 at 18:34
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Sure, but you'd probably want a solid layer in there. Think blood pressure cuff. It's high pressure gas which is doing the sealing, but the rubber (or whatever) distributes the pressure evenly and prevents the gas from escaping. I suppose you could create some sort of glass/metal enclosure, but it'd have to be purpose built to a person and wound site since it can't mold around the bone/muscle/skin structure like a malleable rubber could. Even then, the rigid structure wouldn't stay "stuck" to the wound as the gas would be trying to escape. You'd need some sort of clamp or strap to hold it in place.

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Blood is pushed out of a wound because the blood pressure that the heart creates is greater than the pressure outside the body. Increasing atmospheric pressure would slow the bleeding, and enough pressure would stop it altogether, but it's not that simple.

The effects of high pressure on the human body, whether it's submerged in gas or liquid, are basically the same. Those effects can be serious, and are often fatal. Because divers have to deal with these issues routinely, a lot of easily understood information is available on the subject.

The basic problem is the way chemicals inside the body, primarily oxygen and nitrogen, react to the pressure. Oxygen becomes toxic, and nitrogen causes an effect similar to drunkenness from alcohol, known as the Rapture of the Deep.

Rapid changes in pressure also causes serious issues, even where the pressures involved would not have caused problems otherwise. For example, rapid depressurisation can cause the well known effect that divers call the Bends.

The effects mentioned here are all macroscopic, involving the entire body being under abnormal pressure. If you could localise the pressure around a wound, these issues may not be relevant.

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  • $\begingroup$ Welcome to WorldBuilding! Could you go a bit into detail about the problems that would arise? You briefly mention that point and I think it would be a nice addition to your post and the already existing answers. Have fun! $\endgroup$ – Secespitus Apr 12 '17 at 18:06
  • $\begingroup$ Thanks! I added a link to an article on the effects of increased barometric pressure. To be honest, I don't know much about the effects. I just know that there are some effects, and that they can be serious at pressure levels not much greater than normal. $\endgroup$ – Carl Smith Apr 12 '17 at 18:15
  • $\begingroup$ @CarlSmith It's generally a good idea to put a summary of the information from a link as well as a link itself - in case the link dies in the future. $\endgroup$ – Tim B Apr 12 '17 at 18:36
  • $\begingroup$ Thanks for the tip. I've tried to summarise the information here as best as I can. $\endgroup$ – Carl Smith Apr 15 '17 at 10:08

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