How does a blast wave kill you?

[WallShadow]

Originally Posted by Targan

---snip---You feel the "crumph" right through your body. The first couple of times it creeps you out.

Like being in close proximity to a bunch of bagpipers, only much less damaging!
NOTE: I really do love the pipes, but I couldn't resist the free shot.

[Medic]

As one of the resident medics, I believe, I could clarify the effects of pressure waves on people.

Now, explosion is a sudden, rapid combustion. It causes heat and a shockwave, both of which have potential to kill.

Heat causes burns and combusts flammable materials. Clothing protects from the worst of it, but if it is not fire resistant, it might combust. Especially synthetic materials often have a nasty tendency to melt when subjected to great heat.

The shockwave is caused by the overpressure, caused by the air expanding due to the explosion. This has several results.

Depending on the force of the explosion, the shockwave sends things flying. The only problem is, it also leaves a vacuum in the ground zero, and should the explosion be powerful enough, the vacuum takes up to a couple of seconds to fill. This means, with bigger explosions, you need to duck not once but twice, as all the stuff that flew off with the shockwave has the nasty tendency of coming back shortly. Best idea is to sit in a foxhole and keep your head down.

Human body has about 60-70% of water and water is a relatively good conductor for a shockwave. While the bones form a rigid case around the lungs, but it isn't enough to stop the shockwave. While the overpressure from the shockwave simply compresses the gases inside the sinuses of the body, the rapid decompression after the shockwave causes the gases to expand so rapidly, the tissues can not compensate. Particularly vulnerable to damage from this kind of decompression is the bowel, filled with fecal matter and gas. It has been documented that people subjected to explosion shockwaves have had extensive damage to their bowels, up to several meters of bowel splitting open inside the abdominal cavity, which leads to a very nasty infection.

Overpressure in turn can cause damage to ears as the tympanic membrane , though flexible, can stand only up to so much. And it is not only the tympanic membranes in the ears that can be damaged. Hearing works through the tympanic membrane moving two very small and delicate bony structures - the hammer and the anvil, both very vulnerable to damage.

Overpressure also causes (usually small) tears in the lung tissue, due to the pressure differences outside and within the thoracic cavity. Lungs are not the only inthe thoracic cavity, that can be damaged. Heart in itself can be damaged by violent external pressure - for an example the F1 driver, Ayrton Senna, died of cardiac contusion after colliding the track wall in high speed.

In a nutshell, if you encounter someone who has been close to an explosion and that person is bleeding from his ears, it is safe to assume that he has a) perforated eardrums and b) perforated bowel until proved otherwise.

A great deal of injuries in explosions are so called secondary injuries that come not from the debris or the explosion itself but falling over or falling from somewhere. As a rule of fist, falling from higher than your own height is considered to be a high energy injuries.

[Michael Lewis]

Wow. I looked up body cavities. There's quite a lot of them.

[Medic]

I believe, if you put that as a search on the internet, you'd get plenty of porn.

Mostly the problem is there if the cavity is either filled with something compressable (bowel) or is in close connection to the outside (ear). Technically opening one's mouth when the shockwave hits might help with the ears, but the bowel - well, just try to keep out of the way of the blast.

[Michael Lewis]

Yeah, I don't think that would be too much fun to game/role-play.

[Medic]

Well, in roleplaying games, you might make a house rule about damage caused by shockwave - if it hits abdomen, make a check against the damage in point. If unsuccessful, you have just received internal damage that requires surgery. If it hits the head, same thing, except that you are deafened (at least for a while).