cardio + shivving=dead?

December 16, 2007 12:35 PM

Would getting a person to exercise before stabbing them cause them to die faster?

In the nonfiction book Mexican Mafia (pretty good read, by the way), there is a story about the Eme deciding to kill one of its members who is in prison. The killers asked the man to play a game of basketball. After the game is over they stab him in the chest, the idea being that his raised heart rate will cause him to bleed out before the guards can get him medical attention. The man does die, but would the exercise really cause him to bleed more?

I'm not planning on shanking anybody, by the way. I want to use this in a short story, but I want to make sure it makes sense first.

posted by Bookhouse to health (23 comments total)

I would imagine getting stabbed is going to put you into panic mode and your heart will be racing even if the killers woke you up from a nap.
posted by Bonzai at 12:42 PM on December 16, 2007

It seems like the terror of getting shivved would be more than sufficient to get your heart rate up as high as it needs to be. Reasonably fit people return to a lower heart rate only a few minutes after ceasing exercise, so they'd need to do it pretty quick.
posted by 0xFCAF at 12:43 PM on December 16, 2007

Yes, they do.
posted by fluffycreature at 12:45 PM on December 16, 2007

It looks like the pulse rate is elevated in Hypovolaemic shock anyway, so I'm not sure exercise will have any great effect. In any case, if you are being stabbed in the right part of the chest your chances are not so good.

--

From emedicine.com:

(More than 90% of thoracic great vessel injuries are caused by penetrating trauma (ie, gunshot, shrapnel, stab wounds, therapeutic misadventures). Historically, thoracic injuries are associated with a high morbidity rate; however, Pate and coworkers reported a 71% survival rate in patients who reach the hospital alive after penetrating chest injuries. The trauma surgeon must resuscitate, diagnose, and treat the patient within minutes following admission to the trauma emergency unit...

Traumatic cardiac penetration is highly lethal, with case fatality rates of 70-80%. The degree of anatomic injury and occurrence of cardiac standstill, both related to the mechanism of injury, determine survival probability. Patients who reach the hospital before cardiac arrest occurs usually survive.)

--

Most puzzling is: If you want the guy to bleed out faster, why not just stab him a bunch more times?
posted by Comrade_robot at 1:36 PM on December 16, 2007 [1 favorite]

I can actually answer that one, comrade robot. From what I understand, it's really hard to kill someone just by stabbing them a bunch of times, thanks to morden medicine. You can read more about it here.
posted by Bookhouse at 1:59 PM on December 16, 2007

Morden medicine being a type so high-tech that you don't know about it yet.
posted by Bookhouse at 2:04 PM on December 16, 2007 [1 favorite]

If their heart is racing, and you stab them (which will pump it even higher), you might induce a cardiac arrest, which would definitely help in their speedy demise.
posted by blue_beetle at 2:26 PM on December 16, 2007

If you want to kill someone quickly with a shiv, go for the large femoral arteries. Gravity helps. It's like cutting the bottom out of a styrofoam cup.
posted by porpoise at 2:29 PM on December 16, 2007

I work in critical care so shock and hypotension are basically my business. I can't answer your question with full certainty as it's obviously sort of the opposite of what I try to do, but there's really only one thing off the top off my head that physiologically would explain this:

I suppose that with exercise, you're raising metabolic demand as your muscles require more oxygen/blood. So your heart rate, respiratory rate, and blood flow (as measured by cardiac output) rise to compensate. Theoretically if you stab someone in the lung or cause acute blood loss in the setting of this high demand, you're probably going to speed along the development of systemic hypoxia and acidemia. At the level of the heart, the cells responsible for normal electrical conduction will more rapidly become ischemic (oxygen deprived), and particularly at low systemic pH are possibly more prone to going into arrhythmias -- basically the heart stopping. Now in all honesty I'm not sure how much of a real world difference this would make. Also if the wound was directly to the aorta or heart, death is usually quite rapid regardless of the exercise I think, but still the same reasoning could probably apply.
posted by drpynchon at 3:15 PM on December 16, 2007

From what I understand, it's really hard to kill someone just by stabbing them a bunch of times, thanks to morden medicine.

This is untrue. Mortality rate with different weapons with similiar wounds form a 1961 study:

mortality rate in pistol wounds was 16.8%, while the rate was 14.3% for ice pick wounds and 13.3% for butcher knife wounds.

So we're looking at a 2-5% difference. I think its obvious that a knife wound is still pretty damn dangerous and a determined attacker with a knife will have absolutely no problem committing murder. No guns needed. Knowing where to strike also makes a bid difference, but an untrained assailant doesnt really need to know anything other than do his best to hit the area with the most organs.

That said, I imagine anything that raises your blood pressure will help, but the mechanics of shock may nullify any gains as shock tends to lower blood pressure.
posted by damn dirty ape at 4:18 PM on December 16, 2007

Damn dirty ape, I didn't read the whole paper (and probably wouldn't understand it if I did), but the first page seems to actually verify what I was saying -- that modern medicine has made it more difficult to kill someone by stabbing them.
posted by Bookhouse at 4:30 PM on December 16, 2007

... I want to use this in a short story, but I want to make sure it makes sense first.

Don't know that it matters if it *really* works this way... only that your antagonist believes that it does.
posted by deCadmus at 5:47 PM on December 16, 2007

I would think you'd want to get both femoral arteries if you could, but barring that the victim's left brachial artery is another good shot as it is very accessible and very close to the heart. I recall seeing a butterfly knife technique book and one of the fatal cuts was aimed right there.
posted by plinth at 6:02 PM on December 16, 2007

What I quoted was accurate. The money shot can be found on this page in a handy graph

I cant copy and paste so I'll re-type it for you:

Mortality rate for abdomen wounds:

Pistol 16.8 %
Ice Pick 14.3 %
Butcher Knife 13.3%
Rifle 7.7%
Switch Blade Knife 5.9%

So if you look at the data you'll find that sharp stabbing weapons like ice picks and butcher knives outperform a rifle shot to the abdomen and the Ice Pick is almost as dangerous as a pistol!

In other words an abdomen shot in the belly is as close to a death sentance you can give with a knife. Yes, of course medicine has done better at treating these wounds but they are still pretty nasty. Of course this data is 40 years old, but its some really meaty wartime data. Which may or may not reflect life in the suburbs or whatever. Hell, I imagine a solider gets faster first aid and hospitalization then a ghetto kid in Chicago.

That said, the idea that you cant kill someone with a knife is a myth. Now, lets define knife. A switchblade is a pretty terrible weapon. 5.9%. Which has half the effectiveness of a decent butcher knife and almost 1/3rd as good as a shotgun.

So in your scenario in the prison the murderer is much better off crafting his own ice pick (long penetration) than trying to aquire a butcher knife or switchblade. A shiv is pretty damn effective even today. A gun raises the odds by only a couple % points. A shotgun raises the odds by quite a bit 20.4% but where is a prisoner going to get a shotgun?

So I think this myth is pretty busted. The idea that a pistol is, say 10x better than killing someone than a knife is just false. Interestingly enough a rifle shot in the abdomen is is weakest one out of the group.

Now a prisoner can find some poison and toxic substances to dress the blade with a lot easier than he can find a shotgun. I imagine a blade treated with dried up drano or rat poison (which inhibits clotting) significantly raises the mortality rate. No need for cardio. An enterprising prison murderer would have lots of luck with a shiv and some chemicals. No need to bake a cake with an ak-47.
posted by damn dirty ape at 6:04 PM on December 16, 2007

Also the war nerd blogs sources exactly ZERO studies on the matter. Just lots of generalizations and tabloid type reporting. This IS NOT SCIENCE (from your link)

Just to make it fair, you'd have to allow those feeble hippies something like a 10-1 numbers advantage. Naw, let's make it 20-1, because I just remembered that bunch I saw thumping each other under the overpass was coed...and once you told the carnals in the Mexican Mafia or Nuestra Familia that they were going up against a gang that had girls in it, and that they could keep the girls if they won.... Well, I just think a numerical advantage of 20-1 is the bare minimum if you wanted the fight to last long enough to be worth videotaping.

Umm, okay. Are you tarantino's ghost writer or something?
posted by damn dirty ape at 6:08 PM on December 16, 2007

The idea that a pistol is, say 10x better than killing someone than a knife is just false.

I see what you're saying, but that report only refers to abdomen wounds, and only in people who made it to the . Pistols can also be used in headshots, which still makes them much deadlier weapons.
posted by Bookhouse at 6:36 PM on December 16, 2007

Oh, and I agree that War Nerd isn't exactly gospel.
posted by Bookhouse at 6:37 PM on December 16, 2007

But ...

If you're trying to kill someone by stabbing them, and you believe that making them exercise before hand will make them bleed more before the EMTs get there, wouldn't stabbing them a whole bunch of times make them bleed way more than making them exercise?

I mean if the point is to get the guy before the EMTs can get there, 'modern medicine' isn't going to help. As the emedicine link I sent you said, getting stabbed in the chest has historically had a very poor outcome....
posted by Comrade_robot at 7:22 PM on December 16, 2007

If you're trying to kill someone by stabbing them, and you believe that making them exercise before hand will make them bleed more before the EMTs get there, wouldn't stabbing them a whole bunch of times make them bleed way more than making them exercise?

Oh, yeah, I see your point.
posted by Bookhouse at 7:56 PM on December 16, 2007

Ask scarabic. I'm sure he has thought about this.
posted by bh at 8:45 PM on December 16, 2007

If you want this to make a difference in the story, set it up such that A can stab B *only once*. Perhaps the stabbing is done by a trap or a machine, rather than a person.

Example: A has figured out a way to modify the license-plate stamping machine to disgorge a flake of steel an inch wide and three long, at high speed, waist high. So as to maximize the damage done to B, and minimize B's attention to safety, he sets up the machine just before B's shift and has C spar, play basketball, or otherwise heavily exercise B, such that B will not only have exercised hard, but will also be running late for his shift, and has to sprint to the machine to make it in time to not be punished.
posted by aeschenkarnos at 9:36 PM on December 16, 2007

For future reference, more on the difference between knife and gun mortality.
posted by Bookhouse at 10:39 PM on December 16, 2007

After stabbing them in the chest, perform CPR, just the chest compressions. Makes you look like a hero for trying to save the guy, but in reality you are pumping him dry.
posted by JujuB at 2:21 AM on December 17, 2007 [1 favorite]