Talk:Hydrostatic shock

ETHICS?

Wikipedia is a fully-public entity, and is used for research purposes by people of all ages - particularly students doing research for schoolwork.

Keeping that in mind - is it truly necessary to describe scientific experimentation on animals in full detail? I'm a male, mid-30s, and I perused this article looking for information on tissue damage caused during sonic treatment of kidney stones. I have seen and read enough about human and animal suffering over the years that I consider myself strong enough to read material that most might find disturbing, and I fully realize that a lot of research goes on that many would consider inhumane.

Despite all that, I still found it gruesome and disturbing when I was reading the article and got to the description of pigs being deliberately shot in the thigh - obviously a non-lethal but very painful injury - all in the name of "science."

Whether or not you consider the practice of using live animals for ballistics research to be ethical is totally irrelevant. BUT, describing the procedure in print in an article such as this seems a little excessive to me. Not because it is describing scientific research, ethical or not - it is not meant to be deceiving, as far as I can tell.

Anyway - my suggestion - and I WON'T change it myself, since I am not an expert... I see no reason why the experimentation couldn't be described in a manner such as "research on animal tissue has shown that injury to the hippocampus....." - and THEN following that with a footnote reference OR a direct link where the reader can find more information.

In that way, the information is still given and made available - maybe even more so than as originally written - but is less likely to cause sensitive readers any grief.

I'm not writing this as an anti-gun activist in any way. But I do know that there are many people in the general population who are disturbed by material that refers to scientific experimentation on animals, especially when such material can come off as sounding inhumane. - DM

There are a number of Wiki pages which describe animal research with a comparable level of detail. Some give even more detail. Effectively communicating a scientific result often requires describing the experiment. An article on wound ballistics is going to describe wounds.

Michael Courtney (talk) 12:20, 11 April 2008 (UTC)

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—Preceding unsigned comment added by Crux1234 (talk • contribs) 04:34, 5 April 2008 (UTC)

So if the bullet lodges in a person’s body, does the shock wave still do as much damage as if the bullet passes through the body?

Since the shock wave does precisely zero damage, yes. The shockwaves of being shot with an anti-aircraft gun with several thousands of rounds per day, over a period of years, may cause some slight loss of innervation and circulation to the kidneys, but that is all. -Arrkhal 00:49, 23 January 2006 (UTC)

Why does the article link to a page that contains simply a copy of it, crediting Wikipedia? Seems kind of pointless. --Vadim

Perhaps someone with medical training could elaborate? --Anders Törlind

I found a few web pages that contend the hydrostatic shock effect of bullet penetration; that is they do not believe that bullets damage humans in this way. No real science or pathology either way though. --drj

Merge?

Discussion on whether to merge this article with stopping power:

• No - Hydrostatic shock, while closely associated with stopping power, is a concept in its own right, and merging it would make stopping power a bit of an omnibus article. --Orborde 22:16, 12 September 2005 (UTC)
• I meant merge the section on hydrostatic shock from stopping power to here, not vice-versa. ··gracefool |☺ 06:49, 13 September 2005 (UTC)
• No - Even with this new information regarding the original intention of merging, the article stopping power needs some sort of summary. Although some of the information in stopping power could be merged, bullets have special regard to hydrostatic shock, and that information should be kept in the article stopping power. --DarthFredd
• No - Hydrostatic shock is extra wounding caused by the shock waves inside the body, caused by the passage of the bullet. Any scientific evidence I've read suggests that Stopping Power (the damage that puts a target down) is loss of blood, nerve function and shock. --Eon

Okay, I've removed the merge templates. ··gracefool |☺ 23:55, 18 October 2005 (UTC)

Can anymore evidence be cited in this topic? I have personal experiances that would suggest to me the validity of the workings of hydrostatic shock, though it takes a round of considerably higher velocity then anything that can be fired from a handgun. Try instead a 200 grain round from a .30-378 Weatherby traveling at around 3,400 fps. I have personally seen this combination drop deer and larger size animals instantly, even when no wounds were inflicted that should have been immediatly fatal. I'm not saying one way or another if the subject in question is a valid idea, however if someone knows of some more evidence it would be nice to see it.

Blunt trauma to the spinal cord due to temporary cavity. Damage inflicted by the temporary cavity is limited to stretching damage, and blunt trauma. The blunt trauma component can extend for a couple inches around the temporary cavity due to tissue compression. If this "wave" of compression hits the spinal cord, it can cause instant unconsciousness, exactly like a "rabbit punch." Arrkhal 01:09, 30 December 2005 (UTC)

Ok, but what about the exist wounds. I think hydrostactic may be a misnomer but parts of the body have a resonance.

Baloney

Who ever says that hydrostatic shock has been dis-proven is full of bologna. This is only true for wounds caused by small caliber low velocity nonexpanding bullets. These wounds are refered to in medical literature as an "ice pick wound". Wounds caused by high velocity big bore expanding bullets resemble an explosion. There is tremendous tissue damage far from the axis if bullet penetration. Those supposed idiots that write for gun magazines know exactly what they're talking about. They have seen the effects of these weapons many times on the bodies of big game animals.

204.227.223.74 21:05, 21 June 2006 (UTC)Tlaloc

{sigh}. Another person who either didn't read or didn't comprehend the article. Go read stopping power as many times as it takes to understand what's written there, and get back to me. Arrkhal 22:40, 22 June 2006 (UTC)

"Tissue does behave similarly enough to water that a sonic pressure wave can be created by a bullet impact, generating pressures in excess of 100 atmospheres. However, a device known as the lithotriptor, commonly used to break up kidney stones, produces sonic pressure waves of approximately 5 times the amplitude of those caused by bullets. Up to 2000 such pressure waves are used in a single treatment session, with no damage to soft tissues whatsoever." - This comparison is ludicrous.

A lithotriptor prodcues tiny, highly focused waves from a small emitter. A 5.56mm bullet travelling at over 900 m/s results in a near-instananeous energy transfer in the order of 1800 joules, nothing like what a lithotriptor can generate. And since it's a broad spectrum physical impact, the affected tissues, because the shock waves generated are of far lower frequency than those produced by an ultrasonic instrument, are wrenched back and forth over a much greater distance by the pressure wave. It is usually localised by the shock absorbing affects of tissue, and therefore does not merit much discussion, however, in an area such as the brain, the pressure waves generated cannot dissipate, and cause severe damage as the brain tissue is compressed against the hard cranium. As a footnote, lithtriptors have been known to cause renal capillary damage, among other problems, which can lead to renal failure.

Dallas 01:24, 24 July 2006 (UTC)

Yeah, this doesn't exist. Take two beer cans. Drink one. Go ahead and open the other one. Sit them both side-by-side down range. Shoot each of them with a high power (1000+ ft/s) .177 pellet rifle. The empty can will have a small entry hole and a somewhat bigger exit hole. The other can will be torn almost in half. Here's the kicker: The tear in the can most of the time is nowhere near the exit hole. Its usually near the entrance. What's tearing the can?

209.134.164.170 20:31, 3 August 2007 (UTC)

What's tearing the can? The same stuff that makes you burp after you have drunk the first can before handling your gun: carbon dioxide. When it's released by the entry of the pellet, the pressure will tear the can wall (same as if you open the can, but the top is stronger than the wall). Not convinced? Alright: Try shooting a plastic bag filled with water (entirely) and closed tight with your pellet rifle. Does the bag burst, or does it just leak water from two holes? Herringgull2 (talk) 12:33, 9 January 2009 (UTC)

Incompressible fluid

I have a problem with the statement: "The claim that tissue behaves like water is obviously false. Water is an incompressible fluid, while tissue is a compressible solid." First of all, nothing in science is obvious, and the first sentence could be changed into "evidence shows that..." or sth like that. No one claims that tissue behaves like water all the time, but that they can have similar behaviours under some circumstances. Then, saying that water is incompressible is simply wrong. Nothing is incompressible. If water really was, the oceanic level would be roughly 30m higher than it is now, there would be no shock wave in water, and the speed of sound in it would be infinite (later the article correctly quotes the speed 1500 m/s). "less compressible than tissue" would be more appropriate. Finally, I'm not sure that opposing tissue as a solid to water is relevent either. Water is a liquid for most applications, but when very quick phenomena are studied, like the penetration of a bullet, it can behave similarly to a solid. In the end, I think a sentence like "Experiments show that tissue and water behave differently, because they have different compressibility values" would be better. Chacal 00:00, 20 September 2006 (UTC)

Should Be Designated Stub

I think this article should be flagged as a stub or something until someone can take the time to properly edit it. Several sound contentions are listed above, and the article doesn't make any distinction between high-powered rifle rounds and handgun rounds. It's just silly. No personal offense, but it reads as if some gradeschooler tried to pontificate on a random subject.

Tone

"The claim that tissue behaves like water is obviously false..." That entire line (if not section) has POV and tone issues. I think it should be deleted/rewritten. Adropofreason 23:16, 10 April 2007 (UTC)

Debates in the Gun Community are Funny

So, how long has this hydrostatic shock [sic] debate been going on, and how contentious will it get before it is finally resolved? Will those on either side ever be able to admit that they were wrong?

Anyway, the actual article needs a serious rewrite to get it up to the standards of the better articles on Wiki. —Preceding unsigned comment added by 64.179.121.20 (talk) 16:48, 11 November 2007 (UTC)

There have been many debates in the history of science where the side that is wrong never really admits that they were wrong. However, eventually all scientists die, and the new generation of scientists tends to believe the side that has better support in the published data. Sometimes it takes a generation or two for wrong ideas to fall out of favor. But repeatable experiment usually wins in the end. The scientific method is a slow process; in many cases revolutions are quick; in other cases, change takes a generation.Michael Courtney (talk) 23:13, 22 December 2007 (UTC)

Random collection of thoughts

I've been thinking recently about the topic of hydrostatic shock, and I figured I'd go ahead and do a brain dump, with some observations and questions that I have.

High speed projectiles appear to have three distinct effects when hitting an object. We'll assume ballistic gelatin for now, as it's standardized and roughly replicates tissue.

1. Hydrostatic shock. This is a compression wave that travels through the medium--in other words, a sound wave. And with regards to comments above, water IS slightly compressible, otherwise compression waves would NOT travel through it.
2. Temporary cavitation. This is tissue that is displaced by the projectile, but springs back. Unlike the compression wave, which travels at the speed of sound in the medium, this is a displacement wave, and travels much slower, though it can readily exceed the speed of the projectile. This effect only exists in elastic mediums, like ballistic gelatin, which will spring back wherever the tensile strength of the material is not exceeded.
3. Permanent cavitation. This is the hole that remains after the medium comes to rest. This is cause by stressing the material to beyond its elastic limits, typically by direct contact of the projectile, but may also result from remote stretching exceeding the material strength, such as the "splash" of a high speed impact crater.

All of these are demonstrable, and measurable. A hydrophone will measure the hydrostatic shock in μPa, the temporary cavity can be seen in high speed photographs (and its size and speed estimated from them), and the permanent cavity volume is readily measured by filling with fluid, and its perimeter may be estimated if a transparent medium is used. That these phenomena exist is pretty much beyond question. The question is, how much impact does each have in relation to wounding? This is where the issue becomes very murky.

Permanent cavities are sufficient to cause lethal wounds; this can be readily demonstrated by looking at wounds by low velocity penetrations, such as knife wounds and similar mechanical trauma. These impacts produce negligible amounts of hydrostatic shock and temporary cavities, and kill by direct destruction of vital organs and blood loss.

Temporary cavities are more contentious, but are again sufficient to cause lethal wounds. Many organs are relatively inelastic, and can be damaged by stretching; this damage may arguably be called a permanent cavity, and shows up in ballistic gelatin as radial tears along the wound path, largest near the point of entry. A good example of a temporary cavity with little or no hydrostatic shock or permanent cavity is blunt trauma such as a punch to the abdomen. This elastically displaces the tissue, tears blood vessels, and can rupture organs. An example of this is the ruptured appendix said to have claimed Houdini's life.

Now for the most contentious part, the effect of hydrostatic shock on wounding. Various assertions are made about wave pressures required for incapacitation, ranging from 45 psi to 1500 psi. Information on where the pressure is measured, or how the pressure waves attenuate as they propagate through the body, doesn't seem to be available. The body is not a homogeneous medium, and compression waves reflect and refract significantly at the junction between areas of dissimilar density. This doesn't necessarily cause greater attenuation, however. Just like the internal reflection in an optic fiber, certain conditions in an acoustic medium can reduce attenuation and cause sound to travel much farther than the inverse square law would predict.

A lithotripter, according to one reference I found, generates pressure waves on the order of 100 MPa, while the hydrostatic shock causing value of 1500 psi you cite translates to 10 MPa. While some tissue destruction has been shown to happen from lithotripter use, the most significant side effects appear to be greater risk for hypertension and adult onset diabetes, not sudden loss of consciousness. An examination of the methods by which these shockwaves can cause cell damage and hemorrhaging showed that it was due to cavitation, which is caused by negative pressure waves in excess of 1 MPa. This damage was only seen in areas adjacent to the application of the shockwave. Lithotripsy also involves thousands of these 100 MPa shockwaves in a session.[1][2]

None of the cited papers I've looked at claiming to show incapacitation from remote injuries appear to decouple hydrostatic shock (sound waves) from effects caused by the temporary or permanent cavitation, which are both dynamic effects (pushing material around). This should be simple enough to do, simply by using a lithotropter or other similar device to apply hydrostatic shock waves to the central nervous system of a suitable test subject. Since hydrostatic pressure is easily measured, and appears to be readily decoupled from other variables, it seems irresponsible to draw any conclusions from the existing data. If hydrostatic shock can be shown to be a significant wounding factor, then it should be simple enough to design bullets to maximize the level of hydrostatic shock; certainly there are designs intended to maximize temporal cavities (like the THV and Devel concave ogive bullets) and permanent cavities (like large meplat, flat nosed solids) so there is no reason there could not be a design to maximize hydrostatic shock. Bullet shape will certainly have an effect on hydrostatic shock; just listen to the sound waves generated by a diver entering the water in different ways. The energy and velocity will be the same for a given diver falling the same distance, but the sound levels between a clean, head-first dive and a belly flop will be very different (as will penetration and splash). Based on the diving analogy, I suspect that hydrostatic shock will be strongly coupled to the temporary cavity size. I also suspect, based on the use of lithotripsy to remove stones from areas very near the central nervous system, such as the salivary glands, that hydrostatic shock will be found to have little or no immediate impact on incapacitation.

One possibility that popped into mind when mentioning the optic fiber above is the soliton wave. These waves, in their fluid form, are unique not only in the fact that they suffer far reduced attenuation, but also because they result in a significant shift of mass; the discoverer originally called them a "wave of translation" because of this property. It seems that temporary cavity formation in any region containing large blood vessels, especially in the thorax, could create an unusually large soliton in the circulatory system. There are a number of papers that provide some tangential support for this, comparing normal blood flow to soliton waves, where the elasticity of the blood vessels allows the blood to travel in waves of translation, rather than pressure driven flow[3], and there are a number of other papers that provide the mathematical solutions for generating solitons in thin walled, elastic tubes. A soliton would also provide a pressure peak detectable with a transducer, but the soliton would travel far slower than the compression wave of hydrostatic shock wave, which (by definition) travels at the speed of sound in the medium.

Well, that's it. Anyone out there who might, say, have a research laboratory and the means do some testing is welcome to have a go at the problem. Unless one has an infinite supply of goats then it's probably best to first approach the issue of relative incapacitation effects of dynamic vs. static pressure waves, using non-ballistic means. That knowledge in hand, a set of pressure transducers embedded in a block of ballistic gelatin could be used to measure and differentiate between static and dynamic pressure waves, allowing a reproducible medium to be used for further testing. scot (talk) 14:51, 28 March 2008 (UTC)

  I haven't read the work of Suneson, but if the article writer is explaining it accurately, it's bad science. If you shoot a pig -even an anaesthetised pig- in the leg, well, you'll get a massive spike in intra-cranial pressure (which is what the researcher's transducers are measuring). But you'd get that same spike if you passed a suction catheter down the animals' throat- discomfort causes spikes in ICP.

That's nothing new (and doesn't really justify shooting pigs). It doesn't in itself indicate the presence of a pressure-wave emanating from the axis of injury up to the brain; why didn't the researchers think of placing intra-abdominal and intra-thoracic transducers which would be able to demonstrate the transmission of a pressure-wave?

  As for the resultant rise in ICP (intra-cranial pressure), you'd need a sustained- not fleeting- pressure of 20-30 mm Hg to disrupt cognitive function. And the effects would take too long to manifest themselves to alter the outcome of a firefight.  The fact is, raised ICPs are only witnessed (in the context of smallarms) after direct head-trauma, not after thoracic or abdominal wounds. It's just a fact. Check with any reputable neurosurgeon who's treated gunshot victims. Similarly, if effects of hydrostatic shock can damage the brain from afar, how come anyone ever survives a penetrating head wound from a bullet? (Admittedly rare, but I've known a few). Doesn't the Kellie-Monroe principle apply?

However, you don't need a neurosurgeon to tell you that being shot hurts- this is more than enough to explain any momentary pausing by a wounded man; it doesn't require pseudo-science and the sacrifice of pigs.

  And if- as proponents of 'hdrostatic shock' claim, these pressure-waves travel via major blood vessels (and apart from via cerebro-spinal fluid in the case of the spine being hit, there doesn't seem to be any other credible mechanism)- why aren't the lungs / heart damaged? No immediate trauma, no thrombo-embolytic events, no raised troponin-T, no disruption of cardiac pacing. Most significantly, there's no loss of blood-pressure autoregulation (and resultant neurogenic cardiac shock), although such a pressure-wave would presumably impinge on baro-receptors which are sensitive  to, er, pressure. 
  As for apnea in shot pigs- well, if I was shot, I might gasp or briefly hold my breath too.

The fact is, if hydrostatic pressure-waves occur during smallarms injury, they seem to have little clinical effect. —Preceding unsigned comment added by Cappuchin (talk • contribs) 03:12, 29 March 2008 (UTC)

My understanding is that discussion on the Talk page should be confined to discussing improvements to the article. The last few posts seem more of a general discussion on the hydrostatic shock topic. To be sure, some interesting points are raised that are worthy of discussion. I propose moving the discussion to a more appropriate forum. This space should be used mainly for discussing article improvements. Since there is already a discussion on the topic at www.thehighroad.org I will answer the points that have been raised there. See: http://www.thehighroad.org/showthread.php?p=4343280&posted=1#post4343280 Michael Courtney (talk) 13:48, 29 March 2008 (UTC)

Above comment read as: "Too many people here think I am full of crap. Please come over to a forum filled with more similar basement-dwelling firearms know-it-alls who will shower you with insults until you stop bothering to post, and I win." This poster has apparently started this little pissing contest over what is at best a theory elsewhere, with the apparent misapprehension that so long as a smarty-looking guy in a lab coat has a test indicating something, it becomes fact. This is not, nor hopefully will it ever, be the way scientific research operates. The place to discuss the content, or more specifically, the validity of Wikipedia articles is Wikipedia. NOT a topical forum elsewhere. —Preceding unsigned comment added by 24.255.205.234 (talk) 00:46, 6 May 2008 (UTC)

I doubt that you can cite many references that meet Wikipedia standards for reliable sources that disagree with the numerous references cited in the Hydrostatic Shock article. There are sufficient references to the peer-reviewed literature to support the article. Certainly, contrary views can be included in the article, provided that they meet Wikipedia standards for reliable sources. Scientific research operates based on published data. There is quite a bit of published data supporting remote pressure wave effects. To date, we have found no published data contradicting remote neural effects of ballistic pressure waves.Michael Courtney (talk) 19:57, 6 May 2008 (UTC)

Good job avoiding the issue on that one. The point remains: 'please follow me and discuss this on another page' is not a good response to an argument here - it's tantamount to 'let's take it to the parking lot.' I am not saying that anything isn't properly sourced or doesn't belong or even that anything in article should be changed - just that debating the issue should be done here not on a page you already know is overrun with people who agree with your position. —Preceding unsigned comment added by 24.255.205.234 (talk) 05:33, 8 May 2008 (UTC)

This Wikipedia talk page is for discussing article improvements, not for general discussion of the topic. My intent was to steer more general topic discussion to an alternate forum, so that the discussion here could focus on more specific suggestions for improvements to the article. If your point is that the hydrostatic shock article is somehow wrong or incomplete, you need to bring reliable sources to the discussion if you are suggesting that the existing article be modified to include information from additional sources. If your point is a general discussion to better understand the topic, then it is appropriate to suggest an alternate forum. All this is established Wikipedia policy.Michael Courtney (talk) 17:17, 8 May 2008 (UTC)

'Does the evidence cited actually show this' is a pretty legitimate 'article improvement' discussion. Removing potentially spurious claims that may or may not conform with basic logic is as well. —Preceding unsigned comment added by 24.255.205.234 (talk) 09:17, 9 May 2008 (UTC)

Introduction

The first sentence defines the term as a theory and briefly describes it. The second sentence states that there is supporting evidence (Many references are cited later in the article). The third sentence gives some context. Given the amount of supporting evidence cited in the main body, asserting that the theory is supported with scientific evidence is a reasonable component of the introduction. Remote wounding effects are not seriously doubted in the scientific literature, and the last significant objection was published 19 years ago and relied on a personal communication that did not agree with the findings that were published the following year (by RF Bellamy). This objection is discussed frankly.Michael Courtney (talk) 03:16, 14 July 2008 (UTC)

FBI

The article contains this wording:

"The FBI recommends that loads intended for self-defense and law enforcement applications meet a minimum penetration requirement of 12” in ballistic gelatin [8]. Maximizing the ballistic pressure wave effects requires transferring maximum energy in a penetration distance that meets this requirement. In addition, bullets that fragment and meet minimum penetration requirements generate higher pressure waves than bullets which do not fragment."

Correct me if I'm wrong, but if it's the FBI article I've read regarding 'stopping power' the author goes out of his way to assert that HS does not exist. He spends entire pages describing how the only reliable ways to stop a human being are incapacitation through CNS disruption (fast) or blood loss (slow). The requirements for deep penetration and fragmentation were in order to directly impact major organs, not induce HS. This is a hell of a spin job, however. —Preceding unsigned comment added by 214.13.82.22 (talk) 10:06, 4 May 2009 (UTC)

Tone and Impartiality

As a casual reader with no knowledge of the area, I cannot help but notice that whoever wrote this article is firmly of the opinion that hydrostatic shock exists. Note that where opinions supporting this point of view are cited, the author(s) are keen to point out evidence which backs up those opinions, while dissenting opinions are attacked. Furthermore, there is a clear difference in the use of language: the two major dissenters here (Fackler and McPherson) both 'claimed', while supporters of the theory 'noted', 'described', 'showed', 'demonstrated'; in other words, the case against hydrostatic shock is given as opinion, while the case for hydrostatic shock is given as fact.

I know little about the subject, but I can spot a biased article. If there is no real debate in the scientific community as to the existence of hydrostatic shock, then this should be stated. If there is debate, the reader should know why without clear bias.

I am interested to note that one of the contributors to this discussion is Michael Courtney, whose own work is frequently cited in the article and who has an obvious professional bias towards the existence of hydrostatic shock. While it is pleasing that an expert in the field is contributing to this page, the fact that he is so clearly on one side of the argument could itself suggest bias. (It is, perhaps, more worrying that, while Courtney and Courtney are cited in footnote 15 as a source for the repudiation of Fackler's opinion, there is no such suggestion in the body, where their research is regurgitated as fact.)

I think this needs a clean up by a neutral party. It certainly is curiously schizophrenic at the moment; on the one hand debating the existence of hydrostatic shock, and on the other hand giving some detailed outcomes for recent research. One way or another, the linguistic bias should be cleaned up. 62.253.112.209 (talk) 04:52, 21 September 2009 (UTC)