Tourniquet Application (Combat and Legality)

[Arclight]

Some of this has been said, but to add some formality to it:

Tourniquets should be carried and can save lives, but their use is still inherently risky. Some prehospital tourniquets are relatively safer than others and proper application of these models helps mitigate the risks.

While modern prehospital care has gotten over the old belief that any limb with a tourniquet applied must be amputated, tourniquets are still a last-resort tool with good reason.

Medical research going back to at least the 1970s shows serious nerve damage in cases of prolonged pressure to tissue. Note that this example from the journal Transactions of the American Neurological Association uses a pneumatic cuff, which is considered less damaging than the narrow, manually tightened cuffs in modern military tourniquets due to the pneumatic cuff's relatively even pressure over the tissue. Pneumatic cuffs are typically used in surgical situations.:
Using a cuff inflated to 1000 mm Hg round- the leg of the baboon for 1 to 2 hours, it had been found that the anatomical lesions were concentrated under the edges of the cuff, with sparing in the centre . Furthermore, the lesions themselves involved displacement of structures within the nerve fibres, suggesting that there had been axoplasmic movement from the site of compression towards uncompressed tissue.(Ochoa, Fowler, Danta, and Gilliatt, 1971) In other words, the edges of the tourniquet compressed the tissue with enough pressure to pinch the long part of the neuron (the axon), causing damage.

One reason I highlight this is that there's a difference in pressure distribution (and absolute amount) caused by different types of tourniquets. Most notably, elastic band tourniquets can cause extremely high pressures. Many law enforcement agencies select this variety because they are typically cheaper.

Rather than try to re-characterize it all, I'll just share how Tacmedsolutions' blog reported quite clearly the additional risks of elastic band tourniquets:
As noted in the Journal of Medicine and Biomedical Research, “[t]he pressure induced by the rubber bandage increases at a rate of 3 to 4 times the initial pressure when the bandage is stretched after each wrap.”(1)(3) This is dangerous due to the shearing effect generated on the underling tissues, specifically the nerves. In fact, Graham et al found that at above 300mm Hg shearing forces increased exponentially.(2)(3) With RBTs this is concerning as “[t]he pressure applied to the limb could easily exceed the safe limits and put the limb at risk of complications because the rubber bandage is capable of generating pressures in excess of 1000mmHg beneath it.” “At such extremely high pressure,” Ogbemudia continues, “neurovascular damage becomes likely and makes the use of the RBT relatively unsafe.”
[1] Ogbemudia A et al. Adaptation of the rubber bandage for the safe use as tourniquet. Journal of Medicine and biomedical Research 2006; Vol. 5 No. 2 pp-69-74.
[2] Graham B et al. Perinerual pressures under the pneumatic tourniquet in the upper and lower extremity. Journal of Hand Surgery 1992: 17B: 262-6.
[3] McEwen J. A. and Casey V. Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets.

In other words, tourniquets can cause lasting damage if they apply too much pressure to the tissue. Elastic band tourniquets are, by nature, most prone to inadvertent overtightening. While any tourniquet is better than no tourniquet if circumstances require one, if you have the option to carry the relatively safer models, and you use them properly and only when needed, your patient's outcome will likely be better.

[Hmac]

Some of this has been said, but to add some formality to it:

Tourniquets should be carried and can save lives, but their use is still inherently risky. Some prehospital tourniquets are relatively safer than others and proper application of these models helps mitigate the risks.

While modern prehospital care has gotten over the old belief that any limb with a tourniquet applied must be amputated, tourniquets are still a last-resort tool with good reason.

Medical research going back to at least the 1970s shows serious nerve damage in cases of prolonged pressure to tissue. Note that this example from the journal Transactions of the American Neurological Association uses a pneumatic cuff, which is considered less damaging than the narrow, manually tightened cuffs in modern military tourniquets due to the pneumatic cuff's relatively even pressure over the tissue. Pneumatic cuffs are typically used in surgical situations.:
Using a cuff inflated to 1000 mm Hg round- the leg of the baboon for 1 to 2 hours, it had been found that the anatomical lesions were concentrated under the edges of the cuff, with sparing in the centre . Furthermore, the lesions themselves involved displacement of structures within the nerve fibres, suggesting that there had been axoplasmic movement from the site of compression towards uncompressed tissue.(Ochoa, Fowler, Danta, and Gilliatt, 1971) In other words, the edges of the tourniquet compressed the tissue with enough pressure to pinch the long part of the neuron (the axon), causing damage.

One reason I highlight this is that there's a difference in pressure distribution (and absolute amount) caused by different types of tourniquets. Most notably, elastic band tourniquets can cause extremely high pressures. Many law enforcement agencies select this variety because they are typically cheaper.

Rather than try to re-characterize it all, I'll just share how Tacmedsolutions' blog reported quite clearly the additional risks of elastic band tourniquets:
As noted in the Journal of Medicine and Biomedical Research, “[t]he pressure induced by the rubber bandage increases at a rate of 3 to 4 times the initial pressure when the bandage is stretched after each wrap.”(1)(3) This is dangerous due to the shearing effect generated on the underling tissues, specifically the nerves. In fact, Graham et al found that at above 300mm Hg shearing forces increased exponentially.(2)(3) With RBTs this is concerning as “[t]he pressure applied to the limb could easily exceed the safe limits and put the limb at risk of complications because the rubber bandage is capable of generating pressures in excess of 1000mmHg beneath it.” “At such extremely high pressure,” Ogbemudia continues, “neurovascular damage becomes likely and makes the use of the RBT relatively unsafe.”
[1] Ogbemudia A et al. Adaptation of the rubber bandage for the safe use as tourniquet. Journal of Medicine and biomedical Research 2006; Vol. 5 No. 2 pp-69-74.
[2] Graham B et al. Perinerual pressures under the pneumatic tourniquet in the upper and lower extremity. Journal of Hand Surgery 1992: 17B: 262-6.
[3] McEwen J. A. and Casey V. Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets.

In other words, tourniquets can cause lasting damage if they apply too much pressure to the tissue. Elastic band tourniquets are, by nature, most prone to inadvertent overtightening. While any tourniquet is better than no tourniquet if circumstances require one, if you have the option to carry the relatively safer models, and you use them properly and only when needed, your patient's outcome will likely be better.

In addition to direct to nerve and muscle injury from the localized pressure of a carelessly applied tourniquet, the lack of limb perfusion has a significant deleterious effect on the muscle. You can take a wide-based, double-cuff, pneumatic tourniquet like we use in the OR and if you leave it on long enough (much over an hour) you'll get significant lactic acidosis in the limb, with muscle and nerve damage from the ischemia. When the tourniquet is released, that results in a significant acid load to the system which can cause dysrhythmia or worse, as well as myoglobin from damaged muscle which has to be filtered through the kidney, which isn't good for the kidney...as in renal failure. Additionally, the subsequent swelling in the soft tissues once the limb is re-perfused will create high limb compartment pressures which in turn can cause more muscle and nerve damage and will inevitably require multi-compartment fasciotomies...a morbid problem in itself.

Now, all of that is better than bleeding to death, so don't take this as me being opposed to tourniquets. Let's just make sure we carefully learn this particular life-saving-but-potentially-dangerous tool. I have little concern for misuse by qualified pre-hospital personnel, but I do start to get a little worried when I see little tourniquet sets being issued to police officers and highway workers. I know how paramedics are trained, not so sure about the others.

[DireWulf]

Hmac makes good points. My brother is an orthopaedic surgeon (20 years) and informed me that pneumatic cuff tourniquets, which distribute the pressure of the tourniquet well, are used in nearly all total knee replacements. They are typically inflated and in place for 45 to 90 minutes at about 300 mmHg (about 6 psi). He claims that 400 mmHg (about 7 psi) should be the absolute maximum that the tourniquet is inflated to and at that pressure he feels that 30 minutes might be the time limit. According to him, if the surgery runs longer than expected they are typically deflated after 90 minutes to allow blood flow for a few minutes and then re-inflated. He states that the 300 mmHg pressure is enough to stop virtually all macroscopic blood flow, but still allows a slight microscopic flow. This aids in preventing hypoxia and Deep Vein Thrombosis (DVT). He thinks it can also reduce the buildup of cellular debris and reduce vaso-constriction distally, which typically occurs at the time the tourniquet pressure is applied. His advice to me was to try to utilize a tourniquet that distributes the pressure across a wider band than that of a belt or nylon pack strap and only apply the moderate pressure required to halt major blood flow. This echoes what I was taught in school.

JBJS has a few interesting white papers on this subject as it applies to wound healing and range of motion post-op:

http://web.jbjs.org.uk/cgi/reprint/81-B/1/30.pdf

http://web.jbjs.org.uk/cgi/reprint/83-B/1/40.pdf

If there are measurable differences in the use of a surgical tourniquet vs non use of one, there is surely concern with the use of the "stick and strap" methods. Proper training and emphasis on recognizing when to apply it, what kind to apply and where to apply should be part of an LE agency's routine training cycles, but it rarely is.

[Gutshot John]

Per TCCC there is ample evidence from the battlefield that a proper tourniquet properly applied can be in place for multiple hours with only a minimal chance of long-term neurological deficits. IIRC the percentage thrown out was only that 3% had any longer term issues and most of those included numbness etc. It is something of a myth that a TQ restricts all blood flow and they are certainly a good tool for anyone to have in their kit.

There is almost no chance of someone losing a limb if a tourniquet is of a proper width of 2". I disagree with the premise that a TQ shouldn't be used by lay people, this isn't a needle decompression where you have the potential to kill someone if you do something wrong. There is far greater danger in not doing anything.

In terms of the proper amount of pressure, you keep tightening until the hemorrhage either ceases or there is no distal arterial pulse.

The issue of width is only relevant to improvised TQs and that does require proper training. Most commercially available TQs are of proper width (CAT-T/SOF-T) and are comparatively idiot proof, the exception being a SWAT-T which does require some training/understanding in order to use properly.

The current trend is for increasing/more aggressive use of a TQ earlier on in treatment protocols. This is trickling down to civilian EMS from the military experience in the sandbox where the number 1 cause of preventable death is penetrating trauma to the extremity and so generally a TQ gets applied in those cases even before you do any ABCs.

[Hmac]

There is almost no chance of someone losing a limb if a tourniquet is of a proper width of 2". I disagree with the premise that a TQ shouldn't be used by lay people, this isn't a needle decompression where you have the potential to kill someone if you do something wrong. There is far greater danger in not doing anything.

Of course there's a far greater danger in doing nothing. But that doesnt give license to be careless or for someone to use that tool with incomplete training or understanding. The survival of the patient and not having lost the limb does not necessarily equal successful or appropriate and safe use of a tourniquet. There's a whole lot more that happens to that patient in the days and weeks after he's been dropped off alive at the ER. That the patient has survived is certainly a victory. That victory is less than complete if the patient is left with a limb whose function is unnecessarily impaired because of casual misuse of that particular tool. And like many such tools, that's a very real possibility that may not be in any way apparent to the EMTs who will never see or hear of that patient again after he's left the ER for the OR.

[Gutshot John]

Of course there's a far greater danger in doing nothing. But that doesnt give license to be careless or for someone to use that tool with incomplete training or understanding. The survival of the patient and not having lost the limb does not necessarily equal successful or appropriate and safe use of a tourniquet. There's a whole lot more that happens to that patient in the days and weeks after he's been dropped off alive at the ER. That the patient has survived is certainly a victory. That victory is less than complete if the patient is left with a limb whose function is unnecessarily impaired because of casual misuse of that particular tool. And like many such tools, that's a very real possibility that may not be in any way apparent to the EMTs who will never see or hear of that patient again after he's left the ER for the OR.

Improper application of the TQ invariably results in ineffectual control hemorrhage/shock/death, not neurologic/limb damage. Given that a TQ is almost never on a limb in the civilian EMS setting as long as it is on a military setting means this it is even less of an issue.

http://www.ncbi.nlm.nih.gov/pubmed/12768129

Conclusion from the above study:

Tourniquet application is an effective and easily applied (by medical and nonmedical personnel) method for prevention of exsanguination in the military prehospital setting.

http://journals.lww.com/annalsofsurg...to_Stop.1.aspx

Results/Conclusions of the above study which refers to civilian setting.

There were 31 deaths (13%). Tourniquet use when shock was absent was strongly associated with survival (90% vs. 10%; P < 0.001). Prehospital tourniquets were applied in 194 patients of which 22 died (11% mortality), whereas 38 patients had ED application of which 9 died (24% mortality; P = 0.05). The 5 casualties indicated for tourniquets but had none used had a survival rate of 0% versus 87% for those casualties with tourniquets used (P < 0.001). Four patients (1.7%) sustained transient nerve palsy at the level of the tourniquet. No amputations resulted solely from tourniquet use.

Conclusions: Tourniquet use when shock was absent was strongly associated with saved lives, and prehospital use was also strongly associated with lifesaving.

There are many studies that have reached the same conclusion. This is why you will see increased use of TQs in the prehospital EMS setting.

It is also why there is almost no risk to the application of TQ assuming it isn't made of piano wire. Training is certainly valuable since it's the best way to prevent hemorrhage, "careless" application is certainly ineffectual because if fails to control bleeding, but it almost never results in long-term damage to the limb.

[Gutshot John]

From JEMS.

http://www.jems.com/article/patient-...ts-original-re

The BMC/BEMS cohort study indicates that prehospital tourniquets can be appropriately applied to control life-threatening hemorrhage from an extremity injury, and that their use isn't associated with neurovascular complications. In similar case series, some of the patients we've described appear to have died because of inadequate hemorrhage control. It's thus quite unlikely that a well-controlled clinical trial could be conducted to truly determine the safety and efficacy of this intervention. Nevertheless, our findings emphasize the need to re-evaluate the standard teaching that tourniquets are to be used only as a last resort because of safety concerns.

The long and short of this is that TQs should be more aggressively applied and more universally available to lay medics. The potential to save lives far outweighs the minimal risk of neurologic damage even with improper use. The principle of "do no harm" doesn't really apply here. Civilian EMS is far slower in coming to this conclusion than the military but it is changing.

[GIJew766]

Funny this is coming up. This week spent a day at Jefferson discussing TQs to students. There are a lot of misconceptions, and I'm glad to finally see the stigma of the tourniquet start to wash away.

As has been said, the PROPER application of a TQ is the best way to control exsanguinating bleeding. It's better to get the TQ on and bleeding controlled than to waste time and the patient's blood trying to control the same bleed with direct pressure.

I remember in Boy Scouts as a kid being told the tourniquet is the last resort. But as a Scout, we didn't have proper medical training. Besides, EMS practices evolve often times from the Medics' and Corpsmans' experiences in combat zones. The use of tourniquets is just one example.

H