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March 31, 2011
Tourniquets: From combat to commonplace
As long as there have been wars, tourniquets have been in use. A simple device designed to stop blood flow, the tourniquet has seen changes over the centuries. Over the past 10 years in particular, the tourniquet has moved to the forefront of basic combat medical care. It is now ready to move from combat to common place in EMS. This article will look at the history of the tourniquet, how they work, and the basic types available. Discussion will also focus on indications for use in EMS as well as in tactical EMS.
The ancient Greeks first described medical devices used to decrease blood loss(1). Generally, these very early tourniquets consisted of bands that were tightened to stop blood flow. The first major design change was in the 17th century when Etienne Morel and William Fabry began to use a stick to turn as a windlass and tighten the constricting bands. Interestingly, this concept in still in use today in one of the most common types of tourniquets.
How they work
Tourniquets work when the band surrounding an extremity is compressed. This compression forces the muscle and tissue surrounding the artery to collapse the vessel, decreasing blood flow. The amount of force needed to collapse the vessel is dependent on three variables: the size and circumference of the limb, the width of the strap or band of the tourniquet, and the amount of force that can be applied to the constricting band.
Interestingly, a wider band on a tourniquet is more effective at stopping blood flow in an extremity rather than a narrow band at the same tension(3). In addition to the width of the strap, studies have shown that a larger extremity with an increased circumference requires higher correlates to higher required tension to stop the flow of blood(4). This requires the design of the tourniquet to allow for variability in the amount of tension that can be applied to the limb.
Commercially available tourniquets typically have a strap which is about 1 ½" wide. This provides the necessary amount of width to stop blood flow for both upper and lower extremities. The length is also predetermined to ensure it will wrap around an extremity.
The first is called the SOF Tactical Tourniquet, which uses a windlass to provide the tension for constriction. Tested and used by the military, it has proven to be extremely effective in high stress situations. It is very easy to carry, especially on the outside of packs and tactical vests.
One note of caution with the windlass style military tourniquets: These have been very popular with combat re-enactors, who strive for realism in their uniforms. This has led to a number of them that are not actual working units, but designed to look like them — essentially counterfeits. It is difficult to tell the difference until they are used and fail.
Some of these counterfeits have actually ended up in the military supply chain. If you purchase them, ensure you are buying them from a medical retailer, and not a third party vendor. These are also available with a training model to allow providers to have actual hands-on training.
The other style is called the Mechanical Advantage Tourniquet (MAT) and is solely manufactured by Pyng. The design is a rigid collar that goes around the extremity, and an attaching constricting strap. A handle is turned and very easily applies the tension to stop blood flow.
One disadvantage is that the MAT's design of a rigid collar makes it more difficult to pack in a small area, like on a vest. In comparative testing of various tourniquets in 2005 by the Naval Sea Systems Command, Navy Experimental Diving Unit, the MAT received the highest scores in the following evaluations(5):
Each organization should test all the available types to determine what works best for their needs, including how they will be carried and deployed.
Indications for use in EMS
Ideally, tourniquets offer EMS providers the ability to quickly control extremity bleeding quickly and effectively. This allows the provider time to assess the patient for other injuries or possibly treat other patients. The military has incorporated tourniquet training and use into all levels of medical care.
These tactical teams are operating in much the same environment as combat soldiers and facing the same types of weapons. SWAT teams need to rely on their own equipment and training, and traditional EMS will likely not be available. Tourniquets are an important tool for all members of SWAT teams.
1. Tuttle, A.D. Handbook for the Medical Soldier. New York : William Wood and Company, 1926.
2. Tien, H. C., Jung, V. An evaluation of tactical combat casualty care interventions in a combat environment. Journal of Special Operations Medicine. Winter, 2009, Vol. 9, 1.
3. Crenshaw AG, Hargens AR, Gershuni DH, Rydevik B. Wide tourniquets cuffs are more effective at lower inflation pressures. Acta Ortho Scand. 1988, Vol. 59, 4.
4. Shaw, J. A., Murrary, D. G. The relationship between tourniquet pressure and underlying soft-tissue pressure on the thigh. Journal of Bone Joint Surgery America. 1982, Vol. 64, 8.
5. Naval Sea Systems Command, Navy Experimental Diving Unit. Evaluation of self-applied tourniquets for combat applications. 2005.
6. Lakstein D, Blumenfeld A, Sokolov T, Lin G, Bssorai R, Lynn M. Tourniquets for hemorrhage control on the battlefield: a 4-year accumulated experience. Journal of Trauma. 5-Supplement, 2003, Vol. 54.