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Back to Basics: Tourniquets

 The use of tourniquets has long been taught as a last resort to control major hemorrhaging.  Tourniquet use has recently become more liberal as more case studies are analyzed from years of conflict in Iraq and Afghanistan.   The current threat that has plagued the streets of Iraq and Afghanistan are Improvised Explosive Devices (IEDs).  These IEDs, sometimes made from old artillery munitions, have the ability to shred the bodies of Soldiers with relative ease.  These blasts can cause massive extremity hemorrhage, which can kill a human quickly.  The Department of Defense has conducted a study detailing the three preventable causes of death in Soldiers: exsanguination from an extremity (9%), tension pneumothorax (5%), and airway problems  (Parsons, 2004).  The new Tactical Combat Casualty Care protocol, which Soldiers adhere to, states a military tourniquet as an initial lifesaving intervention to control massive hemorrhage from an extremity.  The Department of Defense recognizes the need for tourniquets in war.  From 2001 to September 1st, 2010, there have been 1,621 amputations from conflict in all the services participation in Operation Iraqi Freedom and Operation Enduring Freedom (Fischer, 2010).  Soldiers now carry two Combat Application Tourniquets (C.A.T.) on their person in most combat units per SOP.  Tactical Officers have the ability to witness war-like trauma here at home (gunshot wounds, car accidents).  Awareness of rapid blood loss is vital for the Tactical Officer, as delayed tourniquet application can result in death.

Anatomy and Physiology

The arms and legs contain major vessels that supply the extremities with gallons of arterial blood circulation per hour.  Main arteries that supply the arm are the brachial (upper arm near the bicep) and the radial and ulnar (in the forearm).  The leg is supplied by the massive femoral artery (upper leg), which branches off into the popliteal (back of knee) and tibial arteries.  The human body has about 5-6 liters of blood, which carries life-sustaining oxygen to the organs and the brain. The human body has compensatory mechanisms for blood loss, to an extent.  To compensate for this blood loss the human body will increase the heart rate, speed up respirations, and shunt blood from the skin, but without immediate action, the body is liable to quickly slip into decompensated shock, and ultimately irreversible shock. 


Assessing the bleed is also very important.  There are three general types of bleeds.  Capillary bleeding is slow and oozes.  This is usually from minor abrasions and lacerations.  Venous bleeding is steady and flows, this can sometimes be life-threatening as there are major veins in the body.  Venous and capillary bleeds can typically be controlled with pressure, while arterial bleeds are the ones that will usually require tourniquets.  This is bright red bleeding which may be spurting out of the body with every heartbeat. 

The Scenario

You are stacked outside the door of a single story house on a high-risk arrest warrant with your team.  As you enter and clear the living room a shot rings out from a corner and your point man goes down screaming.  Your point man just took a .45 caliber round to the leg, severing the femoral artery.  The threat is neutralized as the man lays on the ground calling for the medic.  Let’s look at the physiology of the point man as he enters the room, to the moment he receives treatment.  The S.W.A.T. Officer is an adult male in his late twenties or early thirties and in reasonably good shape.  The Officer enters the room as his fight or flight response creates a hyper-alert state.  The potent hormones and neurotransmitters like epinephrine and norepinephrine raise his resting heart rate from 50bpm to 90bpm.  His peripheral vision diminishes and his eyes dilate to allow maximal light to visualize the threat as his vessels constrict throughout his body.  The bullet enters from the front and directly impacts the unprotected leg.  Pain and concern cause the Officer’s heart rate to increase to 100bpm.  The heart pumps approximately 70mL of blood per contraction (stroke volume), and that blood is now spurting outside his leg and onto the cold tile floor at 100 contractions a second.  During hemorrhaging, the preload (venous return) to the heart diminishes and the stroke volume falls to 50mL.   It takes a brief second to realize the dramatic blood loss this Officer is about to sustain. How much of the 5-6 liters of blood will he have left in the minute it takes a fellow Officer to drag the victim outside to the medical unit?

CO (Cardiac Output mL/min) = SV (Stroke Volume mL/beat) * HR (BPM)

5,000mL (5 liters) = 50mL * 100

The wounded Officer is now groggy and has an altered mental status due to the lack of blood to the brain.  His skin is pale, cool and clammy from the body shunting the blood from the skin to the major organs.  His pulse is now weak and very fast, and a radial pulse may be absent as his blood pressure drops drastically.  As the blood loss nears 15-25%, the victim begins to cross into decompensated shock.  

 In the past, tourniquet use has been associated with the complete loss of the injured limb from the location of where the tourniquet was placed and down.  Mechanical stress placed on the nerves and vessels can occur.  “Damage to nerves can occur at two hours” (page 75) and ischemic (lack of oxygen) death of other tissue can occur around five hours (68W Combat Medic Skills, 2010).  This means that a tourniquet is by no means a loss of a limb, but rather a temporary lifesaving intervention that can be applied by the victim himself until he reaches the emergency department.   Remember, tourniquets are applied for arterial bleeds (bright red spurting), a venous bleed (flowing dark red) can usually be controlled by direct pressure. 


Training must be scenario based and realistic to show the importance of prompt hemorrhage control.  Dedicated tourniquets are important as well.  The idea that a Tactical Officer will just use a belt if he needs it can and will cost blood on the floor. Leather belts can be difficult to tighten down and are not as effective as an actual emergency tourniquet.  Train and know how to use one if that is your only option, but there is no need to improvise when you can carry actual tourniquets.

The Market

Since 2004, the Combat Applications Tourniquet (C.A.T.) has been the official tourniquet for the military and has been issued to over 1 million service members.  The effectiveness and ability to be placed one-handed made this a very popular tourniquet.  The tourniquet is now part of “self aid” and can be applied by the victim himself.  The SOF-T (Special Operations Forces Tourniquet) is now also becoming popular among the military.  The windlass is made of steel and does not use velcro to secure the tails.  Both are excellent tourniquets, and the Tactical Officer needs to be familiar with the use of both, as well as how to make improvised tourniquets quickly.

Recap of the important principles of tourniquet application:

Place the tourniquet 2-3 inches between the wound and the heart and never over a joint.

While opening and preparing the tourniquet, a knee directly on the wound or where the tourniquet will be placed may slow the bleeding. 

  • Apply the tourniquet directly on the skin if possible.  If the extent of the injury involves multiple wounds and/or cannot be visualized (low light settings, chaos) then apply as high as possible.
  • Tighten the tourniquet until bright red bleeding AND venous bleeding stop.
  • Do not cover the tourniquet and ensure receiving medical personnel are notified of the applied tourniquet. 
  • Lower extremities may require two tourniquets due to the musculature.
  • If making an improvised tourniquet, use material that is at least 2 inches wide (no 550-cord or extension cords). A blood pressure cuff pumped to at least 200 mmHG can work.
  • Note the time the tourniquet is placed.

AAOS. (2010) 68W Advanced Field Craft.  Combat Medic Skills. Massachusetts:  Jones and Bartlett.

C. Bianco (2010) Montana University.  Heart Physiology.  Retrieved from

D. Parsons (2004) Professional Forum. Battlefield A New Perspective. Retrieved from

H. Fischer (2010) Congressional Research Service.  U.S. Military Casualty Statistics: Operation New Dawn, Operation Iraqi Freedom, and Operation Enduring Freedom. Retrieved from

J.A. McEwen (2012) Tourniquets.  Complications and Preventative Measures.  Retrieved from

Picture Credits: Texas Heart Institute


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