First Aid & Tourniquets
Uncontrolled heavy bleeding can lead to death in as little as a few minutes and prior to the arrival of EMS responders. If a limb is bleeding heavily, circumferential pressure around the limb between the limb and the torso can squeeze soft tissue down against a central long bone and collapse large blood vessels, shutting off all forward blood flow and stopping the bleeding. This is not a difficult concept to understand. Using a tourniquet to control heavy bleeding has been done for centuries.
When Tourniquets Should Be Used
The purpose of a tourniquet is to apply sufficient pressure to a limb so that arterial blood flow below the tourniquet will be completely blocked. This can stop even the strongest or most pervasive bleeding, but it also deprives the limb’s tissue of the oxygen and nutrients that it needs to survive.
The Types of Tourniquets That Are Available
Commercial tourniquets include the combat application tourniquet (CAT) and the special operations force tactical tourniquet (SOF-TT). The CAT is used by paramedics in British Columbia and has the advantage of being a little lighter and smaller than its counterpart, but the plastic construction is less durable. The SOF-TT is military-grade, and its metal construction is known for its reliability, but it is bulky and heavy and may not be practical for users concerned with weight and mobility.
The Challenges Associated with the Use of Tourniquets
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Applying a tourniquet too loosely can cause bleeding to worsen when venous blood is blocked, but arterial blood continues to bypass the tourniquet.
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Releasing a tourniquet too soon can cause severe bleeding to resume. Not only can the bleeding result in death, but the returning blood flow can damage the compressed blood vessels.
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Leaving a tourniquet on too long can cause neurovascular and tissue damage. Generally, permanent nerve, muscle, and blood vessel damage can occur after approximately two hours.
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Placing a tourniquet too far away from a wound or directly over a joint can cause a tourniquet to be ineffective.
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Fabricating a tourniquet from improper material, such as a parachute cord, can cut into the skin. Tourniquets should be between 1” and 2” wide. The wider the tourniquet, the more pressure will be required. Commercially available tourniquets, such as the CAT (shown above), are recommended over improvised tourniquets made from found materials.
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Periodic loosening because of pain or concerns about blood flow to vital organs can lead to severe blood loss and death.
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Applying tourniquets to a patient with low blood pressure (e.g., someone who is in shock or someone who is receiving CPR) can lead to increased bleeding once the patient is treated or resuscitated. The tourniquet pressure that was once effective may be insufficient with higher, reestablished blood pressure.
The Benefits of Tourniquets
The bottom line is that tourniquets save lives.
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A properly applied tourniquet provides secure and reliable hemorrhage control. This is particularly the case in catastrophic hemorrhages in harsh environments where the importance of hypothermia treatment in trauma victims requires a responder to cover their patients with bulky, insulating layers. Pressure dressings and soaker bandages may become dislodged under insulating layers and allow slow bleeding to go undetected.
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Tourniquets are fast, but applying manual pressure followed by pressure dressings to control severe bleeding may take 10 minutes or more. The application of a tourniquet will quickly allow a wilderness first-aid responder to move on to other treatments, including critical hypothermia prevention.
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Life over the limb, but limbs are saved too. Accumulated evidence shows that the deterioration caused by ischemia below a tourniquet is not as irreversible as once believed. There are cases of soldiers in Afghanistan who wore properly applied tourniquets for over 10 hours to recover their limbs fully.