A tourniquet is a device designed to apply localized pressure around an arm or leg to control severe bleeding. It functions as a temporary measure to stop the flow of blood, particularly in emergency situations where blood loss is life-threatening.
How Tourniquets Control Bleeding
A tourniquet stops blood flow by compressing the arteries and veins in a limb. When tightened sufficiently, it occludes blood vessels, preventing blood from reaching the injured area. This compression stems external hemorrhage.
Commercial tourniquets often feature a band or strap with a tightening mechanism, such as a windlass rod. The windlass is twisted to increase tension, applying pressure until blood flow ceases. The goal is to achieve arterial occlusion, meaning the complete stoppage of blood flow through the arteries, not just the veins. If a tourniquet is not applied tightly enough, it may only occlude veins, which can worsen bleeding by preventing venous return while arterial blood continues to flow into the limb.
Critical Situations for Tourniquet Use
Tourniquets are for life-threatening limb hemorrhage that cannot be controlled by direct pressure alone. Direct pressure is the initial and preferred method for most bleeding injuries, and it should be applied for several minutes to allow blood to clot. If direct pressure is insufficient or impractical, such as in cases of severe traumatic amputations, deeply embedded objects, or multiple casualties, a tourniquet becomes a necessary intervention.
Uncontrolled bleeding is a significant cause of preventable death in both civilian and military contexts. In situations where a person could rapidly lose a large volume of blood, a tourniquet can be a life-saving measure. Emergency medical services and first responders utilize tourniquets alongside other bleeding control methods for such critical injuries.
Applying a Tourniquet Effectively
The tourniquet should be placed two to three inches above the wound, between the injury and the heart, avoiding placement directly over a joint or an impaled object. While some guidelines suggest “high and tight” placement, meaning as high as possible on the limb, this is typically for situations with immediate threats or when the exact wound location is unclear. When conditions allow for a thorough assessment, positioning the tourniquet two to three inches above the bleeding site is often preferred to preserve more of the limb.
The tourniquet must be tightened until the bleeding stops completely. This may cause considerable pain for the injured individual, but it is necessary to control the hemorrhage. Once tightened, the windlass rod or other securing mechanism should be clipped or secured to prevent it from loosening. If the first tourniquet does not stop the bleeding, a second tourniquet can be applied immediately above the first, closer to the heart.
After application, it is important to note the exact time the tourniquet was applied. This information is valuable for medical professionals, helping them understand how long circulation has been restricted. Many commercial tourniquets have a designated area to write this time.
Important Safety Considerations
Once a tourniquet has been applied, it should not be loosened or removed by untrained individuals. Only medical professionals in a controlled setting should remove a tourniquet. Loosening the tourniquet prematurely can cause re-bleeding and may lead to a sudden rush of toxins from the deprived limb into the bloodstream, a phenomenon known as reperfusion injury.
While tourniquets are life-saving, prolonged application carries risks, including temporary or permanent nerve damage, tissue damage, and in severe cases, limb loss. Nerve injury is the most common complication, potentially leading to tingling, numbness, weakness, or even paralysis. The general guideline suggests that a tourniquet should not remain in place for more than two hours to minimize these risks. However, the benefit of stopping life-threatening bleeding outweighs the immediate risk of limb complications.
Immediate professional medical help should be sought after a tourniquet is applied. The time of application helps medical staff assess the situation and plan for definitive treatment. Continuous monitoring of the patient and the tourniquet’s tightness is important until medical personnel arrive.