A tourniquet is a specialized medical device used to control catastrophic external bleeding on an arm or leg when direct pressure alone is insufficient. Its primary function is to completely constrict blood flow from the heart to the injured limb, preventing life-threatening blood loss. The application of a tourniquet is a temporary, life-saving measure that buys time until the injured person receives definitive medical care at a hospital. Correct anatomical placement is paramount, as a poorly placed tourniquet can fail to stop hemorrhage.
Primary Anatomical Zones for Tourniquet Placement
The fundamental rule for tourniquet placement is to position the device proximal to the injury, meaning closer to the center of the body or the heart. This ensures the device is positioned upstream of the severed blood vessels, cutting off the arterial supply to the wound. The two acceptable anatomical zones are the upper arm (between the shoulder and the elbow) and the upper thigh (between the groin and the knee).
If the exact wound location is unclear, or the environment is unsafe for a detailed assessment, the tourniquet must be applied using the “high and tight” principle. This involves placing the device as high on the injured limb as possible, directly in the armpit or the crease of the groin. This location ensures the tourniquet is above any potential bleeding site, providing the quickest and most reliable hemorrhage control. Successful application completely stops arterial blood flow, confirmed by the cessation of bleeding and the absence of a pulse below the device.
Fine-Tuning Placement: Avoiding Joints and Obstacles
While the “high and tight” method offers fast, reliable application, a more deliberate placement is preferred when time allows for a detailed wound assessment. In these cases, the tourniquet should be placed approximately two to three inches above the wound itself. This slightly lower placement helps preserve healthy, uninjured tissue, which can improve the patient’s recovery and outcome.
A refinement to placement is the rule to never place a tourniquet directly over a joint, such as the elbow, knee, wrist, or ankle. Joints are structurally complex areas where bone and soft tissues make it difficult to achieve the necessary compression to occlude major arteries. Placing the tourniquet over a joint is ineffective at stopping blood flow and may increase the risk of nerve or blood vessel damage.
The tourniquet should ideally be applied directly to the skin for the most effective compression and to prevent slipping. If conditions demand it, the device can be placed over thin clothing, but bulky items, such as a heavy coat or a large pocket, must be removed. Placing a tourniquet over thick, bunched-up fabric significantly reduces the pressure transmitted to the underlying arteries, leading to failure. If there are multiple wounds on the same limb, the tourniquet must be placed above the wound closest to the torso.
Limitations and Contraindications for Tourniquet Use
Tourniquets are designed only for use on the limbs and are not appropriate for injuries to the head, neck, or torso. These areas lack the single-bone structure or sufficient circumference needed for a constricting band to effectively compress major vessels against an underlying structure. Attempting to use a tourniquet on these parts of the body is ineffective and can cause severe, irreversible injury or death.
A tourniquet should not be the initial treatment choice if bleeding is minor or easily controlled with sustained direct pressure and a pressure dressing. The device is reserved for life-threatening hemorrhage not manageable by other means. A limitation is the lower arm and lower leg, which contain two parallel bones; compression in these areas is less effective than on the single-bone upper arm or thigh.
Once a tourniquet has been properly applied and tightened, it should not be loosened or removed by an untrained person. Loosening the device can allow blood to rush back to the injury, potentially dislodging clots and causing further blood loss, which can be fatal. It is crucial to note the exact time of application, as the risk of tissue damage increases significantly if the device remains in place for longer than two hours without professional medical intervention.