Modern commercial tourniquets are highly effective and life-saving tools specifically designed to stop massive bleeding from an arm or leg injury. Uncontrolled hemorrhage from an extremity can lead to death in a matter of minutes, often before professional medical help can arrive. A tourniquet is a device that applies mechanical pressure circumferentially around a limb to completely stop the flow of blood. The reintroduction of these devices into trauma care has shifted the focus of initial trauma response to prioritize immediate bleeding control.
Indications for Use
Tourniquets are reserved for situations involving catastrophic, life-threatening extremity hemorrhage that cannot be stopped by applying direct pressure alone. Due to the speed of blood loss, delaying application to try other methods is often not advisable. The primary goal is to prevent the rapid onset of hypovolemic shock, which occurs when the body loses so much blood that the circulatory system fails.
Specific situations appropriate for immediate application include:
- Traumatic amputations.
- Mangled limbs with multiple bleeding points.
- Incidents involving mass casualties where a rescuer must rapidly treat multiple people.
- Active threat situations where self-application allows the casualty to move to safety.
The decision to use a tourniquet hinges on the severity of the bleeding; if the blood loss is rapid, profuse, and spurting, it is the appropriate first line of treatment.
Understanding Blood Flow Occlusion
The effectiveness of a tourniquet relies on its ability to achieve complete arterial blood flow occlusion, stopping the flow of blood through the arteries into the limb. Arteries are deep and carry blood at high pressure, requiring a substantial amount of external force to compress them. If a tourniquet is applied with insufficient pressure, it may only stop the lower-pressure venous blood returning from the limb.
This partial occlusion can actually worsen bleeding, as blood continues to pump into the limb through the arteries but cannot exit through the compressed veins, increasing pressure in the limb and at the wound site. Commercial tourniquets, which are typically at least 1.5 inches wide, are engineered with a windlass system to generate the high, even circumferential pressure needed to collapse the artery against the bone. Improvised devices, such as belts, often fail because they are too narrow and lack the mechanical advantage to achieve the necessary arterial pressure.
Proper Application Technique
The application of a commercial windlass-style tourniquet, such as the Combat Application Tourniquet (CAT), follows a clear, step-by-step process designed for maximum effectiveness.
Application Steps
- Place the device high on the injured limb, approximately two to three inches above the bleeding site, avoiding placement directly over a joint. If the wound location is not immediately visible, the safest placement is “high and tight” on the limb.
- Route the self-adhering band around the limb and pull it through the buckle, tightening it firmly until it is snug. The band should be tight enough that you cannot slide more than three fingertips underneath it.
- Twist the windlass rod until the bright red, life-threatening bleeding completely stops and there is no pulse detectable below the tourniquet.
- Secure the windlass rod by locking it into the retaining clip, which prevents it from unwinding and losing tension.
- Route the strap over the rod and clip, and record the time of application clearly on the strap or with a marker near the tourniquet.
If the bleeding continues after the first one is fully tightened, a second tourniquet should be applied immediately above and side-by-side to the first one.
Safety Concerns and Time Limits
The belief that applying a tourniquet guarantees the loss of a limb is a misconception rooted in outdated practices. Modern medical consensus holds that the risk of death from uncontrolled bleeding far outweighs the low risk of complications from temporary limb ischemia. Studies show that most patients with a tourniquet in place for two hours or less experience no permanent ischemic injury.
Tourniquets are generally safe for several hours, though significant risk of muscle and nerve damage typically begins after four to six hours of continuous application. Once applied and bleeding is controlled, the device should not be loosened or removed by a layperson. Removal without proper medical supervision can cause bleeding to restart or lead to systemic complications like reperfusion injury, which requires management in a controlled medical setting.