CAT

Combat Application Tourniquet

 

In the past, emphasis has been placed on elevation of an extremity and compression on a pressure point (proximal to the bleeding site) as intermediate steps in hemorrhage control. No research has been published on whether or not elevation of a bleeding extremity slows hemorrhage. If a bone in the extremity is fractured, this maneuver could potentially result in converting a closed fracture to an open one or in causing increased internal hemorrhage. Similarly, the use of pressure points for hemorrhage control has not been studied. Thus, in the absence of compelling data, these interventions can no longer be recommended for situations in which direct pressure or a pressure dressing has failed to control hemorrhage.

 

If external bleeding from an extremity cannot be controlled by pressure, application of a tourniquet is the reasonable next step in hemorrhage control. Tourniquets had fallen out of favor because of concern about potential complications, including damage to nerves and blood vessels and potential loss of the limb if the tourniquet is left on too long. None of these have been proven and, in fact, data from the Iraq and Afghanistan wars have demonstrated just the opposite. Although there is a small risk that all or part of a limb may be sacrificed, given the choice between losing a limb or saving the patient’s life, the obvious decision is to preserve life. Data from the military experience suggest that appropriately applied tourniquets could potentially have prevented 7 of 100 combat deaths. Tourniquets control of exsanguinating hemorrhage is 80% or better. Tourniquets occluding arterial inflow have been widely used in the operating room (OR) by surgeons for many years with satisfactory results. Used properly, tourniquets are not only safe, but also lifesaving.

 

For hemorrhage from locations not amendable to placement of a tourniquet, such as on the torso or neck, it is reasonable to use hemostatic agents. As of this publication date, the US Army Surgical Research Institute recommends Combat Gauze as the preferred third-generation product. This may change over time. Please watch the PHTLS website (phtls.org) for the latest information.

 

Device Options. Traditionally, a tourniquet has been devised from a cravat folded into a width of about 4 inches (10cm) and wrapped twice around the extremity—the “Spanish windlass.” A knot is tied in the bandage, a metal or wooden rod is placed on top of the knot, and a second knot is tied. The rod is twisted until hemorrhage ceases, and the rod is then secured in place. Tourniquets that are narrow and band-like should be avoided. Wider tourniquets are more effective at controlling bleeding, and they control bleeding at lower pressure. An inverse relationship exists between tourniquets width and the pressure required to occlude arterial inflow. In addition, a very narrow band is also more likely to result in damage to arteries and superficial nerves. A blood pressure cuff represents another alternative that can be used as a tourniquet, although air may leak out of the cuff, diminishing its effectiveness.

 

Application Site. A tourniquet should be applied just proximal to the hemorrhage wound. If one tourniquet does not stop completely the hemorrhage, then another one should be applied just proximal to the first. Once applied, the tourniquet site should not be covered so that it can be easily seen and monitored for recurrent hemorrhage.

 

Application Tightness. A tourniquet should be applied tight enough to block arterial flow and occlude the distal pulse. A device that only occludes venous outflow from a limb will actually increase hemorrhage from a wound. A direct relationship exists between the amount of pressure required to control hemorrhage and the size of the limb. Thus, on average, a tourniquet will need to be placed more tightly on a leg to achieve hemorrhage control than on an arm.

 

Time Limit. Arterial tourniquets have been used safely for up to 120 to 150 minutes in operating rooms without significant nerve or muscle damage. Even in suburban or rural settings, many EMS transport times are significantly less than this period. In general, a tourniquet placed in the prehospital setting should remain in place until the patient reaches definitive care at the closest appropriate hospital. Military use has not shown significant deterioration with prolonged application times. If application of a tourniquet is required, the patient will most likely need emergency surgery to control hemorrhage. Thus, the ideal receiving facility for such a patient is one with surgical capabilities.

 

 

 

"Shock." PHTLS: Prehospital Trauma Life Support. Ed. Norman E. McSwain, Jr., MD, FACS, NREMT-P. 7th ed. St. Louis, MO: Mosby Jems/Elsevier, 2011. 199-201. Print.

 
 
 
 
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