Tourniquets for Extremity Trauma

On Monday, April 15^th, 2013 there were two explosions at 2:50pm near the Boylston Street finish line of the Boston Marathon. Immediately, Boston emergency medical services sprang into action to care for these patients with severe injuries, including many exsanguinating extremity blast injuries. The risk from injuries such as these, aren’t negligible: the National Trauma Databank reports a 2.8% mortality rate for patients with isolated lower extremity traumatic arterial injuries. This same group of patients has a 6.5% risk of lower extremity amputation secondary to their injuries. In many cases that day, people ripped off their shirts, used, their belts, or found anyway they possibly could to help stop some of the victims from bleeding. This event accelerated the distribution of commercially made tourniquets to EMS and police personnel, both in Boston and other areas of the country, despite some previously held misgivings about their use.

Despite the potential advantages of using tourniquets in a prehospital setting to control extremity hemorrhage, their use has been debated due to the complications often seen with their use. The use of tourniquets is in no way a new controversy. They were likely first developed in ancient Roman times, but the term tourniquet was coined by Ambrose Pare (1510-1590), who defined the word and first made recommendations for its use in an operative setting. His original tourniquet consisted of a screw that was placed over the main vessel of an extremity with a circumferential strap around the extremity that was used to tighten the apparatus. The pneumatic tourniquet used by many surgeons today was developed in 1904, and has the advantage over previous versions of providing more even pressure around a limb, as well as easier placement and removal. The debate over tourniquet use began in the Civil War, as more surgeons in that day started seeing more ischemic complications of their placement. Alternatively, many argue that despite complications, tourniquets still confer the benefit of saving the lives of those who may otherwise have died from uncontrolled hemorrhage.

Controversy exists because the use of tourniquets has long been feared in the civilian world due to the concern over improper use. Serious complications can arise if tourniquets are left in place too long, resulting in limb ischemia, muscle injury, nerve deficits, gangrene, and even amputation.

Potential Complications of Tourniquet Use

Local	Systemic
Compression neuropraxia	Increased central venous pressure
Postoperative swelling / stiffness	Arterial hypertension
Delay in muscle recovery	Deep vein thrombosis
Direct vascular injury	Alteration in acid-base balance
Bone necrosis	Rhabdomyolysis
Soft tissue necrosis	Fibrinolysis
Compartment syndrome

These unfortunate side effects are inherent in the physiology behind how and why a tourniquet works. They function by compressing muscle and other soft tissues that surround an extremity artery, and this then compresses the lumen of these arteries to arrest distal flow. Generally, the risks increase in limbs with larger circumference, given that this correlates with a higher required tension in order to stop arterial flow.

Prolonged tourniquet application more than 1.5 – 2 hours can result in tourniquet palsy or tourniquet paralysis due to injuries to extremity muscles or nerves. Overall tourniquet time is important because it has been shown in animal studies that while after one hour, little to no muscle damage was seen, two hours of tourniquet placement led to elevated levels of lactic acid and CPK, suggesting some degree of muscle damage, while three hours led to actual myonecrosis of the muscles directly beneath the tourniquet. Nerve injuries have been reported after only 30 minutes of tourniquet time. Irreversible ischemic damage occurs after six hours of tourniquet placement, and in this case, amputation of a limb above the level of tourniquet placement is routinely recommended. The less severe phenomenon known as post-tourniquet syndrome is a clinical entity comprised of extremity weakness, paresthesias, pallor, and stiffness. This constellation of symptoms is common after any length of tourniquet placement, but seems to often resolve in about three weeks.

Tourniquets are also associated with venous complications. They are a known cause of venous thromboembolism due to the venous stasis that occurs during their use, and these clots have the potential to embolize once the tourniquet is removed. Paradoxically, they can actually cause increased bleeding once applied by occluding venous return while not completely arresting arterial flow.

Despite this seemingly daunting list of complications, in the military with individuals well trained in tourniquet use, the risk of complications was less than 2%, so a new school of thought is arising that with proper training, EMS and civilian health care providers can be taught the safe principles of tourniquet application, and the benefits will then be seen in trauma patients. Tourniquet use can also indirectly save lives in triage situations where EMS personnel can stop extremity hemorrhage in some patients quickly and effectively, and then move on to other victims who also require prompt attention. Guidelines regarding proper tourniquet application have been developed, as seen below, but generally the rule of thumb is that tourniquet time should be minimized whenever possible, and total application time should not exceed more than two hours.

In 2014, the American College of Surgeons Committee on Trauma convened a panel of nationally recognized experts in prehospital trauma care to develop recommendations for use of tourniquets in external hemorrhage control.

They looked at 16 studies on tourniquet placement, the large majority of which were studies conducted by the US military. An algorithm of their prehospital external hemorrhage control recommendations is presented below. Generally, they strongly recommended the use of tourniquets in the prehospital setting when direct pressure is ineffective or impractical based on the evidence for survival benefits. The panel also suggested against releasing a tourniquet properly applied in the field before the patient reaches definitive care, however, the evidence for this recommendation was less strong.

 In general, safe prehospital tourniquet use depends on a number of factors, including tourniquet design, placement location, tourniquet tightness, and tourniquet time. Fundamentally, for tourniquet use to gain more widespread acceptance, specific protocols need to be set in place and regular training on these protocols for prehospital providers is required.

References:

Bulger EM, Snyder D, et al. An evidence-based prehospital guideline for external hemorrhage control: American College of Surgeons Committee on Trauma. Prehosp Emerg Care. 2014;18:163-173.

Callcut RA, Mell MW. Modern advances in vascular trauma. Surg Clin North Am. 2013 Aug; 93(4):941-61

Doyle GS, Taillac PP. Tourniquets: A review of current use with proposals for expanded prehospital use. Prehosp Emerg Care. 2008;12:241-256.

Johnson, K. “Marathon bombing prompts police to carry tourniquets.” USA Today. 17 Apr 2014: Web.

from Dr. Julie Boll