EMS Recap: Tourniquets

Today, medics involved in tactical operations, mass casualty events, disasters or working in rural communities should consider the tourniquet as another method to prevent extremity exsanguinations.¹ Tactical operations, disasters and mass casualty events offer medics performing triage in the prehospital environment opportunities to use tourniquets to save more lives during that first round of triage. Tourniquets should be considered another treatment modality and not a treatment of last resort.² Applying a tourniquet to stop a severely bleeding extremity wound³ in the prehospital environment prior to the onset of poor perfusion is associated with positive patient outcomes.⁴

Tourniquet Application

Elimination of distal artery flow is the primary purpose of a tourniquet. Any tourniquet that cannot stop arterial flow is not effective.¹ One precursor to the tourniquet was the use of tight bandages placed proximal to the point of surgical amputation.⁵ Most commercially manufactured tourniquets are designed for quick application, usually within 60 seconds. A tourniquet replaces the need for direct pressure, additional bandages or a second care provider during transport. A properly trained medic should be able to effectively stop extremity hemorrhage, accomplish multiple interventions and initiate immediate transport without the need for additional responders.²

Currently, most medics are trained to place the tourniquet just above the sight of the injury while avoiding placement over a joint. Placing the tourniquet more proximally to the injury on the thickest portion of the extremity helps to limit damage to the underlying tissue and prevent any minor bleeds near the injury.² Once positioned, tourniquet tightness requirements will increase with the size of the limb. There is an inverse relationship between the width of the tourniquet and the pressure needed to halt arterial blood flow. Complete occlusion of arterial flow on the lower extremities is extremely difficult, if not impossible, with a one inch wide tourniquet. A wide tourniquet will be more effective on a lower extremity, as there is less pressure needed on the greater surface area to successfully occlude arterial blood flow, and less tissue damage will occur.¹

The original strap tourniquets and their manufacturers were not subject to FDA testing and approval as of 2005, so the military developed minimum effectiveness standards for testing. All military tourniquets must achieve distal artery occlusion for thigh applications at least 80% of the time to be considered effective. Testing revealed the need for a windlass or another type of mechanical advantage to effectively tighten the tourniquet.¹

You should be reluctant to use an improvised tourniquet, as most of them will not be effective at occluding arterial blood flow. If an improvised tourniquet is the difference between your patient living or dying, the best improvised tourniquet in your arsenal is the manual blood pressure cuff.2 Regardless of the type of tourniquet used, once applied, do not remove it if the patient is in shock, the limb was amputated, there are obvious arterial disruptions, the tourniquet has been on for an extended period, or you will be transferring care and can no longer observe the patient.3 The tourniquet may need to be tightened after initial application as the arterial pressure increases from sympathetic nervous system response to pain and injury or air has leaked from the manual blood pressure cuff.⁶

Two hours is considered the length of time a tourniquet can be in place before neuromuscular injury and functional loss begin. For applications longer than 2 hours, cooling the limb may help delay injury and loss of function. The best method to save a limb is rapid transport and converting to a less-damaging means of hemorrhage control as soon as practicable.³

Systemic complications of tourniquet application in adults are deep vein thrombosis and pulmonary embolism. Localized complications include skin, muscle, vessel and nerve injury at the site of application, varying with tourniquet width, pressure applied and duration of application.⁷ Most irreversible ischemic damage occurs after tourniquet application of six or more hours.² When using a tourniquet, apply only pressure sufficient to stop the bleeding. Compartment syndrome can occur with excessive tourniquet pressures and prolonged application.² Be aware that a tourniquet may need to be tightened after initial application as the arterial pressure increases from sympathetic nervous system response to pain and injury.⁶

The tissue under the tourniquet will develop local inflammation immediately after the tourniquet is applied, and there will be a decrease in PO₂ and an increase in PCO₂ in the tissue cells. Between 15 and 45 minutes after application, a physiological nerve conduction block develops, affecting motor and sensory transmissions. Direct compression of the nerves causes a second conduction block known as tourniquet paralysis. The stored cellular ATP will be exhausted after 2 hours and creatine phosphate after 3 hours. Lactate concentrations will increase when the cells switch from aerobic to anaerobic metabolism, with a corresponding decrease in pH as metabolic acidosis develops. Microvascular injuries will begin after 2 hours.⁶

After tourniquet release, the increased vascular permeability produces both interstitial and intracellular edema and post-tourniquet syndrome. End-tidal CO₂ levels peak within the first minute and will return to normal levels after 3 to 5 minutes. Cerebral blood flow increases with the increased end-tidal CO₂ level. In patients with head injuries, tourniquet release may require hyperventilation to maintain normal ICP. Additionally, increased fibrinolytic activity with possible increased bleeding for approximately 15-30 minutes may occur. Neurologic complications are more common with lower limb tourniquets. The sciatic nerve is most often affected in the lower limb and, when observed, the radial nerve in the upper limb.⁶ Post-tourniquet syndrome is the weakness, paresthesia, pallor and stiffness felt in the limb after tourniquet removal.² Post-tourniquet syndrome typically lasts 1-6 weeks.6 Nerve conduction velocities return to normal if the tourniquet has been on less than 2 hours and the pressure was less than 500 mmHg.⁸ Tourniquet paralysis resolution post-tourniquet may exist for as long as 6 months.⁶

Be careful using an alcohol-based solution to cleanse near a tourniquet, as the solution may seep under the band and lie against the skin, causing chemical burns.⁶ Additionally, protecting the skin under the tourniquet prior to application helps to reduce other skin complications.⁹ Never cover a tourniquet.²

Summary

The CABC approach to field triage starts with the medic assessing for catastrophic hemorrhage(C) before assessing airway (A), breathing (B) and circulation (C).¹⁰ If catastrophic hemorrhage is found and the patient is still awake, applying a tourniquet may require pain medication.² Once applied, do not attempt reperfusion intervals in the prehospital environment. Slow exsanguination of the patient will be the end result.²

Using a tourniquet to limit blood loss and expedite transport for definitive care may constitute one of the best life-saving techniques. Additionally, using a tourniquet to stop hemorrhaging prior to beginning resuscitative efforts may help preserve the patient’s own blood volume.² Pediatric trauma victims often have the same injury patterns as adults and may benefit even more from rapid application of a tourniquet to stop hemorrhaging.²

References

1. Walters TJ, Wenke JC, Kauvar DS, et al. Effectiveness of self-applied tourniquets in human volunteers. Prehosp Emerg Care 9(4), 2005.

2. Doyle GS, Taillac PP. Tourniquets: A review of current use with proposals for expanded prehospital use. Prehosp Emerg Care 12(2), 2008.

3. Walters TJ, Mabry RL. Issues related to the use of tourniquets on the battlefield. Military Medicine 170(9):770-775, 2005.

4. Salvucci A. Literature review: Tourniquet use. EMS News Network, 2009.

5. Mabry RL. Tourniquet use on the battlefield. Military Medicine 171(5):352-356, 2006.

6. Deloughry JL, Griffiths R. Arterial tourniquets. Continuing Education in Anesthesia, Critical Care & Pain 9(2), 2009.

7. Sinicina I, Bise K, Hetterich R, Pankratz H. Tourniquet use in childhood: A harmless procedure? Pediatric Anesthesia 17, 167-170, 2007.

8. Dayan L, Zinmann C, Stahl S, Doron N. Complications associated with prolonged tourniquet application on the battlefield. Military Medicine 173(1):63-66, 2008.

9. Din R, Geddes T. Skin protection beneath the tourniquet: A prospective randomized trial. ANZ J Surg 74, 721-722, 2004.

10. Niven M, Castle N. Use of tourniquets in combat and civilian trauma situations. Emergency Nurse 18(3), 2010.

Robert E. Sippel, Major, USAF (Ret.), MS, MAEd, NREMT-P, LP is an assistant professor and clinical coordinator in the Emergency Health Sciences Department at the University of Texas Health Science Center, San Antonio, TX.