Figure 1: Direct force can cause crush injuries, some resulting in open wounds.
Figure 2: A stroke patient who has fallen and trapped her right leg beneath her body weight
Figure 3: Assess circulation in an extremity following a crush injury
Figure 4: Consider trauma to structures below the surface of soft tissue injuries
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Crush injuries and compartment syndrome damage tissues in a very specific way. Crush injury is a form of blunt trauma, whereas compartment syndrome is a complication of blunt trauma. These particular types of injury present the EMT with very specific challenges to patient assessment and care. Compartment syndrome requires an EMT to think long term and prevent ongoing injury, whereas crush injuries force the EMT to consider some very different treatment modalities. In this topic we discuss both of these specific circumstances as they pertain to blunt trauma.
Even with these specific circumstances in mind, you should remember the basic principles of assessing and treating blunt force trauma. In particular, recall that when dealing with soft tissue injuries you must consider not just the outside of the skin but also the potential for injury beneath the skin.
Blunt trauma damages by applying force and stretching tissues beyond their normal tolerances. A crush injury—a particular type of blunt trauma—damages tissues by compressive force (see Figure 1). This force is generally applied over larger areas and damages more tissue, either through direct compression (direct, crushing force) or by compressing tissues and limiting blood flow (perfusion) to the cells in that area. Crush injuries can occur over a relatively small area, such as striking the thumb with a hammer, or over a large area, such as traumatic asphyxia of the chest. The mechanism of injury remains similar.
This type of injury can occur from either external or internal forces. An example of external direct compression might be a beam that has fallen and trapped a patient’s leg. A different mechanism that might have a similar net effect would be compartment syndrome. In compartment syndrome, internal swelling causes high pressure to build up within the relatively closed muscular compartment of an extremity. This pressure can damage nerve, muscle, and vascular tissue and limit perfusion to that area. As compartment syndrome emerges, tissue is destroyed just as it would be by direct force.
The broad definition of soft tissue injury (non-bony, non-organ injury) accounts for the vast majority of traumatic injuries. Crush injuries are only a small portion of this category, but they result from a wide range of mechanisms.
Direct force crush injuries are the most common types of crush injuries. In this case, an object (or objects) applies force and destroys tissue by direct compression. Examples of this include injuries caused by falling objects and blunt trauma distributed over larger areas.
In this situation, compression of tissue is caused by the patient’s position. This damage typically manifests over hours—and sometimes days. The inability of a patient to shift position causes compression and restricts blood flow. Cells are deprived of oxygen, and waste products build up. Dramatic examples of this include victims trapped and pinned by earthquakes and bomb blasts, but more common examples occur in patients who fall and are unable to get up; their weight causes the crushing force on dependent structures.
Consider a stroke patient who collapses and pins her own leg beneath her body weight (see Figure 2). Her stroke renders her unable to get up or even change her position. Her own body weight compresses her leg and causes a crush-type injury.
Internal swelling causes compartment syndrome and damages tissue by direct, internal compression and by limiting
Direct compression destroys cells in the same manner as any other direct force trauma does. Energy is transferred from an offending object into the tissues. When tissues are stretched beyond their normal tolerances, damage occurs. With crush injuries, that damage can be spread over wide areas and extend deep into tissues below the skin.
Blood flow—for delivery of oxygen and nutrients and for the removal of waste products—is essential to cells. Crush injuries can restrict and even stop blood flow to the areas that are being compressed. These types of injuries are common when, for example, a patient’s lower extremities are pinned under rubble after a building collapse. As the legs are compressed, cells are destroyed, not just by the direct force but also by the lack of perfusion.
If compression continues over an extended time (typically longer than four hours), the muscle tissue will actually begin to break down and may cause systemic problems by releasing toxins into the bloodstream. These toxins can cause cardiac problems, a drop in blood pressure, and even kidney failure.
Compartment syndrome is compression from the opposite direction. Fascia is a fibrous membrane that serves to separate areas of muscle. Because fascia does not stretch, these muscular compartments form relatively closed containers. When bleeding or swelling occurs inside these compartments, pressure can build up. If this pressure continues to rise, it can reduce perfusion and destroy cells; this buildup of pressure is compartment syndrome.
Remember that all assessment begins with a thorough primary assessment. Although your attention may be immediately grab-bed by pinned extremities, the airway and breathing still take precedence. Treat life-threatening emergencies first.
Crush injuries often cause massive internal hemorrhage. Be vigilant for the signs and symptoms of shock. Again, dramatic injuries may mask more serious underlying issues.
The actual crush injury will generally appear similar to any other blunt trauma wound. Typically, the chief complaint will be pain in the affected area. Discoloration—such as bruising, tenderness, and even deformity—can indicate such an injury. In prolonged or massive compression injuries, blood vessels and nervous tissue may be destroyed. As such, it is not uncommon to see diminished circulatory, sensory, and motor function in distal areas (see Figure 3).
Assessment may be extremely difficult if the patient is trapped under an object. Understand the limitations of your assessment at this point, and be prepared for further injuries and unexpected complications once the patient is disentangled.
Assessment of Compartment Syndrome
Compartment syndrome typically occurs in the extremities; however, it can also occur in the buttocks and even the abdomen. Compartment syndrome is generally not an acute problem and typically takes hours and even days to develop. As such, much of your assessment will be geared to preventing compartment syndrome rather than identifying it. Signs and symptoms of compartment syndrome include the following:
- Pain, discomfort and/or burning sensation in the affected extremity, especially pain that continues or increases after immobilization
- Tenderness (pain on palpation) in the affected extremity
- Unusual firmness or rigidity in the affected area
- Altered motor function, circulation, or sensation in the distal areas of the extremity (Note: Loss of a distal pulse is an unusual finding in compartment syndrome. Typically a pulse is present, even though circulation may be impaired. This pulse may feel weaker than the same pulse in the unaffected extremity. Delayed capillary refill time may be a more important finding).
- Weakness or paralysis of the muscles.
Remember that assessment of soft tissue injuries will often be a lower priority than treating the ABCs. Always ensure that the primary assessment has been completed prior to evaluating such wounds.
Emergency Medical Care
Scene safety will be an important element in treating crush injuries. Before initiating any patient contact, ensure that the mechanism of injury that injured the patient will not injure you. Treating patients in a collapse zone requires specialized training and rescue resources. Be sure to know what resources are available in your area
and how to access those resources when necessary.
The most important care in crush injuries will be to treat immediate life threats first. Always address airway and breathing complications and life-threatening hemorrhage immediately. Only after treating these more important priorities should you be concerned with addressing soft tissue injuries. Beware of being distracted by a dramatic soft tissue injury while more subtle complications rapidly kill your patient.
Crush injuries can encompass virtually any area of the body. As a result, you will have to tailor your treatment to best treat the affected area. For example, crush injuries to the chest, such as traumatic asphyxia, might require immediate ventilatory support. Massive crush injuries will also require immediate and rapid transport to an appropriate trauma facility.
Often, soft tissue injuries will mask more serious internal injuries, such as internal bleeding (see Figure 4). Always think of the structures that lie beneath the outer injury and consider how damaging those structures might affect your patient’s overall status.
In compression-related injuries (whether they are caused by an external force or by the patient’s position), relieving the pressure is important. Restoring blood flow to the affected area will limit tissue damage.
Keep in mind that patients who have been trapped for prolonged periods may have systemic complications as a result of their compression-related injuries. When compression is released, waste products and toxins from the affected area may be released into the patient’s system. These toxins can cause cardiac dysrhythmias, hypotension, and other systemic complications. With patients who have been trapped longer than four hours, consider contacting advanced life support and/or medical control prior to removing large objects (when possible).
Remember also that large, entrapping objects may be limiting hemorrhage in the affected area and, when released, may allow massive bleeding to occur. Always be prepared for rapid patient deterioration after removal from entrapment.
In general, treat crush injuries as you would any other blunt force trauma. Immobilize potential fractures, elevate the involved extremity and use ice to reduce swelling and for pain control. Consider spinal immobilization when appropriate.
Preventing and Treating Compartment Syndrome
As stated, compartment syndrome generally develops over long periods of time. As a result, it is typically not a major concern for the short contact times of most EMS systems. However, in many situations EMS may be in prolonged contact with patients, and in such circumstances preventive measures will help avoid compartment syndrome.
The following actions are necessary to prevent compartment syndrome:
- Elevate extremities. Although some experts disagree, it is generally accepted that keeping an extremity elevated above the level of the heart will help minimize swelling and maximize the work of the lymphatic system to remove accumulated fluid from the area.
- Beware of constricting immobilization. Although splinting material may be just right at the time of initial immobilization, remember that swelling can cause these same bands to become constricting. Monitor equipment frequently to ensure appropriate tightness. Remove any constrictive jewelry.
- Apply cold. Appropriately applied cold packs and ice can help limit edema and mitigate pain.
- Monitor distal circulatory, sensory, and motor function. Changes in these findings can indicate rising pressure and could identify a reason to modify response and/or transport modalities.
Crush injuries and compartment syndrome are infrequent circumstances that require critical decision making. Use good patient assessment to identify life threats and treat specific injuries appropriately.
1. Which of the following would be considered a mechanism of injury leading to a crush injury?
A. A stroke patient who falls and traps his leg under his body weight for eight hours
B. A stab wound to the left thigh
C. A syncope patient who falls and strikes his head against the dresser
D. An angulated tibia/fibula fracture
2. Which of the following signs would potentially indicate compartment syndrome in an injured extremity?
A. Firmness or rigidity
B. Swelling at the site of the fracture
C. Red discoloration
D. Decreased capillary refill time in the distal areas
3. Which of the following is a step you might take to prevent compartment syndrome?
A. Elevate the extremity.
B. Use compression bandages to wrap the extremity.
C. Place the extremity in a position below the heart.
D. Apply heat packs.
4. Which of the following patients would have the potential for systemic effects of a crush injury?
A. A patient recently freed after having his extremities pinned for four hours
B. A patient recently freed after having his extremities pinned for four minutes
C. A patient who has crushed his thumb with a hammer
D. A patient who has broken his leg while inline skating
5. Which of the following would cause damage as the result of compartment syndrome?
A. Internal compression
B. Direct compression
C. Entrapment/weight-based compression
D. Organic/inorganic compression
List three signs of compartment syndrome.
Unusual firmness/rigidity, altered circulatory function (weak pulse), delayed capillary refill.
Describe how the mechanism of entrapment/weight-based compression damages soft tissue.
Compression of the tissue is caused by the patient’s own body weight and position. One major problem that develops is the restriction of blood flow; cells become deprived of oxygen and nutrients while waste products continue to accumulate. This environment becomes very toxic to the cells.
Describe the relationship between fascia and compartment syndrome.
Fascia is a layer of fiber that encases the muscles, and it does not stretch. When an event occurs that causes the volume inside the fascia to increase, the pressure will increase as the volume attempts to increase. As the injury increases in severity and the volume attempts to increase, the fascia will not stretch and the pressure inside the tissue will continue to increase.
You respond to a roof collapse with people trapped. On arrival, you stage and wait for rescue personnel to secure the scene. About four hours later, you are directed in. Rescue workers bring you to a patient whose legs are trapped beneath a collapsed beam. The workers state they are almost ready to lift the beam off the patient.
1. What types of injuries would you expect from this mechanism?
It is reasonable to at least expect crush injuries from the beam and compartment syndrome due to the time the patient was trapped.
2. What immediate assessment steps should you take?
Initiate any spinal precautions necessary and asses for any major life threats.
Your partner completes the assessment as you prepare the stretcher. Your partner tells you the patient is breathing only four times per minute. At that moment, the captain of the rescue team tells you to step back, as rescue workers are now ready to move the beam.
3. What should your next action be?
Step back since safety for you takes priority over treating the patient.
4. Is ventilating the patient worth delaying extrication?
The beam is moved and you move the patient to the backboard for transport. Your partner tells you, “I don’t think he has a pulse.” At no time does safety for you or other rescuers receive any other priority than first while managing any patient or any scene.
5. Explain why the patient may have gone into cardiac arrest now (there may be more than one reason).
By systems, this could be the product of cardiovascular, respiratory, neurological, or metabolic (toxicological) events. Failure within any of these systems will lead to death.
6. Why might having advanced life support on scene prior to removal of the beam be important?
Using advanced life support at this particular scene could be important because of the interventions that could be initiated both prior to the patient being extricated as well as after the patient is extricated. These interventions will target the body systems so as to prevent their failure that leads to death.
Joseph J. Mistovich, MEd, NREMT-P, is chair of the Department of Health Professions and a professor at Youngstown State University in Youngstown, OH. He has more than 25 years of experience as an educator in emergency medical services. He is an author or coauthor of numerous EMS books and journal articles and is a frequent presenter at national and state EMS conferences.
Daniel Limmer, AS, EMT-P, has been involved in EMS for 31 years. He is active as a paramedic with Kennebunk Fire-Rescue in Kennebunk, ME. A passionate educator, Dan teaches basic, advanced and continuing education EMS courses throughout Maine.
Howard A. Werman, MD, FACEP, is professor of emergency medicine at The Ohio State University. He is a teacher of medical students in the College of Medicine and the residency training program in emergency medicine at The Ohio State University Medical Center.