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THE ENTRAPPED PATIENT – February 2017
 

Case Presentation 

Paramedics are on scene of a traffic collision where a 32 year-old healthy male in a pickup truck rear-ended a big rig at highway speed and is entrapped in his vehicle. He is pinned by his dashboard, which was displaced into the passenger compartment by the force of impact.    Paramedics are able to communicate with the patient, who is alert and oriented to person, place and time.  His main concern is severe pain in his legs - he states his legs are pinned at the level of his thighs and he cannot move them at all.  Rescue has been working for approximately 1 hour to free him. It is unclear how much longer it will take, but rescue personnel have just gained initial access through the passenger side of the vehicle.  His vital signs include blood pressure 142/86, heart rate 110, respiratory rate 16, O2 saturation 99% on room air, and pain scale 10/10

1.

What are the initial considerations for patient management?

The first step is always assessment of the ABCs.  Even prior to accessing the patient, paramedics can assess through verbal communication that his airway is patent and his breathing is unlabored.  His normal blood pressure and mental status suggest that his general perfusion is adequate and there is no visible external bleeding in the upper torso or arms.  The lower extremities cannot be assessed. 

 

After the primary survey, the most pressing concern is the patient’s extreme pain.  Given the delay in extrication, it is appropriate to begin treatment in place as long as the scene is safe to do so.  In this case, paramedics can access the patient through the passenger side of the car and his right arm is available to place an IV and begin treatment.  Morphine or Fentanyl is the appropriate analgesic per LA County protocol.  Alleviating the patient’s pain will facilitate extrication; with improved comfort he may be able to cooperate more easily or at least not fight rescue efforts.

 

Additional treatment considerations are directed by this patient’s particular situation.  By history, his bilateral lower extremities have been pinned between the seat and dashboard at the level of his thighs for over 1 hour.  This should immediately raise concern for crush injury and prompt evaluation for signs of hyperkalemia and initiation of treatment to prevent crush syndrome.

2.

What is crush syndrome?

Crush injury is tissue damage that results from excessive pressure to an area of the body.   Crush syndrome occurs when toxins that develop in the injured tissue are suddenly released into the patient’s circulation. 

 

Excessive pressure on the tissues causes extensive cellular damage; this can occur even in the absence significant external signs of injury.  Compression of the blood vessels produces a local ischemia resulting in a buildup of lactic acid and further accelerating cell death in the affected area.  Intracellular contents, particularly potassium and myoglobin from muscle cells, are released into surrounding tissues; but they remain localized in the muscle until the pressure is released and blood flow is restored. 

 

When the patient is extricated, reperfusion of the crushed tissue causes a sudden systemic hyperkalemia and acidemia that can cause dysrhythmias and sudden cardiac death.  This occurs very rapidly, earning crush syndrome the nickname ‘death by rescue’.   Further, patients lose massive amounts of fluid through cellular breakdown and capillary leak leading to hypovolemic shock.  Those that do not succumb to a dysrhythmias and/or shock may develop severe kidney injury from the myoglobin release. Without proper management, this can result in need for long-term dialysis or death.

3.

Who is at risk for crush syndrome?

If a patient has a significant amount of crush injury from an external compressive force, he or she is at risk for crush syndrome upon release of that force.  The three components required for crush syndrome are: circumferential compression of a large muscle group forgreater than one hour.  If these 3 components are present, then the patient is at risk for crush syndrome and should receive treatment prior to release of the crushed body part.  Circumferential compression distinguishes crush syndrome from patients who develop rhabdomyolysis from prolonged immobilization, in which there is a slower release of the cellular contents into the bloodstream over time and not the sudden release that occurs with a release of a compressive force.  Large muscle group refers to the entire lower extremity or bilateral lower extremities, with or without the pelvic girdle or upper extremities with the pectoral girdle.  Crush injuries involving just an upper extremity or lower extremity below the knee do not generate enough tissue damage to result in crush syndrome.  Crush injury to the head, chest or abdomen are generally incompatible with life.  Although cell necrosis occurs around 4 hours, significant muscle cell damage will begin after just one hour of compression. Depending on the amount of muscle involved, this is enough to result in crush syndrome.  Therefore, circumferential compression to a large muscle group for greater than one hour should prompt treatment for crush syndrome.  This treatment must begin prior to extrication.

4.

What is the field management of crush syndrome?

Management of crush syndrome involves fluid resuscitation as well as assessment and management of hyperkalemia and acidemia.  Initiate a normal saline bolus of 20 ml/kg, reassessing at 250ml increments and consult with the base hospital physician regarding further fluid management - patients can require large volume resuscitation.  Caution should be taken as always in the elderly and those with comorbidities such as congestive heart failure.  Cardiac monitoring should be performed to assess for signs of hyperkalemia including peaked T-waves, prolonged PR interval and widening of the QRS (Figure 1).  But remember that these signs may not be reliably present, despite massive crush injury, because most of the damage is locally contained until release of the compression.  While ECG changes heighten concern, lack of ECG changes is NOT a reason to forgo pre-treatment for crush syndrome in a patient at risk.  In addition to IV hydration, treatment includes calcium chloride 1gram slow IV push, sodium bicarbonate 1 mEq/kg IV, and albuterol 5mg nebulized.   The base hospital should be consulted.  For prolonged entrapments or severe crush these medications may need to be repeated; the duration of effectiveness is approximately 30-60 minutes.  These medications (calcium, bicarbonate, albuterol) should be administered upon recognizing signs of hyperkalemia and/or hemodynamic instability or just prior to release of the compressive force.  If the patient is at risk for bleeding, consider tourniquet placement.  A tourniquet should be placed for all uncontrolled bleeding not amenable to direct compression, including mangled extremities and amputations.  Pain management should be ongoing.

Figure 1

Hyperkalemia

Photo Courtesy of: Mosby's Medical Dictionary, 9th edition. © 2009, Elsevier.

5.

What additional resources are available to the paramedics to assist with patient management?

In the case of a potential prolonged extrication or other complex scene (e.g. large mass casualty incident), it is appropriate to request activation of the Hospital Emergency Response Team (HERT). LA County has two HERTs, one based at LAC-USC and the other at Harbor-UCLA Medical Center. These are teams made up of two physicians (one trauma surgeon and one emergency physician) and one critical care or mobile intensive care nurse that can respond to a scene within 30 minutes to provide higher level resources. The LA County HERTs are established by Reference 817. The HERT response is coordinated by the MAC; the incident commander simply has to request the resource. The HERT will usually arrive by air, so field personnel will need to establish a landing zone. Given the time it takes for the team to arrive, it is best to request the resource early. The team can always be cancelled if the extrication takes less time than expected and the patient can be moved to a Trauma Center. The HERT brings their own equipment and is able to provide additional pain medications, manage complex airways, and perform surgical procedures including chest tubes, cricothyroidotomy and limb amputation when necessary.

6.

Case conclusion

Paramedics placed an IV in the patient’s right arm and initiated a normal saline bolus of 20ml/kg.  They administered morphine 8mg IV and repeated the dose after 15 minutes for additional pain relief.  They consulted the base to request further morphine prn and an additional normal saline bolus. Given the prolonged extrication, they requested MAC deploy the HERT.  This would allow them further resources to manage the patient’s pain, backup for airway management should the patient decompensate, and provide surgical support at the scene.  The paramedics recognized that the patient’s bilateral lower extremity entrapment for greater than one hour put him at risk for crush syndrome; therefore, they initiated cardiac monitoring and repeated the patient’s vital signs every 5 minutes during on scene management.  They coordinated with their colleagues working on the rescue to inform them of the progress in extricating the patient.  Prior to HERT arrival, rescue informed the medics that they were nearly able to release the patient.  At this point, the paramedics treated the patient with calcium chloride, bicarbonate and albuterol.  The patient was already receiving the normal saline bolus, which was continued for a total of 2 liters in consultation with the base hospital.  The patient was successfully extricated from the vehicle.  His limbs were splinted to reduce pain and an additional dose of morphine 8mg IV was administered.  The HERT deployment was called off and the patient was transported to the closest Trauma Center. 


By Nichole Bosson, MD, MPH, Los Angeles EMS Agency