Introduction
Crush injuries occur when part of the body is subjected to compressive forces for an extended period. These injuries can lead to a range of complications, including tissue damage, compartment syndrome, and systemic effects known as crush syndrome. In the past, severely injured crush patients were quickly extricated and brought to waiting EMS.
This often resulted in the proverbial “death by rescue,” as medical care was placed secondary to victim rescue. Modern medicine requires that advanced prehospital management of crush injuries begin before the rescue commences. This approach offers the best chance of survivability and positive patient outcome.
Crush injuries can result from a variety of trauma, including motor vehicle accidents, industrial accidents, natural disasters, and terrorist events. However, two often-overlooked causes of crush injuries are falls and overdose.
An elderly person who falls and is unable to get up for an extended period and a person who overdoses and remains stationary for an extended period can both experience less-obvious crush injuries caused by bodyweight alone. While they may look very different, these crush injury patients have an important commonality: compressive forces for an extended duration.
Crush Syndrome
When crush injury complications become systemic, it’s known as crush syndrome. Crush syndrome is characterized by systemic inflammation, rhabdomyolysis, and kidney damage/failure.
The goal of prehospital interventions in crush injury is preventing and managing these systemic complications. If medical care is delayed until the patient is extracted, the complications have already onset and management will be difficult to impossible. This often results in death.
When a limb or body part is entrapped and crushed, immediate trauma to the impinged body part results in cell damage. The damage to the cell membrane causes extracellular products like water, calcium, and sodium to rush into the call. Intracellular products like potassium, myoglobin, and lactate dehydrogenase to flow out of the cell. With blood flow stopped or greatly reduced to that limb, these toxins build up and enter the bloodstream.
Once pressure is released off the trapped body part, those toxins quickly become systemic and cause severe damage to organs, sometimes resulting in instantaneous death. Hyperkalemia, or high potassium, can cause potassium to enter the heart, leading to lethal dysrhythmias. Excess myoglobin cannot be properly filtered by the kidneys and binds to proteins in the kidneys, causing casts that prevent blood flow, leading to kidney damage.
Anaerobic respiration in oxygen-deprived cells causes a further accumulation of cellular byproducts. This results in an acidosis that further worsens kidney function, heart function, and clotting. This cycle of complications is known as rhabdomyolysis. Knowing how to prevent or lessen these complications result in better survivability and outcomes.
As with all emergencies, rescuer and provider safety must be an initial priority. Proper personal protective equipment is required, and the scene must be stabilized to the extent possible. That means chocking wheels at auto accidents, cribbing and shoring at collapses, and lock-out, tag-out at industrial sites. This should be accomplished by responding fire/rescue personnel who are trained to do so.
Once the scene has been stabilized to the extent possible, medical personnel should begin care. Part of providing that care is often to pace rescuers who will often be eager to pull the patient out at the earliest possibility. The medical provider may need to explain the severity of the complications to rescue personnel who are not medically trained. The provider also should be directly involved with the extrication plan.
Basic Management
As with all patients, assessing a crush injury patient begins with the ABCs. Special attention should be paid during airway and breathing steps. Some rescue environments may dictate that airway management or oxygen therapy cannot be performed or maintained during extrication.
Life-threatening bleeding should be stopped when it’s detectable. If a large piece of soil, building material, or equipment is crushing a limb, it should be assumed that severe bleeding can or will result when that object is moved. If no bleeding is apparent, routine prophylactic tourniquet use is no longer recommended for crushed limbs. The old idea was that a tourniquet would prevent reflow of toxins built up because of crush injuries, however the more likely scenario is that it will cause complications later.
After ABCs and the severity of the crush injury are assessed, cardiac monitoring is essential. It will allow the provider to monitor for EKG changes resulting from electrolyte imbalances, mainly hyperkalemia. Monitoring the EKG for the progression of peaked T-waves, flattening P-waves, ST depression, and widening QRS complexes will allow the provider to know the severity of hyperkalemia the patient is experiencing. The provider can tailor a pharmacological course based on this to include IV fluids, bicarbonate, calcium, and albuterol.
Medications
Administration of crystalloid solutions is the first line of treatment in crush injuries. Crystalloids replenish fluids lost to third spacing, reduce serum concentration of toxins and electrolytes, and encourage diuresis.
A long-held belief that Lactated Ringer’s solution (LR) should be avoided in hyperkalemic patients is incorrect. While LR does contain potassium, it only contains 4 mmol/L compared to the >5.3 mmol/L that a hyperkalemic patient will have in their blood serum. This will result in a decreased concentration of potassium, although the net amount of potassium will be lower. The cells do not care about the overall amount, only the concentration. The same is true of LR’s calcium content.
The other reason LR has been avoided is its sodium lactate content. When a lactate level is drawn in the hospital, it will likely reflect an elevated lactate level however it is not measuring the lactic acid level but rather the sodium lactate from the LR solution. Sodium lactate is also metabolized in the liver into sodium bicarbonate, a newly controversial medication that’s long been given to crush injury patients.
Sodium bicarbonate acts as a buffer when acidic toxins are released systemically in crush syndrome and prevents myoglobin deposits in the kidneys. Unfortunately, sodium bicarbonate alone is hypertonic and therefore needs to be mixed into a solution to make it isotonic. Adding three (3) 50mEq amps of sodium bicarbonate to a liter bag of D5W (with 150mL removed) accomplishes this task and can be given like any other bag of IV fluid.
Lastly, nebulizing albuterol is indicated due to albuterol’s ability to “push” potassium back into cells, thus reducing serum concentration and its effects on the heart. Avoiding normal saline (NS) is recommended due to it being acidic (pH ~5-5.5), hypernatremic, and hyperchloremic.
Analgesia
Not to be forgotten during pharmacological interventions is analgesia. Fentanyl is the primary analgesic medication due to its short onset, short duration, and relative hemodynamic stability. For prolonged extrication, multiple doses may be needed and may exceed the contents of a single unit’s controlled substance stock. Providers should also use caution when they’re in enclosed locations where an entire drug kit is not accessible. Naloxone should be within arm’s reach anytime an opioid is administered, including in a confined space.
Lastly, ketamine is an effect dissociative which can ease a patient’s pain with little effect on hemodynamic stability. Caution should still be maintained as ketamine may increase muscle tone, which could interfere with the extrication stage.
Extrication
Only once the patient has been stabilized to a reasonable degree should extrication begin. During this extrication process, the patient must remain monitored, when practical, or periodic breaks from the extrication process must be taken for the patient to be reevaluated or treated.
The provider should accompany the patient through this extrication process when possible. Once extricated, the provider should accompany the patient to a trauma center or a detailed report should be provided to the transporting unit.
Conclusion
Crush injuries demand a multifaceted prehospital approach, starting from access and initial stabilization to pharmacological interventions. Timely and effective patient care can significantly affect the outcomes for patients with crush injuries, reducing morbidity and improving their quality of life. Collaboration among EMS providers, rescuers, and field physicians is necessary to accomplish this care.
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