MED-NERD

Crush Syndrome-Full Text

Outline:

• Introduction
• Historical view
• Overview
• Etiology
• Pathophysiology
• Clinical Presentation
• Investigations
• Management and Treatment
• References

Introduction:

Historical view:

-In 1909, Crush syndrome (CS) was first described in Italy during the Messina earthquake.

-In 1941, during the World War II, victims from bombed buildings that presented with swollen limbs, dark urine, hypovolemic shock, and renal failure, died later due to kidney failure despite being in a good condition upon rescue. This was reported by Bywaters and Beall during the World War II and crush syndrome was described clinically. Later on, the disorder was known as Bywaters’ syndrome.

-In August 1999, the Great Marmara earthquake occurred in north western Turkey leaving thousands of crush injury patients.

-The latest disaster that was the Turkey-Syria earthquake that occurred in February 2023.

-A variety of disorders were identified by Mubarak et al including compartment syndrome and crush syndrome.

-Hyperbaric oxygen therapy became essential in treatment of crush syndrome about 30 years ago.

-In the European Continent, haemodialysis became a primary modality of treatment of crush syndrome.

-The current concern is about early detection of crush syndrome considering fluid regimen and renal replacement therapy (RRT).

-The clinical aspect and the pathogenesis of crush syndrome have become clear over years due increasing the report of crush syndrome cases in natural disasters like earthquakes and other global conflicts that increased the information about and the interest in crush syndrome.

N.B:

It is important to differentiate between the following terms:

-Crush injury >> is something heavy causing a direct physical crushing of the muscles leading to injury of the affected muscles.

-Crush syndrome (or rhabdomyolysis) >> is an injury of the skeletal muscles leading to disruption of muscle cells, release of its contents into the blood causing metabolic and electrolyte disturbances.

-Compartment syndrome >> occurs when the tension within the muscle compartment rapidly rises leading to metabolic changes.

-Compression syndrome >> is an indirect injury of the muscles through simple and slow compression of a group of muscles causing ischemia and release of the muscle contents into the circulation.

Overview:

Crush syndrome (also known as traumatic rhabdomyolysis, Bywaters’ syndrome), is a systemic disorder due to high-degree crush injury or traumatic compression, whether direct or indirect, leading to long-term crushing of the muscle (extremities or torso or other parts of the body) with compression and destruction of striated muscle cells. When the compressive forces become removed, swelling and injury of muscles with necrosis and neurologic dysfunction in the affected parts may occur. The damage is whether due to the primary direct effect of the trauma or the ischemia that occurred as a result of the compression. Due to restoration of blood, the cell contents such as phosphate, urate, potassium, nephrotoxicity myoglobin (Mb), and other contents are released into the circulation leading to myoglobinuria, acute kidney injury (AKI), electrolyte disturbance (hyperkalaemia and hypocalcaemia), metabolic disturbance (acidosis), arrhythmias, Adult Respiratory Distress Syndrome (ARDS) as a result of the inflammatory response, Disseminated Intravascular Coagulation (DIC) due to the released thromboplastin, hypovolemic shock, and multiple organ dysfunction syndrome (MODS) and eventually death. Compartment syndrome can also occur in Crush syndrome. The body parts affected in crush syndrome include lower extremities (74%), upper extremities (10%), and trunk (9%).

Crush syndrome is a life-threatening condition and is the second leading cause of death in earthquakes, following direct trauma. The incidence of crush syndrome is about 2-15% with nearly 50% developing acute renal failure and over 50% that require fasciotomy. About 50% of the renal failure patients require dialysis. The diagnosis and the treatment are difficult due to inability to reach the areas of disasters and provide the treatment early with difficulties in communication and transportation. The treatment is mainly focused on the management of circulatory shock, arrhythmias, and kidney failure. This is achieved by early fluid resuscitation, forced diuresis, and renal replacement therapy (RRT) (haemodialysis, peritoneal dialysis, haemodiafiltration, haemofiltration, and eventually kidney transplantation). Removing the myoglobin until repair of kidney function is performed through hemodialysis or continuous venovenous haemofiltration (CVVHF). Despite the treatment modalities, a wide range of patients develop systemic inflammatory response syndrome (SIRS) later on that eventually progresses into multiple organ failure (MOF) and death.

Crush syndrome may occur in non-traumatic conditions with impaired consciousness such as prolonged immobilization, burns, stroke, coma, and electrical injury. In prolonged immobilization under anaesthesia, the weight of body part alone without relief with increased local pressure may be one of the causes of rhabdomyolysis and compartment syndrome.

In comatosed, postoperative, and intoxicated patients with prolonged immobilization which is a condition known as "Gluteal compartment syndrome" may also lead to crush syndrome.

Etiology of crush syndrome:

Crush syndrome is mainly due to crush injury or compression with heavy weight or collapse such as:

-Natural disasters like earthquakes >> structural collapse for more than 24 hours is associated with high mortality rate. About 20% of earthquake victims have crush injuries due to entrapment and building collapse.

-Accidents, whether constructural, industrial, agricultural, or vehicular accidents (being trapped under a vehicle).

-Wars (being trapped under a bombed building).

-Stampede >> crush injuries and traumatic asphyxia may occur in mass crowd stampedes.

Pathophysiology of crush syndrome:

About 80% of crush injury mortality rate is due to asphyxia or head injuries and trauma. About 10% out of the 20% that reach the hospital can make recovery. The rest of patients representing the remaining 10% of crush injury cases develop crush syndrome that is associated with severe metabolic and electrolyte disturbances.

Due to rupture of muscles in crush injury, myoglobin become released from the muscle cells into the circulation. Later it becomes converted into methmyoglobin, and eventually into acid haematin that passes into the circulation. Other components of muscle cells that are toxic become released into the circulation such as phosphate, potassium, magnesium, acids, and enzymes including lactate dehydrogenase (LDH) and creatine phosphokinase (CKMM). ATP and CK become exhausted. Calcium, sodium, and fluids become released into the muscle increasing the tension and volume of muscles. This is due to ischemia of muscles as a result of crush injury occluding the circulations of the muscles. Activation of nitric oxide system also causes vasodilation in the muscles and hypotension.

When victims become rescued and once the tension become released, disruption of sodium-potassium-ATPase pump due to correction of ischemia and reperfusion of muscles. Multiple components become released into the circulation including ions (potassium, calcium, phosphate), muscle enzymes (aldolase, creatinine phosphokinase), myoglobin degradation products, uric acid, and lactic acid.

When myoglobin exceeds the renal threshold and the filtration rate of the glomeruli, it becomes precipitated in the distal convoluted tubules leading to their obstruction. Moreover, myoglobin degradation products lead to vasoconstriction of the afferent arterioles which contributes to the destruction of tubules. The serum creatinine phosphokinase is considered the most important indicator of muscle damage. Muscle ischemia and elevated lactic acid levels are proportional to each other. The gross changes of muscle include swelling, hardness, cold, insensitivity, and necrosis of affected muscles.

Kidney damage and oliguria is not coordinated with the severity of muscle damage and injury. The kidney become oedematous. Cardiac dysrhythmias occur due to releasing potassium into the circulation. Metabolic and electrolyte disturbance eventually lead to shock. Lung oedema occur which deteriorates lung functions and gas exchange leading to Adult Respiratory Distress Syndrome (ARDS).

Although crush injuries are not common after chest and head injuries, some studies showed about 10% of chest traumas are associated with crush injuries. Crush syndrome is usually due to prolonged pressure that results in death in most cases.

Direct tissue damage and occlusion of venous circulation occur due to the compressive force. Myonecrosis (cellular death) occur leading to crush syndrome. Death occurs within 20 minutes of rescue due to sudden arrest from ventricular fibrillation which occurs due to potassium, myoglobin, and phosphorus release in the area of injury. The patient dies smiling after rescue which is known as "smiling death".

Clinical presentation of crush syndrome:

The release of muscle components including myoglobin and electrolytes affect various organs including the heart, kidney, the metabolic and acid-base balance. Sudden release of compressive forces of a crushed limb is associated with a condition known as reperfusion syndrome which is characterized by metabolic abnormalities, acute hypovolemia, and may lead to fatal cardiac arrhythmias.

According to the organ or the system affected, clinical presentation can be classified as the following:

1-Limbs injury:

Peripheral limb injury ranges from superficial injuries, petechiae, erythema, muscle blisters, swelling, bruising, open fractures, rhabdomyolysis, sensory deficit, paralysis, myalgia and deformities.

2-Chest injury:

Chest compression causes increase in intrathoracic pressure, pulmonary contusions, fracture of ribs, pneumothorax, hemothorax. Pneumonia and fever may also occur.

3-Renal damage:

Muscle injury and rhabdomyolysis lead to release of muscle components including myoglobin, creatinine, potassium, and phosphorous into the blood circulation. If treatments of myoglobinuria is delayed, renal tubular necrosis occur. Moreover, metabolic abnormalities occur due to the release of electrolytes from ischemic muscles. The results of renal damage include oliguria, haematuria or dark urine, and renal failure.

4-Metabolic Abnormalities:

-systemic hypocalcaemia >> due to entry of calcium through the muscle cell membrane

-hyperkalaemia >> due to releasing potassium from ischemic muscle into the circulation

-Imbalance of calcium and potassium may cause cardiac arrhythmias and cardiac arrest

-Metabolic acidosis >> due to releasing lactic acid from ischemic muscle into the circulation. Metabolic acidosis may worsen cardiac arrhythmias.

5-Cardiovascular system impairment:

Cardiovascular damage include tachycardia, cardiac dysrhythmias, haemorrhage, hypovolemia, hypotension, and pallor. Hypotension may worsen renal failure. Third space loss requires fluid therapy during the first 24 hours. More than 12 L of fluid may be trapped in crushed area over 48 hours. Compartment syndrome is a swelling in a closed anatomical space which worsens vascular abnormalities and usually require fasciotomy.

6-Other symptoms:

Delirium, agitation, nausea, and vomiting.

Investigations of crush syndrome:

-Complete Blood Count (CBC)

-Coagulation studies

-Serum creatinine kinase (CKMM) >> normal range of serum creatinine kinase (CKMM) is 25-175 U/l. Greater than 1000 IU/l level of serum creatinine kinase (CKMM) is usually considered an indicator of crush syndrome. CKMM level after a crush injury usually rises after 2-12 hours, reaches maximum within 1 to 3 days, and decreases after 3-5 days.

-Serum myoglobin and myoglobin degradation products >> highly sensitive

-Serum aldolase

-Serum aspartate aminotransferase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), Lactic acid >> show steady elevation

-Serum uric acid >> shows moderate elevation

-Serum urea and creatinine >> show steep elevation after prolonged crush injury

-Serum potassium >> early elevation is detected and is a predictor for dialysis

-Serum calcium levels >> show hypocalcaemia

-Blood glucose >> stress related hyperglycaemia may occur

-Arterial Blood Gases (ABGs) >> show acidosis

-Haemogram and Electrocardiogram (ECG)

-Intracompartmental pressure monitoring >> levels greater than 30 mm Hg are indicators for fasciotomy

-Doppler >> to detect limb ischemia

-Emergency CT

-Kidney function tests

-Urine analysis >> show the presence of myoglobin products and creatine kinase

-Measuring body weight

Management and Treatment of Crush syndrome:

The Management of crush syndrome includes the following steps:

-Rescue

-Resuscitation

-Recognition of the syndrome and treatment

-Rehabilitation

1-Rescue:

Is done by a professional rescue team to transport patients to healthcare facilities. Potassium binders like oral polystyrene sulfonate sometimes may be given to patients before transportation to avoid renal damage.

2-Resuscitation:

The syndrome may be insidious in patients looking well. Treatment should start with aggressive fluid therapy as most patients are in shock.

3-Recognition of crush syndrome and treatment:

The treatment process represents cooperation of surgeons, physicians, radiologists, biochemists and other healthcare workers.

4-Rehabilitation:

Rehabilitation involves physical as well as psychiatric consultation.

Treatment of crush syndrome:

Initial management >> Advanced trauma life support(ABCDE):

-Airway >> check the patency of the airway

-Breathing >> check breathing

-Circulation >> check the heart beating

-Disability >> check consciousness

-Exposure >> look for injuries (assessment of mechanism of injuries and potential injuries) or bleeding

-Intravenous (IV) hydration through Isotonic saline administration with monitoring until transport to hospital. The main line of treatment is fluid therapy. Fluid therapy is started as early as possible within the first 6 hours even before the victim is extricated. Some studies report more than 25 litres of saline administrated to patients in one day, but there are variations in the quantity of fluids should be given to patients.

Hospital management:

-Physical examination and ABCDE assessment

-Assessment of response to initial management and the need for operation

-Continue IV hydration

-Blood product transfusions

-Urine output monitoring

-Correction of electrolyte disturbance

-Correction of metabolic disturbances such as alkalinization of urine in acidosis. For metabolic acidosis, bicarbonate and lactate or even oral citrate are administrated to correct metabolic acidosis. Insulin glucose drip is given to reduce the elevated levels of serum potassium. Monitoring of Blood pressure (BP), Central Venous Pressure (CVP), pulmonary function and urine output is essential.

-Diuresis:

Maintaining effective kidney function is the major concern in management of crush syndrome. Urine output should be at least 300 ml/hr (equals at least 12 lit of fluid/day). The fluid trapped inside the damaged muscles and tissue may reach up to 4 litres. Mannitol diuresis can be used to prevent renal failure. Dopamine also can be used as it increases the renal blood flow and helps to achieve a steady blood pressure.

-Dialysis (including Haemodialysis):

Factors indicating dialysis include fluid overload, anuria, bicarbonate levels, serum creatinine levels, and Blood Urea Nitrogen(BUN). Another important indicator for dialysis is potassium level above 7 meq/1. Dialysis is performed at least 2 or 3 times daily and may continue up to 15 days. In high risk patients with hyperkalaemia, prophylactic dialysis may be used.

-Hyperbaric oxygen:

Hyperbaric oxygen means oxygen provided at high pressures. The usual dose is nearly 2.5 atmospheres for 1.5 hours twice daily for a one week duration. The oxygen levels increases in plasma. The use of hyperbaric oxygen can improve tissue viability. It can reduce tissue oedema. It can promote fibroblast proliferation and therefore improves wound healing. Moreover, hyperbaric oxygen can reduce the growth if anaerobic bacteria in the necrosed muscles.

-Analgesia

-Wound care

-Proper antibiotics (multiple broad spectrum non nephrotoxic antibiotics)

-Immunization against Tetanus, toxoid

-Surgery:

Debridement of all necrosed muscles followed by primary or secondary suturing (Laparotomy and thoracotomy). Fasciotomy is performed in compartment syndrome. Early fasciotomy is preferred. Most cases after 8-10 hours of crush require amputation.

-Management of fractures by fixation and management of internal organ injury

-Complications such as muscle contracture require good rehabilitation therapy.

References:

(1)Li N, Wang X, Wang P, Fan H, Hou S, Gong Y. Emerging medical therapies in crush syndrome - progress report from basic sciences and potential future avenues.
https://pubmed.ncbi.nlm.nih.gov/32662306/

(2)Rajagopalan S. Crush Injuries and the Crush Syndrome. Med J Armed Forces India. 2010 Oct;66(4):317-20.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4919827/

(3)Emily Lovallo, Alex Koyfman, Mark Foran,
Crush syndrome, African Journal of Emergency, Medicine,Volume 2, Issue 3, 2012, Pages 117-123, ISSN 2211-419X.
https://www.sciencedirect.com/science/article/pii/S2211419X12000675

(4)Stanley Oiseth, Lindsay Jones, Evelin Maza, crush syndrome, lecturio.
https://www.lecturio.com/concepts/crush-syndrome/

(5)Laura N Haines, MD, FACSJay J Doucet, MD,.FRCSC, FACS Severe crush injury in adults.
https://www.uptodate.com/contents/severe-crush-injury-in-adults#topicContent

(6)Crush Injury and Crush Syndrome, American College of Emergency Physicians.
https://www.acep.org/imports/clinical-and-practice-management/resources/ems-and-disaster-preparedness/disaster-preparedness-grant-projects/cdc---blast-injury/cdc-blast-injury-fact-sheets/crush-injury-and-crush-syndrome

(7)Demirkiran O, Dikmen Y, Utku T, et al, Crush syndrome patients after the Marmara earthquake.
Emergency Medicine Journal 2003;20:247-250.
https://emj.bmj.com/content/20/3/247