Rhabdomyolysis Flashcards
What is Rhabdomyolysis?
Rhabdomyolysis involves the breakdown of skeletal muscle cells (myocytes) and the release of chemicals into the blood, including myoglobin, potassium, phosphate, and creatine kinase.
What is the most immediately dangerous breakdown product in Rhabdomyolysis?
Potassium is the most immediately dangerous breakdown product, as hyperkalaemia can cause cardiac arrhythmias and cardiac arrest.
How can the breakdown products of Rhabdomyolysis cause acute kidney injury?
Breakdown products, especially myoglobin, are toxic in high concentrations and can accumulate in the blood, causing kidney damage and resulting in acute kidney injury.
What are other complications associated with Rhabdomyolysis?
Other complications include:
* Compartment syndrome
* Disseminated intravascular coagulation (DIC)
What are common causes of Rhabdomyolysis?
Causes include:
* Prolonged immobility (e.g., frail patients who fall)
* Rigorous exercise beyond fitness level (e.g., endurance events, CrossFit)
* Crush injuries
* Seizures
* Statin use
What are the signs and symptoms of Rhabdomyolysis?
Signs and symptoms include:
* Muscle pain
* Muscle weakness
* Muscle swelling
* Reduced urine output (oliguria)
* Red-brown urine (myoglobinuria)
* Fatigue
* Nausea and vomiting
* Confusion (especially in frail patients)
What is the crucial diagnostic blood test for Rhabdomyolysis?
The crucial diagnostic test is Creatine kinase (CK). Normal levels are around 150 U/L, but in rhabdomyolysis, it can range from 1,000-100,000 U/L.
How does Creatine kinase (CK) change in Rhabdomyolysis?
CK typically rises within the first 12 hours, remains elevated for 1-3 days, and then gradually falls. The higher the CK, the greater the risk of kidney injury.
What is myoglobinuria, and how does it relate to Rhabdomyolysis?
Myoglobinuria is the presence of myoglobin in the urine, which gives it a red-brown colour. A urine dipstick will show a positive result for blood.
What investigations are required for Rhabdomyolysis?
Investigations include:
* Urea and electrolytes (U&E) to assess acute kidney injury and hyperkalaemia
* ECGs to monitor the heart’s response to hyperkalaemia
What is the mainstay treatment for Rhabdomyolysis?
Intravenous fluids are the mainstay of treatment to correct hypovolaemia and promote filtration of breakdown products.
What additional treatments may be considered for Rhabdomyolysis, and what are their risks?
Additional treatments include:
* Intravenous sodium bicarbonate (to increase urinary pH and reduce toxic effects of myoglobinuria)
* Intravenous mannitol (to increase urine output and reduce oedema)
These have associated risks and are considered on a case-by-case basis.
