Rhabdomyolysis Flashcards
Rhabdomyolysis definition
Destruction of skeletal muscles that results in injury to myocytes and membranes releasing intracellular contents into blood.
2 Broad Causes of rhabdomyolysis
Direct damage to the skeletal muscle
Depletion of ATP within the myocyte due to damaged ATP pumps.
Both results in unregulated intracellular calcium which leads to eventual necrosis and death of muscle cells
Intracellular contents released into blood stream from rhabdomyolysis
Myoglobin
Potassium and phosphorus
enzymes: CK, AST, ALT, LDH, Aldolase
All will be elevated in rhabdomyolysis
Specific causes of rhabdomyolysis
Trauma, crush or compression syndrome/injury’s
Excessive muscle contraction: causes failure of sarcolemma sodium/potassium ATP pumps.
Statin medications
restrained psychiatric patients
Drug abuse: specifically alcohol, sedatives and sympathomimetic meds.
Bites that inject venom.
Influenza virus (In children)
Metabolic and genetic disorders.
Statin medications
Meds that lower lipid levels
Class of HMG-CoA reductive inhibitors that block the production of coenzyme Q.
Disrupts ETC and leads to ATP disruption which once ATP is depleted can cause rhabdomyolysis
Sympathomimetic medications
Cocaine, amphetamines, methamphetamines, PCP
Medications that cause agitation and increase demands on the cell and depletion of ATP.
Other Signs and symptoms
Muscle pain
Weakness
Red brown urine
Creatinine kinase
Enzyme responsible for reversible transfer of terminal phosphate group of ATP to generate phosphocreatinine.
In rhabdomyolysis, serum CK levels are At least 1500 units/L but can be way higher like 5000.
Isotopes can tell you where the damage is.
CK-MM: skeletal muscle
CK-BB: brain tissues
CK: MB: heart muscle
Myoglobin
Functional oxygen reservoir similar to hemoglobin but in muscle cells and higher affinity for oxygen.
Elevated levels rise within 1 hour of rhabdomyolysis.
Complications of rhabdomyolysis
Can lead to the following
Acute kidney injury/failure
Electrolyte derangements : specifically hyperkalemia MOST SIGNIFICANT
Compartment syndrome
Disseminated intravascular coagulation resulting in severe bleeding.
Testing for myoglobin levels
Urine dipstick
- easy and quick method of checking for possible rhabdomyolysis
- reports high levels of blood with no red blood cells being present on microscopy. Indicates myoglobin in urine
Signs of hyperkalemia on an EKG
Spiking of T waves
widening of the QRS complexes
flattening of the P waves
Treatment of rhabdomyolysis
IV fluids with 1-2 liters of saline
Monitor enzymes, urine output and electrolytes
Compartment syndrome
Increased pressure (usually via compression) within non-expendable compartments within the body surrounded by fascia.
When compartment pressure is higher than capillary perfusion pressure, tissue hypoxia occurs.
Histamine is released to try and compensate with increases blood flow, but also increases leakage of proteins and increases the pressure even further.
Risks of compartment syndrome
Severe trauma
Open fractures
Vascular injury
leg/tibia fractures are the most common cause of compartment syndrome
Symptoms of compartment syndrome
Pain that is out of proportion with physician findings
Most reliable early non physical sign
Paresthesias in Nerve distribution
Pallor and diminished pulses
Progression to lack of pulses (implies compressed blood supply and nerves which leads to necrosis if unchecked).
5 P’s in compartment syndrome
Pain
Paresthesia
Pallor
Pulselessness
Paralysis
Most reliable physical sign of compartment syndrome
Difference between diastolic BP and compartment pressure is less than 30mm
(Diastolic pressure - compartment pressure = less than 30 (requires fasciotomy)
Volkmanns contracture
Compartment syndrome caused usually by a Supracondylar fracture of elbow. Results in hand loss of function.
Exertional Rhabdomyolysis
Depletion of ATP causes inflammation which damages myocytes
-caused by exercise induced inflammation
Myocytes release potassium, myoglobin and creatine kinase
Exertional compartment syndrome
Muscle swelling causes increased interstitial pressure. Impairs microcirculatory perfusion.
Causes muscle damage and pain
Induces a self-propagating cycle (body’s natural response to compartment syndrome is to increase the pressure via histamine and dilating blood vessels to try to get blood to the affected area.)
Poikilothermia
Found in compartment syndrome.
Distal end of the limb = cold
Proximal end of the limb = hot
Fasciotomy
Treatment for compartment syndrome. Relives pressure and is required to save the limb most of the time.
Alcohol and ethanol
Direct toxicity to uncles and can cause prolonged immobilization when passed out
Same goes with sedatives and hypnotic medications
Renal failure
Complication of rhabdomyolysis due to accumulation of Uric acid and myoglobin in the nephrons
- dehydration, heat stress and trauma can all contribute to increased renal failure by decreasing blood flow through kidney
Normal compartment pressure
0-10 mmHg
Once you hit 30 mmHg, blood circulation becomes impaired and compartment syndrome is likely.
Diastolic- compartment pressure = <30 mmHg is compartment syndrome 100%
Treatment of compartment syndrome
Fasciotomy, IV fluids and do not elevate the limb.
