Rhabdomyolysis

Question 1

Rhabdomyolysis definition

Answer 1

Destruction of skeletal muscles that results in injury to myocytes and membranes releasing intracellular contents into blood.

Question 2

2 Broad Causes of rhabdomyolysis

Answer 2

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

Question 3

Intracellular contents released into blood stream from rhabdomyolysis

Answer 3

Myoglobin

Potassium and phosphorus

enzymes: CK, AST, ALT, LDH, Aldolase

All will be elevated in rhabdomyolysis

Question 4

Specific causes of rhabdomyolysis

Answer 4

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.

Question 5

Statin medications

Answer 5

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

Question 6

Sympathomimetic medications

Answer 6

Cocaine, amphetamines, methamphetamines, PCP

Medications that cause agitation and increase demands on the cell and depletion of ATP.

Question 7

Other Signs and symptoms

Answer 7

Muscle pain

Weakness

Red brown urine

Question 8

Creatinine kinase

Answer 8

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

Question 9

Myoglobin

Answer 9

Functional oxygen reservoir similar to hemoglobin but in muscle cells and higher affinity for oxygen.

Elevated levels rise within 1 hour of rhabdomyolysis.

Question 10

Complications of rhabdomyolysis

Answer 10

Can lead to the following

Acute kidney injury/failure

Electrolyte derangements : specifically hyperkalemia MOST SIGNIFICANT

Compartment syndrome

Disseminated intravascular coagulation resulting in severe bleeding.

Question 11

Testing for myoglobin levels

Answer 11

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

Question 12

Signs of hyperkalemia on an EKG

Answer 12

Spiking of T waves

widening of the QRS complexes

flattening of the P waves

Question 13

Treatment of rhabdomyolysis

Answer 13

IV fluids with 1-2 liters of saline

Monitor enzymes, urine output and electrolytes

Question 14

Compartment syndrome

Answer 14

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.

Question 15

Risks of compartment syndrome

Answer 15

Severe trauma

Open fractures

Vascular injury

leg/tibia fractures are the most common cause of compartment syndrome

Question 16

Symptoms of compartment syndrome

Answer 16

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).

Question 17

5 P’s in compartment syndrome

Answer 17

Pain

Paresthesia

Pallor

Pulselessness

Paralysis

Question 18

Most reliable physical sign of compartment syndrome

Answer 18

Difference between diastolic BP and compartment pressure is less than 30mm

(Diastolic pressure - compartment pressure = less than 30 (requires fasciotomy)

Question 19

Volkmanns contracture

Answer 19

Compartment syndrome caused usually by a Supracondylar fracture of elbow. Results in hand loss of function.

Question 20

Exertional Rhabdomyolysis

Answer 20

Depletion of ATP causes inflammation which damages myocytes

-caused by exercise induced inflammation

Myocytes release potassium, myoglobin and creatine kinase

Question 21

Exertional compartment syndrome

Answer 21

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.)

Question 22

Poikilothermia

Answer 22

Found in compartment syndrome.

Distal end of the limb = cold
Proximal end of the limb = hot

Question 23

Fasciotomy

Answer 23

Treatment for compartment syndrome. Relives pressure and is required to save the limb most of the time.

Question 24

Alcohol and ethanol

Answer 24

Direct toxicity to uncles and can cause prolonged immobilization when passed out

Same goes with sedatives and hypnotic medications

Question 25

Renal failure

Answer 25

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

Question 26

Normal compartment pressure

Answer 26

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%

Question 27

Treatment of compartment syndrome

Answer 27

Fasciotomy, IV fluids and do not elevate the limb.