3 Rhabdomyolysis

Question 1

In general, the most common causes of rhabdomyolysis in adults

Answer 1

drugs of abuse and alcohol
Alcohol consumption can result in rhabdomyolysis secondary to coma-induced muscle compression and a direct toxic effect

Question 2

drug class that may cause rhabdomyolysis

Answer 2

Statins
-dose-related

Question 3

the common terminal event in rhabdomyolysis

Answer 3

disruption of the Na+K+ ATPase pump and calcium transport, which results in increased intracellular calcium and subsequent muscle cell necrosis
In addition, calcium activates phospholipase A2 and various vasoactive molecules and proteases and induces the production of free oxygen radicals

Question 4

remarks on PE in rhabdomyolysis

Answer 4

Acute rhabdomyolysis may be present without any signs or symptoms with a normal physical examination

Question 5

most sensitive and reliable indicator of muscle injury

Answer 5

an elevated serum creatine kinase
the degree of elevation correlates with the amount of muscle injury and the severity of symptoms,
but not the development of AKI or other morbidity

Question 6

requirement for the diagnosis of rhabdomyolysis

Answer 6

Most authors consider a fivefold or greater increase above the upper threshold of normal in serum creatine kinase level, in the absence of cardiac or brain injury, as the requirement for the diagnosis of rhabdomyolysis
(approx 800 to 1000 IU/L)

Question 7

Creatine kinase trend

Answer 7

in general, the level begins to rise approx 2-12 hours after onset of muscle injury, peaks within 24-72 hours,
and then declines at the relatively constant rate of 39% of the previous day’s value
ongoing muscle necrosis should be suspected in patietns with elevated values that fail to decrease in this manner

Question 8

Remarks on CK-MB

Answer 8

the MB fraction of creatine kinase (found primarily in cardiac but also in skeletal muscle) may also be elevated but should not exceed 5% of the total creatine kinase

Question 9

Remarks on myoglobin

Answer 9

Myoglobin elevation occurs before creatine kinase elevation
and then is rapidly cleared from the plasma through renal excretion and metabolism to bilirubin
Because myoglobin levels may return to baseline quickly, the absence of an elevated serum myoglobin level or of myoglobinuria does NOT exclude the diagnosis

In a study of 475 patients with rhabdomyolysis, only 19% were found to have myoglobinuria

Question 10

Suspect myoglobinuria when

Answer 10

urine dipstick is positive for blood but zero or rare RBCs are present on microscopic exam

Question 11

potential complications of rhabdomyolysis

Answer 11

AKI
Hyperkalemia
DIC
Compartment syndrome
Peripheral nerve injury

Question 12

Most important treatment to prevent acute kidney injury in rhabdomyolysis

Answer 12

early and vigorous IV fluid resuscitation
Prehospital:
IV normal saline 1L/hour
continued at 500mL,
alternating with 5% dextrose in NS at 1L/hour

Question 13

IV rehydration in the ED

Answer 13

rapid correction of the fluid deficit with IV crystalloids
followed by infusion of 4 mL/kg/h
with the goal of maintaining a minimum urine output of 3 to 4 mL/kg/h
or 200 to 300 mL/hour

Question 14

Calcium correction in rhabdomyolysis

Answer 14

Hypocalcemia observed early in rhabdomyolysis usually requires NO treatment.
Calcium should be given only to treat hyperkalemia-induced cardiotoxicity or profound signs and symptoms of hypocalcemia