092. Rhabdomyolysis

General

Acute necrosis of skeletal muscle fibers and leakage of cellular contents into circulation.

MCC: alcohol (chronic alcoholics also have deficits in hypokalemia/hypomagnesium/hypophosphatemia which can exacerbate) as well as drugs of abuse (cocaine, PCP, LSD, amphetamines). 3 categories: traumatic (crush injuries), non-traumatic exertional (marathoners), non-traumatic non-exertional (drugs)

Other drugs: antipsychotics, lipid-lowering agents (statins, chofibrate), SSRIs, zidovudine, colchine, lithium, antihistamines, narcotics.

Infectious causes: influenza, legionella

Causes of Rhabdomylosis. Taken from Tintinalli

Clinical Features

Myalgias, stiffness, weakness, malaise, low-grade fever, dark urine. Swelling/tenderness to involved muscle groups though can be localized or diffuse (postural muscles common: thigh, calves, lower back).

Diagnosis

Elevated CK correlates with amount of muscle injury and severity of illness though does not correlate with chances of renal failure or mortality. Usually 5x normal range. Rises 2-12 hours after vent, peaks at 24-72 hours, then drops at about 40% per day afterward.

Myoglobin rises before CPK. Contains heme so urine dipstick will be positive though negative RBCs. About 20% of rhabdo will have myoglobinuremia (Alhedi, 2014). Very specific, though not very sensitive.

BUN/Cr will be lower likely less than 10 due to elevated creatinine rise with muscle breakdown. Look for elevated potassium/phosphate due to muscle cell breakdown.

Treatment

Complications include DIC, elevated LFTs, renal failure (obviously)

IV fluids is the maintain of therapy. NS > LR. Need urine output at 250cc/hr if admitted.

Urine alkalization (theory is myoglobin which typically causes the nephrotoxicity is worse in acidic environment; sodium bicarb 1amp/1 NS L at 100cc/hr), diuretics, mannitol have no benefit in the ED (or likely at all).

Healthy patients with exertional rhabdo with no co-morbidites can be discharged after oral and IV fluids. Paper looking at patients at risk for severe renal failure only showed if initial creatinine > 1.7 was only true RF (Fernandez, 2005). Also consider >6000 and continuing to trend upward.

Questions

 

References/Resources

Tintinalli, Seventh Edition, Chapter 92: Rhabdomyolysis

CrashingPatient.com, Rhabdomyolysis

EMRAP, C3 Project, June 2012

EMCAST, November 2009

092. Rhabdomyolysis

Leave a Reply

Your email address will not be published. Required fields are marked *