Acute renal failure and rhabdomyolysis

The clinical syndrome of rhabdomyolysis is caused by injury of skeletal muscles, leading to the release of various intracellular muscle constituents. Rhabdomyolysis occurs frequently but is usually asymptomatic (i.e., lab abnormalities only). However, in more serious cases, severe electrolyte disorders and acute renal failure may occur, leading to life-threatening situations. Rhabdomyolysis can develop in any circumstances where energy demands in muscles exceed the available energy supplies; it accounts for between 2 and 5% of all cases of acute renal failure in the ICU. Frequent causes of severe rhabdomyolysis include crush injuries, prolonged immobilization, seizures, severe infections and drug toxicity. Factors contributing to the development of more severe clinical symptoms include hypovolemia, hyperthermia, electrolyte disorders and the presence of pre-existing (congenital) muscle disorders. The diagnosis is established by elevation of serum muscle enzymes and muscle constituents such as creatinine phosphokinase and myoglobin. Preventive measures include maintenance of normal or high intravascular volume and administration of diuretics (loop diuretics rather than mannitol) once hypervolemia/euvolemia have been achieved. Some evidence suggests that early initiation of renal replacement therapy can help improve outcome. Administration of bicarbonate to induce urinary alkalosis can be considered, but it has not been proven to be effective.