Rhabdomyolysis Diagnosis and Management
Rhabdomyolysis requires aggressive intravenous fluid resuscitation with normal saline to maintain a urine output of at least 300 mL/hour to prevent acute kidney injury, along with close monitoring of electrolytes and renal function. 1, 2
Diagnosis
Clinical Presentation
- Symptoms range from asymptomatic creatine kinase (CK) elevation to severe manifestations including myalgias, muscle weakness, and dark urine 1, 3
- The classic triad of myalgias, weakness, and dark urine is present in approximately half of patients 4
- Pain (spontaneous or with passive stretch), tension, paraesthesia, and paresis are early signs of compartment syndrome, which can both cause and complicate rhabdomyolysis 5
- Late signs of compartment syndrome include pulselessness and pallor, which often indicate irreversible damage 5
Laboratory Diagnosis
- CK elevation at least 10 times the upper limit of normal is diagnostic of rhabdomyolysis 1, 3
- Repeated bioassessment should include plasma myoglobin, CK, and potassium measurements 5
- Myoglobinuria is a confirmatory finding, presenting as reddish or dark urine 1, 4
- Monitor electrolytes closely, particularly potassium, as hyperkalemia can lead to cardiac arrhythmias 5, 1
Risk Factors
- Trauma, especially crush injuries and severe limb trauma 5
- Exertional causes, particularly novel overexertion or unaccustomed exercise volume/intensity 5
- Medications (particularly statins) and toxins 5, 4
- Infections, immobility, extreme temperature changes, and genetic conditions 2, 4
Management
Immediate Interventions
- Initiate aggressive intravenous fluid resuscitation with normal saline immediately upon diagnosis 1, 2
- Target urine output of at least 300 mL/hour to prevent acute kidney injury 1, 2
- For severe rhabdomyolysis (CK >15,000 IU/L), volumes greater than 6L may be required; for moderate cases, 3-6L per day is typically sufficient 5
- Early initiation of fluid resuscitation is critical, as delayed treatment is associated with higher risk of acute kidney injury 5
Adjunctive Therapies
- Consider sodium bicarbonate for patients with acidosis to alkalinize urine 1, 2
- Mannitol may be used if urine output goals are not achieved with fluid resuscitation alone 1, 6
- Monitor and correct significant electrolyte abnormalities, particularly hyperkalemia 5, 1
- Continue intravenous fluids until CK levels decrease to below 1,000 U/L 1
Management of Complications
Compartment Syndrome
- Early fasciotomy is indicated for established compartment syndrome 5
- Fasciotomy should involve wide incision of skin, subcutaneous tissue, and fascia 5
- Consider fasciotomy when compartment pressure exceeds 30 mmHg or when differential pressure (diastolic blood pressure – compartment pressure) is <30 mmHg 5
Acute Kidney Injury
- Monitor renal function through creatinine measurements and urine output 5
- Maintain urine pH at approximately 6.5 through fluid management and possibly bicarbonate 5
- Consider renal replacement therapy on a case-by-case basis for severe acute kidney injury 2
Other Complications
- Monitor for disseminated intravascular coagulation 1, 2
- Assess for liver dysfunction 2
- Be vigilant for signs of respiratory compromise in severe cases 5
Special Considerations
Perioperative Management
- Avoid medications that can exacerbate rhabdomyolysis, particularly succinylcholine 5
- Maintain adequate hydration throughout the perioperative period 5
- Monitor for hypoglycemia in the pre-, peri-, and postoperative periods 5
- Coordinate with surgical and anesthesia teams to maintain glucose >70 mg/dL during procedures 5
Prevention in High-Risk Settings
- Properly calibrate training and conditioning sessions, especially during transition periods (e.g., returning after injury) 5
- Limit volume and intensity of activity during the first 4 days of new exercise regimens 5
- Document all training sessions and include appropriate work-to-rest ratios 5
- Develop and rehearse venue-specific emergency action plans for exertional rhabdomyolysis 5