What is the next step in managing a 78-year-old male with unwitnessed fall, elevated white blood cell (WBC) count, possible urinary tract infection (UTI), and significantly elevated creatine kinase (CK) levels indicating rhabdomyolysis?

Management of Rhabdomyolysis in a 78-Year-Old Male with Elevated CK Levels

Immediate aggressive intravenous fluid resuscitation with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour for the first hour, followed by 4-14 mL/kg/hour, targeting at least 6L daily is the essential first step in managing this patient's rhabdomyolysis to prevent acute kidney injury. 1

Initial Management in the ER

Fluid Resuscitation

• Start with 1-1.5L of isotonic saline (0.9% NaCl) in the first hour
• Continue aggressive fluid resuscitation at 4-14 mL/kg/hour with a target of at least 6L daily for severe rhabdomyolysis (CK >13,000 U/L qualifies as severe) 1
• Place Foley catheter to monitor urine output hourly
• Target urine output of at least 200-300 mL/hour 2

Laboratory Monitoring

• Obtain immediate electrolyte panel with focus on potassium, calcium, phosphorus
• Monitor acid-base status with arterial blood gas
• Check BUN, creatinine every 4-6 hours initially
• Serial CK measurements every 6-12 hours
• Urinalysis to assess for myoglobinuria (dark/tea-colored urine)
• Blood cultures to evaluate for potential infectious source of WBC elevation 1

Electrolyte Management

• Closely monitor and correct hyperkalemia if present
• Do NOT add potassium to IV fluids initially until renal function is assured
• Monitor for hypocalcemia, which may develop as calcium binds to phosphate released from damaged muscle 2

Addressing Concurrent UTI

• Obtain urine culture before starting antibiotics
• Initiate empiric antibiotic therapy based on local resistance patterns for UTI
• Consider broader coverage if sepsis is suspected based on vital signs

Monitoring for Complications

Compartment Syndrome

• Perform frequent neurovascular checks of all extremities
• Assess for the 5 P's: pain, paresthesia, pallor, pulselessness, and paralysis
• Consider compartment pressure measurement if clinical suspicion exists
• Compartment pressure >30 mmHg or differential pressure (diastolic BP - compartment pressure) <30 mmHg suggests compartment syndrome requiring surgical consultation 2

Renal Function

• Monitor for signs of acute kidney injury
• Consider early nephrology consultation given the significantly elevated CK level (>13,000 U/L)
• Be prepared for potential need for renal replacement therapy if the patient develops:
  • Refractory hyperkalemia
  • Severe metabolic acidosis
  • Volume overload unresponsive to diuretics
  • Uremic symptoms 2

Additional Considerations

Bicarbonate Administration

• Current evidence does not strongly support routine use of bicarbonate for alkalinization over aggressive fluid resuscitation alone 2
• However, if urine pH remains <6.5 despite adequate hydration, consider adding sodium bicarbonate to IV fluids to alkalinize urine and potentially reduce myoglobin precipitation in renal tubules 1

Mannitol

• Not routinely recommended for all cases of rhabdomyolysis
• May be considered only in patients with very high CK levels (>30,000 U/L) who have adequate urine output and no evidence of heart failure 2
• Should be administered carefully and is contraindicated in patients with oligoanuria 2

Admission Considerations

• Admit to ICU for close monitoring given:
  • Advanced age (78 years)
  • Significantly elevated CK (13,540 U/L)
  • Presence of UTI with elevated WBC count
  • History of unwitnessed fall with prolonged down time (12 hours)

Pitfalls to Avoid

• Delaying fluid resuscitation while waiting for complete diagnostic workup
• Underestimating fluid requirements in elderly patients
• Overlooking potential compartment syndrome
• Failing to monitor for and correct electrolyte abnormalities
• Assuming pre-renal azotemia based solely on BUN:Creatinine ratio
• Discontinuing fluids prematurely before significant reduction in CK levels 1

This patient requires immediate aggressive management to prevent progression of rhabdomyolysis to acute kidney injury, which would significantly increase morbidity and mortality in this elderly patient.