What is the recommended fluid management strategy for a patient with rhabdomyolysis?

Fluid Management of Rhabdomyolysis

Immediate Fluid Resuscitation Strategy

Begin aggressive intravenous fluid resuscitation with 0.9% normal saline at 1 liter per hour immediately upon patient contact, targeting a urine output of 300 mL/hour to prevent acute kidney injury and reduce mortality. 1, 2

Initial Resuscitation Protocol

• Establish IV access as soon as the patient is located, even before extrication is complete; if peripheral access is impossible and a lower limb is accessible, use an intra-osseous needle 3, 1
• Infuse 0.9% normal saline at 1000 mL/hour during the initial extrication phase 3, 1
• Reduce the infusion rate by at least 50% if extrication takes longer than 2 hours to avoid volume overload 3, 1
• After extrication, continue aggressive fluid resuscitation with 3-6 liters per day for moderate rhabdomyolysis, or >6 liters per day for severe cases (CK >30,000 U/L) 2

Target Urine Output

• Maintain urine output ≥300 mL/hour (approximately 3-5 mL/kg/hour for a 70 kg patient), which is 6-10 times higher than the standard oliguria threshold used in general AKI 1, 2, 4
• Insert a bladder catheter to monitor hourly urine output unless there is evidence of urethral injury 3, 2

Fluid Type Selection

Recommended Fluids

• Use 0.9% normal saline (isotonic saline) exclusively for initial volume expansion 1, 2
• Avoid potassium-containing fluids (Lactated Ringer's solution, Hartmann's solution, Plasmalyte A) as potassium levels may increase markedly after reperfusion, even with intact renal function 3, 1, 2
• Avoid starch-based fluids due to their association with increased rates of AKI and bleeding 3, 2

Adjunctive Therapies: What NOT to Use

Bicarbonate (Urinary Alkalinization)

Do not use sodium bicarbonate for urinary alkalinization in rhabdomyolysis. 2, 5

• Current evidence does not demonstrate benefit over aggressive fluid resuscitation with crystalloids alone 2, 5
• Large doses of bicarbonate can worsen hypocalcemia by decreasing free calcium levels 2
• The Eastern Association for the Surgery of Trauma meta-analysis found that bicarbonate did not improve the incidence of acute kidney injury or need for dialysis 5
• Bicarbonate adds extra volume without proven benefit 2

Mannitol

Do not routinely use mannitol in rhabdomyolysis management. 2, 5

• Studies suggest little additional benefit compared to crystalloid resuscitation alone 2
• Mannitol is potentially nephrotoxic and requires close monitoring, which is often impossible after disasters 3, 2
• May only benefit patients with markedly elevated CK (>30,000 U/L), though even this benefit remains undefined 2
• Mannitol is contraindicated in patients with oligoanuria 2
• The Eastern Association for the Surgery of Trauma meta-analysis found that mannitol did not improve outcomes 5

Loop Diuretics

Do not use diuretics as a primary treatment strategy in rhabdomyolysis. 2

• Diuresis may increase the risk of acute kidney injury unless adequate volume resuscitation has first been achieved 2
• Diuretics should only be considered after adequate volume expansion for management of volume overload, not as primary treatment 2

Monitoring Parameters

Laboratory Monitoring

• Monitor electrolytes (potassium, calcium, phosphorus) every 6-12 hours 1
• Perform repeated bio-assessments of plasma myoglobin, CPK, and potassium levels 2
• Use point-of-care devices (e.g., iStat) if standard laboratory infrastructure is unavailable, noting they have a narrow operational temperature range (16-30°C) 3
• Continue intravenous fluids until CK levels decrease below 1,000 U/L, urine output remains adequate, electrolytes normalize, and renal function stabilizes 1, 4

Hemodynamic Monitoring

• Monitor urine pH, targeting approximately 6.5 2
• Assess volume status carefully to avoid over- or under-resuscitation 3
• Target low/normal cardiac output values with continuous monitoring to avoid fluid overload and vasopressor abuse 3

Individualization Factors

Scale Fluid Administration Based On:

• Time spent under rubble: More fluid needed for delayed rescue, but use conservative approach if rescue takes several days as many patients will be anuric with established AKI 3
• Environmental conditions: Less fluid needed in low ambient temperatures 3
• Patient demographics: Older victims, children, and patients with low body mass or mild trauma are more prone to volume overload and should receive less fluid 3
• Volume status: Hypotension, bleeding, and third spacing suggest hypovolemia requiring more fluid; reduce fluids with signs of overload, especially in anuria 3

Common Pitfalls to Avoid

• Delayed fluid resuscitation is associated with higher risk of acute kidney injury 2
• Excessive fluid administration in patients with cardiac or renal compromise can cause fluid overload 2
• Failure to avoid potassium-containing fluids can lead to life-threatening hyperkalemia 3, 1
• Using high-rate maintenance fluid infusions instead of frequent, small-volume fluid boluses 3

Renal Replacement Therapy Indications

Initiate dialysis early for: 1

• Refractory hyperkalemia
• Severe metabolic acidosis
• Fluid overload despite conservative management
• Persistently elevated CK levels after 4 days of adequate hydration

Intermittent hemodialysis is the preferred modality as it provides rapid clearance of potassium and allows treatment of several patients per day on the same machine 3

Evidence Quality Note

The Eastern Association for the Surgery of Trauma meta-analysis found that aggressive IVFR decreased the incidence of acute renal failure and need for dialysis, while bicarbonate and mannitol did not improve outcomes 5. However, the quality of evidence was deemed very low, with the vast majority being retrospective studies 5. Despite this limitation, the consistent finding across multiple guidelines strongly supports aggressive crystalloid resuscitation as the cornerstone of rhabdomyolysis management. 1, 2, 5