Fluid Management and Resuscitation

Introduction to Fluid Resuscitation

• The Kidney International recommends normal saline (0.9% NaCl) as the first-line IV fluid for rhabdomyolysis to prevent acute kidney injury and reduce the need for dialysis, with an initial rate of 1 L/hour during extrication (if applicable) 1
• The Kidney International suggests targeting 3-6 L of IV fluids per day, depending on clinical condition and response, to maintain urine output of at least 300 mL/hour 1
• For severe rhabdomyolysis (CPK >15,000 IU/L), the Anaesthesia guideline recommends volumes greater than 6 L may be required to prevent acute kidney injury 2

Choice of Fluid

• Balanced crystalloid solutions like Plasmalyte or Lactated Ringer's are recommended as the first-line IV fluid therapy in the ICU due to their lower risk of adverse renal events and better acid-base balance compared to 0.9% NaCl, with a reduced incidence of major adverse kidney events (MAKE 30), as recommended by the American Society of Anesthesiologists 3
• Lactated Ringer's (LR) solution is a balanced crystalloid solution compatible with potassium supplementation and safe to use in patients with reduced kidney function, with a potassium concentration of 4 mmol/L, according to the American Society of Anesthesiologists 3
• The composition of LR solution closely resembles human plasma, making it a suitable choice for fluid resuscitation, as stated by the American Society of Anesthesiologists 3
• Plasmalyte has a composition of Na+ 140 mmol/L, K+ 5 mmol/L, Cl- 98 mmol/L, buffers: Acetate 27 mmol/L, Gluconate 23 mmol/L, osmolarity: 295 mOsm/L, and pH: 6.5-7.5, which is closer to human plasma composition, as shown in the table below:

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• Lactated Ringer's has a composition of Na+ 130 mmol/L, K+ 4 mmol/L, Cl- 108 mmol/L, Ca2+ 0.9 mmol/L, buffer: Lactate 27.6 mmol/L, osmolarity: 277 mOsm/L, and pH: 6.7-5, which is also closer to human plasma composition, as compared to Normal Saline in the table below:

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• Normal Saline is preferred in traumatic brain injury to maintain higher plasma osmolality and reduce risk of cerebral edema, and in severe hyperkalemia due to the absence of potassium, as recommended by 4, 3

Monitoring and Adjunctive Therapy

• The Anaesthesia guideline recommends maintaining urine pH at 6.5, and considering sodium bicarbonate only in patients with metabolic acidosis to achieve this goal 2
• The Anaesthesia guideline suggests being vigilant for compartment syndrome, which may require fasciotomy, and monitoring for signs of fluid overload, especially in patients with cardiac or renal dysfunction 2
• Regular assessment of electrolyte levels, acid-base status, fluid balance, and clinical signs of adequate perfusion is recommended, with a target urine output of 0.5-1 mL/kg/hr, as recommended by the American Society of Anesthesiologists 3
• Monitor vital signs (heart rate, blood pressure, respiratory rate), urine output (target 0.5-1 mL/kg/hr), laboratory values (electrolytes, acid-base status), and clinical signs of adequate perfusion, as recommended by the American Society of Anesthesiologists 3
• Evaluation of renal function is necessary to minimize the risk of adverse kidney events, as recommended by the American Society of Anesthesiologists 3
• Consider advanced hemodynamic monitoring in critically ill patients, as recommended by the American Society of Anesthesiologists 3

Timing and Risks

• The Kidney International states that delayed initiation of fluid resuscitation increases the risk of acute kidney injury 1
• The Anaesthesia guideline notes that inadequate fluid volumes, particularly in severe rhabdomyolysis (CPK >15,000 IU/L), can lead to acute kidney injury 2
• In patients with traumatic brain injury (TBI), hypotonic solutions like lactated Ringer's (LR) should be avoided to prevent worsening of brain edema, according to the Critical Care society 5
• In patients with crush injuries or rhabdomyolysis and renal impairment, potassium-containing fluids like LR should be avoided initially to prevent hyperkalemia, as recommended by the Kidney International society 1
• Permissive hypotension may be contraindicated in patients with chronic arterial hypertension, as recommended by 6
• Avoid aggressive fluid resuscitation before bleeding control as it may increase risk of secondary abdominal compartment syndrome, worsen coagulopathy, and disrupt clot formation, as recommended by 6
• Excessive fluid administration before hemorrhage control can increase blood pressure excessively, disrupt clot formation, dilute clotting factors, and lead to hypothermia and acidosis, as recommended by 6
• The balance between permissive hypotension and adequate tissue perfusion requires clinical judgment, and rigid adherence to one approach regardless of clinical context should be avoided, as recommended by the American Society of Anesthesiologists 3
• Target systolic BP 80-90 mmHg until bleeding is controlled (higher targets for patients with traumatic brain injury), as recommended by the American Society of Anesthesiologists 3, 5

Contraindications and Precautions

• Hydroxyethyl starches are contraindicated due to increased risk of renal failure, with a strength of evidence grade of 1- recommendation, as recommended by the American Society of Anesthesiologists 3
• Albumin shows no benefit in hemorrhagic shock and is more expensive than crystalloids, with a strength of evidence grade of 1- recommendation, as recommended by the American Society of Anesthesiologists 3
• 3% or 7.5% hypertonic saline solutions are not recommended as first-line treatment, with a strength of evidence grade of 1- recommendation 3