What is the recommended fluid therapy approach for a child with Acute Kidney Injury (AKI)?

Fluid Management in Pediatric Acute Kidney Injury

Initial Approach: Assess Volume Status and Etiology

In children with AKI, fluid therapy must be guided by careful hemodynamic assessment to achieve euvolemia while avoiding fluid overload, which independently predicts mortality and delayed renal recovery. 1, 2

Step 1: Discontinue Nephrotoxic Medications First

• Stop all nephrotoxic drugs immediately before initiating any fluid therapy, including NSAIDs, ACE inhibitors, ARBs, and diuretics 1, 3
• Withdraw diuretics specifically before attempting any fluid challenge, as they worsen volume depletion in prerenal states 1, 3

Step 2: Determine Volume Status Clinically

• Hypovolemia indicators: tachycardia, hypotension, decreased urine output, dry mucous membranes 1, 2
• Hypervolemia indicators: peripheral edema, pulmonary edema, elevated jugular venous pressure 1, 2
• Rule out urinary obstruction through clinical assessment and imaging 3

Fluid Resuscitation Protocol for Prerenal AKI

Choice of Fluid

• Use balanced crystalloids (lactated Ringer's) as first-line therapy rather than 0.9% saline to prevent metabolic acidosis and hyperchloremia 1, 2, 3
• Avoid synthetic colloids (hydroxyethyl starches) completely as they increase kidney dysfunction and mortality risk, especially in sepsis 1, 2, 3

Administration Method

• Administer 500-1000 mL (or 10-20 mL/kg in smaller children) over 30-60 minutes 1, 2
• Reassess hemodynamics after each bolus using dynamic indices such as passive leg raise test or pulse pressure variation 1, 2
• Target mean arterial pressure ≥65 mmHg to ensure adequate renal perfusion 3
• Stop fluid administration once euvolemia is achieved—do not continue beyond this point 1, 2

Critical Safety Threshold: Fluid Overload

Fluid overload exceeding 10-15% of body weight is associated with increased mortality and delayed renal recovery in children. 1, 2, 4, 5

• Monitor cumulative fluid balance every 6-12 hours in critically ill children 2, 4
• Track total intake versus output over 24-hour periods with running totals 2
• Use daily weights to objectively assess fluid accumulation 2, 4
• Once hemodynamic stability is achieved, switch to neutral or negative fluid balance 5

When NOT to Give Fluids

• Established oliguric AKI without hemodynamic instability does not require fluid administration 2
• Volume overload is present (peripheral edema, pulmonary edema, elevated JVP) 2
• No clear temporal relationship between volume depletion and AKI onset 2

Management of Established AKI with Fluid Overload

Diuretic Use

• Do not use diuretics to prevent AKI (KDIGO 1B recommendation) 6
• Do not use diuretics to treat AKI except for managing volume overload (KDIGO 2C recommendation) 6
• Furosemide may be used only in hemodynamically stable patients with volume overload, but carries risk of precipitating further volume depletion and renal hypoperfusion 6

Renal Replacement Therapy

• Consider RRT as second-line therapy for fluid overload unresponsive to fluid restriction and diuretics in children with septic shock or other organ dysfunction 6
• Initiate RRT for refractory hyperkalemia, severe acidosis, or symptomatic uremia 6, 3, 7
• Earlier RRT initiation may be needed when conservative fluid management is required to prevent further fluid accumulation 5
• Use standard-volume continuous renal replacement therapy rather than high-volume hemofiltration, as HVHF shows no mortality benefit and increases hyperglycemia risk in children 6

Polyuric Recovery Phase Management

• Replace 80-100% of measured urine losses with balanced crystalloids to prevent dehydration during the polyuric phase 1, 2
• Monitor for signs of volume depletion: tachycardia, hypotension, worsening renal function 1, 2
• Measure serum creatinine and electrolytes at least every 48 hours, more frequently if clinically indicated 1, 3

Monitoring Parameters

• Serum creatinine and electrolytes every 12-24 hours during acute management 3
• Urine output monitoring continuously in first 48-72 hours 3
• Hemodynamic parameters using dynamic indices rather than static measurements 2, 3
• Daily weights for objective fluid status assessment 2, 4

Common Pitfalls to Avoid

• Do not interpret all AKI as "hypovolemic" requiring aggressive fluid resuscitation—clinical context and hemodynamic assessment are critical 2, 3
• Never use furosemide in hemodynamically unstable patients—it worsens volume depletion and reduces renal perfusion 3
• Avoid indiscriminate fluid administration based solely on the label "prerenal" without repeated hemodynamic assessment 3
• Do not use dopamine, fenoldopam, or atrial natriuretic peptide—these have no benefit in preventing or treating AKI 6, 3

Long-Term Follow-Up

• All children who experience AKI require lifelong monitoring for late development of chronic kidney disease, even with complete recovery 3, 7, 8
• Assess serum creatinine, blood pressure, and urinalysis at least every 2-4 weeks during the first 6 months after discharge 3

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