What are the steps for managing Acute Kidney Injury (AKI)?

Management of Acute Kidney Injury

Immediately discontinue all nephrotoxic medications (ACE inhibitors, ARBs, NSAIDs, diuretics) and assess volume status to guide fluid management, while monitoring for urgent indications for renal replacement therapy. 1, 2

Diagnosis and Classification

• Define AKI using KDIGO criteria: serum creatinine increase ≥0.3 mg/dL within 48 hours, increase ≥50% from baseline within 7 days, or urine output <0.5 mL/kg/hour for 6 hours 1, 2
• Stage AKI severity (Stage 1-3) using KDIGO criteria, with Stage 3 representing the most severe form requiring urgent intervention 1, 3
• Classify the underlying cause as prerenal (volume depletion, hypoperfusion), intrinsic renal (acute tubular necrosis, glomerulonephritis), or postrenal (obstruction) to guide targeted treatment 1, 4

Immediate Management Steps

Medication Review and Adjustment

• Stop all nephrotoxic medications immediately: ACE inhibitors, ARBs, NSAIDs, and diuretics must be discontinued to prevent further kidney damage 1, 3, 2
• Avoid the "triple whammy" combination of NSAIDs, diuretics, and ACE inhibitors/ARBs, which more than doubles AKI risk 2
• Adjust dosages of all remaining medications based on reduced GFR and reassess frequently as kidney function changes 3, 2

Volume Status Assessment and Fluid Management

• Assess volume status through clinical examination (jugular venous pressure, peripheral edema, lung auscultation) and consider central venous pressure monitoring in severe cases 1, 2
• For hypovolemic patients: administer isotonic crystalloids (normal saline or lactated Ringer's) rather than colloids for fluid repletion 1, 2
• For euvolemic or hypervolemic patients: implement fluid restriction to prevent volume overload and worsening outcomes 2
• Monitor for signs of fluid overload including peripheral edema, pulmonary congestion, and weight gain 2
• Avoid hypotonic fluids which can worsen hyponatremia 3, 2

Diagnostic Workup

• Obtain kidney ultrasound immediately to rule out obstructive uropathy (postrenal cause), particularly in older men 3, 2
• Perform urinalysis with microscopy to detect hematuria, proteinuria, or abnormal urinary sediment that may indicate glomerulonephritis or other structural renal diseases 1, 2
• Calculate fractional excretion of sodium to differentiate prerenal from intrinsic renal causes 5

Hemodynamic Support

• Maintain mean arterial pressure >65 mmHg to ensure adequate renal perfusion using vasopressors when needed 1
• Determine optimal vasopressor targets based on individual patient factors and underlying acute medical illness 1, 2

Monitoring and Complication Management

Laboratory Monitoring

• Monitor serum electrolytes, BUN, and creatinine every 4-6 hours initially in severe AKI 1, 3, 2
• Track fluid balance with strict input/output measurements 3, 2
• Monitor for signs of uremic complications (encephalopathy, pericarditis, bleeding) 3, 2

Electrolyte Management

• Correct hyperkalemia urgently if present, as this represents a life-threatening complication 1
• Avoid overly rapid correction of hyponatremia (>8-10 mEq/L in 24 hours) to prevent osmotic demyelination syndrome 3, 2
• Consider sodium bicarbonate for patients with severe metabolic acidosis 2

Renal Replacement Therapy (RRT)

Urgent Indications for RRT

• Initiate RRT urgently for: severe oliguria unresponsive to fluid resuscitation, refractory hyperkalemia, severe metabolic acidosis, uremic complications (encephalopathy, pericarditis, pleuritis), or refractory volume overload 1, 3, 2
• Stage 3 AKI with complications warrants consideration for RRT 2

RRT Management

• Reassess the need for continued RRT daily to avoid unnecessary prolongation 1, 3, 2
• Evaluate renal function within 3-7 days after the last RRT session to determine recovery 2

Special Considerations for Cirrhosis Patients

• Perform diagnostic paracentesis to evaluate for spontaneous bacterial peritonitis, as infection is a common precipitant 1, 2
• Hold diuretics, beta-blockers, and all nephrotoxic drugs 2
• Administer albumin 1 g/kg/day (maximum 100 g/day) for 2 days if serum creatinine doubles from baseline 1, 2
• For hepatorenal syndrome (HRS-AKI), treat with albumin 1 g/kg IV on day 1 followed by 20-40 g daily, plus vasoactive agents (terlipressin preferred; or octreotide with midodrine; or norepinephrine if terlipressin unavailable) 1

Infection Management

• Perform rigorous search for infection in all AKI patients, as infection is a common and treatable cause 1, 2
• Start broad-spectrum antibiotics whenever infection is strongly suspected, as early treatment improves outcomes 1

Follow-up and Long-term Management

• Schedule close post-discharge clinical evaluation for patients with moderate to severe AKI (Stage 2-3) 1
• Perform follow-up at 3 months after AKI to assess for resolution or progression to chronic kidney disease 2
• Consider nephrology referral for severe AKI (Stage 2-3), unclear etiology, or risk factors for progression to chronic kidney disease 2, 6
• Provide patient education regarding avoidance of over-the-counter NSAIDs and when to seek medical attention for worsening kidney function 2

Critical Pitfalls to Avoid

• Delaying RRT when clear indications exist increases mortality significantly 1, 3, 2
• Failing to identify and address the underlying cause leads to continued kidney damage 1, 3, 2
• Inappropriate continuation of nephrotoxic medications during AKI recovery prevents healing 1, 2
• Overly aggressive fluid administration in non-hypovolemic patients worsens outcomes and can cause pulmonary edema 2
• Neglecting to adjust medication dosages as kidney function changes during recovery leads to toxicity or underdosing 2