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 treatment 1, 4

Immediate Management Steps

Medication Review and Adjustment

• Stop all nephrotoxic medications immediately: ACE inhibitors, ARBs, NSAIDs, and diuretics must be discontinued 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
• Implement comprehensive drug stewardship with identification of at-risk patients and dynamic prescription adjustments 1, 2

Volume Status Assessment and Fluid Management

• Assess volume status through clinical examination (jugular venous pressure, peripheral edema, lung auscultation, orthostatic vital signs) and consider central venous pressure monitoring in severe cases 1, 3, 2

For hypovolemic patients:

• Provide fluid repletion with isotonic crystalloids (normal saline or lactated Ringer's) rather than colloids 1, 2
• Avoid hypotonic fluids which worsen hyponatremia 3, 2

For euvolemic or hypervolemic patients:

• Implement fluid restriction to prevent volume overload 2
• Monitor for signs of fluid overload: peripheral edema, pulmonary congestion, weight gain 2
• Avoid overly aggressive fluid administration in non-hypovolemic patients, which worsens outcomes 2

Hemodynamic Support

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

Diagnostic Workup

• Obtain urinalysis with microscopy to detect hematuria, proteinuria, or abnormal urinary sediment to exclude structural renal diseases 1, 2
• Perform kidney ultrasound immediately to rule out obstructive uropathy, particularly in older men 3, 2
• Measure fractional excretion of sodium to differentiate prerenal from intrinsic renal causes 5

Monitoring and Laboratory Surveillance

• 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
• Correct electrolyte abnormalities, particularly hyperkalemia, which may require urgent intervention 1

Management of Complications

Electrolyte Abnormalities

• Correct hyperkalemia urgently if present (calcium gluconate for cardiac protection, insulin/glucose, sodium bicarbonate, potassium binders) 1
• Avoid overly rapid correction of hyponatremia (limit to <8-10 mEq/L per 24 hours) to prevent osmotic demyelination syndrome 3, 2

Metabolic Acidosis

• Consider sodium bicarbonate for patients with AKI and severe metabolic acidosis 2

Renal Replacement Therapy (RRT)

Urgent indications for RRT include: 1, 3, 2

• Severe oliguria unresponsive to fluid resuscitation

• Refractory hyperkalemia

• Severe metabolic acidosis

• Uremic complications (encephalopathy, pericarditis, pleuritis)

• Refractory volume overload causing pulmonary edema

• Certain toxin removal

• Reassess the need for continued RRT daily 1, 2

• Evaluate renal function within 3-7 days after the last RRT session 2

• The timing of RRT initiation remains controversial, with studies not consistently demonstrating benefit to early-start dialysis 6

Special Considerations for Cirrhosis Patients

• Perform rigorous search for infection including diagnostic paracentesis to evaluate for spontaneous bacterial peritonitis 1, 2
• Hold diuretics, beta-blockers, and nephrotoxic drugs 2
• Administer albumin 1 g/kg/day (maximum 100 g/day) for 2 days if serum creatinine shows doubling from baseline 1, 2
• For hepatorenal syndrome-AKI: give albumin 1 g/kg IV on day 1 followed by 20-40 g daily, plus vasoactive agents (terlipressin; or if unavailable, octreotide and midodrine; or norepinephrine) 1

Prevention Strategies

• Identify high-risk patients: older age, diabetes, chronic kidney disease, heart failure, sepsis, cardiac surgery, contrast exposure 1, 2, 5
• Ensure adequate hydration before procedures involving contrast agents 1
• Provide patient education regarding avoidance of over-the-counter NSAIDs 2

Follow-up and Long-term Management

• Schedule close post-discharge clinical evaluation for patients with moderate to severe AKI (within 3-7 days) 1
• Perform follow-up at 3 months after AKI to assess resolution or progression to chronic kidney disease 2
• Consider nephrology referral for patients with severe AKI (Stage 2-3), unclear etiology, or risk factors for progression to chronic kidney disease 2, 7
• Recognize that even one episode of AKI increases long-term risk of cardiovascular disease, chronic kidney disease, and death 4

Critical Pitfalls to Avoid

• Delaying RRT when clear indications exist increases mortality 1, 3, 2
• Failing to identify and address the underlying cause leads to continued kidney damage 1, 3
• Inappropriate continuation of nephrotoxic medications during AKI recovery phase 1, 2
• Overly aggressive fluid administration in non-hypovolemic patients worsens outcomes and can cause pulmonary edema 3, 2
• Neglecting to adjust medication dosages as kidney function changes during recovery 2
• Failing to recognize fluid overload from excessive resuscitation, which worsens respiratory status and tissue oxygenation 3