What is the treatment for acute kidney injury?

Treatment of Acute Kidney Injury

The cornerstone of AKI treatment is ensuring adequate hydration and renal perfusion through judicious fluid management, immediate discontinuation of all nephrotoxic medications, and early initiation of renal replacement therapy when specific life-threatening indications are present. 1, 2

Immediate Assessment and Risk Stratification

• Assess volume status through clinical examination focusing on jugular venous pressure, peripheral edema, pulmonary congestion, and orthostatic vital signs to determine if the patient is hypovolemic, euvolemic, or volume overloaded 1
• Obtain renal ultrasound immediately to rule out obstructive uropathy, particularly in older men with prostatic hypertrophy 2, 3
• Perform urinalysis to detect hematuria, proteinuria, or abnormal urinary sediment that may indicate intrinsic renal disease 2, 3
• Calculate fractional excretion of sodium to differentiate prerenal from intrinsic renal causes 3

Drug Stewardship: The Critical First Step

Immediately discontinue all nephrotoxic medications including NSAIDs, ACE inhibitors, ARBs, diuretics, and any other potentially nephrotoxic agents 1, 2. This is paramount as drug-induced AKI accounts for up to 25% of all AKI cases in critically ill patients 4.

• Avoid the "triple whammy" combination of NSAIDs, diuretics, and ACE inhibitors/ARBs, which more than doubles AKI risk 2
• Review all chronic medications and evaluate their indication for continuation versus discontinuation 1
• Adjust dosages of all remaining medications based on reduced GFR and reassess frequently as kidney function changes 1, 2
• Perform medication reconciliation at every transition of care to prevent inadvertent nephrotoxic exposures 1

Fluid Management Strategy

For Hypovolemic Patients

Administer isotonic crystalloids (lactated Ringer's or balanced crystalloids) for volume repletion, as evidence shows 0.9% saline is associated with worse biochemical abnormalities and adverse clinical outcomes compared to more physiological crystalloids 1.

• Use repeated hemodynamic assessments and dynamic tests of fluid responsiveness (passive leg-raising test, pulse/stroke volume variation) rather than static targets, as both the physiological response to fluids and the underlying AKI condition are dynamic over time 1
• Consider earlier use of vasoactive medications for hypotension rather than excessive fluid administration, particularly in septic patients 1

For Euvolemic or Volume-Overloaded Patients

Avoid aggressive fluid administration which worsens outcomes and can lead to fluid overload 1, 2. Volume overload and venous congestion have direct adverse effects on kidney function and mortality 1.

• Implement fluid restriction and monitor for signs of fluid overload including peripheral edema, pulmonary congestion, and weight gain 2
• Consider early fluid removal when fluid overload exceeds 10-15% of body weight, as this threshold is associated with adverse outcomes 1

Critical Fluid Management Caveats

• Avoid synthetic colloids entirely in critically ill patients, especially those with sepsis, due to increased incidence of kidney dysfunction and mortality 1
• Goal-directed fluid therapy protocols lack benefit for survival and kidney outcomes in septic shock, though they may benefit perioperative patients 1

Renal Replacement Therapy Indications

Initiate urgent RRT when any of the following life-threatening indications are present 2:

• Severe oliguria unresponsive to fluid resuscitation
• Refractory hyperkalemia
• Severe metabolic acidosis (intractable acidosis)
• Volume overload refractory to diuretics
• Uremic complications (encephalopathy, pericarditis, pleuritis)
• Certain toxin removal needs

Reassess the need for continued RRT daily and monitor for signs of renal recovery 2

Electrolyte and Metabolic Management

• Monitor serum electrolytes, BUN, and creatinine every 4-6 hours initially in severe AKI 2
• Track fluid balance with strict input/output measurements 2
• Avoid overly rapid correction of severe hyponatremia, which can lead to osmotic demyelination syndrome 2
• Optimize nutritional status and glycemic control as supportive care measures 5

Treating Underlying Causes

• Identify and treat infections promptly with appropriate antibiotics, as sepsis is a common precipitant of AKI 2
• Hold diuretics, ACE inhibitors, ARBs, and beta-blockers when AKI is diagnosed to prevent worsening kidney function 2
• Obtain urine culture before starting antibiotics if UTI is suspected, to guide definitive therapy 6

Common Pitfalls to Avoid

• Delaying RRT when clear indications exist increases mortality significantly 2
• Overly aggressive fluid resuscitation in non-hypovolemic patients worsens outcomes and can precipitate pulmonary edema 1, 2
• Continuing nephrotoxic medications during the AKI recovery phase leads to continued kidney damage 2
• Failing to adjust medication dosages as kidney function changes during recovery can result in drug toxicity or therapeutic failure 1, 2
• Using lowest effective doses for shortest duration when nephrotoxic agents cannot be avoided 7

Monitoring and Follow-up

• Implement pharmacist-led quality-improvement programs to reduce nephrotoxic exposures, as these have been shown to reduce rates of AKI in hospital settings 5
• Consider nephrology consultation for stage 3 or higher AKI, inadequate response to supportive treatment, AKI without clear cause, or preexisting stage 4 or higher CKD 5
• Recognize long-term risks including progression to chronic kidney disease, cardiovascular events, and increased long-term mortality, necessitating close outpatient follow-up 8, 5