What are the initial steps to work up and manage a patient with Acute Kidney Injury (AKI)?

From the Guidelines

The initial steps to work up and manage a patient with Acute Kidney Injury (AKI) involve prompt recognition, identifying the cause, and implementing appropriate interventions, starting with assessing the patient's volume status and discontinuing nephrotoxic agents, as recommended by the most recent guidelines 1.

Initial Assessment and Management

To work up AKI, the following steps should be taken:

• Assess the patient's volume status, vital signs, and review their medication list to identify and discontinue nephrotoxic agents such as NSAIDs, ACE inhibitors, ARBs, and certain antibiotics.
• Order basic laboratory tests including serum creatinine, BUN, electrolytes, urinalysis, and urine microscopy.
• Calculate the patient's baseline and current GFR to determine AKI severity using KDIGO criteria, as defined by a increase in serum creatinine by ≥0.3 mg/dL within 48 hours or is ≥50% from baseline or when the urine output is reduced below 0.5 mL/kg/h for >6 hours 1.

Fluid Management and Hemodynamic Support

• Ensure adequate hydration with isotonic fluids if the patient is hypovolemic, typically starting with normal saline at 10-20 mL/kg, and consider the use of albumin 1 g/kg/d for 2 days if the serum creatinine shows doubling from baseline 1.
• Monitor urine output closely, aiming for at least 0.5 mL/kg/hour.

Electrolyte Management and Nephrology Consultation

• Correct electrolyte abnormalities, particularly hyperkalemia, which may require calcium gluconate 10% (10 mL IV), insulin (10 units regular insulin with 50 mL of 50% dextrose), and sodium bicarbonate (50 mEq IV) for severe cases.
• Consider renal ultrasound to rule out obstruction, especially in older patients or those with anuria.
• Nephrology consultation is warranted for severe AKI, rapidly rising creatinine, or if dialysis might be needed, and should be guided by the most recent and highest quality evidence, such as the KDIGO guidelines 1.

From the Research

Initial Steps to Work Up AKI

To work up a patient with Acute Kidney Injury (AKI), the following initial steps can be taken:

• Assess the patient's history to identify potential causes of AKI, such as nephrotoxic medication use or systemic illnesses that may cause poor renal perfusion or directly impair renal function 2
• Perform a physical examination to assess intravascular volume status and identify skin rashes indicative of systemic illness 2
• Order laboratory tests, including:
  • Serum creatinine level
  • Complete blood count
  • Urinalysis
  • Fractional excretion of sodium 2
• Use ultrasonography to rule out obstruction, particularly in older men 2

Classification of AKI

AKI can be classified into three categories:

• Prerenal: caused by decreased blood flow to the kidneys
• Intrinsic renal: caused by damage to the kidneys themselves
• Postrenal: caused by obstruction of the urinary tract 3, 4, 2

Management of AKI

Management of AKI involves:

• Fluid resuscitation
• Avoidance of nephrotoxic medications and contrast media exposure
• Correction of electrolyte imbalances
• Renal replacement therapy (dialysis) if necessary 2, 5, 6
• Identification and reversal of underlying cause 3
• Referral to appropriate specialty care 3

Assessment of Volume Status

Assessment of volume status is crucial in AKI management, and can be done using:

• Central venous and arterial blood pressure monitoring
• Inferior vena cava echocardiography
• Urine analysis and microscopy 5