Acute Kidney Injury (AKI) | Clinical Medicine

Introduction

This tutorial provides an overview of Acute Kidney Injury (AKI), including its causes, pathophysiology, and management strategies. Understanding AKI is essential for healthcare professionals, as it can significantly impact patient outcomes. This guide distills the key points from a comprehensive lecture by Professor Zach Murphy, offering clear steps for identification and treatment.

Step 1: Understand the Pathophysiology of AKI

• Definition: AKI is a sudden decline in kidney function, characterized by an increase in serum creatinine or a decrease in urine output.
• Mechanisms:
  • Prerenal: Caused by inadequate blood flow to the kidneys.
  • Intrarenal: Resulting from direct damage to the kidneys.
  • Postrenal: Due to obstruction in the urinary tract.

Step 2: Identify the Causes of AKI

Prerenal Causes

• Hypovolemia: Dehydration, blood loss, or excessive diuretics.
• Decreased Cardiac Output: Heart failure or shock.
• Vasodilation: Sepsis or anaphylaxis.

Intrarenal Causes

• Acute Tubular Necrosis (ATN): Often due to ischemia or nephrotoxic agents (e.g., certain medications).
• Glomerulonephritis: Inflammation of the kidney's filtering units.
• Interstitial Nephritis: Allergic reactions to medications.

Postrenal Causes

• Obstruction: Kidney stones, tumors, or enlarged prostate can impede urine flow.

Step 3: Recognize the Clinical Features of AKI

• Common Symptoms:
  • Decreased urine output.
  • Swelling due to fluid retention.
  • Fatigue and confusion.
• Signs:
  • Elevated blood pressure.
  • Electrolyte imbalances (e.g., hyperkalemia).

Step 4: Diagnostic Approach

• History and Physical Exam: Assess patient symptoms and history of kidney disease or risk factors.
• Laboratory Tests:
  • Serum creatinine and blood urea nitrogen (BUN).
  • Electrolytes to check for imbalances.
• Imaging: Ultrasound may help identify obstructive causes.

Step 5: Treatment Strategies

Acute Management

• Stabilize the Patient: Ensure adequate hydration and correct electrolyte imbalances.
• Monitor Kidney Function: Regularly check kidney function tests to track recovery.

Treatment for Specific Causes

Prerenal AKI

• Fluid Resuscitation: Administer IV fluids to restore blood volume.
• Address Underlying Causes: Treat conditions causing decreased blood flow.

Intrarenal AKI

• Remove Nephrotoxins: Discontinue any harmful medications.
• Supportive Care: Manage complications like electrolyte imbalances.

Postrenal AKI

• Relieve Obstruction: Catheterization or surgical intervention may be necessary.

Step 6: Monitor for Complications

• Metabolic Acidosis: May require bicarbonate therapy.
• Hyperkalemia: Can be managed with medications or dialysis if severe.
• Uremia: Severe cases may need renal replacement therapy (dialysis).

Conclusion

Acute Kidney Injury is a critical condition that requires prompt recognition and management. By understanding its causes, clinical features, and treatment protocols, healthcare providers can improve patient outcomes. As a next step, consider reviewing case studies or clinical guidelines for further insights into managing AKI in practice.