Acute Kidney Injury (AKI) Lecture Notes

Overview

• Presenter: Sarah, Registered Nurse
• Topic: Acute Kidney Injury (AKI), also known as Acute Renal Failure
• Series: Part of an NCLEX review series on the renal system
• Quiz: Available at the end of the video to test knowledge on AKI

What is Acute Kidney Injury?

• Definition: A sudden decrease in renal function.
• Symptoms: Kidneys fail to filter blood, leading to waste buildup (e.g., BUN, creatinine), fluid buildup, and electrolyte imbalances.
• Reversibility: Can be reversible if caught early and treated appropriately.

Causes of Acute Kidney Injury

1. Pre-Renal Causes:

   • Occur before the kidney, affecting blood flow/perfusion.
   • Examples:
     • Cardiac issues (e.g., myocardial infarction)
     • Massive bleeding (internal/external)
     • Dehydration (excessive diarrhea, vomiting)
     • Burns

2. Intra-Renal Causes:

   • Damage to the nephrons within the kidney.
   • Examples:
     • Nephrotoxic drugs (e.g., NSAIDs, aminoglycoside antibiotics, chemotherapy drugs)
     • Infections (e.g., glomerulonephritis)

3. Post-Renal Causes:

   • Obstructions in the urinary system.
   • Examples:
     • Renal calculi
     • Enlarged prostate
     • Neurological damage affecting bladder emptying

Kidney Function Basics

• Normal Urinary Output: 1-2 liters per day.
• Substances in Urine: Water, ions (sodium, chloride, calcium), waste products (urea, creatinine).

Key Lab Tests

• Creatinine Levels:

  • Normal: 0.6 to 1.2 mg/dL
  • Important for determining kidney filtering ability.

• Creatinine Clearance:

  • Females: 85-125 mL/min
  • Males: 95-140 mL/min

• Glomerular Filtration Rate (GFR):

  • Normal: ≥ 90 mL/min
  • Indicates rate of blood filtration through kidneys.

• BUN (Blood Urea Nitrogen):

  • Normal: 6-20 mg/dL

Stages of Acute Kidney Injury

1. Initiation Stage:

   • Begins with kidney injury cause, ends when symptoms appear.
   • Early detection and treatment are crucial.

2. Oliguric Stage:

   • Characteristics: Urinary output < 400 mL/day.
   • Signs/Symptoms: Increased BUN/creatinine, azotemia, neuro changes, hyperkalemia, edema, metabolic acidosis, hyponatremia.
   • Interventions: Limit protein, monitor EKG, restrict fluids, manage electrolytes.

3. Diuresis Stage:

   • Characteristics: Increased urinary output (3-6 L/day).
   • Signs/Symptoms: Hypovolemia, dehydration, hypokalemia, dilute urine.
   • Interventions: Fluid/electrolyte monitoring, IV fluids, daily weights.

4. Recovery Stage:

   • Characteristics: GFR returns to normal.
   • Recovery Time: Can take up to a year or more.
   • Some patients may not recover and develop chronic kidney disease.

Conclusion

• Acute Kidney Injury is a critical condition that requires prompt diagnosis and treatment.
• Understanding the causes, stages, and appropriate interventions is crucial for patient care.
• Stay updated and practice with quizzes to enhance knowledge and readiness for exams.