Acute Kidney Injury (AKI) Overview

Acute Kidney Injury (AKI)

• AKI is defined as an abrupt or rapid decline in renal function, characterized by a loss of the kidneys' ability to filter waste products, regulate fluid and electrolyte balance, and maintain acid-base balance.
• AKI can be classified by a rise in creatinine (≥0.3 mg/dL or more within 48 hours), a 1.5 increase from baseline creatinine in 7 days, or urine volume less than 0.5 mL/kg/hr for 6 hours (call at 2 hours-ICU).
• The condition is often temporary and completely reversible if the underlying cause is identified and treated quickly.
• Twenty percent of hospitalized clients and 60% of ICU patients develop AKI.
• Nursing Safety Priority: Assess all clients for low urine output, decreased blood pressure, decreased pulse pressure, and thirst, and intervene with fluids as needed.

Learning Objectives for AKI

• Understanding the pathophysiology, clinical manifestations, and medical/nursing management of clients experiencing AKI and prevention of acute renal failure (ARF)
• Examining risk factors for AKI across the lifespan and identifying nursing strategies to mitigate these risks.
• Differentiating between the three classifications of AKI (prerenal, intrarenal, postrenal)
• Application of the nursing process to provide age-appropriate and culturally sensitive care for clients with AKI
• Developing relevant patient teaching strategies for clients experiencing AKI.

Etiology of AKI

• Pre-renal: Kidneys not perfused due to issues before blood reaches the kidneys. This often results from decreased blood flow.
• Intra-renal: Damage to the kidneys themselves. This can be result of conditions like nephrotoxic medications, infections, or other diseases.
• Post-renal: Obstruction of urine flow out of the kidneys due to issues in the urinary tract like blockages from Benign Prostatic Hyperplasia (BPH) , tumors, stones, or bladder or urethra cancers.

Types of AKI

• Prerenal: Decreased blood flow to the kidneys (MAP < 65 mmHg), often due to dehydration, decreased cardiac output, renal artery problems, or other conditions.
• Intrarenal: Damage directly to the kidneys themselves. This can be due to nephrotoxic medications, infections, or other kidney diseases, including Acute Tubular Necrosis (ATN).
• Postrenal: Obstruction of urine flow. This can be caused by anything blocking urine flow through the ureters, bladder, or urethra, like blockages from Benign Prostatic Hyperplasia (BPH) , tumors, stones, or bladder or urethra cancers.

Putting It Together

• Various medical problems such as glomerulonephritis, lupus, heart failure, pelvic malignancy, dehydration, septic shock, contrast dye procedures, and motor vehicle accidents with blood loss can lead to AKI.

Assessment of AKI

• History: Recent surgery, trauma, hypotension, and exposure to nephrotoxins, especially medications like antibiotics, ACE inhibitors, and NSAIDs. Diagnostic test use of contrast agents, diseases impairing renal function i.e., diabetes, lupus, infections, and any recent acute illnesses.
• Ask about urine color, frequency, and volume.
• History of kidney problems, trauma, cancers, or obstructions.

KDIGO Classification System

• Staging AKI based on serum creatinine levels and urine volume.

RIFLE Classification System

• RIFLE stands for Risk, Injury, Failure, Loss, End-stage renal disease.
• Measures AKI based on GFR (glomerular filtration rate) and urine output.

Phases of AKI

• Oliguric Phase: Kidney function is impaired, leading to decreased urine output.
• Diuretic Phase: Kidneys start to recover some function but may excrete more water, leading to decreased fluid volume.
• Recovery Phase: Kidney function returns to normal, and urine output stabilizes.

Oliguric Phase: Manifestations

• Severe fluid overload
• Metabolic acidosis
• Electrolyte imbalances (sodium, potassium)
• Elevated BUN and creatinine
• Neurologic problems.
• Hematologic problems

Diuretic Phase: Manifestations

• Hypovolemia/hypotension
• Electrolyte imbalances.
• Fluid imbalances.

Recovery Phase: Manifestations

• GFR increases and BUN and creatinine return to normal
• May take up to 12 months for full recovery
• Recovery depends on overall health, severity of kidney injury, and complications

Diagnosis

• History (recent surgery, trauma, nephrotoxins, etc.)
• Laboratory tests (BUN, creatinine, specific gravity of urine)
• Imaging studies (e.g., ultrasound, CT)
• Biopsy (in some cases).

Responding-Fluids/Electrolytes

• Fluid volume deficit: Treat the underlying cause including blood loss and replace fluids. Monitor I&O, and assess electrolytes.
• Fluid volume excess: Restrict fluids, monitor I&O, and consider diuretics. Monitor electrolytes.

Responding-Medications

• Discontinue any nephrotoxic medications, or adjust doses based on kidney function.
• Watch for diuretics, and possible potassium issues.
• Carefully monitor patients on ACE inhibitors/ARBs or NSAIDs.
• Assess kidney function before contrast dye procedures are administered.

Responding - Diet

• High rate of catabolism in AKI, so higher calories and protein are needed to meet the body's needs.
• Sodium intake will vary based on clinical status.
• Potassium intake should be monitored.
• Fat intake may be increased to meet the body's calorie needs.
• Monitor daily intake for calories.

Responding - Infection

• Infection is a leading cause of death in AKI.
• Use aseptic techniques, and watch for signs of infection.

Kidney Replacement Therapy (Indications for dialysis)

• Symptomatic uremia (high BUN),
• Persistent hyperkalemia,
• Severe metabolic acidosis,
• Fluid overload compromising tissue perfusion,
• Significant mental status changes.

Dialysis Therapies (Hemodialysis, CRRT)

• Types of dialysis.

Management of AKI

• Correcting the underlying cause.
• Supportive care (fluid and electrolyte balance, etc.).
• Potentially kidney replacement therapy.

Stage-Based Management of AKI

• Stage-specific guidelines to manage AKI, which are crucial factors to consider when providing patient care.

Prevention of AKI

• Preventing dehydration.
• Monitoring input/output (I & O)
• Recognizing nephrotoxic medications or agents.
• Monitor serum creatinine, and BUN.
• Being aware of baseline eGFR.

Web Resources

• Links to relevant websites for further research on AKI.

This quiz covers the essentials of Acute Kidney Injury (AKI), including its definitions, classification criteria, and clinical implications. You'll learn about the pathophysiology, management strategies, and the importance of early intervention in preventing complications. Test your knowledge on this critical nursing priority for patient safety.