Acute Kidney Injury Overview

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Questions and Answers

What is the primary effect of acute kidney injury (AKI)?

Improved kidney function

Increased urine production

Electrolyte balance stabilization

Waste product retention (correct)

Which classification system for AKI utilizes changes in serum creatinine and urinary output?

AKIN

RIFLE (correct)

KDIGO

NICE

In the AKI classification systems, which term refers to the most severe stage of kidney injury?

End-stage (correct)

Injury

Failure

Risk

What does the serum creatinine level indicate in the context of AKI?

Delayed indication of injury Signup and view all the answers

Which of the following is a common characteristic of the AKI classification systems?

They standardize definitions and severity levels of AKI. Signup and view all the answers

What is the primary goal of renal replacement therapy in the context of AKI?

To replace the function of failed kidneys Signup and view all the answers

What does the AKIN classification focus on for categorizing AKI?

Percentage increase in serum creatinine and urinary output Signup and view all the answers

Which of the following best describes 'Risk' in the RIFLE classification?

Slight increase in serum creatinine and urinary changes Signup and view all the answers

What constitutes a significant increase in serum creatinine (SCr) according to KDIGO guidelines?

A 0.3 mg/dL increase within 48 hours Signup and view all the answers

Which of the following is NOT a risk factor for acute kidney injury (AKI)?

Smoking habits Signup and view all the answers

What type of AKI is caused by obstruction of urinary outflow?

Post-renal AKI Signup and view all the answers

A 50% increase in serum creatinine must occur within what time frame to be considered significant?

7 days Signup and view all the answers

Which of the following would most likely indicate a pre-renal cause of AKI?

Hypoperfusion to the kidney Signup and view all the answers

Which health condition is NOT commonly associated with an increased risk of AKI?

Chronic lung disease Signup and view all the answers

What is the minimum urine output rate that can indicate potential kidney issues if sustained for 48 hours?

0.5 mL/kg/hour Signup and view all the answers

Which type of AKI is characterized by structural damage to the kidney?

Intrinsic AKI Signup and view all the answers

What is the duration of time in which a serum creatinine increase of $0.3 ext{ mg/dL}$ should be noted to indicate potential AKI?

Within 48 hours Signup and view all the answers

What is the primary fluid type recommended for intravascular volume expansion?

Isotonic crystalloids Signup and view all the answers

What could be a potential cause of post-operative AKI in patients?

Major surgery Signup and view all the answers

Which fluid type should be avoided due to associated adverse effects?

Hydroxyethylstarch Signup and view all the answers

What is the main role of diuretics in the management of Acute Kidney Injury (AKI)?

Facilitate fluid management Signup and view all the answers

What does total body water volume approximately equal in a healthy body?

40 L Signup and view all the answers

Which type of diuretics is recommended for treating volume overload in AKI?

Loop diuretics Signup and view all the answers

What is the characteristic of crystalloids that makes them commonly used in AKI treatment?

Maintain intravascular volume Signup and view all the answers

Colloid solutions such as albumin are particularly beneficial for what purpose?

Increase intravascular oncotic pressure Signup and view all the answers

What is the primary purpose of comprehensive lab testing in acute kidney injury?

To monitor kidney function and guide treatment Signup and view all the answers

Which of the following is NOT an important aspect to assess during a physical examination for acute kidney injury?

Skin color Signup and view all the answers

Which imaging test is used to evaluate blood flow to the kidneys?

Renal Doppler Ultrasonography Signup and view all the answers

What should be done regarding nephrotoxins in the context of acute kidney injury?

Discontinue nephrotoxins to protect the kidneys Signup and view all the answers

Which of the following factors is NOT a risk factor to look for in a patient with potential acute kidney injury?

History of cancer Signup and view all the answers

Which lab test is essential for evaluating urine composition in suspected kidney issues?

Urinalysis Signup and view all the answers

What is the main objective when treating acute kidney injury?

To treat the underlying cause of the injury Signup and view all the answers

Which of the following tests can provide insights into the structure of the kidneys during an evaluation?

Renal Biopsy Signup and view all the answers

In addition to evaluating vital signs, what other assessment is critical for determining fluid status?

Fluid losses and gain history Signup and view all the answers

Which of the following is a common electrolyte imbalance associated with acute kidney injury?

Hyperkalemia Signup and view all the answers

Which of the following is a pre-renal cause of acute kidney injury?

Sepsis Signup and view all the answers

What can lead to intrinsic acute kidney injury due to nephrotoxic effects?

Antibiotics Signup and view all the answers

Which of the following medications is known to cause vasodilation affecting kidney blood flow?

ACE inhibitors Signup and view all the answers

Which condition is a post-renal cause of acute kidney injury?

Benign prostatic hypertrophy Signup and view all the answers

What is a common risk factor for drug-induced crystalluria?

High drug doses Signup and view all the answers

Which type of injury is associated with inflammation of kidney tissue?

Tubulointerstitial injury Signup and view all the answers

Which autoimmune disorder can cause glomerular injury?

Systemic lupus erythematosus Signup and view all the answers

What condition can result from the obstruction caused by kidney stones?

Post-renal acute kidney injury Signup and view all the answers

Which of the following medications is associated with vancomycin nephrotoxicity?

Aminoglycosides Signup and view all the answers

What is considered a systemic condition impacting kidney function?

Hypertension Signup and view all the answers

Study Notes

Acute Kidney Injury (AKI) Overview

AKI is defined as an abrupt loss of kidney function.
Effects include waste product retention, electrolyte imbalances, and changes in fluid balance.
Detection relies on biomarker changes, particularly serum creatinine (SCr), which often lags 48-72 hours behind the onset of injury.

Learning Outcomes

Differentiate various types of AKI.
Understand and apply different treatments for AKI.
Demonstrate knowledge of renal replacement therapy (RRT).

AKI Classification Systems

RIFLE: Risk, Injury, Failure, Loss, End-stage
AKIN: Acute Kidney Injury Network
KDIGO: Kidney Disease Improving Global Outcomes

RIFLE Classification

Criteria are based on changes in serum creatinine and urine output.
Stages include risk, injury, failure, loss, and end-stage.
Purpose is to standardize the definition and severity of AKI.

AKIN Criteria

SCr increase of 0.3 mg/dL or more within 48 hours.
50% or greater increase in SCr within 7 days.
Less than 0.5 mL/kg/hour urine output for more than 6 hours.

KDIGO Guidelines

SCr increase of 0.3 mg/dL or more within 48 hours.
50% or greater increase in SCr within 7 days.

Types of AKI

Pre-renal: Hypoperfusion (e.g., shock, dehydration).
Intrinsic (or Intrarenal): Damage to kidney tissues (e.g., acute tubular necrosis, glomerulonephritis).
Post-renal: Obstruction to urine outflow (e.g., kidney stones, enlarged prostate).

Risk Factors for AKI

Age (increased risk with advanced age).
Comorbidities (e.g., hypertension, diabetes).
Major surgery.
Proteinuria.
Dehydration.
High blood pressure.
Infections.

Medications Affecting Kidney Function

Certain drugs may cause vasoconstriction (e.g., afferent arteriole) or vasodilation (efferent arteriole).
Prostaglandin inhibition
Use of nephrotoxic drugs.

Tubular Causes of Intrinsic AKI

Acute tubular injury.
Tubulointerstitial injury.
Glomerulonephritis.

Glomerular Causes of Intrinsic AKI

Autoimmune disorders.
Oncology Drugs.
Specific Medications

Tubular Causes of Intrinsic AKI (Part 1)

Antimicrobials
Nephrotoxic Drugs
Acute Tubular Necrosis

Tubular Causes of Intrinsic AKI (Part 2)

Aminoglycoside-associated ATN
Amphotericin B
Vancomycin Nephrotoxicity
Contrast-induced Nephrotoxicity

Vascular/Thrombotic Causes of Intrinsic AKI

Vasculitis
Malignant hypertension
Thrombotic disorders

Interstitial Causes of Intrinsic AKI

Infections (e.g., pyelonephritis, renal tuberculosis, fungal nephritis).
Medications (e.g., antibiotics, NSAIDs, diuretics).
Immune disorders.

Post-Renal AKI Obstruction Causes

Nephrolithiasis (kidney stones).
Benign prostatic hypertrophy.
Surgical complications.

Drug-Induced Crystalluria

Mechanism: Low solubility drugs crystallize in urine.
Effects: Crystals block the collecting system.
Risk Factors: High drug doses, dehydration, and acidic urine.

Common Causes of AKI

Pre-renal: Hypovolemia, dehydration, decreased cardiac output, decreased peripheral vascular resistance.
Intrarenal: Nephrotoxic injury, contrast dye, crush injury, interstitial nephritis, allergies, infections, acute glomerulonephritis, malignant hypertension, thrombotic disorders, vasculitis.
Post-renal: Benign prostatic hypertrophy, bladder cancer, calculi formation.

Clinical Workup

Comprehensive evaluation of the patient's medical condition, including history, physical examination, and diagnostic tests.

Medical History and Physical Examination

Gathering information on fluid loss, prior lab results, comorbidities, and medication history.
Identifying risk factors (e.g., heart/liver disease, infections, prior urinary tract issues).
Assessing vital signs, volume status, and underlying conditions during a physical examination.

Labs Work

Comprehensive lab testing (electrolytes, kidney biomarkers).

Laboratory Studies

Serum Chemistry: Analyzing blood samples for electrolytes and metabolic status.
Urinalysis: Evaluating urine composition and sediment.
Complete blood count: Measuring RBC and WBC to detect abnormalities.

Radiographic Studies

Imaging tests provide valuable insights into underlying causes of acute kidney injury.
Renal Ultrasonography: Evaluating kidney size, shape, and structure.
Renal Doppler Ultrasonography: Assessing blood flow to the kidneys, helpful in diagnosing renal artery stenosis.
Renal Biopsy: Obtaining a small sample of kidney tissue for microscopic examination.

Therapy for Acute Kidney Injury (AKI)

Treat underlying cause.
Discontinue nephrotoxins.
Ensure proper perfusion (monitor fluid status and BP).

Fluid Replacement

Crystalloids are more commonly used than colloids for resuscitation in pre-renal AKI.
Colloids increase intravascular oncotic pressure (e.g., using albumin, gelatins, etc.).

KDIGO Guideline

Isotonic crystalloids are the preferred fluid for volume expansion.
Avoid Hydroxyethylstarch (HES).
Colloids may still be used in patients requiring larger fluid volumes (e.g., albumin).

Diuretics

Diuretics are used to manage fluid overload in AKI.
Loop diuretics (e.g., furosemide) are commonly used to reduce fluid overload and hyperkalemia.

Vasopressors

Used to maintain adequate mean arterial pressure (MAP).
Fluid resuscitation may not be enough.
Norepinephrine and dopamine common vasopressors.

Renal Replacement Therapy (RRT)

Indications include anuria, acute fluid overload, severe hyperkalemia, metabolic acidosis, and a BUN level above 100 mg/dL.
Early initiation of RRT has shown reduced mortality.
Modalities include intermittent and continuous therapies.

Timing of RRT

Early initiation of RRT can improve mortality.
Volume overload and solute imbalances suggest RRT.
Consideration of risk and benefits of early versus late RRT.

CRRT Advantages

Maintaining hemodynamic stability.
Reduced downtime for procedures.

Drug Dosing in Dialysis

Smaller molecular weight drugs are more easily removed.
Highly protein-bound drugs have less unbound drug for dialysis.
Drugs with larger volumes of distribution are poorly dialyzable.

Common Dialyzable Drugs

List of drugs effectively removed by dialysis.
Monitoring drug levels crucial in dialysis patients.

Case Study Introduction

A 75-year-old man with a right hemi-colectomy.
Decreased urine output.
Vital signs: HR 116 BPM, BP 90/60 mmHg.

Patient Medical History

Hypertension, type 2 diabetes mellitus, gout.
Medications: Lisinopril, diclofenac, allopurinol, spironolactone.

Case Study: 75-year-old Man (continued)

The patient had right hemi-colectomy.
History of hypertension, type 2 diabetes, and gout.
Current medications.

Question 1

Classify the patient's renal failure.
- Pre-renal (due to hypovolemia).

Question 2

Immediate action for decreased urine output.
- Fluid challenge with saline (0.9% normal saline).

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Description

This quiz explores the fundamentals of Acute Kidney Injury (AKI), including its definition, effects, and classification systems such as RIFLE and AKIN. Participants will learn to differentiate types of AKI, apply treatments, and understand renal replacement therapy. Improve your knowledge of this critical renal condition!