Acute Renal Failure and Urinary System Anatomy
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Questions and Answers

Which of the following factors influence drug clearance during Continuous Renal Replacement Therapy (CRRT)?

  • Ultrafiltration rate (correct)
  • Dialysate flow rate (correct)
  • Patient age
  • Medication dosage

    • The sieving coefficient is unrelated to the clearance of a drug during hemodialysis.

    False

    What daily parameters should be monitored in patients undergoing CRRT?

    Patient weight, hemodynamics, blood chemistry, drug regimens.

    The clearance of a drug during CRRT is a function of the membrane permeability for the drug, known as the __________.

    <p>sieving coefficient</p> Signup and view all the answers

    Match the following parameters with their corresponding measures:

    <p>Blood pressure = Hemodynamics Sodium = Blood chemistry Creatinine clearance = Renal function assessment Dosing regimens = Drug management</p> Signup and view all the answers

    What is a key characteristic of Acute Renal Failure?

    <p>Sudden decline in the kidneys' ability to maintain homeostasis</p> Signup and view all the answers

    Acute Renal Failure is a common condition in healthy populations.

    <p>False</p> Signup and view all the answers

    Name one classification system used to stage the severity of Acute Kidney Injury.

    <p>RIFLE, AKIN, KDIGO</p> Signup and view all the answers

    The presence of chronic kidney disease increases the risk of Acute Kidney Injury by _____ times.

    <p>3</p> Signup and view all the answers

    Match the following categories of Acute Renal Failure with their definitions:

    <p>Prerenal = Due to decreased blood flow to the kidneys Intrinsic = Damage to the kidney tissue itself Postrenal = Obstruction of urine flow leading to kidney damage</p> Signup and view all the answers

    What is the annual incidence of Acute Renal Failure in the general population?

    <p>0.02%</p> Signup and view all the answers

    Older age is a risk factor for developing Acute Kidney Injury.

    <p>True</p> Signup and view all the answers

    What is the overall survival rate of hospitalized patients at risk of Acute Renal Failure?

    <p>30%–50%</p> Signup and view all the answers

    Which of the following conditions is an indication for Renal Replacement Therapy (RRT)?

    <p>Hyperkalemia</p> Signup and view all the answers

    Fluid overload is a common reason for administering RRT.

    <p>True</p> Signup and view all the answers

    What is the most frequently used type of Renal Replacement Therapy?

    <p>Intermittent Hemodialysis (IHD)</p> Signup and view all the answers

    Elevated levels of _______ can cause tissue destruction in the early stages of AKI.

    <p>phosphorous</p> Signup and view all the answers

    Match the following substances with their related effects on the body:

    <p>Salicylates = Intoxication requiring RRT Hypermagnesemia = Electrolyte imbalance Uremia = Accumulation of uremic toxins Metabolic acidosis = Acid-base abnormality requiring RRT</p> Signup and view all the answers

    What is a common complication of Intermittent Hemodialysis?

    <p>Hypotension</p> Signup and view all the answers

    Calcium-containing antacids are advisable for patients with hyperphosphatemia.

    <p>False</p> Signup and view all the answers

    What range of blood flow rates is typical for hemodialysis treatments?

    <p>200 to 400 mL/min</p> Signup and view all the answers

    What causes postrenal acute renal failure?

    <p>Obstruction of urine flow downstream from the kidney</p> Signup and view all the answers

    A high BUN to Scr ratio indicates normal renal function.

    <p>False</p> Signup and view all the answers

    What is a significant benefit of daily IHD over three times weekly IHD?

    <p>Improved survival rates</p> Signup and view all the answers

    What is a common characteristic of intrinsic acute renal failure?

    <p>Structural kidney damage, often due to ischemic or toxic insult.</p> Signup and view all the answers

    Continuous RRT is less expensive than IHD.

    <p>False</p> Signup and view all the answers

    In prerenal acute renal failure, the BUN to Scr ratio is typically greater than ____.

    <p>20:1</p> Signup and view all the answers

    What is a common issue that arises with anticoagulation in Continuous RRT?

    <p>Thrombosis</p> Signup and view all the answers

    Which lab finding is suggestive of prerenal acute renal failure?

    <p>High urinary specific gravity</p> Signup and view all the answers

    Loop diuretics are primarily used for managing __________ overload in patients with AKI.

    <p>fluid</p> Signup and view all the answers

    Match the acute renal failure type with its corresponding description:

    <p>Prerenal = Due to decreased renal perfusion Intrinsic = Structural kidney damage Postrenal = Obstruction of urine flow Acute kidney injury = Rapid onset of kidney dysfunction</p> Signup and view all the answers

    Match the following treatment approaches with their characteristics:

    <p>IHD = Commonly used for regular dialysis sessions CRRT = Used mainly for critically ill patients Loop diuretics = Increases urine output but may worsen AKI Anticoagulation = Essential in Continuous RRT to prevent thrombosis</p> Signup and view all the answers

    Glomerular damage is indicated by proteinuria in a patient with acute renal failure.

    <p>True</p> Signup and view all the answers

    What is a recommended action regarding the use of loop diuretics in AKI management?

    <p>Limit use to managing fluid overload</p> Signup and view all the answers

    Which drug is frequently combined with furosemide for effective diuresis in patients with a GFR less than 20 mL/min?

    <p>Metolazone</p> Signup and view all the answers

    What should be monitored frequently in cases of acute renal failure to prevent life-threatening complications?

    <p>Serum potassium levels.</p> Signup and view all the answers

    Diuretic resistance is a common problem in patients with AKI.

    <p>True</p> Signup and view all the answers

    Fluid accumulation does not influence drug dosing in AKI.

    <p>False</p> Signup and view all the answers

    What factors limit the availability of Continuous RRT?

    <p>Limited special equipment and intensive nursing care requirements</p> Signup and view all the answers

    Name one factor that alters the pharmacokinetics of drugs in patients with fluid overload.

    <p>Volume overload</p> Signup and view all the answers

    For drugs eliminated primarily by the liver, ___________ function may be preferred in patients with AKI.

    <p>normal hepatic</p> Signup and view all the answers

    Match the following drug classes with their primary considerations in AKI:

    <p>Vancomycin = Requires careful monitoring due to altered pharmacokinetics AGs (Aminoglycosides) = Dosing adjustments needed based on renal function LMWHs = May require adjustment in volume overloaded patients Ceftriaxone = Higher residual nonrenal clearance in AKI than CKD</p> Signup and view all the answers

    What should be frequently reassessed in ARF patients due to altered pharmacokinetics?

    <p>Maintenance dosing regimens</p> Signup and view all the answers

    The volume of distribution for drugs is generally decreased in patients with anasarca.

    <p>False</p> Signup and view all the answers

    What type of renal replacement therapy requires individualization of drug therapy?

    <p>Continuous renal replacement therapy (CRRT)</p> Signup and view all the answers

    Study Notes

    Acute Renal Failure/Injury Definition

    • A sudden decline in the kidneys' ability to maintain homeostasis, resulting in the buildup of metabolic wastes like urea and creatinine.
    • Electrolyte, acid-base, and fluid balance disturbances are common features.
    • Clinicians use a combination of serum creatinine (Scr) levels, changes in Scr over time, and urine output for diagnosis.
    • There is no universally accepted definition.

    Anatomy of the Urinary System

    • The urinary system includes the kidneys, ureters, bladder, and urethra.
    • Kidneys have an outer cortex and inner medulla.
    • The renal pelvis collects urine from the pyramids.
    • Urine passes through the ureters to the bladder and exits through the urethra.

    Urine Formation

    • Glomerular filtration is the movement of substances from the blood in the glomerulus to the capsular space.
    • Tubular reabsorption returns substances from the tubular fluid back into the blood.
    • Tubular secretion moves substances from the blood into the tubular fluid.
    • The loop of Henle and collecting duct further modify urine composition.

    ARF Classification

    • Staging severity based on serum creatinine (Scr) and urine output (UOP).
    • Different classifications (RIFLE, AKIN, KDIGO).
    • Each classification system uses GFR, urine output and clinical outcomes to categorize ARF stages.

    ARF Epidemiology

    • Uncommon condition in the general population.
    • Annual incidence is about 0.02%.
    • Patients with pre-existing chronic kidney disease (CKD) have a higher incidence (13%).
    • Hospitalized patients have a higher risk of AKI (incidence ~7%).
    • Overall survival rates vary widely (30%–95%).

    Etiology of Acute Kidney Injury (AKI)

    • Presence of Chronic Kidney Disease (CKD) triples the risk of AKI.
    • Advanced age (>65 years old) increases AKI risk.
    • Multisystem organ failure.
    • Sepsis, Infections.
    • Preexisting chronic conditions.
    • Surgery.
    • Malignancy are factors.

    Pathophysiological Basis of AKI

    • Prerenal AKI: Reduced renal perfusion (often due to decreased blood volume).
    • Intrinsic AKI: Damage to the kidney; caused by ischemia or toxins.
    • Postrenal AKI: Obstruction of urine outflow.
    • AKI causes frequently include factors such as glomerular, vascular, tubular, interstitial damage or obstruction.

    Clinical Presentation

    • Signs and symptoms are highly variable and depend on the underlying cause.
    • Outpatients with AKI often have nonspecific symptoms.
    • Hospitalized patients are more likely to have AKI detected earlier due to frequent monitoring.

    Patient Assessment (Clinical History)

    • Past medical history, chronic renal conditions and poorly controlled hypertension (HTN) and diabetes mellitus (DM) may suggest CKD instead of AKI.
    • Medication history may suggest causes such as acute interstitial nephritis (e.g., NSAIDs, diuretics, contrast dyes).
    • Lab tests: proteinuria, or elevated serum creatinine (Scr).

    Patient Assessment (Lab Tests)

    • Serum creatinine (Scr), blood urea nitrogen (BUN), urine output, and urine osmolality help determine the cause.
    • Elevated serum potassium, a reduction in calcium, and acidosis suggest complications.
    • Urine analysis may reveal proteinuria, hematuria, casts (indicating tubular or glomerular injury) or crystals.

    Patient Assessment (Lab Interpretation)

    • Scr and GFR changes are not always immediate.
    • There is a lag time between the initial kidney injury and the detectable increase in abnormal values.
    • Scr values may not always reflect the severity of the underlying kidney damage.
    • Modification of Diet in Renal Disease (MDRD) equations are not valid for AKI cases.
    • Urine output, BUN/Scr ratio & specific gravity help assess kidney function, and distinguish various factors contributing to AKI.
    • Urine electrolyte & microscopic analyses provide additional details about kidney function.

    Treatment of Acute Kidney Injury (AKI)

    • Supportive care for hemodynamic stability, fluid balance, and electrolyte abnormalities is essential and usually the main treatment.
    • Correction of underlying causes (i.e., removing obstructions).
    • Renal replacement therapy (RRT) (e.g., hemodialysis, continuous renal replacement therapy) may be indicated for severe cases.

    Prevention of Acute Kidney Injury (AKI)

    • Optimal daily fluid intake (typically ~2 liters).
    • Avoidance or reduction of nephrotoxic medications (including certain antibiotics and contrast agents).
    • Evaluate/monitor fluid balance closely.
    • Preemptive preventive measures when surgical patients are high-risk.

    Nonpharmacologic Therapies

    • Hydration with isotonic saline or balanced electrolyte solutions to maintain fluid balance can help prevent or mitigate AKI.
    • Avoid potentially nephrotoxic drugs like contrast dyes for a higher risk population.

    Pharmacologic Treatments for AKI

    • Prevention of AKI may be considered through antioxidant use (ascorbic acid + N-acetylcysteine)
    • Control of blood sugars (glycemia).
    • Limit the use of loop diuretics.

    Diuretic Resistance

    • Factors include excessive sodium intake, reduced functioning nephrons, and drug absorption issues.
    • Continuous infusion of loop diuretics may be necessary in such cases to overcome resistance.
    • Combination therapy (i.e., combining loop diuretics with other diuretics from different classes) may be beneficial.

    Drug Dosing in AKI

    • Factors that influence drug response, include residual renal drug clearance, fluid volume, delivery of renal replacement therapy.
    • Edema in ARF, can significantly alter the dosing/distribution of drugs.
    • Patients with ARF may require adjustments to dosing regimens or selection of drugs based on hepatic or renal function.

    Monitoring

    • Vital signs (BP, HR, weight).
    • Daily input and output of fluids.
    • Daily labs for electrolytes to confirm effective hydration and appropriate fluid balance.
    • Measurement of serum drug concentrations for drugs with narrow therapeutic windows.

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    Description

    This quiz covers key concepts related to acute renal failure, including its definition and diagnostic criteria. Additionally, it explores the anatomy of the urinary system, detailing the structure and function of the kidneys, ureters, bladder, and urethra. Test your understanding of urine formation and the processes involved in renal function.

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