Week12_Renal_Disorders_1_

Renal Disorders and Therapeutic Management

Introduction

  • Week 12 class focuses on Renal Disorders, specifically Acute Renal Failure (ARF) and Acute Tubular Necrosis (ATN).

  • Objectives:

    • Discuss two renal disorders: ARF and ATN.

    • Understand the pathophysiology associated with these renal diseases.

    • Identify nursing measures that can improve patients' quality of life.

Acute Renal Failure (ARF)

Overview

  • Critical illness can lead to ARF with mortality rates ranging from 38% to 80%.

  • Comorbid conditions include heart failure, respiratory failure, and diabetes mellitus.

  • Patients with asymptomatic elevated serum creatinine at high risk for ARF.

Definition

  • ARF is characterized by a sudden decline in glomerular filtration rate (GFR), leading to retention of metabolic waste and an inability to maintain electrolyte balance and acid-base homeostasis.

Causes of ARF

Classification of ARF

  1. Prerenal ARF

    • Caused by renal hypoperfusion affecting fluid volume regulation due to:

      • Low cardiac output, bleeding, sepsis, thrombosis, myocardial infarction, burns, trauma, septic shock, renal artery obstruction.

    • Symptoms: Oliguria (urine output < 0.30 mL/hr or < 400 mL/day).

    • Treatment: Monitor urine output closely; prognosis usually reversible with prompt treatment.

  2. Intrarenal ARF

    • Resulting from direct damage to the nephron.

    • Causes include:

      • Ischemia due to prolonged hypotension.

      • Toxic insults from drugs (e.g., antimicrobials, contrast dye), rhabdomyolysis.

    • Acute tubular necrosis accounts for 90% of acute oliguria cases.

  3. Postrenal ARF

    • Resulting from any obstruction hindering urine flow; it is uncommon.

    • Nursing management includes checking the patency of drainage systems (e.g., Foley catheter) during sudden anuria.

Pathophysiology

  • Azotemia refers to an acute rise in blood urea nitrogen (BUN) and is linked to renal failure.

  • Uremic syndrome indicates an inability to eliminate toxins, often leading to end-stage kidney failure.

Risk Factors for ARF

  • Older age, heart failure, respiratory failure, sepsis, trauma, and contrast-induced nephrotoxic injury.

Prevention Strategies

  • Hydration: Ensure adequate fluid intake in at-risk patients.

  • Shock: Prompt treatment with fluids and blood replacement.

  • Monitoring: Central venous and arterial pressures, hourly urine output to detect renal failure early.

  • Infection: Prevent and treat to avoid renal damage.

  • Toxins: Monitor dosages and blood levels of medications metabolized by kidneys.

Diagnostic Findings

  • Urine output notably decreases during ARF:

    • Anuric phase: < 100 mL/24 hr.

    • Oliguric phase: < 400 mL/24 hr.

    • Nonoliguric renal failure with nephrotoxins may exceed 400 mL/24 hr.

  • Lab tests:

    • Elevated serum BUN/Cr indicates renal dysfunction.

    • Fractional sodium excretion helps differentiate prerenal from intrarenal causes.

Diagnostic Tests

  • Renal ultrasound, non-nuclear CT scans, and MRI reveal kidney size, presence of masses, and soft tissue damage.

Acute Tubular Necrosis (ATN)

Definition

  • Damage to renal tubular epithelium caused by nephrotoxicity or ischemia.

Epidemiology

  • Ischemic ATN caused by prolonged hypotension or sepsis; toxic ATN often due to drugs or chemical agents.

Pathophysiology

  • ATN leads to:

    • Tubular obstruction from cellular debris.

    • Tubular edema and injury due to increased intracellular calcium and oxygen radicals.

Phases of ATN

  1. Initiation: Initial insult leading to decreased GFR.

  2. Oliguria: Increased serum levels of excretory substances.

  3. Diuresis: Increase in urine output indicating recovery in GFR.

  4. Recovery: Gradual return of renal function, potentially over months.

Nursing Management

Assessment

  • Monitor urine output, blood presence, and laboratory values.

  • Evaluate signs of dehydration or overload.

Fluid Balance

  • Hemodynamic monitoring essential to assess volume status; compare daily weights to detect fluid retention.

Electrolyte Imbalance Management

  • Frequent observations required, especially potassium levels.

  • Treatments for hyperkalemia: Diuretics, insulin, calcium gluconate, albuterol, and dialysis if needed.

  • Sodium, calcium, and phosphorus levels must also be managed carefully.

Medical Management

  • Focus on preventing and addressing renal function deterioration.

  • Fluid balance management includes resuscitation and removal strategies via diuretics or dialysis.

Conclusion

  • High mortality rate associated with ARF highlights the importance of prevention strategies and collaborative care among healthcare providers.