Renal failure signifies a reduction in the kidney’s ability to function effectively. This impairment can manifest as either an acute or chronic condition.

Acute Renal Failure (ARF)

Acute renal failure (ARF), also known as acute kidney injury (AKI), is characterized by a rapid decline in the kidneys’ capacity to filter toxic substances from the blood. This can occur due to various factors, including exposure to poisons, certain drugs, or antibodies that target the kidneys. Consequently, metabolic waste products, such as urea, accumulate in the bloodstream.

A healthy adult with a standard diet requires a minimum daily urine output of approximately 400 ml to efficiently eliminate bodily waste products through the kidneys. A urine output below this threshold suggests a decreased glomerular filtration rate (GFR), indicating impaired kidney function.

Pathophysiology of Acute Renal Failure

While the precise mechanisms underlying ARF and reduced urine output (oliguria) are not always fully understood, a specific underlying cause is frequently identifiable. Conditions that can precipitate ARF include:

• Hypovolemia: A decrease in blood volume.

• Hypotension: Abnormally low blood pressure.

• Reduced Cardiac Output and Failure: Insufficient blood pumping by the heart.

• Obstruction of the Kidney: Blockage preventing urine flow.

Illustrative Example: Hypovolemia-Induced ARF

Consider a scenario where hypovolemia is the primary cause. The resulting pathophysiology unfolds as follows:

1. Glomerular Hypoperfusion: Reduced blood volume leads to decreased blood flow to the glomeruli, the kidney’s filtering units.

2. Compensatory Mechanisms: In cases of mild hypoperfusion, the kidneys attempt to maintain the filtration rate through compensatory mechanisms, notably the Renin-Angiotensin-Aldosterone System (RAAS).

3. Overwhelmed Compensation: With more severe hypoperfusion, these compensatory responses become inadequate.

4. Decreased Glomerular Filtration: The glomerular filtration rate falls, leading to pre-renal acute renal failure.

5. Impaired Kidney Function: Inadequate blood flow compromises the kidney’s ability to function.

6. Potential for Permanent Damage: If the underlying cause is not addressed promptly, it can result in irreversible damage to the kidneys.

Etiology of Acute Renal Failure

The causes of ARF are broadly classified into three categories:

A. Pre-Renal Acute Renal Failure: This occurs due to conditions that reduce blood supply to the kidneys, leading to ischemia (lack of oxygen) in the kidney tissue.

• Hypovolemia:

  • Hemorrhage, anemia, asphyxia, burns, and dehydration.

  • Gastrointestinal fluid loss (vomiting, surgical drainage, diarrhea).

  • Renal fluid loss (osmotic diuresis, e.g., diabetes mellitus, hypoadrenalism).

  • Fluid sequestration in highly vascular areas (e.g., pancreatitis, trauma).

• Low Cardiac Output:

  • Diseases of the myocardium (heart muscle), valves, and pericardium (sac surrounding the heart).

  • Arrhythmias (irregular heartbeats).

  • Cardiac tamponade (excessive fluid in the pericardium hindering heart muscle dilation).

  • Pulmonary hypertension (high blood pressure in the lungs).

  • Massive pulmonary embolus (blood clot in the lungs).

  • Septic shock (severe infection causing widespread inflammation and low blood pressure).

B. Intrarenal/Intrinsic Renal Causes: These involve actual tissue damage to the kidneys, often caused by inflammatory or immunological responses.

• Toxins:

  • Nephrotoxic drugs (e.g., aminoglycosides like streptomycin and gentamicin, rifampicin, tetracycline).

  • Heavy metals (e.g., phenol, carbon tetrachloride, chlorates).

• Diseases of the Glomeruli:

  • Glomerulonephritis (inflammation of the glomeruli).

  • Pyelonephritis (kidney infection).

• Acute Tubular Necrosis: Damage to the kidney tubules.

• Vasculitis: Inflammation of blood vessels.

• Endogenous Factors:

  • Hemolysis (destruction of red blood cells, e.g., Rh incompatibility).

  • Uric acid and oxalate deposition.

C. Post-Renal Causes: These arise from conditions that obstruct the outflow of urine from the kidneys.

• Tumors

• Kidney stones

• Edema (swelling)

• Prostatic hyperplasia (enlargement of the prostate gland)

Phases/Stages of Acute Renal Failure

ARF progresses through distinct phases:

• Initiation Phase: This period begins with the initial injury or insult to the kidneys and ends when oliguria develops.

• Oliguric Phase (Oliguria): Characterized by significantly reduced urine output (<400 ml/day). This phase typically lasts for a few days and is accompanied by an increase in the serum concentration of substances normally excreted by the kidneys.

• Diuretic Phase (Diuresis): Urine output increases dramatically, potentially reaching as high as 4000 ml/day. However, this urine initially lacks waste products. Improvement may begin to be seen towards the end of this phase as glomerular filtration starts to recover.

• Recovery Phase: This signifies the restoration of renal function and can take 3 to 12 months. Incomplete recovery may lead to chronic renal failure.

Clinical Features of Acute Renal Failure

Clinical manifestations of ARF include:

• Oliguria: Reduced urine output with a rapid increase in blood urea and creatinine levels, typically occurring within 1-3 days. This can persist for 7-20 days.

• Electrolyte Imbalance: Most notably hyperkalemia (elevated potassium levels).

• Fluid Imbalance: Generalized edema (swelling) due to fluid retention.

• Gastrointestinal Symptoms: Decreased appetite, nausea, and vomiting.

• Neurological Symptoms: Lethargy, drowsiness, headache, muscle twitching, and potentially seizures or convulsions.

• Pallor: Paleness of the skin.

• Pulmonary Edema: Fluid buildup in the lungs, leading to dyspnea (shortness of breath).

• Dehydration Signs: Dryness of the skin and mucous membranes.

• Signs of Congestive Heart Failure: May develop due to fluid overload.

• Severe Hypertension: Elevated blood pressure.

Investigations/Diagnostic Findings for Acute Renal Failure

Diagnostic assessments for ARF involve analyzing urine and blood, along with imaging techniques:

Urine Analysis:

• Volume: Typically less than 100 mL/24 hours (anuric phase) or 400 mL/24 hours (oliguric phase).

• Color: Dirty, brown sediment may indicate the presence of red blood cells and hemoglobin.

• Specific Gravity: Less than 1.020 can suggest kidney disease (e.g., glomerulonephritis, pyelonephritis).

• Protein: High-grade proteinuria (3-4+) strongly suggests glomerular damage, especially when accompanied by red blood cells and casts.

Blood Analysis:

• BUN/Creatinine: Elevated levels.

• Complete Blood Count (CBC): Hemoglobin may be decreased, indicating anemia.

• Arterial Blood Gases (ABGs): May reveal metabolic acidosis (pH less than 7.2) due to the kidneys’ reduced ability to excrete hydrogen ions and metabolic byproducts.

• Electrolytes (Chloride, Phosphorus, Magnesium, Sodium, Potassium): Often elevated due to retention and cellular shifts (acidosis) or tissue release (red blood cell hemolysis).

Imaging:

• Retrograde Pyelogram: Visualizes abnormalities of the renal pelvis and ureters.

• Renal Arteriogram: Assesses renal blood circulation and identifies extravascularities or masses.

• Voiding Cystoureterogram: Shows bladder size, reflux of urine into the ureters, and urinary retention.

• Renal Ultrasound: Determines kidney size and the presence of masses, cysts, or obstructions in the upper urinary tract.

• Nonnuclear Computed Tomography (CT) Scan: Provides cross-sectional views of the kidney and urinary tract to detect the presence and extent of disease.

• Magnetic Resonance Imaging (MRI): Offers detailed information about soft tissue damage.

• Excretory Urography (Intravenous Urogram/Pyelogram): Radiopaque contrast concentrates in the urine, allowing visualization of the kidneys, ureters, and bladder (KUB).

Management of Acute Renal Failure

The primary aims of ARF management are to restore normal chemical balance and prevent complications while renal tissue repairs.

In-Hospital Management:

1. Admission and Rest: Admit the patient and ensure adequate rest. Assist with daily activities to conserve energy.

2. Fluid and Salt Restriction: The nurse should consider restricting fluid and salt intake (e.g., half a teaspoon of salt per day).

3. Fluid Balance Monitoring: Closely monitor fluid intake and output using a fluid balance chart to assess improvement and manage fluid deficits or excesses. Aim to provide 600 ml plus the amount of previous fluid loss.

4. Edema and Hydration Assessment: Assess for edema, skin turgor, and fontanelles (in infants) to evaluate fluid overload or dehydration.

5. Vital Sign Monitoring: Monitor blood pressure and weigh the patient twice daily, along with other vital observations.

6. Dialysis: Initiate dialysis (either hemodialysis or peritoneal dialysis) in cases of severe fluid overload, pulmonary edema, congestive cardiac failure, severe hypertension, hyperkalemia, and significantly increased BUN.

7. Nutritional Management: Maintain adequate nutrition while restricting protein intake. Ensure sufficient calorie intake.

8. Electrolyte Monitoring: Frequently check urine and electrolyte levels.

9. Complication Management: Treat complications such as hypertension, convulsions, and infections as they arise.

10. Metabolic Acidosis Correction: Administer sodium bicarbonate (50-100 mcg) for metabolic acidosis.

11. Hyperkalemia Management: Administer IV dextrose 50%, insulin, and calcium replacement to shift potassium back into cells. Diuretic agents may be used to control fluid volume.

12. Skin Integrity Maintenance: Provide proper care to pressure areas and ensure regular turning of severely ill patients to prevent pressure ulcers.

13. Nephrotoxic Drug Discontinuation: Stop any medications that can harm the kidneys.

14. Shock Management: Treat shock with blood transfusions in cases of hemorrhagic shock to replace blood loss.

Chronic Renal Failure (CRF)

Chronic renal failure (CRF), also known as chronic kidney disease (CKD), refers to the gradual and progressive loss of renal function due to irreversible damage to the nephrons. Symptoms typically manifest when approximately 75% of kidney function is lost, but it is considered chronic when there is a 90-95% loss of function.

Etiology of Chronic Renal Failure

The causes of CRF are varied and include:

• Polycystic kidney disease

• Nephritic syndrome

• Primary kidney diseases such as glomerulonephritis and pyelonephritis

• Secondary causes such as diabetes nephropathy and hypertensive nephrosclerosis

• Systemic diseases like sickle cell anemia, vasculitis, and HIV-associated nephropathy

• Reflux nephropathy due to any cause

• Analgesic nephropathy (kidney damage from pain relievers)

Clinical Presentation of Chronic Renal Failure

CRF manifests with a wide range of symptoms affecting multiple body systems:

1. Cardiovascular Symptoms: Hypertension, arrhythmias, pericardial effusion, peripheral edema, chest pain, fatigue.

2. Neurological Symptoms: Burning pain, itching, paresthesia (abnormal sensations), muscle cramping and twitching due to uremia (urea in the blood), apathy and lethargy, drowsiness, confusion, seizures, coma, and changes on electroencephalogram (EEG).

3. Renal Symptoms: Salt overload, potassium accumulation with muscle weakness, fluid overload, metabolic acidosis, proteinuria (protein in the urine), glycosuria (glucose in the urine), and the presence of red blood cells, white blood cells, and casts in the urine.

4. Gastrointestinal Tract Symptoms: Stomatitis (inflammation of the mouth), peptic ulcers due to gastritis, pancreatitis, constipation, nausea, and vomiting.

5. Respiratory Tract Symptoms: Pulmonary edema, pleural effusion, dyspnea, and Kussmaul’s respirations (deep, rapid breathing) from acidosis.

6. Endocrine Symptoms: Stunted growth in children, amenorrhea (absence of menstruation), male impotence, thyroid and parathyroid abnormalities.

7. Hematopoietic Symptoms: Anemia, bleeding and clotting disorders (e.g., purpura, hemorrhage from body orifices, ecchymoses/bruising).

8. Skeletal Symptoms: Muscle and bone pain, pathological fractures (fractures occurring without significant trauma).

Management of Chronic Renal Failure

Management of CRF focuses on slowing the progression of the disease, managing symptoms, and improving quality of life.

1. Fluid and Salt Restriction: Closely monitor and restrict fluid and salt intake.

2. Protein Restriction: Limit protein intake due to the kidneys’ reduced ability to eliminate waste products.

3. Diuretic Therapy: Administer diuretics, such as furosemide, to manage fluid overload.

4. Antihypertensives: Prescribe antihypertensive medications to treat high blood pressure.

5. Erythropoietin or Transfusion: Administer erythropoietin or blood transfusions to treat anemia.

6. Vitamin D Supplementation: Provide vitamin D to prevent bone disease.

7. Dialysis and Renal Transplant: In the later stages, dialysis and renal transplantation become necessary.

8. Regular Monitoring: Continuously monitor GFR, serum creatinine, and serum urea levels.

9. Potassium Restriction: Advise patients to avoid foods high in potassium, such as certain fruits.

10. Cardiac Monitoring: Closely monitor cardiac rhythm and blood pressure, especially for severely admitted patients (e.g., every 8 hours).

11. Dietary Guidance: Encourage a diet high in carbohydrates with prescribed limits on sodium, potassium, phosphorus, and protein.

12. Injury Prevention: Protect confused patients from injury.

13. Avoid Nephrotoxic Medications: Avoid medications that can negatively affect the kidneys.

14. Weight Monitoring: Regularly monitor the patient’s weight.