PathoPhysiology Chapter 28

1. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
CHAPTER 28
ACUTE RENAL FAILURE AND
CHRONIC KIDNEY DISEASE

2. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE
Etiology and Pathophysiology
• ARF: an abrupt reduction in renal function
producing an accumulation of waste materials in
the blood
• May be due to aging, associated with
comorbidities, or due to insults to the kidney
• Renal function monitored by serum creatinine and
creatinine clearance

3. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
• Retention of metabolic wastes (azotemia/uremia)
monitored by BUN, produces widespread systemic
effects (uremic syndrome)

4. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
Prerenal Acute Renal Failure
• Due to conditions that impair renal blood flow, such
as hypovolemia, hypotension, cardiac failure, and
renal artery obstruction
• Characterized by low GFR, oliguria, high urine
specific gravity and osmolality, and low urine
sodium
• S/S of fluid overload are present
• Prolonged prerenal ARF leads to intrarenal RF

5. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)

6. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
Postrenal Acute Renal Failure
• Due to obstruction within the urinary collecting
system distal to the kidney; elevated pressure in
Bowman capsule; impedes glomerular filtration
• Clinical findings based on duration of the
obstruction
• Prolonged postrenal ARF leads to intrarenal RF

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ACUTE RENAL FAILURE (CONT.)

8. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
Intrarenal Acute Renal Failure
• Due to a primary dysfunction of the nephrons
• Most often due to problem within the renal tubules
resulting in acute tubular necrosis; may also occur
with glomerular, vascular, or interstitial etiologies
• ATN may occur with nephrotoxic or ischemic insults;
clinical manifestations depend on stage of ATN

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ACUTE RENAL FAILURE (CONT.)

10. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
Clinical Presentation of Acute Tubular
Necrosis: Oliguric Stage
• Characterized by oliguria and progressive uremia;
decreased GFR; hypervolemia
• May last 1 to 2 weeks
• Dialysis may be required

11. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
ACUTE RENAL FAILURE (CONT.)
Clinical Presentation of Acute Tubular
Necrosis: Diuretic Stage
• Urine volume increases, but tubular function remains
impaired and azotemia continues
• May last 2 to 10 days

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ACUTE RENAL FAILURE (CONT.)
Clinical Presentation of Acute Tubular
Necrosis: Recovery Stage
• Characterized by gradual normalization of serum
creatinine and BUN
• May last up to 12 months
• Often a degree of renal insufficiency

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ACUTE RENAL FAILURE (CONT.)

14. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
CHRONIC KIDNEY DISEASE
• Outcome of the progressive and irrevocable loss of
nephrons
• Progressive process: CKD – CRF – ESRD
• A global health problem often linked with other
comorbidities, primarily hypertension and DM

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CHRONIC KIDNEY DISEASE (CONT.)
• Defined as decreased kidney function or kidney
damage of 3 months’ duration based on blood
tests, urinalysis, and imaging studies; GFR <60
ml/minute/1.73 m2
for 3 months with or without
indication of damage to the kidney

16. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
CHRONIC KIDNEY DISEASE (CONT.)
Risk Factors
• Most commonly associated with DM, hypertension,
recurrent pyelonephritis, glomerulonephritis, and
polycystic kidney disease
• Cause alterations in glomerular perfusion and
filtration, sodium reabsorption, renal sympathetic
activity, and activity of the RAAS

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CHRONIC KIDNEY DISEASE (CONT.)
Pathophysiology of Progression of
Chronic Kidney Disease
• Glomerulosclerosis and interstitial inflammation and
fibrosis
• Monitored by two staging systems
• Percentage of nephron loss
• Reduction in GFR
• GFR reduction occurs with nephron loss

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CHRONIC KIDNEY DISEASE (CONT.)

19. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
CHRONIC KIDNEY DISEASE (CONT.)
Stages of Chronic Kidney Disease
• Defined by level of function per GFR
• Decreased renal reserve is not associated with S/S
of renal failure; interventions required to slow
disease progression
• Renal insufficiency characterized by increase in
metabolic wastes at levels proportional to nephron
loss; polyuria

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CHRONIC KIDNEY DISEASE (CONT.)

21. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.
CHRONIC KIDNEY DISEASE (CONT.)
Complications of Chronic Kidney Disease
• Hypertension and cardiovascular disease: due to
hypervolemia, escalated atherosclerotic process,
heightened RAAS activity, and increased SNS
activity
• Uremic syndrome: due to retention of metabolic
wastes
• Metabolic acidosis: due to retention of acidic waste
products; kidneys lose ability to secrete H+
ions and
bicarbonate

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CHRONIC KIDNEY DISEASE (CONT.)
Complications of Chronic Kidney Disease
• Electrolyte Imbalances: retention of potassium,
phosphorus, and magnesium in the blood
• Renal osteodystrophy: elevated PTH causes altered
bone and mineral metabolism; kidneys unable to
reabsorb calcium

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CHRONIC KIDNEY DISEASE (CONT.)
• Malnutrition: decreased intake due to uremic
syndrome, depression, dietary limitations, and
changes in taste
• Anemia: due to lack of erythropoietin

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CLINICAL MANAGEMENT
Prevention
• Early identification of risk; addressing lifestyle
modifications and comorbidities
• Maintenance of fluid volume status and cardiac
output
• Avoid and monitor nephrotoxic chemicals
• Avoid and aggressively treat infections

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CLINICAL MANAGEMENT (CONT.)
Therapeutic Interventions
• Slowing the progression of CKD is focus of
intervention until stage 4 or 5
• Primary foci are appropriate management of ATN,
blood glucose control in diabetes, ACE inhibitors or
AII blockers to reduce proteinuria, and aggressive
management of hypertension and cardiovascular
disease

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CLINICAL MANAGEMENT (CONT.)
Therapeutic Interventions
• Nutritional needs for patients with CKD include
increased calories, calcium, and vitamin
supplementation
• Fluids, phosphorus, potassium, sodium, and protein
intake are usually restricted
• Drug therapy for CKD is used to control
hypertension, anemia, and some of the electrolyte
imbalances