Chapter 22 Renal failure

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Chapter 22

RENALFAILURE

FERNANDEZ, ROWENA S.

BSP 4A


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The Urinary Structure


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Pathophysiology

Renal system is uniquely susceptible to

toxic injury.

In humans, the kidneys receive 20% to25% of the cardiac output despite

weighing only 150g each.

Kidney is metabolically active, containing

several enzyme systems capable of

bioactivating a non-toxic substance into a

toxic compound.


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ACUTE RENAL FAILURE

occurs when kidney function declinerapidly and the kidney are no longer ableto filter waste products from the blood.

Manifests as an abrupt decline inglomerular filtration rate occurring over aperiod of days or weeks.

This results in an accumulation of water,nitrogenous waste products and othertoxins.


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Classification

of

ACUTE RENAL FAILURE

Prerenal failure

Intrinsic renal failure

Post renal failure


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Pre-renal failure

Characterized by inadequate bloodcirculation to the kidney w/c leaves themunable to clean the body properly.

Causes: dehydration, heart failure, sepsis,(severe infection), and severe blood loss.

Signs: volume depletion, dizziness, drymucous membrane, tachycardia,orthostatic hypotension, and weight loss.


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Mechanisms that lead to hypotenion

and decrease renal perfusion:

1. toxin-induced cardiotoxicity resulting in

a lowered cardiac output.

2. toxin-induced vasodilation3. toxin-induced vasoconstriction

4. toxin-induced loss of effective circulatory

volume


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Substances decreased glomerular

perfusion via intrarenal vascular

effects:

ACE inhibitor

Cyclosporine

Radiocontrast agents

NSAIDs

Mannitol


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Intrinsic renal failure

Involves damage within both kidneys.

Causes: vascular disease, disease of tubules

and interstitium, and acute tubular necrosis.

Signs and symptoms: fever, rash, flank pain, and

oliguria (decreased urine output), peripheraledema, lethargy, dyspnea.


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Substances cause Glomerulonephritis:

Heroin abuse

Hydrocarbons

Hydralazine

Halogenated alkanes

D-penicillamine

Methimazole

Captopril

Thiopronine

Gold Mercurous and Mercuric salts

Silicon


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Substances that cause Direct tubular

toxicity:

Aminoglycosides, Polymyxin, Uranium

Cisplatin, Arsenic, Bismuth

Mithramycin, Chromium, Mycotoxins

Ifosfamide, mercurous and mercuric salts

Streptozotocin, Perchloroethylene, Hydrocarbons

Amphotericin B, Cadmium, Fluorinated Anesthetics

Diethylene glycol, Diquat, Paraquat

Toluene

Carbon tetrachloride

Radiocontrast agent


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Substances that cause Insterstitial

nephritis:

Allopurinol

B-lactam antibiotics

CimetidineNSAIDs

Rifampin

sulfonamides


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Postrenal failure

Caused by an acute obstruction that affects the

normal flow of urine out of both kidneys.

Causes: renal injury, retroperitoneal fibrosis,

bladder obstruction.

Signs and symptoms: distended bladder,edema, complain of hesitancy, decreased

urinary flow and abdominal pain.


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Substances that cause Obstractive

Uropathy due to Tubular

precipitation:

Ethylene glycol metabolites

Acyclovir

Methotrexate

Sulfonamides


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Laboratory Studies

Microscopic Examination

Blood Urea Nitrogen (BUN)

Serum Creatinine

Urinalysis

Cystoscopy

Voiding Cystourethrography

Intravenous Urography

Renal Ultrasoound


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Poisoned patient with prerenal failure:

Urinary sodium (UNa+) level less than

20 mEq/L

Urinary osmolality (UOsm) greater than500 mOsm/kg

Urine:plasma creatinine ration (U/PCr)

greater than 40


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Definitive treatment:

PRERENAL FAILURE

Increased chronotropy and inotropy,vasopressor support, fluid resuscitation,

and blood transfusion


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INTRINSIC RENAL FAILURE

Causative agent should be discontinued.

Life-threatening complications:

Pulmonary edema managed with oxygen,diuretics, and preload and afterload reducers.

Hyperkalemia treatment may include calcium,

insulin and glucose, sodium bicarbonate,

sodium polysterene sulfonate, furosemide, andalbuterol.


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POSTRENAL FAILURE

Treated by relieving the obstruction.Can be accomplished by Foley catheter

insertion or urologic consultation for

nephrostomy tube placement.


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Emergent hemodialysis

Reserved for severe volume overload and life

threatening metabolic disturbances.


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Disposition/Need for Consultants:

Patients with acute renal failure should be

admitted to hospital.

Discharge patients with mild renalinsufficiency and no underlying medical

conditions.

Nephrology consultation in patients with

hyperkalemia, pulmonary or

cadrdiovascular compromise, need for

emergent hemodialysis or renal biopsy for

definitive diagnosis.

Chapter 22 Renal failure

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