Transcript Acute Renal Failure

Acute Renal Failure
Dr. Belal Hijji, RN, PhD
April 9 & 16, 2012
Learning Outcomes
At the end of this lecture, students will be able to:
• Define renal failure and discuss its pathophysiological
changes.
• Describe the categories of acute renal failure (ARF).
• Recognise the clinical manifestations of ARF.
• Discuss the assessment and diagnostic findings associated with
ARF.
• Describe the medical management of a patient with ARF.
• Discuss the nursing interventions designed to meet specific
goals associated with ARF.
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Renal Failure
• Renal failure results when the kidneys cannot remove the body’s metabolic
wastes (urea) or perform their regulatory functions. The wastes accumulate
in the body fluids, leading to a disruption in endocrine and metabolic
functions as well as fluid, electrolyte, and acid–base disturbances. Renal
failure is a systemic disease and is a final common pathway of many
different kidney and urinary tract diseases.
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Acute Renal Failure
• Pathophysiology: Acute renal failure (ARF) is a sudden and
almost complete loss of kidney function over a period of hours
to days. ARF manifests with oliguria (less than 400 mL/day of
urine), anuria (less than 50 mL/day of urine), or normal urine
volume. The patient has high serum creatinine and BUN levels
(azotemia) and retention of other metabolic waste products
normally excreted by the kidneys.
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Categories of Renal Failure
• Prerenal conditions occur as a result of impaired blood flow that
leads to hypoperfusion of the kidney and a drop in the GFR. The
causes could be hemorrhage, myocardial infarction, heart failure, or
cardiogenic shock, sepsis or anaphylaxis.
• Intrarenal causes of ARF are the result of actual parenchymal
damage to the glomeruli. Conditions such as burns, crush injuries,
and infections, nephrotoxic agents (nonsteroidal anti-inflammatory
drugs (NSAIDs); angiotensin-converting enzyme (ACE) inhibitors),
may lead to acute tubular necrosis and cessation of renal function.
With burns and crush injuries, myoglobin (a protein released from
muscle when injury occurs) and hemoglobin are liberated, causing
renal toxicity, ischemia, or both.
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Categories of Renal Failure (Continued…)
• Postrenal causes of ARF are usually the result of an obstruction
somewhere distal to the kidney. Pressure rises in the kidney
tubules; eventually, the GFR decreases. Common causes
include calculi (stones), tumors, benign prostatic hyperplasia,
strictures, and blood clots.
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Clinical Manifestations
• Almost every system of the body is affected when there is
failure of the normal renal regulatory mechanisms.
• The patient may appear critically ill and lethargic [‫]يميل للنوم‬,
with persistent nausea, vomiting and diarrhea. The skin and
mucous membranes are dry from dehydration, and the breath
may have the odor of urine. Central nervous system signs and
symptoms include drowsiness, headache, muscle twitching
[‫]ارتعاش‬, and seizures [‫]نوبات مرضية‬. Next slide summarizes
some common clinical findings for all three categories of
ARF.
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Comparing Types of Acute Renal Failure
TYPES
Characteristics
Prerenal
Intrarenal
Postrenal
Etiology
BUN value
Hypoperfusion
Increased
Parenchymal damage
Increased
Obstruction
Increased
Creatinine
Increased
Increased
Increased
Urine output
Decreased
Varies, often decreased
Varies, may be
decreased, or
sudden anuria
Urine sodium
Decreased to
<20 mEq/L
Increased to >40 mEq/L Varies, often
decreased to
20 mEq/L or less
Urine specific
gravity
Increased
Low normal, 1.010
Varies
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Assessment and Diagnostic Findings
• Changes in urine: Please refer to the previous slide to see the
urine changes based on the type of ARF.
• Increased BUN and creatinine levels: Rise in the BUN
depends on the degree of catabolism (breakdown of protein),
renal perfusion, and protein intake. Serum creatinine levels are
useful in monitoring kidney function and disease progression.
• Hyperkalemia: With a declining GFR, the patient cannot
excrete potassium normally. Protein catabolism results in the
release of cellular potassium into the body fluids, causing
severe hyperkalemia. Hyperkalemia may lead to dysrhythmias
and cardiac arrest.
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Medical Management
• The kidney has a remarkable ability to recover from insult.
The objectives of treatment of ARF are to restore normal
chemical balance and prevent complications.
• The medical management includes maintaining fluid balance,
avoiding fluid excesses, or possibly performing dialysis.
– Maintenance of fluid balance is based on daily body weight,
serial measurements of central venous pressure, serum and urine
concentrations, fluid losses, blood pressure, and the clinical
status of the patient. The parenteral and oral intake and the
output, including insensible loss, are calculated and are used as
the basis for fluid replacement.
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Medical Management (Continued…)
– Because excessive administration of parenteral fluids may cause
pulmonary edema, extreme caution must be used to prevent fluid
overload (Characterised by dyspnea, tachycardia, distended neck
veins, and crackles) . Generalized edema is assessed by
examining the presacral and pretibial areas several times daily.
Mannitol, furosemide, or ethacrynic acid may be prescribed to
initiate a diuresis and prevent or minimise subsequent renal
failure.
– Adequate blood flow to the kidneys in patients with prerenal
causes of ARF may be restored by intravenous fluids or blood
product transfusions.
– Dialysis may be initiated to prevent serious complications of
ARF, such as hyperkalemia, severe metabolic acidosis,
pericarditis, and pulmonary edema.
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Pharmacologic Therapy
[Hyperkalemia]
• Hyperkalemia is a life-threatening condition. Therefore, the
patient is monitored for:
– Serum potassium levels
– Electrocardiogram (ECG) changes (tall, tented, or peaked T
waves) (next slide)
– Signs and symptoms (muscle weakness, diarrhea, abdominal
cramps)
Schematic representation of normal ECG
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Peaked T waves
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Pharmacologic Therapy (Continued…)
• Hyperkalemia may be reduced by administering cation-exchange
resins (sodium polystyrene sulfonate [Kayexalate]) orally or by
retention enema. Kayexalate exchanges a sodium ion for a
potassium ion in the colon (major site for potassuim exchange).
Sorbitol is often administered in combination with Kayexalate to
induce a diarrhea-type effect.
• Administration of a retention enema requires a rectal catheter
with a balloon to facilitate retention for 30 to 45 minutes.
Afterward, a cleansing enema is administered to remove the
Kayexalate resin as a precaution against fecal impaction.
• Immediate dialysis.
• Intravenous glucose and insulin or calcium gluconate may be
used as emergency measures to treat hyperkalemia.
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Nursing Management of ARF
• Monitoring fluid and electrolyte balance. The nurse:
– monitors the patient’s serum electrolyte levels and physical
indicators of fluid and electrolyte imbalances.
– carefully screens parenteral fluids, all oral intake, and all
medications to ensure that hidden sources of potassium are not
inadvertently administered or consumed.
– monitors the patient closely for signs and symptoms of
hyperkalemia (Slide 12).
– monitors fluid status by paying careful attention to fluid intake,
urine output, apparent edema, distention of the jugular veins,
breath sounds, and increasing difficulty in breathing.
– maintains accurate daily weight, and intake and output record.
– reports to physician indicators of deteriorating fluid and
electrolyte status, and prepares for emergency treatment.
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Nursing Management of ARF (Continued…)
• Reducing metabolic rate. The nurse:
– should reduce the patient’s metabolic rate to reduce catabolism
and the subsequent release of potassium and accumulation of
waste products (urea and creatinine).
– may keep the patient on bed rest to reduce exertion and the
metabolic rate during the most acute stage of ARF.
– should prevent or promptly treat fever and infection to decrease
the metabolic rate and catabolism.
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Nursing Management of ARF (Continued…)
• Promoting pulmonary function. The nurse:
– assist the patient to turn, cough, and take deep breaths frequently
to prevent atelectasis and respiratory tract infection.
• Preventing infection. The nurse:
– strictly observes aseptic technique when caring for the patient to
minimise the risk of infection and increased metabolism.
– avoids, when possible, inserting an indwelling urinary catheter as
it is a high risk for urinary tract infection (UTI).
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