OLIGURIA AND ACUTE RENAL FAILURE HOUSSAM OSMAN HEMODIALYSIS

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OLIGURIA AND ACUTE RENAL FAILURE

• HOUSSAM OSMAN

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• Your patient has a low urine output

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FACTS

• ARF develops in about 5 of patients admitted to
  the ICU.
• the prevention of renal failure by appropriate
  resuscitation and hemodynamic manipulation has a
  big impact in improving outcome in multiorgan
  failure syndrome (MODS). In critically ill
  patients who develop renal failure the mortality
  rate increases from 10 to greater than 60.
• Acute hemodialysis has no impact on mortality !
• Oliguria urine output less than 0.5 ml/kg/hr

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Causes of acute oliguria in ICU
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A MANAGEMENT STRATEGY FOR OLIGURIA

• The first thing to do is simple rule out a
  post-renal cause flush or change the urinary
  catheter.
• Review patient history and medication (home and
  current medication).
• Examine the patient quickly for evidence of heart
  failure gallop rhythm, bibasal crackles,
  raised JVP, parasternal heave, hepatomegaly,
  sacral edema. If the patient is not in heart
  failure, load them with isotonic fluid (lactated
  ringers, normal saline or colloid), and follow
  vital signs heart rate, blood pressure and
  urinary output.
• Do not give diuretics until you are certain that
  the patient is fully fluid loaded (and still
  oliguric).

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• If unresponsive to multiple challenges, evaluate
  intravascular volume by inserting a CVP line.
• Urine study
• spot urine Na a urine Na lt 20 mEq/L usually
  indicates a pre renal condition
• FENa lt 1 probable prerenal condition
• gt 2 probable renal injury
• urine microscopy
• abundant tubular epithelial cells with
  epithelial casts-gt ATN
• white cell casts -gt interstitial nephritis
• pigmented casts -gt myoglobinuria

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• urine (Na) / plasma (Na)
• FENa x 100
• urine (Cr) / plasma (Cr)

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• Serum creatinine concentration
• Fluid challenges are continued until there is a
  response or you are concerned about volume
  overload.
• If the patient is fully volume loaded or
  overloaded, it is time to flush the renal
  tubules, and use diuretics.

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SPECIAL RENAL DISORDERS

• Contrast induced renal failure
• Rising serum creatinine within 72 hr.
• Predisposing condition include DM, HTN, CHF, and
  pre existing renal disease.
• Mechanism of injury hyperosmolar injury to
  endothelium of small vessels in the kidney and
  oxidative injury to the renal tubular epithelial
  cells.
• Oliguria is uncommon but can occur in patients
  with preexisting renal disease.

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• Prevention
• 1- volume infusion isotonic saline at 100-150
  ml/hr 3-12 hr before the procedure, and urine out
  put should be maintained at 150ml/hr for at least
  6 hr after the procedure.
• 2- mucomyst
• Elective-gt 600 mg po BID 24 hr before and after
  the procedure
• Emergent-gt 600 mg IV at time of procedure and 600
  mg po BID for 48 hr after the procedure.

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• Acute interstitial nephritis
• Inflammatory condition that involves the
  interstitium.
• Usually there is no oliguria
• Result of hypersensitivity drug reaction or
  infection.
• The presence of eosinophils and leukocytes casts
  on urine microscopy are the most characteristic
  diagnostic finding.
• d/c any possible offending agent.
• Prednisone 0.5-1 mg/kg po daily for 1-4 weeks

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• Myoglobinuric renal failure
• Rhabdomolysis.
• Myoglobin in urine, increasing serum CPK and
  myoglobin.
• Management
• 1- aggressive volume resuscitation, and diuresis.
• 2- alkalinizing the urine.
• 3- monitor K and phosh levels.

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HEMODIALYSIS

• The decision to initiate dialysis or
  hemofiltration in patients with renal failure can
  depend on several factors, which can be divided
  into acute or chronic indications.
• Acute indications for dialysis/hemofiltration
• Hyperkalemia
• Metabolic acidosis
• Fluid overload (which usually manifests as
  pulmonary edema)
• Uremic Serositis complications, such as uremic
  pericarditis and uremic encephalopathy
• And in patients without renal failure, acute
  poisoning with a dialysable drug, such as
  lithium, or aspirin
• Chronic indications for dialysis
• Symptomatic renal failure
• Low glomerular filtration rate (GFR) (RRT often
  recommended to commence at a GFR of less than
  10-15 mls/min/1.73m2)
• Difficulty in medically controlling serum
  phosphorus or anaemia when the GFR is very low