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ACUTE RENAL FAILURE
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Background Reversible illness
Commonin Hospitalizedpatients Associated withhigh Morbidityand
Mortality
Often Multifactorial
Identifiable riskfactors.
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Acute Renal Failure Suddendecrease kidneyfunction(hours-
days)
Oftenmultifactorial
Pre-renalandintrinsicrenalcauses : 70%
oliguric UOP < 400-500 ml (35%)
Non-oliguric (upto 65%) Associated withhighmortalityand
morbidity,ifnotttedproperly
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Acute Renal Failure
Diagnosis Laboratory Evaluation:
Scr, More reliable markerofGFR
smallchange reflectslarge change in GFR
BUN/urea,generallyfollowsScrincrease
Elevation may be independent of GFR ( normal
kidney function but high urea/bun)
Steroids, GIB, Catabolic state, hypovolemia
BUN/Cr ratiohelpfulinclassifyingcause of
ARF
ratio> 20:1 suggestsprerenal cause
ratio 10-15:1 suggestsintrinsic renal cause
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Acute Renal Failure
Diagnosis (contd) Urinalysis
MAY BE NORMAL in,pre and post renal
causes
Renal
Differentiates ATN vs. AIN. vs. AGN
Muddybrowncastsin ATN WBC castsin AIN
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Prerenal ARF Nearlyascommonas ATN (thinkofas
earlypartofthe disease spectrum)
Diagnose byhistoryandphysical exam N/V, Diarrhea, Diureticuse,...
highBUN/creatratio,
normalurinarysediment Treat: correctionofpredisposingfactors
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Acute Renal Failure
Etiologies Acute TubularNecrosis
Mostcommonintrinsic ARF
Oftenmultifactorial
LOW URINE OUTPUT,carriesbetterprognosis
(1) Ischemic ATN:
Hypotension,sepsis,prolongedpre-renalstate
(2) Nephrotoxic ATN:
Contrast/ DYE, Antibiotics, Heme proteins
COMBINATION OF BOTH, MANY TIMES
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Acute TubularNecrosis (ATN) -- 2
Diagnosebyhistory,
Urine sediment withcoarse granularcasts,
Treatment;
(A) supportive care.
(1)Maintenance ofeuvolemia /normalbody volume
(with judicioususe ofdiuretics, IVF,asnecessary)
(2) T reat,hypotension
(3) Avoid,nephrotoxicdrugs (including NSAIDsand
ACE-I) whenpossible
(B) Dialysis,if norecovery
OUTCOME: 80% willrecover,ifinitialinsult
treateda ressivel
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Contrastnephropathy 12-24 hourspost exposure,peaksin 3-5
days
Non-oliguric
treatment/Prevention: 1/2 NS 1 cc/kg/hr12
hourspre/post
Mucomyst 600 BID pre/post (4 doses)
RiskFactors: CRF, Hypovolemia./DM
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Rhabdomyolytic ARF
CAUSE : aftertrauma (crushinjuries),
seizures,burns
Diagnose:
o serum CPK(usu.> 10,000),
urine dipstick(+) forblood, without RBCs
onmicroscopy,
pigmentedgranularcasts
Treatment; HYDRATION &
Alkalinizationofurine .
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Acute Interstitial Nephritis Usuallydruginduced
methicillin, rifampin, NSAIDS
Develops3-7 days afterexposure
Fever, Rash,and eosinophiliacommon
Urine: revealsWBC,WBC casts, +
HanselstainTreatment: Oftenresolves
spontaneously
Steroids maybe beneficial ( ifScr>2.5
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Acute Renal Failure
Etiologies Post-Renal
Bladderoutletobstruction
BPH,intrapelvicpathology Crystalluria (DRUGS)
Acyclovir, Indanivir, Uric Acid
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PreventionWhat works?
Maintenance ofeuvolemia
Avoidance ofnephrotoxins whenpossible
NSAIDs,aminoglycoside, Amphotericin, IV
contrast
BPcontrol--avoidance ofexcessive hypo-
orhypertension
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PreventionWhatdoesnt work?
Empiricuse of:
Diuretics (i.e.,? Furosemide, Mannitol)
Dopamine (orDopamine agonistssuchas
Fenoldopam)
Calcium-channelblockers
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Acute Renal Failure
Treatment Waterandsodiumrestriction
Proteinrestriction
Potassiumandphosphate restriction
Adjustmedicationdosages
Avoidance offurtherinsults
BPsupport Nephrotoxins
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Hyperkalemia Dangeroustoheart
Highly Arrhythmogenic
ECG changes Peaked T waves --->Widened QRS-->Sinus wave
K> 5.5 meq/L needs evaluation/intervention
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Dialysis Indications Refractoryhyperkalemia
Metabolicacidosis
Volume overload
Mentalstatuschanges
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