Download Acute Renal Failure

Acute Renal Failure
Deb Goldstein
Argy Resident
September, 2005
Acute Renal Failure
• Rapid decline in the GFR over days to
weeks.
• Cr increases by >0.5 mg/dL
• GFR <10mL/min, or <25% of normal
Acute Renal Insufficiency
• Deterioration over days-wks
• GFR 10-20 mL/min
Definitions
Anuria: No UOP
Oliguria: UOP<400-500 mL/d
Azotemia: Incr Cr, BUN
• May be prerenal, renal, postrenal
• Does not require any clinical findings
Chronic Renal Insufficiency
• Deterioration over mos-yrs
• GFR 10-20 mL/min, or 20-50% of normal
ESRD = GFR <5% of nl
ARF: Signs and Symptoms
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•
•
•
•
•
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Hyperkalemia
Nausea/Vomiting
HTN
Pulmonary edema
Ascites
Asterixis
Encephalopathy
Causes of ARF in hospitalized pts
45% ATN
• Ischemia, Nephrotoxins
21% Prerenal
• CHF, volume depletion, sepsis
10% Urinary obstruction
4% Glomerulonephritis or vasculitis
2% AIN
1% Atheroemboli
ARF: Focused History
• Nausea? Vomiting? Diarrhea?
• Hx of heart disease, liver disease, previous renal
disease, kidney stones, BPH?
• Any recent illnesses?
• Any edema, change in
urination?
• Any new medications?
• Any recent radiology studies?
• Rashes?
Physical Exam
• Volume Status
– Mucus membranes, orthostatics
• Cardiovascular
– JVD, rubs
• Pulmonary
– Decreased breath sounds
– Rales
• Rash (Allergic interstitial nephritis)
• Large prostate
• Extremities (Skin turgor, Edema)
W/U for ARF
• Chem 7
• Urine
– Urine electrolytes and Urine Cr to calculate
FeNa
– Urine eosinophils
– Urine sediment: casts, cells, protein
– Uosm
• Kidney U/S - r/o hydronephrosis
FeNa = (urine Na x plasma Cr)
(plasma Na x urine Cr)
FeNa <1%
1. PRERENAL
• Urine Na < 20. Functioning tubules reabsorb lots of
filtered Na
2. ATN (unusual)
• Postischemic dz: most of UOP comes from few normal
nephrons, which handle Na appropriately
• ATN + chronic prerenal dz (cirrhosis, CHF)
3. Glomerular or vascular injury
• Despite glomerular or vascular injury, pt may still have
well-preserved tubular function and be able to
concentrate Na
More FeNa
FeNa 1%-2%
1. Prerenal-sometimes
2. ATN-sometimes
3. AIN-higher FeNa due to tubular damage
FeNa >2%
1. ATN
•
Damaged tubules can't reabsorb Na
Calculating FeNa after pt has
gotten Lasix...
• Caution with calculating FeNa if pt has gotten Loop
Diuretics in past 24-48 h
• Loop diuretics cause natriuresis (incr urinary Na excretion)
that raises U Na-even if pt is prerenal
• So if FeNa>1%, you don’t know if this is because pt is
euvolemic or because Lasix increased the U Na
• So helpful if FeNa still <1%, but not if FeNa >1%
1. Fractional Excretion of Lithium (endogenous)
2. Fractional Excretion of Uric Acid
3. Fractional Excretion of Urea
A 22yo male with sickle cell anemia and
abdominal pain who has been vomiting
nonstop for 2 days. BUN=45, Cr=2.2.
A. ATN
B. Glomerulonephritis
C. Dehydration
D. AIN from
NSAIDs
Prerenal ARF
• Hyaline casts can be seen in normal pts
– NOT an abnormal finding
•
•
•
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UA in prerenal ARF is normal
Prerenal: causes 21% of ARF in hosp. pts
Reversible
Prevent ATN with volume replacement
– Fluid boluses or continuous IVF
– Monitor Uop
Prerenal causes
• Intravascular volume depletion
– Hemorrhage
– Vomiting, diarrhea
– “Third spacing”
– Diuretics
• Reduced Cardiac output
– Cardiogenic shock, CHF, tamponade, huge PE....
• Systemic vasodilation
– Sepsis
– Anaphylaxis, Antihypertensive drugs
• Renal vasoconstriction
– Hepatorenal syndrome
Intrinsic ARF
1.
2.
3.
4.
Tubular (ATN)
Interstitial (AIN)
Glomerular (Glomerulonephritis)
Vascular
You evaluate a 57yo man w/ oliguria
and rapidly increasing BUN, Cr.
A.
B.
C.
D.
ATN
Acute glomerulonephritis
Acute interstitial nephritis
Nephrotic Syndrome
ATN
• Muddy brown granular casts (last slide)
• Renal tubular epithelial cell casts (below)
More ATN
•Broad casts (form in dilated, damaged tubules)
ATN Causes
1. Hypotension
• Relative low BP
• May occur immediately after low BP episode or up to
7 days later!
2. Post-op Ischemia
• Post-aortic clamping, post-CABG
3. Crystal precipitation
4. Myoglobinuria (Rhabdo)
5. Contrast Dye
– ARF usually 1-2 days after test
6. Aminoglycosides (10-26%)
ATN—What to do
• Remove any offending agent
– IVF
– Try Lasix if euvolemic pt is not peeing
– Dialysis
• Most pts return to baseline Cr in 7-21 days
ATN
Prerenal
Cr
increases at
0.3-0.5 /day
U Na,
FeNa
increases
slower than
0.3 /day
UNa<20
FeNa<1%
Normal
UNa>40
FeNa >2%
epi cells,
granular casts
Cr won’t
Cr improves
improve
with IVF
much
10-15:1
>20:1
UA
Response
to volume
BUN/Cr
Which UA is most compatible
w/contrast-induced ATN?
A. Spec grav 1.012, 20-30 RBC, 15-20 WBC, +Eos
B. Spec grav 1.010, 1-3 WBC, 5-10 renal tubular
cells, many granular casts, occasional renal
tubular cell casts, no eos
C. Spec grav 1.012, 5-10 RBC, 25-50 WBC, many
bact, occasional fine granular casts, no eos
D. Spec grav 1.020, 10-20 RBC, 2-4 WBC, 1-3
RBC casts, no eos
ATN
B. Spec grav 1.010, 1-3 WBC, 5-10 renal
tubular cells, many granular casts,
occasional renal tubular cell casts, no
eos
• Dilute urine: failure to concentrate urine
• No RBC casts or WBC casts in ATN
• Eos classically in AIN or renal
atheroemboli, but nonspecific
56yo woman with previously normal
renal function now has BUN=24,
Cr 1.8. Which drug is responsible?
A.
B.
C.
D.
Indinavir for her
HIV
Gentamicin for her
SBE
Motrin for her OA
Cyclosporin for her
SLE
WBC Casts
Cells in the cast have
nuclei
(unlike RBC casts)
Pathognomonic for
Acute Interstitial
Nephritis
Acute Interstitial Nephritis
70% Drug hypersensitivity
• 30% Antibiotics: PCNs (Methicillin), Cephalosporins, Cipro
• Sulfa drugs
• NSAIDs
• Allopurinol...
15% Infection
• Strep, Legionella, CMV, other bact/viruses
8% Idiopathic
6% Autoimmune Dz (Sarcoid, Tubulointerstitial
nephritis/Uveitis)
AIN from Drugs
Renal damage is NOT dose-dependent
May take wks after initial exposure to drug
• Up to 18 mos to get AIN from NSAIDS!
But only 3-5 d to develop AIN after second exposure to drug
• Fever (27%)
• Serum Eosinophilia (23%)
• Maculopapular rash (15%)
• Bland sediment or WBCs, RBCs, non-nephrotic proteinuria
• WBC Casts are pathognomonic!
• Urine eosinophils on Wright’s or Hansel’s Stain
– Also see urine eos in RPGN, renal atheroemboli...
AIN Management
• Remove offending agent
• Most patients recover full kidney function
in 1 year
• Poor prognostic factors
– ARF > 3 weeks
– Advanced age at onset
You evaluate a 32yo woman with HTN, oliguria, and
rapidly increasing Cr, BUN. You spin her urine:
A. ATN
B. Acute
glomerulonephritis
C. Acute interstitial
nephritis
D. Nephrotic Syndrome
Acute Glomerulonephritis
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•
•
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RBC casts: cells have no nuclei
Casts in urine: think INTRINSIC renal dz
If she has Lupus w/recent viral prodrome,
think Rapidly Progressive
Glomerulonephritis
If she had a sore throat 10 days ago, think
Postinfectious Proliferative
Glomerulonephritis
What are these?
Glomerular Dz
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•
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Hematuria (dysmorphic RBCs)
RBC casts
Lipiduria (increased glomerular
permeability)
Proteinuria (may be in nephrotic range)
Fever, rash, arthralgias, pulmonary sx
Elevated ESR, low complement levels
Rapidly Progressive Glomerulonephritis
Type 1: Anti-GBM dz
Type 2: Immune complex
• IgA nephropathy
• Postinfectious glomerulonephritis
• Lupus nephritis
• Mixed cryoglobulinemia
Type 3: Pauci-immune
• Necrotizing glomerulonephritis (often ANCA-positive, assoc. w/vasculitis)
Can present with viral-like prodrome
• Myalgias, arthralgias, back pain, fever, malaise
Kidney bx : Extensive cellular crescents with or w/o immune complexes
Can develop ESRD in days to weeks.
Treat w/glucocorticoids & cyclophosphamide.
Postinfectious Proliferative
Glomerulonephritis
• Usually after strep infxn of upper respiratory tract or
skin – 8-14 day latent period
– Can also occur in subacute bacterial endocarditis, visceral
abscesses, osteomyelitis, bacterial sepsis
• Hematuria, HTN, edema, proteinuria
• Positive antistreptolysin O titer (90% upper
respiratory and 50% skin)
• Treatment is supportive
– Screen family members with throat culture and treat with
antibiotics if necessary
A 19yo woman with Breast Cancer s/p chemo in
the ER has weakness, fever, rash. WBC=15.4,
Hct 24, Cr 2.9, LDH 600, CK=600. UA=3+ prot,
3+blood, 20 RBC. What next test do you order?
What’s her likely dx?
A. Nephrotic Syn
B. Systemic Vasculitis
C. Acute
Glomerulonephritis
D. Hemolytic-Uremic
Syn
E. Rhabdomyolysis
TTP
• Order blood smear to r/o TTP
• TTP associated with malignancy, chemo
• TTP may mimic Glomerulonephritis on UA
(RBCs, WBCs)
• Thrombocytopenia, anemia not consistent
with nephrotic or nephritic syndrome
• Need CK in the thousands to cause ARF
Microvascular ARF
• TTP/HUS
• HELLP syndrome
• Platelets form thrombi and deposit in
kidneysGlomerular capillary occlusion or
thrombosis
• Plasma exchange, steroids, Vincristine,
IVIG, splenectomy....
Macrovascular ARF
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Aortic Aneurysm
Renal artery dissection or thrombosis
Renal vein thrombus
Atheroembolic disease
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–
–
–
New onset or accelerated HTN?
Abdominal bruits, reduced femoral pulses?
Vascular disease?
Embolic source?
Your 68yo male inpatient with baseline
Cr=1.2 had negative cardiac cath 4 days
ago, now Cr=1.8 and blanching rash.
A. Renal Artery
Stenosis
B. ContrastInduced
Nephropathy
C. Abdominal
Aortic
Aneurysm
D. Cholesterol
Atheroemboli
Why do his toes look like this?
Renal Atheroembolic Dz
1% of Cardiac caths: atheromatous debris scraped from the
aortic wall will embolize
– Retinal
– Cerebral
– Skin (Livedo Reticularis, Purple toes)
– Renal (ARF)
– Gut (Mesenteric ischemia)
• Unlike in Contrast-Induced Nephropathy, Cr will NOT
improve with IVF
• Diagnosis of exclusion: will NOT show up on MRI or
Renal U/S; WILL show up on renal bx
• Tx: supportive
Post-Renal ARF
• Urethral obstruction: prostate, urethral
stricture.
• Bladder calculi or neoplasms.
• Pelvic or retroperitoneal neoplams.
• Bilateral ureteral obstruction (neoplasm,
calculi).
• Retroperitoneal fibrosis.
“Doc, your pt hasn’t peed in 5
hrs....what do you want to do?”
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•
•
•
Examine pt: Dry? Septic (vasodilated)?
Flush foley (sediment can obstruct outflow)
Check I/Os (has she been drinking?)
Give IV BOLUS (250-500cc IVF), see if pt pees
in next 30-60 min
– If she pees, then she was dry
– If she doesn’t pee, then she’s either REALLY dry or in
renal failure
• Check UA, UCx, urine lytes
• Consider Renal U/S if reasonable
You’re called to the ER to see...
• A 35yo woman with previously normal
renal function now with BUN=60, Cr=3.5.
Do you call the Renal fellow to dialyze this
pt?
• What if her K=5.9?
• What if her K=7.8?
Indications for acute dialysis
AEIOU
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Acidosis (metabolic)
Electrolytes (hyperkalemia)
Ingestion of drugs/Ischemia
Overload (fluid)
Uremia
• You admit this pt to telemetry and
aggressively hydrate her.
• You recheck labs 6h later and BUN=85,
Cr=4.2. Suddenly the pt starts to seize.
• Now what?
Uremia—So what?
•
General
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Mental status change
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Uremic encephalopathy
Seizures
Asterixis
GI disturbance
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Fatigue, weakness
Pruritis
Anorexia, early satiety, N/V,
Uremic Pericarditis
Plt dysfunction/bleeding
A pt with chronic lung disease has acute
pleuritic pain and desats to 92%RA. You
want to r/o PE but her Cr=1.4. Can you get a
CT with IV contrast?
A.
B.
C.
D.
E.
F.
Send her for Stat CT with IV contrast
Send her for Stat CT without IV contrast
Just give her heparin
Begin IV hydration
Begin pre-procedure Mannitol
Get a VQ scan instead
Contrast-Induced Nephrotoxicity
• Cr increases by 25% or >0.05 postprocedure
• Contrast causes renal vasoconstriction
renal hypoxia
• Iodine itself may be renally toxic
• If Cr>1.4, use pre-procedure prophylaxis
Pre-Procedure Prophylaxis
1. IVF ( 0.9NS)
1-1.5 mg/kg/hour x12 hours prior to procedure and 6-12
hours after
2. Mucomyst (N-acetylcysteine)
Free radical scavenger; prevents oxidative tissue damage
600mg po BID x 4 doses (2 before procedure, 2 after)
3. Bicarbonate (JAMA 2004)
Alkalinizing urine should reduce renal medullary damage
D5W with 3 amps HCO3; bolus 3.5 mL/kg 1 hour
preprocedure, then 1mL/kg/hour for 6 hours
postprocedure
4. Possibly helpful? Fenoldopam, Dopamine
5. Not helpful! Diuretics, Mannitol