Download Back to Basics: Acute Renal Failure

Back to Basics:
Acute Renal Failure
• 1% of patients have ARF at time of
admission
• 2-5% develop ARF during
hospitalization
• Important to recognize and manage
patients early since mortality rate
increases in patients with ARF
- 40-50% in general ward
- 80-90% in patients in the ICU
Acute Renal Failure: Definition
• Acute rise in serum creatinine from
baseline (increase of at least 0.5
mg/dl)
• Oliguria or anuria may or may not be
present
– Oliguria - < 400 ml/day
– Anuria - < 50 ml/day
Anuria vs. oliguria vs. non-oliguria
 Anuria - < 50ml/day
• If abrupt, consider:
• Obstruction
• vast majority of patients with anuria
• Bilateral renal cortical necrosis
• Fulminant glomerulonephritis
• usually some type of rapidly progressive
glomerulonephritis
• Acute bilateral renal artery or vein occlusion
(rare)
 Oliguria - <400ml/day
• Is it ARF or acute on chronic renal
failure?
• Is there renal tract obstruction
• Is there a reduction in effective
ECF?
• Has there been a major vascular
occlusion?
• Is there parenchymal disease other
than ATN?
Types of Acute Renal Failure
Acute Renal Failure
Prerenal Causes
Intrinsic Causes
Postrenal Causes
Tubular Necrosis
Interstitial Nephritis
(10%)
Acute
Glomerulonephritis
(5%)
Ischemia
(50%)
Toxin
(35%)
Exclude pre-renal and postobstructive first then look for
possible causes of intrinsic
renal failure
Prerenal Acute Renal Failure
• True Intravascular depletion
– Sepsis, hemorrhage, overdiuresis,
vomiting, diarrhea, burns
• Decreased effective volume to the kidneys
– CHF, cirrhosis, hepatorenal syndrome,
nephrotic syndrome, anaphylaxis
• Impaired renal autoregulation
– Pre-glomerular (afferent arteriolar)
vasoconstriction
• Sepsis, Hypercalcemia, Hepatorenal syndrome
• NSAIDS, cyclosporine, Amphotericin, epinephrine
– Postglomerular (efferent arteriolar)
vasodilation
• ACE Inhibitors, AT1 receptor antagonist
Postrenal or Postobstructive ARF
• Intratubular obstruction
– Uric acid nephropathy
– Methotrexate crystal deposition
– myeloma light chain
• Ureteric obstruction
– Retroperitoneal Disorders – fibrosis or malignancies
– Cervical Cancer
– Pelvic mass or invasive pelvic malignancies
• Intrinsic causes/ Intraluminal
– Nephrolithiasis
– Necrotic papillae
– Blood clots or fungus ball
• Urethral obstruction
– Benign Prostatic Hyperplasia
– Neurogenic Bladder
– Urethral strictures
Types of Acute Renal Failure
Acute Renal Failure
Prerenal Causes
Intrinsic Causes
Postrenal Causes
Tubular Necrosis
Interstitial Nephritis
(10%)
Acute
Glomerulonephritis
(5%)
Ischemia
(50%)
Toxin
(35%)
Drugs Associated with ARF
Mechanism
Drug
Reduction in renal perfusion NSAIDS, ACE In, cyclosporine, tacrolimus, radiocontrast
through alteration of
agents, Amphotericin B, Interleukin-2
intrarenal hemodynamics
Direct tubular injury
Aminoglycoside, radiocontrast agents, cisplatin, cyclosporine,
tacrolimus, Amphotericin B, methotrexate, foscarnet,
pentamidine, organic solvents, heavy metals, IV Ig
Heme-pigment induced
tubular toxicity
(rhabdomyolysis
Cocaine, ethanol, lipid lowering agents
Intratubular obstruction
Acyclovir, sulfonamides, ethylene glycol, chemotherapeutic
agents, methotrexate
Allergic Interstitial nephritis Penicillin, cephalosporin, sulfonamide, rifampicin,
ciprofloxacin, NSAIDS, thiazide diuretics, furosemide,
phenytoin, allopurinol
Hemolytic- uremic
syndrome
Cyclosporine, tacrolimus, mitomycin, cocaine, quinine,
conjugated estrogens
Types of Acute Renal Failure
Acute Renal Failure
Prerenal Causes
Intrinsic Causes
Postrenal Causes
Tubular Necrosis
Interstitial Nephritis
(10%)
Acute
Glomerulonephritis
(5%)
Ischemia
(50%)
Toxin
(35%)
History
• Pulmonary symptoms
– Sinus or URI or hemoptysis
• Cardiac
– CHF, Valvular Disease
• GI
– Diarrhea, vomiting, poor intake
– Flank pain, colicky abdominal pain
• Musculoskeletal
– Trauma, joint pain, arthritis
• GU
– BPH, history of stones, recurrent UTI
History
• Chart Review
– I/O, hypotension, drugs, procedures
• Skin
– Rash, skin infections
• Drug History
– ACE In, NSAIDs, antibiotics, antivirals, IVDA
• Past Medical History
– DM, HTN, multiple sclerosis, stroke, previous
malignancy
• Past Surgical History and procedures
– CABG, angiogram, CT
*Stratify as to severity of symptoms
Determine if there are symptoms of uremia
What P.E. findings
would be helpful?
Key Points in Physical
Examination
• Vital signs
– Temperature
• infection
– Blood Pressure
• orthostatic hypotension for volume
• Malignant hypertension
– Weight loss or gain
• Mouth
• Jugular veins
• Pulmonary and Cardiovascular System
• Abdomen
• Pelvis
• Rectum
• Skin
– Petechaie, rash, gangrene, livedo
What laboratory tests
will you order?
Laboratory Evaluation
•
•
•
•
•
•
BUN and creatinine
Electrolytes
Arterial blood gas
CBC and peripheral blood smear
Radiologic procedures
Urinalysis
– Urine electrolytes
– Urinary sediment
BUN:Crea Ratio
Cause
High: >20:1
Prerenal failure
Urinary tract obstruction
Increased urea production: catabolic
states, GI Bleed, increased protein
intake, infusion of amino acids,
corticosteroids, tetracycline
Low: <5-10:1
Reduced urea production: severe
liver disease, malnutrition
Increased creatinine release of
creatinine from muscle:
rhabdomyolysis
Decreased tubular secretion of
creatinine: cimetidine, trimethoprim
Interference with assay:
cephalosporin, ketone
Sediment Characteristics
•Prerenal ARF
–Scant; few hyaline casts,
Specific gravity increased
•Postrenal ARF
–Scant; few hyaline cast,
possible red cells
–SG inc early; 1.010-1.012 late
in course
Sediment Characteristics
ATN- epithelial cells,
muddy-brown casts, WBC
cells, low-grade proteinuria,
SG increased
Allergic interstitial
nephritis- wbc, rbc, epithelial
cells, eosinophils, WBC cast,
low to moderate grade
proteinuria, SG 1.010-1.012
GN- RBC cast, dysmorphic
RBC, moderate to severe
proteinuria, SG 1.010-1.012
* FENa - helps detect an extreme renal avidity for sodium
(i.e.,pre-renal azotemia, hepatorenal syndrome)
FENa = (UNa/PNa) / (UCr/PCr) X 100
* The FENa assay is useful in ARF only in the presence of oliguria.
* Exceptions to this rule
-ATN caused by radiocontrast nephropathy or severe burns.
-in liver disease, FENa can be < 1% in the presence of ATN.
-administration of diuretics, AIN may cause the FENa > 1%
Positive antinuclear antibody or
antibody to double-stranded DNA
Systemic lupus erythematosus
Positive antibody to glomerular
basement membrane
Goodpasture's syndrome
Positive antibodies to streptolysin O,
streptokinase or hyaluronidase
Poststreptococcal
glomerulonephritis
Schistocytes on peripheral smear,
Hemolytic uremic syndrome or
decreased haptoglobin level,
thrombotic thrombocytopenic
elevated lactate dehydrogenase level purpura
or elevated serum bilirubin level
Low albumin level
Liver disease or nephrotic
syndrome
Elevated uric acid level
Suggestive of malignancy or
tumor lysis syndrome leading to
uric acid crystals; also seen in
prerenal acute renal failure
Elevated creatine kinase or
myoglobin levels
Rhabdomyolysis
Elevated prostate-specific antigen
Prostate cancer
Abnormal serum protein
electrophoresis
Multiple myeloma
Low complement levels
Systemic lupus erythematosus,
postinfectious
glomerulonephritis, subacute
bacterial endocarditis
Positive antineutrophilic cytoplasmic
antibody
Small-vessel vasculitis
(Wegener's granulomatosis or
polyarteritis nodosa)
Renal Ultrasound
• Pelvicalyceal dilatationobstruction
• Shrunken kidneys- Chronic kidney
disease
• Normal size- echogenic: acute GN,
ATN
– Normal echo pattern: pre-renal,
renal artery occlusion
• Enlarged kidneys: malignancy, HIV,
renal vein thrombosis, amyloid
General Treatment Guidelines
• Correct fluid and electrolyte imbalance
– Volume depletion
– Hyperkalemia
– Metabolic acidosis
• Nutritional support
– 30-45 kcal/ kg/ day
– 0.6 g/kg protein restriction (1-1.5g/kg if on
dialysis)
– restrict K (<40mmol/day)
– restrict phosphate <800mg/day
– Fluid restriction if anuria or oliguria present
• Look for underlying cause
• Avoid nephrotoxic agents and adjust
medications
• Uremia management
– Indications for dialysis
Complications of ARF
• Metabolic
– Hyponatremia, hyperkalemia, hypocalcemia,
hyperphosphatemia, hypermagnesemia,
hyperuricemia
• Cardiovascular
– CHF, arrhythmias, HTN, pericarditis
• Neurologic
– Asteixis, somnolence, coma, seizures
• Hematologic
– Anemia, coagulopathies, hemorrhagic diathesis
• Gastrointestinal
– Nausea, vomiting
• Infectious
Indications for Dialysis
• Uremia
• Refractory hyperkalemia
• Refractory fluid overload
– Use diuretics- use step-wise approach
• Refractory metabolic acidosis
– If pH<7.2 despite NaHCO3
– If patient cannot tolerate bicarbonate
infusion due to fluid overload
Prognosis
•
Factors:
– Cause of renal failure
– Duration of renal failure prior to therapeutic intervention. even if renal
failure is mild, the mortality rate is 30-60%. If these patients need
dialytic therapy, the mortality rate is 50-90%.
•
Mortality rate
– 31% in patients with normal urine sediment test results
– 74% in patients with abnormal urine sediment test results.
•
APACHE SCORE
– survival rate is nearly 0% among patients with ARF who have a score
higher than 40
– 40% in patients with APACHE II scores of 10-19.
•
Other prognostic factors include the following:
•
•
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•
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Older age
Multiorgan failure (ie, the more organs that fail, the worse the prognosis)
Oliguria
Hypotension
Vasopressor support
Number of transfusions
Noncavitary surgery
Contrast-induced Nephropathy
• Risk Factors:
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–
–
–
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–
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Diabetes
previous CRI
contrast load
Age
Dehydration
nephrotoxic agent
Other diseases:
• myeloma, CHF, liver disease
Contrast-induced Nephropathy
• Intervention
– Identify risk prior to procedure
– Avoid volume depletion
– Hydrate to keep urine output >150 ml/hr preproc, during and 12 hours postprocedure
– Use non-ionic low osmolality in diabetics and
CKD patients
– Minimize contrast volume
– N-acetylcysteine 600 mg twice a day starting
one day before and until 48 hours postprocedure
– Space contrast procedures by at least five days
• Prognosis
– Increased risk of mortality especially in
patients needing dialytic therapy (35% vs.
7.1% vs. 1%)
Medications
• Prophylactic medication
– N-acetylcysteine – 600 mg PO q 12
• Diuretics
• Dopamine- renal-dose
• Calcium-channel blockers
CASE
• 65 y/o diabetic, at the ER with RUQ pain that
raidates to the back, nausea, vomiting,
anorexia, light-headedness and decreased
urine output in the past 24 hours
• PE:
– BP: supine:110/70, PR=80
– Standing: 85/60; 115
– Poor skin turgor, RUQ tenderness
• Labs: WBC:19, BUN= 35; crea= 1.6; Na= 146;
k=4.1; cl=111; ast=35; alkp=289; urinalysis:
ph=5,SG=1.028;Una=10, Ucrea=80, no
sediment
• Patient remained hypotensive, given
gentamicin and ampicillin for acute
cholecystitis
• Urine output: 100 in 12 hours
• Labs:Na=140, k=5, cl=100, CO2=15,
BUN 40, crea 2.5, urinalysis=
SG=1.010, brown muddy cast, Una=80,
Ucrea, 40, (+) blood cultures
• Patient remains oliguric for 3 days, Bun
and crea inc to 110, 5.5
• What is your diagnosis?
• What treatment would you
give?
Back to Basics:
Acute Renal Failure
Yvette Talusan- Tomacruz, M.D.
National Kidney and Transplant Institute
Patient Evaluation
• Determine if pre-renal, intrinsic or postobstructive
– 60-70 % - pre-renal
– 25-40 % - intrinsic
– 5-10 % - obstruction
• KEY: History and Physical examination
Intrinsic Acute Renal Failure
• Acute tubular necrosis
– Ischemia
– Toxins
• drugs, contrast agents, pigments
• Glomerular disease
– RPGN, SLE, small-vessel vasculitis, HSP,
Goodpasture’s syndrome ,Acute proliferative GNPSGN,PIGN, endocarditis
• Vascular disease
– Microvascular disease
• Atheroembolic disease, TTP, HUS, HELLP
– Macrovascular disease
• RAS, Aneurysm
• Others
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–
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Allergic reaction to drugs
Autoimmune Disease
Pyelonephritis
Infiltrative Disease