Acute Kidney Injury
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49 year old man was a single vehicle MVC in which he
was ejected. His injuries include:
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Left temporal epidural hematoma
Left hemo/pneumothorax
Liver laceration
Bilateral open compound femur fractures
He is brought to the ICU postop after an urgent
craniotomy for the epidural.
A chest tube is in place but the fractures are only
splinted.
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6 hours after admission, the nurse calls because
the urine output has fallen.
On assessment, he is sedated and intubated with
both legs in traction.
He is hemodynamically stable, BP 168/86, pulse
96, no vasopressors and afebrile.
There is about 200 mL of dark urine in the foley
bag (emptied upon arrival to ICU).
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Is there a problem with the urine output?
The patient weighs about 75 kg and is known to
have some renal insufficiency with a baseline
creatinine of 200. Creatinine on admission was
305.
Is there a problem with the urine output?
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RIFLE Criteria
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Risk
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Injury
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3X increase in creatinine or UO < 0.5 ml/kg for 24 hours or anuria
for 12 hours
Loss
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2X increase in creatinine or UO < 0.5 ml/kg for 12 hours
Failure
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1.5X increase in creatinine or UO < 0.5 ml/kg for 6 hours
Complete loss of function for more than 4 weeks
ESRD
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Complete loss of function for more than 3 months
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Where is the patient in the RIFLE criteria?
List some possible causes for the renal
dysfunction in this case.
Volume depletion
 Radiocontrast dye
 Myoglobinuria
 Acute on chronic renal insufficiency
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Categorize the different causes of acute renal
insufficiency.
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Prerenal: volume depletion and relative hypotension
Vascular: Consider vasculitis, TTP, nephrosclerosis, renal
artery stenosis
Glomerular: Consider the nephritic and nephrotic
syndromes
Tubular/interstitial: Consider ATN, drugs, PCKD, myeloma,
autoimmune disorders
Obstructive: Consider prostate disease, stones, metastatic
cancer
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What are the most likely causes in hospitalized
patients?
ATN (45%)
 Prerenal (21%)
 Acute on chronic kidney disease (13%)
 Obstruction (10%)
 Glomerulonephritis or vasculitis (4%)
 Acute interstitial nephritis (2%)
 Atheroemboli (1%)
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6 hours later, the patient’s urine output has been
a total of 350 mL since admission. The
creatinine has risen to 455.
What RIFLE criteria is the patient now?
What investigations could be ordered to identify
the cause of the acute kidney injury?
What are the implications on morbidity and
mortality when renal failure occurs in the ICU?
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The urine sodium is 125 mmol/L, urine
osmolarity is 247 mOsm/L, serum osmolality is
315 mOsm/L, CK 98035, and urine myoglobin
15035.
It is now 24 hours since admission and there has
only been another 100 mL of urine with no
urine for the last 12 hours.
What is the RIFLE criteria now?
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What treatments could have been started to
mitigate the development of acute kidney
failure?
What are the indications for renal replacement
therapy in the critical care setting?
How do you choose between continuous versus
intermittent hemodialysis?
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After inserting a femoral dialysis catheter, the
patient is started on hemodialysis.
He is currently has a MAP of 65 requiring
levophed 12 ug/min with a FiO2 of 85%
(increased since starting fluid boluses.
Will this patient tolerate an intermittent run of
dialysis? Why or why not?
How does hemodialysis work?
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What are the different modes of continuous
renal replacement?
Questions??