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Acute Kidney Injury. 49 year old man was a single vehicle MVC in which he was ejected. His injuries include: Left temporal epidural hematoma Left hemo/pneumothorax Liver laceration Bilateral open compound femur fractures
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49 year old man was a single vehicle MVC in which he was ejected. His injuries include: • 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.
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).
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?
RIFLE Criteria • Risk • 1.5X increase in creatinine or UO < 0.5 ml/kg for 6 hours • Injury • 2X increase in creatinine or UO < 0.5 ml/kg for 12 hours • Failure • 3X increase in creatinine or UO < 0.5 ml/kg for 24 hours or anuria for 12 hours • Loss • Complete loss of function for more than 4 weeks • ESRD • Complete loss of function for more than 3 months
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
Categorize the different causes of acute renal insufficiency. • 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
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%)
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?
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?
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?
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?
What are the different modes of continuous renal replacement?
