Exam 3: AKI Flashcards
The term Acute renal failure (ARF) is now reserve for severe ** and implies the need for **.
AKI
Dialysis
What is it called when you have abrupt loss of kidney function resulting in retention of urea and other nitrogenous waste products, as well has dysregulation of volume status and electrolytes?
AKI
What is the diagnosis of AKI based on?
Based on serum creatinine levels or a decrease in patients urine output
What are the potential problems of diagnosing AKI using creatinine?
- in early AKI, serum creatinine may be low even low GFR is markedly reduced
- Creatinine is removed by dialysis so it is not possible to assess kidney function using creatinine when on dialysis
- There is no consensus on what creatinine level actually indicated AKI
What is the diagnostic levels used to confirm AKI?
- Increase in serum creatinine by >0.3 within 48 hours
- Increase in serum creatinine to >1.5 times baseline
- Urine volume < 0.5ml/kg/hr for six hours
If patient has creatinine around 1.9 x their baseline, what stage of AKI are they?
Stage 1
If patient has anuria for <12hrs, what kind of AKI stage are they?
Stage 3, needs dialysis
AKI develops in up to *** of ICU patients?
60%
What are the 3 etiologies of AKI?
- prerenal (decreased renal perfusion)
- Intrinsic renal ( pathology of vessels, glomeruli, or tubules)
- postrenal (obstructive)
AKI in the hospital is most often from ** disease or **.
Prerenal or acute tubular necrosis (ATN)
What is the most commo cause of AKI?
ATN with prerenal being next
What is the least common cause of AKI?
Obstructive (10%)
What are the 5 causes of prerenal disease?
- True volume depletion (GI loss, burns, respiratory loss)
- Hypotension (shock)
- Edematous states (HF, cirrhosis)
- Selective renal ischemia (bilateral renal artery stenosis)
- Drugs affecting GDR (NSAIDS and ACE inhibitors)
What are the causes of intrinsic renal disease?
- Renal ischemia
- Sepsis
- Nephrotoxins (IV CONTRAST)
How does IV contrast cause Intrinsic renal disease?
It causes renal tubular epithelial cell toxicity and renal medullary ischemia from vasoconstriction
What are the risk factors for Contrast induced ATN?
- Preexisting renal disease
- volume depletion
- repeated doses of contrast
- DM, CHF, and age
What is the prevention of contrast induced ATN?
- Hydration
- Low osmolal agents at low dose
- avoid repetitive doses
- Avoid nephrotoxic drugs
What is the cause of post renal disease and what are common examples?
- Obstruction of the flow of urine
- prostatic disease (cancer or hyperplasia), metastatic cancer, and neurologic disease (neurogenic bladder and urinary retention)
If patient has a reduction in GFR and no intrinsic renal disease, what does this mean?
There needs to be BILATERAL obstruction. One kidney stone wont decrease GFR because the other kidney will take over
What is considered nonoliguric?
> 400ml/24hrs usually 1-2 L/day
What is considered oliguric?
<400mL/24hrs
What is considered anuric?
<50 to 100ml/24 hours
What labs do you want to order in a patient with AKI?
- Urinalysis
- Serum metabolic panel (creatinine, GFR, and fractional excretion of Na+ (FENa)
What imaging is commonly helpful in AKI?
Renal US
What are the 3 components of urinalysis?
- Gross eval
- Dipstick analysis
- Microscopric examination
What are pathognomonic for ATN?
Muddy brown casts on urinalysis
What is the normal range of creatinine in males?
0.6-1.2
What is the normal range of creatinine for females?
0.5-1.1
In a oliguric patient, what can FENa help distinguish?
Prerenal AKI from ATN
If FENa is <1, what does it suggest?
Prerenal
If FENa is >2, what does this suggest?
Intrarenal (ATN)
When is FENa not helpful?
- Its unreliable in patients on diuretics
- Serum creatinine is not stable in AKI
What is the major reason to get imaging in AKI?
Assess for urinary tract obstruction
Why is a renal US most commonly used in AKI?
- Safe
- easy
- sensitive to obstruction
What are the risks associated with urinary tract obstruction?
Obstruction may lead to infection, which can lead to urosepsis, which can lead to kidney failure
Renal function after relief of obstruction is dependent on what?
The severity and duration of obstruction
When is a renal biopsy performed?
In patients who have no clear explanation for AKI or it is very severe and rapid
-If creatinine in markedly elevated or significantly worsened over a few days
What are the benefits of a renal biopsy?
Provides a definitive diagnosis and may allow therapeutic intervention to prevent ESRD
What are the contraindications to a renal biopsy?
- Bleeding diathesis
- Severe HTN
- Pyelonephritis
- Renal tumor
- Solitary native kidney
What is considered mild AKI?
Transient increase in serum creatinine or fall in urine output
What are the life threatening complications of AKI?
- Volume imbalance
- Metabolic acidosis
- Hyperkalemia
- Hypocalcemia
- hyperphosphatemia
- urea
- AMS
When a patient has volume depletion (vomiting, diarrhea, hypotension, tachycardia, oliguria) what should you do?
Administer IV fluid
- fluid challenge attempts to identify prerenal failure
- Crystalloid isotonic fluids are preferred
How much fluid replacement should you begin with?
1-3 liters, with careful and repeated clinical assessment
If patients do no respond to fluids, what does this mean?
Patient is unlikely to have prerenal disease and more likely to have ATN or other forms of intrinsic AKI
If you have a volume overloaded patient that is NOT anuric, what is recommended?
Diuretics, but this should not be prolonged.
-If urine output does not increase after diuretics are given, they should be stopped
Why do patients with AKI have metabolic acidosis?
They are not excreted acid they way they should and they are not making bicarbonate the way they should.
What is the treatment of metabolic acidosis?
- Dialysis
- Bicarbonate administration
** choice depends on presence/absence of volume overload, or underlying cause and severity of acidosis
If a patient have oligo-anuric AKI who are volume overloaded and have severe metabolic acidosis, what should you do?
Dialysis
Why is dialysis preferred over the administration of bicarbonate for patients who are volume overloaded?
Bicarbonate administration results in a large sodium load that may cause or contribute to volume overload
In a patient with AKI who is not volume overloaded and have no other indication for acute dialysis, what should you do?
Bicarb instead of dialysis, especially if acidosis is related to diarrhea, or pH <7.1 and awaiting dialysis
What cardiac effects does hyperkalemia have?
-impaired neuromuscular transmission and cardiac conduction abnormalities
What is the treatment of hyperkalemia?
-antagonizing the membrane effects of potassium by driving extracellular K into the cells, or removing excess K from the body
Hypocalcemia in AKI in related to what?
HYperphosphatemia
What are the symptoms of hypocalcemia?
-paresthesias, tetany, confusion, seizures, trousseaus sign, Chvosteks sign, and QT prolongation
What is the treatment for patients with symptomatic hypocalcemia?
IV calcium
What is the treatment for asymptomatic patients with hypocalcemia and hyperphosphatemia?
Correction of hyperphosphatemia (dietary phosphate binders)
Selection of a phosphate binder depends on what?
The level of serum ionized calcium concentration.
If serum calcium is low, what phosphate binders should you use?
Calcium acetate or calcium carbonate
If serum ionized calcium is high, what phosphate binders should you use?
Aluminum hydroxide or Ianthanum carbonate
What should be initiated in patients with severe uremia? What can result from severe uremia?
Dialysis
-uremia can cause pericarditis, neuropathy, and unexplained decline in mental status
What is uremia?
A clinical syndrome associated with fluid, electrolyte, hormone, and metabolic abnormalities which develop in parallel with deterioration of renal function
What does dialysis do?
Removed metabolic wastes and excess body water and replenishes body buffers
-Diffusion of small molecules down their concentration gradient
Patients who recover from AKI are at greater risk for what?
To develop CKD and ESRD
What patients with AKI have the highest morality rate?
ICU patients
