Renal: AKI Flashcards
This process is defined by:
- urea/nitrogen retention
- dysreg of volume status and lytes
- based on GFR or urine output
AKI
KDIGO defines AKI as…
increased Cr of 0.3 + within 48 hrs
OR
Increased Cr by 50% in 7 days
OR
urine output < 0.5 ml/kg/hr for > 6 hours
Which KDIGO stage?
increased Cr of 0.3 + within 48 hrs
OR
Increased Cr by 50-99% in 7 days
OR
urine output < 0.5 ml/kg/hr for > 6-12 hours
stage 1
Which KDIGO Stage?
Increased Cr by 100-199% in
OR
urine output < 0.5 ml/kg/hr for > 12-24 hours
Stage 2
Which KDIGO stage?
increased Cr of 0.3 to 0.4+
OR
Increased Cr by 200+%
OR
urine output < 0.3 ml/kg/hr for 24+ hours
OR
anuria for 12+ hours
OR
Renal replacement therapy
stage 3
AKI develops in what percent of ICU patients?
60%
What is the MC type of AKI in hospitalized patients?
pre-renal
Which type of AKI?
decreased renal perfusion
pre-renal
Which type of AKI?
pathology of vessels, glomeruli or tubules
can be caused by acute tubular necrosis
intrinsic renal
Which type of AKI?
obstruction
post-renal
Can etiologies of AKI overlap?
yes! decreased perfusion can lead to acute tubular necrosis (pre-renal + intrinsic)
Rank the incidence of AKI types
ATN (45%) > Prerenal (20% > obstruction (10%)
5 things that can cause pre-renal AKI…
true volume depletion hypotension edema renal artery ischemia GFR drugs
Which two drugs can affect GFR and cause pre-renal AKI?
NSAIDs and ACE-Is
What are three causes of intrinsic renal AKI?
renal ischemia
sepsis
nephrotixins
What are nephrotoxins that may cause intrinsic renal AKI?
Abx (vanco/aminoglycosides)
IV contrast
Cisplatin
HIV meds
IVIG
Mannitol
Three major risk factors for ATN caused by IV contrast
renal dz
volume depletion
repeat dosing
What are the two mechanisms by which contrast can cause AKI?
tubular epithelial toxicity
medullary ischemia from vasoconstriction
What are 4 prevention factors for IV induced AKI?
hydration
low osmolal agents at low doses
avoid repeat dose
avoid nephrotoxics for 48 hours after
A decreased GFR without intrinsic renal disease requires what kind of obstruction?
bilateral
Post-renal AKI is often caused by what three things?
Prostate disease
Mets
neurogenic bladder
urine output of > 400mL/24 hours…
nonoliguric
urine output of < 400 mL/24 hours
oliguric
Urine output < 50 to 100mL/24 hours
anuric
Labs for AKI…
UA, CMP + CR/BUN, GFR, FENa
Imaging for AKI…
Renal US
Is biopsy used for AKI?
yes
UA should be examined at ______ temperature within _____ hours
room temp w/in 2 hours
Muddy brown casts indicate…
ATN
Normal serum Cr for men…
0.6-1.2
Normal serum Cr for female…
0.5-1.1
Calculating GFR given creatinine…
1/factor of normal cr
ex. 2x Cr = GFR 1/2 of normal, 3x Cr = GFR 1/3 of normal, etc.
FENa is a measure of sodium in urine. It helps distinguish what?
prerenal AKI or ATN
FENa < 1% indicates…
FENa > 2% indicates…
< 1% = prerenal
> 2% = intrarenal/ATN
What are two pitfalls of FENa?
unreliable if on duretics, Cr not stable in AKI
Major reason for imaging with AKI…
obstruction/hydronephrosis
MC type of imaging for AKI…
US
renal fxn after relief of obstruction is dependent on…
severity and duration of obstruction
If no clear AKI etiology, severe disease or increased rate of decline (markedly elevated Cr or worsening), what should be performed?
kidney bx
This is a definitive diagnostic that may allow therapeutic intervention to prevent ESRD…
kidney bx
How often is Bx used to dx AKI?
rarely
The following are C/I for…
bleeding diathesis severe HTN pylo tumor solitary kidney
Biopsy
The following are life threatening complications of…
volume imbalance acidosis hyperkalemia hyperphosphatemia hypocalcemia uremia
AKI
Severe AKI can have what severe sign?
AMS
Life threatening complications of AKI require…
hemodialysis
What should be assessed in all patients with AKI?
volume status
A patient presents with the following. How should they be treated?
- hx of fluid loss
- hypovolemia on PE
- oliguria
fluid challenge via 0.9 NS to confirm pre-renal cause
How much fluid should you begin with for a fluid challenge to assess pre-renal AKI?
1-3 L with repeated clinical assessment
If a patient doesn’t respond to fluid challenge, what etiology is likely?
intrinstic AKI/ATN
In patients that are NOT anuric, what can be given to temporarily relieve hypervolemia?
diuretics
What offers the most efficient method of fluid volume removal?
dialysis
Two considerations of diuretic use for volume overload…
- not prolonged/temporizing measure
2. monitor urine output
what condition can cause a loss of bicarb and worsen metabolic acidosis?
diarrhea
Tx of metabolic acidosis has two options…
dialysis
bicarb
Dialysis or Bicarb?
not volume overloaded
acidosis due to diarrhea
pH < 7.1 and waiting on dialysis
no other acute dialysis indications
Bicarb
Dialysis or Bicarb?
volume overload
severe metabolic acidosis (< 7.1)
dialysis
Bicarb admin in hypervolemic patients should be avoided for what reason?
it is administered with fluids
hyperkalemia is generally axs, but can occur with…
impaired neuromuscular transmission
arrhythmia
what are two treatments for hyperkalemia?
medical therapy, dialysis
increased serum phosphorus due to reduced GFR is a common cause of…
hypocalcemia
the below are sxs of…
Paresthesia, tetany, confusion, seizures.
Trousseau’s and Chvostek’s sign.
prolonged QT
hypocalcemia
how do you tx hypocalcemia?
IV calcium if symptomatic
If hypocalcemia is asymptomatic in presence of hyperphosphatemia, what is the initial therapy?
correction of hyperphosphatemia?
How do you treat hyperphosphatemia? What about low calcium? High calcium?
dietary phosphate binders
low: calcium acetate or carbonate
high (non-calcium sources): aluminum hydroxide or lanthhum carbonate
Is uremia more common in chronic or acute kidney disease?
chronic
the following signs of uremia indicate tx with…
pericarditis (friction rub)
neuropathy (asaterixis)
unexplained AMS
dialysis
Do most patients with AKI recover renal function?
yes: UOP and Cr normalize
AKI makes you more susceptible for…
CKD, ESRD
mortality rate for ICU patients with AKI is…
> 50%