AKI Flashcards
how do NSAIDs damage the kidney?
pre-renal: cause constriction of the afferent arteriole because they impair renal autoregulation by inhibiting prostaglandin-mediated vasodilatation of the afferent arteriole.
renal: can cause acute interstitial nephritis
post -renal: long term use can lead to renal papillary necrosis causing obstruction.
how do ACEis damage the kidney?
cause vasodilation of the efferent arteriole.
this impairs renal autoregulation and reduces eGFR.
what actually is creatinine and why is it good/bad to measure kidney function?
produced by muscle cells at constant rate and filtered by kidneys
creatinine is a slight overestimation of eGFR as creatinine is secreted by the renal tubules. Inulin is more accurate but currently only available in research.
what are the diagnostic criteria for AKI?
any of:
-A rise in serum creatinine of 26 micromol/L or greater within 48 hours.
-A 50% or greater rise in serum creatinine (more than 1.5 times the baseline) which is known or presumed to have occurred within the past 7 days.
-A fall in urine output to less than 0.5 mL/kg/hour for more than 6 hours, if measurable (for example, if there is a catheter in situ).
what are the bedside tests for AKI?
-urine dip
-assessment of fluid status and full exam looking for cause
-ABG/VBG -esp look for hyperkalaemia
what are some risk factors for rhabdo you’d ask about in an AKI history?
skeletal muscle injury
crush injury
muscle overexertion
prolonged immobility
what do the results of a urine dip show in AKI?
negative urinalysis -probably pre renal or drug cause
positive protein and blood -glomerular disease esp if 2+ on both, could also be UTI or catheter trauma
increased white cells -infection or interstitial nephritis
what are the criteria for the different stages of AKI?
stage 1: creatinine rise of 26 or more within 48 hours OR creatinine rise of 1.5-<2x baseline within 7 days or UO <0.5ml/kg/h for >6h
stage 2: creatinine rise of 2-<3x baseline within 7 days or UO <0.5ml/kg/h for >12h
stage 3: creatinine rise 3x baseline or more within 7 days or UO <0.3ml/kg/h for 24h or anuria for 12h or creatinine rise to 354 or more in 7 days with acute rise of 26 within 48 hours
when would you admit someone with AKI?
-stage 3 AKI
-underlying cause requiring urgent hospital management
-no identifiable cause
-urinary tract obstruction
-hypovalaemia and need for IV fluids
-suspected complication of AKI requiring hospital management
what are the complications of AKI that require hospital management?
pulmonary oedema
uraemic encephlopathy
pericarditis
severe hyperkalaemia (potassium 6.5 or more)
what is the general treatment of AKI?
identify and treat cause
stop drugs that might make situation worse: diuretics, aceis/arbs (in most situations), metformin, NSAIDs, iodine based contrast media, some abx
monitor creatinine, vitals, and fluid balance regularly
look out for and treat complications
which antibiotics should you avoid in AKI?
aminoglycosides eg gentamycin
tetracycline
trimethoprim -avoid or reduce dose
when should you refer someone to a specialist following AKI?
if they have known diagnosis of CKD and have had 1 or more episodes of AKI
if their eGFR is under 30
what monitoring do you need to do with a patient post AKI?
monitor for CKD progression for at least 3 years after episode of AKI
check serum potassium and creatinine 1-2 weeks after restarting any medication which has temporarily stopped and think about dose titration
what are the pre renal causes of AKI?
-hypovalaemia eg haemorrhage, GI losses (D+V), renal losses, burns, diuretic use, sweating, DKA, dehydration
-reduced cardiac output eg HF, liver failure, sepsis
-too high doses of drugs which reduce BP
