Acute Kidney Disease Facts

Question 1

RIFLE

Answer 1

Risk - creatinine x1.5 or GFR decrease >25%, urine <0.5ml/kg/hr x6hr
Injury - creatinine x2 or GFR decrease >50%, urine <0.5ml/kg/hr x12hr
Failure - creatinine x3 or GFR decrease >75%, urine <0.5ml/kg/hr x24hr
Loss - complete loss of kidney function >4 weeks
End Stage Kidney Disease - complete loss of kidney function >3 months

Question 2

causes of prerenal AKI

Answer 2

hypoperfusion (hypotension) to kidneys
*hypovolemia
*hemorrhagic blood loss
*loss of plasma volume (burns, peritonitis)
*water and electrolyte loss
*sepsis
*cardiac failure or shock
*renal vasoconstriction
*massive pulmonary embolism
*stenosis or clamping of renal artery

Question 3

intrarenal

Answer 3

acute tubular necrosis
ischemic
nephrotoxic

Question 4

postrenal

Answer 4

obstructive uropathies (usually bilateral)
*ureteral destruction (edema, tumors, stones, clots)
*bladder neck obstruction (enlarged prostate)
*neurogenic bladder
*nephrolithiasis
*benign prostatic hypertrophy

Question 5

what is the most common type of AKI

Answer 5

acute tubular necrosis (ATN)
*caused by ischemia (inadequate blood supply) and nephrotoxins

Question 6

risk factors for acute tubular necrosis

Answer 6

increased in volume depleted patients
elderly
pre-existing renal disease
post-op
anesthesia

Question 7

causes of oliguria

Answer 7

alterations in renal blood flow
tubular obstruction
tubular backleak

Question 8

initiation phase of AKI

Answer 8

24-48 hours after initiating event
period of reduced perfusion when injury is evolving
*no damage YET
*can be reversed with increase volume to kidneys
course r/t level and length of insult

Question 9

maintenance phase of AKI

Answer 9

oliguric stage and period of established injury
*oliguria lasts weeks to months - depending on insult
*non-oliguric acute tubular necrosis (ATN) has better prognosis
*hyperkalemia
*metabolic acidosis
*anemia
*fluid retention
*rise in serum creatinine and BUN

Question 10

recovery phase of AKI

Answer 10

diuretic stage
*output >400cc/day
*volume status may be well controlled, so may not see this
*may occur in 24hr - 6 weeks
*return of normal function takes longer
*hypokalemia, hyponatremia
*dehydration

Question 11

serial creatinine measures to monitor recovery

Answer 11

renal function returns to normal
*normal GFR
*normal concentrating ability
up to 12 months and may never return to baseline