what are two main causes of nephrosis that causes AIRF?
ischemia and nephrotoxicity
what is typical cause of pre-renal azotemia? what is prognosis in most cases?
hypovolemia
if recognized and promptly treated, pre-renal azotemia readily resolves after restoration of renal perfusion
Is systemic arterial hypotension a requirement for ischemic nephrosis to occur?
not required but can be a factor
What antimicrobials are nephrotoxins?
AMINOGLYCOSIDES (gentamicin)
amphotericin
cephaloridine
sulfonamides
tetracyclines
What cancer therapeutic is nephrotoxic?
cisplatin
what mineral in the body is commonly associated with nephrotoxicity?
hypercalcemia (esp. w/malignancy like lymphoma)
what heavy metals are nephrotoxic? what plant is toxic to cats?
arsenic and lead
Easter lily
What part of the kidney is damaged with nephrotoxicity/ischemia? Is this better detected by light or electron microscope?
tubules (direct binding to tubule membranes)
electron microscope more sensitive
How does AIRF relate to GFR?
acute renal failure is associated with decreased filtration rate
how does hypotension affect GFR?
hypotension leads to vasoconstriction of afferent arteriole --> decreased GFR (as seen with large hemorrhage)
How does obstruction in the ureter affect GFR?
obstruction leads to back pressure --> increased hydrostatic pressure in glomerulus overwhelms vessel pressure --> decreased GFR
How does tubular back leak affect pathophysiology of AIRF?
damaged tubules leak filtrate
What does adrenergic (sympathetic) stimulation affect vessels in renal cortex?
vasoconstriction/ischemia
how do prostaglandins effect vessels in renal cortex?
dilation to protect urine flow
what effect do NSAIDs have on prostaglandins?
NSAIDs inhibit PGE synthesis so kidney unable to dilate vessels --> worsens ischemia during hypovolemia/hypotension because unable to reverse constriction
Are Cox2 NSAIDs completely renal safe?
no
are nephrotoxins more damaging due to ischemia or direct cell injury?
direct cell injury more damaging
(add in ischemia = increased risk of injury)
what two qualities of the renal system worsens effect of nephrotoxin exposure?
abundant blood supply so lots of exposure to tubular cells
large tubular surface area for exposure/attachment
Do most patients die during induction, maintenance or recovery phase of AIRF? why?
maintenance
lasts 1-3 weeks so client can't afford hospital care or dialysis required (can't continue pouring fluids in oliguric pt)
Clinical signs are minimal/absent (often undetected) during which period of AIRF? Can removal of insult result in kidney return to normal function at this point?
latent/induction
yes, kidney can return to normal
What is urine output like during maintenance phase?
variable (oliguria, normal, polyuria) depending on severity of insult
What is definition of maintenance phase?
sudden increase in serum creatinine that persists despite correction of pre-renal factors/rehydrate
Why does AIRF patient need a urinary catheter?
quantify urine output and it could be lepto (dog)
which phase signifies a critical amount of lethal tubular cell injury?
