acute intrinsic renal failure Flashcards
discuss the prognosis for a dog with aztema due to glycol acetate consuption
grave
euthanize
this drug damage the kidney and should only be used when necessary
aminoglycosides
usg is the best way to monitor
be vigilant for tubular necrosis
check for urinary casts
nephthrotoxic plant in cats
easter lilly
cause of AIRF in horses
rhabdomyolytis
red maple dz
causes of AIRF in cowas
acorns/oak bud
common cause of AIRF in dogs
raising /grapes
discuss the pathogenesis of
exposure to nephrotoxin/ischemia causes tubular injury
spectrum of injury from degeneration(nephrosis) to acute tubular necrosis
some patients have minimal to no light microscopic lesions but still develop severe renal excretory failure
discuss AIRF due to iscemia
renal cortex is very vascular and adrenergic stimulation during renal ischemia can cause potent vasoconstriction
discuss effect of NSAIDs on the kidney
doesnt cause AIRF but reduces glococorticoids hence reducing the ability of the kidney to vasodilate
negative effects of NSAIDS
- GI bleeding
- volume depletion
- impared vasodilation
discuss mechanism of injury of nephrotoxic AIRF
- delirious effects of true nephrotoxins are direct and occur after binding to the tubular cell membranes
- decreased energy production and cell death
- some nephrotoxins causes renal vasocontrictions
- major effect is direct cell injury rather than ischemia
why are nephrotoxins very toxic to kidney
abundant blood supply guarantee tubular cells to toxin
large tubular cell membrane surface area for exposure and attachment
in which stage does the owner recognise AIRF
maintainance
they will not see the cs in induction unless they see the animal consuming a chemical
in which stage do most dogs die due to AIRF
maintainance stage
the animal has either uligoria or non uloguria
in dogs that progress to CRF,what are the main cs
isothenuria
azotemia
discuss urine output in maintainance phase of AIRF
- it can be
- uligoria
- normal urine output
- polyuria
- presence or absence of uliguria depends on presence of severirity of insult
define maintainance phase of AIRf
sudden increase in serum creatine conc. that persists despite the correction of the prerenal factors
why do patients due under maintainance phase
because maintainance phase lasts for days to weeks
lasts 1-3 weeks
characteristics maintainance stage of AIRF
characterised by severe decrease in renal blood flow
even if rbf returns to normal gfr remains low
conversion from uliguria to polyuria may occur in maintainance phase
discuss recovery phase of AIRF
return to normal BUN and creatine=possible
complete recovery may not be possible
partial improvement= chronic renal failure
BUN and creatine may return to normal but GFR may remain low
urinary conc. may remain low
which test is definitive for AIRF
no single test is definitive for AIRFhistory is important
discuss body condition in a patient with AIRF
no loss of body condition
compare uremia in AIRF and crf
signs of uremia in Airf are more than prerenal azotemia but same as crf
signs of uremia in AIRF and crf
uremic breath
oral uremic ulcer,tongue tip necrosis
hypothemia(nephrosis) or hyperthemia(nephrosis)
absence of pallor to mucus memberanes
postural changes suggesting back pain (renal pain)
physical exam findings of AIRF
dehydration is common before fluids
overhydration may occur after fluids
bradycardia/ arrthymia if marked hyperkalemia
normal to large kidneys
bladder:normal to small ude to less urine
absence of lower urinary obstruction
discuss bladder size in AIRF
normal to small
discuss anemia due to AIRF
not early on
common in crf
discuss proteinemia in AIRF
hyperproteinemia due to dehydration
discuss leukogram for AIRF
inflamatory stress/leukogram
thrombocytopenia.therefore dx or tx patient for lepto who present with AIRF
discuss usg in AIRF
- usg of 1.007-1.017
- same as for crf
- low in both uliguric and non uligoric patients
- there is also hematuria
- and proteinuria
- may see glucosuria with normal glucose levels.this is bcoz they cant reabsorb tubular glucose
discuss sediment in AIRF
may be very active bt absence of casts doesnt r/o AIRF
increased # of oxolate crystals supports a dx for ethyl glycol poisoning in a ulogoric AIRF patient
discuss sediments in AIRF
- increase in wbc,rbc,tubular epithelial cells= non specific reaction to renal injury
- increase in wbc an bacteria =suspected pylonephritis
for increased wbc and bacteria in AIRf what should u suspect
pyelonephritis
if a patient has azotemia,should u consider euthanasia
u cant use the magnitude of azotemia to determine AIRF and crf
u cant use the magnitude of azotemia to determine prerenal,renal and post renal
discuss hyperkalemia in AIRF
remember that K is higher in acute renal failure than in chronic.this is because with acute renal failure,there is rapid decrease in blood flow and less k is going to be cleared while with chronic renal failure,the kidneys are able to adapt
some of the cats with chronic renal failure may be hypokalemic
normal or lower serum k is expected in crf
discuss blood gases in AIRF
moderate/sevewre metabolic acidosis during maintainance phase of AIRF
more severe than the one in compensated crf
discuss the size of kidneys in both AIRF and crf
AIRF:normal to large
CRF:normal to small
no specific cause of AIRF may be infered from ultrasound findings with possible exception of glycol poisoning
normal us findings do not exclude AIRF
severe renal hyperchogenesity in US suggests
ethyl glycol intoxication
discuss the US of hyperthyroid imanging in AIRF
may be helpful to differentiate AIRF vs CRF
dogs with crf may hav an enlarged parathyroid hormone
dogs with AIRF have normal size hyperthyroidism
it requires substantial skill
discuss serology in AIRf
acute/convolescent serum samples for leptosporosis if nephritis= possible cause AIRF
submit samples of borellia if a rapidly progressive glomerular nephritis=suspected cause of AIRF
advantages of renal biopsy
Confirm primary renal origin of azotemia
Differentiate AIRF from CRF
Assess potential for healing / prognosis(e.g. basement membranes intact)
Differentiate nephritis (Lepto) from nephrosis
prgnosis for AIRF with Ethylene Glycol
poor to grave
prognosis for lepto in AIRF
fair to good with adequate tx
prognosis for bacterial pyelonephritis in AIRF
fair
prognosis for aminoglocosides
poor to grave
prognosis of AIRF due to NSAIDS
guarde to poor
prognosis for AIRF with easterlilly
poor to grave
discuss prognosis for patients with severe azotemia in maintainence stage of AIRF
Patients with severe baseline azotemiaduring the maintenance phase often are NOTsuccessfully managed without dialysis
new ways of improving prognosis for AIRF
- Early hemodialysis = increased survival of AIRF patients (UC Davis)
- Dialysis may be needed for several months with severe AIRF
- peritonial dialysis-New catheters now available (T-Fluted)
- Mayincrease survival time (no data yet)
Prognosis of AIRF without Dialysis
Over 80% of patients with AIRF & high level azotemia will either die or be euthanized
Why do Animals with AIRF Die, or are Euthanized
Hyperkalemia
Metabolic acidosis
Severe azotemia
Overhydration and pulmonary edema next major cause of death during vigorous fluid therapy
Treatment Goals for AIRF During the Maintenance Phase
- Provide adequate supportive care and sufficient time for renal healing
- No “quick fix” (may require several weeks)
- No treatment can change lesions already present in kidneys
- Avoid any nephrotoxic drugs
- Avoid periods of hypotension (e.g. anesthesia, surgery)
discuss fluid therapy in AIRF therapy
- Place IV catheter
- Meticulous attention to fluid therapy
- Measurement of urine output is critical initially to avoid overhydration
- “Flushing the kidneys”……NOTalways a good idea!!
Treatment of AIRF –“Ins & Outs
- Normal urine output = 1-2 ml/kg/hr
- < 1 ml/kg/hr = oliguria
- Over each 4-hour period, give a volume of IV fluids equal to the insensible needs for that time period plus a volume equal to the urine output of the preceding 4 hours:
- (20 ml/kg)/6 + measured urine output of preceding 4 hrs
- Will avoid overhydration but may underestimate actual fluid needs
tx for hyperkalemia in AIRF
- Sodium bicarbonate (2 mEq/kg)
- Regular insulin (0.25-0.5 U/kg) and glucose (1-2 ml/kg 50% dextrose) IV
- Calcium gluconate (2-10 ml of a 10% solution)
- Polystyrene sulfonate (each g binds 1 mEq K+and releases 1-3 mEq Na+) mixed with sorbitol and given by retention enema
- IF hyperkalemia persists must proceed to dialysis
discuss tx of oliguria in AIRF
- Diuretics
- Probably of limited value once oliguria is established …
- AIRF prophylaxis?
- Furosemide (2-4 mg/kg IV followed by 1 mg/kg/hr)
- Dopamine (2-4 μg/kg/min)
- Mannitol (0.25-0.50 g/kg IV over 3-5 min)
discuss severity of glycol
- May cause illness
- Usually NOTfatal
in ethlyn glycol metabolism, which step/product signify a point of return
Glycolate
which enzyme converts ethelyn glycol to glucolate
alcohol dehydrogenase
list the final byproducts of ethelyn glycol
- hippurate
- calcium oxylate
- formate and co2
discuss effectsEthylene Glycol Poisoning after 30 mins to 12 hrs
neurologic
Ataxia, stupor, seizures, coma
discuss the effects of ethelyn glycol after 12-24 hrs
- Cardiopulmonary -12 to 24 hrs
- Tachycardia, tachypnea
discuss effect of Ethylene Glycol Poisoning after 24-72 hrs
- renal
- Initial PD/PU
- Progresses to profound oligo-anuric AIRF (almost always fatal once established)
discuss Ethylene Glycol Nephrotoxicity:Pathophysiology
- Cytotoxicity from metabolites (most important)
- Calcium oxalate crystals
- Intraluminal
- Intracellular
- Tubular backleak?
- Compression of RBF by interstitial edema
Ethylene Glycol Measurement
- Colorimetric test for ethylene glycol (EGT Kit® from PRN Laboratories)
- Whole blood or serum
KEY POINT:
Ethylene glycol is
rapidly absorbed from the GI
tract of dogs and is undetectable
in plasma 48 hrs after ingestion
when can u have false -ve measurements in Ethylene Glycol Measurement
- Samples obtained < 30 minutes after ingestion
- Samples obtained > 12 hours after ingestion
potential for false positive in Ethylene Glycol Measurement
- Propylene glycol
- Glycerol
- Metaldehyde
Presumptive EG Poisoning
- Alcohol-like intoxication
- Initial pu/pd to oliguria
- Renal / muscle pain
- Progression to coma
- ask the client if the patient had excess to radiator fluid
dx for ethylene glycol poisoning
- Dilute urine
- Oxalate crystalluria
- ↑ Anion gap metabolic acidosis (up to 24 hrs)
- ↑ Osmolal gap (up to 12-24 hrs)
- Progressive azotemia
- Hypocalcemia (formation of calcium oxalate crystals
Treatment of EG Poisoning
-
Timing is everything!
- For best outcome treat within 4 hours of ingestion
-
Do NOT wait for “definitive” test results
- Induce vomiting
- Gastric lavage with activated charcoal
- Attempts to stimulate urine production with furosemide usually futile
discuss drugs used for treating ethelyn glycol
- Definitive treatment with ethanol or 4-methyl pyrazole to prevent metabolism of ethylene glycol
- Calcium gluconate if symptomatic hypocalcemia
- Sodium bicarbonate for metabolic acidosis
- they complete with ethelyn glycol and ethelyn glycol gets excreted unchanged
discuss how ethanol can be used to tx ethelyn glycol poisoning
- Has greater affinity for alcohol dehydrogenase than ethylene glycol does
- Saves dogs and cats if used within 2-4 hours of ingestion
- Dilute to 20% solution for IV use
- Dogs: 5.5 ml/kg q 4h X 5 then q 6h X 4
- Cats: 5 ml/kg q 6h X 5 then q 8h X 4
discuss tx of ethelyn glycol with fomipizole
- No CNS depression
- Dogs:
- Treat within 8 hrs of EG ingestion
- 20 mg/kg followed by 15 mg/kg at 12 and 24 hrs and 5 mg/kg at 36 hrs
- Cats:
- Require MUCHhigher doses
- Treated within 3 hrs of EG ingestion125 mg/kg followed by 31 mg/k
discuss prognosis for ethelyn glycol poisoning in dogs
- < 3 hr … Excellent
- 3-5 hrs … Good
- 5-8 hrs … Good to Guarded
- > 8 hrs … Guarded
- > 12 hrs … Guarded to Grave
discuss prognosis for ethelyn glycol in cats
< 3 hrs … Good
> 3 hrs … Guarded to GraveTIMING
teristics that define crf
- When compensatory mechanisms of the diseased kidneys are no longer able to maintain:
- EXCRETORYfunctions of the kidneys
- REGULATORYfunctions of the kidneys
- ENDOCRINEfunctions of the kidneys
-
Results in:
- Retention of nitrogenous solutes
- Derangements of fluid
- Alterations in electrolyte and acid-base balance
- Failure of hormone production
