Elimination & Detox 2: Nephrotoxins Flashcards
2 UNIQUE functions of the kidneys?
- VITAMIN D SYNTHESIS
- BP REGULATION
TOXICANTS are more likely to cause RENAL INJURY because… (2)
- KIDNEY TAKES 25% OF ALL CO, so EXPOSED to a HIGH AMOUNT OF BLOOD FLOW
- some toxicants can CONCENTRATE in URINE or TUBULE EPITHELIUM than the rest of the body
give 3 drugs that can ALTER RENAL BLOOD FLOW/GFR
- NSAIDs
- ACE-INHIBITORS
- DIURETICS
if AKI develops, what 3 interventions should we administer?
what should we BE WARY OF? how should we handle it? (2)
- IV fluids
- anti-emetics
- early NUTRITIONAL support
BEWARE OVERHYDRATION;
- patients with AKI can have VARIABLE URINE OUTPUT, so if they become OLIGURIC or ANURIC then MULTIORGAN DAMAGE IS LIKELY
- if URINE OUTPUT DECREASES = DECREASE or STOP IV FLUIDS
what is the MOST COMMON TOXICANT in SMALL ANIMAL MEDICINE?
NSAIDs!
how do NSAIDs STOP PAIN?
what are the 3 ORGANIS that they can IMPACT? how?
what 2 OTHER THINGS can occur with NSAID OVERDOSE?
they INHIBIT COX-1 & COX-2, which then INHIBITS PRODUCTION OF PROSTAGLANDINS, PROSTACYCLIN & THROMBOXANE A2
4 organs?
1. GI TRACT = PROSTAGLANDINS are INHIBITED by NSAIDs, and they help REGULATE PRODUCTION OF GASTRIC ACID, BICARB & MUCOUS
–> NSAIDs can lead to GI ULCERS!
- KIDNEYS = PROSTAGLANDINS usually help cause GLOMERULAR VASODILATION, so NSAIDs can cause TUBULAR NECROSIS & AKI
- PLATELETS = THROMBOXANE A2 helps PLATELET AGGREGATION, so WITHOUT IT w/ NSAIDs CAN CAUSE GI BLEED/THROMBOPATHIA
ACUTE LIVER INJURY & CNS SIGNS can also occur with NSAID OVERDOSE
DECONTAMINATION in NSAID TOXICITY
we should start with ___ INDUCTION or ___ ___ if appropriate (quickly enough)
what 2 other things should we start with?
if an animal has ingested a LIFE-THREATENING OVERDOSE, consider WHAT intervention? why?
we should start with EMESIS INDUCTION or GASTRIC LAVAGE if appropriate (quickly enough)
2 other things?
1. ACTIVATED CHARCOAL to ABSORB WHATEVER IS STILL IN GI TRACT
2. IV LIPID EMULSION = NSAIDs are often LIPID-SOLUBLE, so we can EMULSIFY/BREAK IT DOWN
if LIFE-THREATENING OVERDOSE, consider EXTRACORPOREAL BLOOD PURIFICATION via HEMOPERFUSION or THERAPEUTIC PLASMA EXCHANGE
–> THROWING OUT NSAID & replacing with DONOR PLASMA
NSAID toxicity…
we should monitor WHAT 2 kinds of organ values?
4 other options for MEDICAL TREATMENT? 2 are +/-
MONITOR HEPATIC & RENAL VALUES
MEDICAL tx?
1. GASTROPROTECTANTS
–> MISOPROSTOL (PGE analog)
–> ANTACIDS like FAMOTIDINE
–> SUCRALFATE to BIND & PROTECT ulcers
- IV FLUIDS to MAINTAIN EUHYDRATION & RENAL PERFUSION, but caution with OVERHYDRATION
- +/- HEPATOPROTECTANTS
- +/- DIURETICS if OLIGURIA develops
ETHYLENE GLYCOL…
what is the MOST COMMON kind of EXPOSURE?
this substance is ALSO found in what other 4 things?
METABOLISM of ETHYLENE GLYCOL occurs PRIMARILY in the ___ within ___-____ ____ of INGESTION
pathophysiology (4)
the LETHAL DOSE is..
MOST COMMON EXPOSURE = ANTIFREEZE
this substance is ALSO FOUND IN…
1. SOLVENTS
2. DEICERS
3. STAINS
4. PHOTOGRAPHY DEVELOPING SOLUTIONS
METABOLISM of ETHYLENE GLYCOL occurs PRIMARILY in the LIVER within 2-4 HOURS of INGESTION
pathophysiology?
1. ETHYLENE GLYCOL gets converted to GLYCOALDEHYDE by ALCOHOL DEHYDROGENASE
- eventually, forms OXALIC ACID
- OXALIC ACID will COMPLEX WITH CALCIUM to form CALCIUM OXALATE STONES
- CALCIUM OXALATE STONES will cause TUBULAR OBSTRUCTION & NEPHROTOXICITY
the LETHAL DOSE is NOT MUCH
CLINICAL STAGES of ETHYLENE GLYCOL POISONING (3)
give TIMING post-ingestion, clinical signs
which stage DOES NOT ALWAYS OCCUR?
- STAGE 1 = 30 MINS to 12 HOURS POST-INGESTION
–> V+
–> PU/PD
–> CNS depression
–> ataxia - +/- STAGE 2 = 12 to 24 HOURS POST-INGESTION
–> CNS signs MIGHT IMPROVE SLIGHTLY
–> “FALSE RECOVERY” but even though this doesn’t always happen, MORE COMMON IN DOGS - STAGE 3 = 12 to 36 HOURS POST-INGESTION
–> OLIGURIC to ANURIC AKI
–> severe DEPRESSION
–> SWOLLEN & PAINFUL KIDNEYS
–> ANOREXIA
–> SEIZURES
–> COMA/DEATH
what are the BEST 3 DIAGNOSTIC PARAMETERS we can use for ETHYLENE GLYCOL POISONING?
& include WHY we see them
- HIGH ANION GAP METABOLIC ACIDOSIS = from GLYCOLIC ACID, GLYOXYLIC ACID & OXALIC ACID
–> noticed at 3 HOURS, PEAKS at 6 HOURS, can stay UP TO 48 HOURS - ISOSTHENURIA, HYPOCALCEMIA & CALCIUM OXALATE CRYSTALLURIA within 3 HOURS post-ingestion
- AZOTEMIA around 12-24 HOURS POST-INGESTION
in ETHYLENE GLYCOL POISONING, when does HIGH ANION GAP METABOLIC ACIDOSIS…
BECOME noticeable?
PEAK?
how LONG can it stay increased?
NOTICED WITHIN 3 HOURS post-ingestion
PEAKS at 6 HOURS post-ingestion
can REMAIN INCREASED for 48 HOURS
can we use ACTIVATED CHARCOAL for ETHYLENE GLYCOL?
NO!
3 TREATMENTS for ETHYLENE GLYCOL POISONING?
include WHEN they’re effective, what they can do
- FOMEPIZOLE = EFFECTIVE if given WITHIN FIRST 8 HOURS
–> INHIBITS ALCOHOL DEHYDROGENASE from converting ETHYLENE GLYCOL into GLYCOALDEHYDE - ETHANOL (GRAIN ALCOHOL) = EFFECTIVE if given WITHIN FIRST 8 HOURS
–> has HIGHER AFFINITY FOR ALCOHOL DEHYDROGENASE than ETHYLENE GLYCOL
–> EASILY AVAILABLE - HEMODIALYSIS = usually WITHIN HOURS OF EXPOSURE
–> helps REMOVE EG & METABOLITES to try and PREVENT AKI
why might giving FOMEPIZOLE for ETHYLENE GLYCOL POISONING in a CAT be CONTRAINDICATED? (2)
- CATS NEED A MUCH HIGHER DOSE > DOGS
- EXPENSIVE MEDICATION