Toxicology Flashcards
Charcoal, optimal ratio of charcoal: toxin poorly bound (4)
10:1 small molecules (lithium, iron, cyanide), hydrocarbons, alcohol, acid/alkalai
Antidotes
BAL, DMS (3)
FFP / Vit K / PCCs
Calcium, glucagon, gluc/insulin, intralipids
Sodium nitrite, sodium thiosulfate, hydroxycobalamine
Arsenic, mercury, lead (add EDTA)
warfarin
calcium channel blocker
cyanide
Antidote 2
Alkaline diuresis, hemodialysis (2)
Bicarbonate, ethanol, dialysis, 4-MP (2)
Glucagon, intralipids
Protamine
Aspirin, barbiturates
ethylene glycol, methanol
beta blocker
heparin
Antidote 3
pyridoxine (a.k.a.) sodium bicarbonate, intra-lipids methylene blue (2) calcium, magnesium
INH; vitamin B6
TCA
nitrates, met hemoglobin EMEA
hydrofluoric acid
Dereroxamine
atropine, 2-PAM
octreotide and two other things
Physostigmine
Iron
organophosphate (cholinergic and central nicotinic)
Oral hypoglycemic along with glucagon and glucose
anticholinergics if severe (but not for TCA)
Anion gap formula
MUDPILES pneumonic
(Na) - (Cl + CO2), normal < 12
MUDPILES pneumonic - causes of anion gap metabolic acidosis
M Methanol, metformin, massive ingestions
U Uremia
D DKA
P Paraldehyde
I Iron, INH
L Lactic acidosis (CO, CN)
E Ethylene glycol
S Salicylates
Increased osmolar gap (3)
false positives
amphetamines
TCAs
PCP
Alcohol toxic (acetone, isopropanol, methanol, ethylene glycol) or not, mannitol, ketoacidosis
Osmolar gap = Actual - Calculated (nl 285-295) = 2 Na + BUN/18 + Glu/18 + EtOH/4.6
amphetamines: Sudafed
TCAs: cyclobenzaprine, carbamazepine, diphenhydramine, phenothiazines
PCP: ketamine, dextromethorphan
Drug levels helpful when predictive of subsequent toxicity or guides specific therapy (5)
Iron, lithium, acetaminophen, aspirin, digoxin
Anticholinergic toxidrome
classic examples (5)
key difference with similar toxidrome:
“Hot as hell, blind as a bat, dry as a bone, red as a beet, mad as a hatter”; Dry, flushed skin, dry mucus membranes, mydriasis, decreased bowel sounds, urinary retention
examples: atropine, antihistamine, Jimsonweed, Parkinson’s medications (L dopa), , phenothiazines, TCAs
key difference: sympathomimetic has diaphoresis rather than dry skin
Anticholinergic treatments of
Classic toxidrome (Mad as hatter…..) normal and if severe
wide complex tachycardia
torsade de pointes
Benzodiazepines, Physostigmine if very severe and no TCA
bicarbonate
magnesium, overdrive pacing
Sympathomimetic treatment
Mimic of opiod OD
Benzodiazepine
Clonidine
Cholinergic toxidrome
Key examples (2) and mechanism
muscarinic effects mnemonic
Organophosphate insecticides, chemical warfare agents, some mushrooms
inhibit cholinesterases -> increases acetylcholine
SLUDGEM- Bs
salivation, lacrimation, urination, diarrhea, GI distress, emesis, miosis
Bs: –Bradycardia, Bronchospasm, Bronchorrhea
Cholinergic toxidrome
Nicotinic effects (3)
tx
Muscle weakness, fasciculations, respiratory failure
atropine, 2-PAM (Pralidoxime)
Withdrawal syndromes
common treatment for alcohol, barbiturates, benzodiazepines, cocaine, clonidine
Benzodiazepines, clonidine
Tylenol tox
mechanism
stages
Saturated normal metabolism shifts to minor pathway cytochrome P450 -> when glutathione depletes, toxic free radical metabolits NAPQI accumulates and damages hepatocytes
Tylenol tox
toxic ingestion mg/kg; grams average adult
4 hour toxic level
Mech
Use > 24 hours presentation?
140 mg per kilo, 7 to 10 g
140 at four hours
provides necessary cofactor to metabolize NAPQI
>24 hours: yes
Wernicke’s encephalopathy sx (4)
Korsakoff’s psychosis sx (2)
Wernicke’s encephalopathy: Oculomotor crisis
CN VI palsy (lateral rectus), nystagmus, ataxia, global confusion
Korsakoff’s psychosis: Retrograde amnesia, confabulation
Methanol
metabolic presentation
Pathogenesis
Key symptom
Other sx (3)
Anion gap metabolic acidosis with increased osmolar gap
alcohol dehydrogenase creates formaldehyde and formic acid
Visual changes/blindness
Seizures, resp failure, pancreatitis
Methanol
Antidote (2)
Adjuncts if refractory to above (2)
Fomepizole (4MP) -> prevents conversion leading to renal excretion
Ethanol (preferentially metabolized)
Dialysis, bicarbonate
Ethylene glycol
toxidrome key:
mechanism of toxicity
toxidrome key: altered mental status + elevated anion and osmolar gap acidosis
mechanism of toxicity: toxic metabolites oxalic acid and glycolic acid
other findings: renal failure, hematuria, hypocalcemia; calcium oxalate crystals in the urine
Ethylene glycol
treatment similar to other toxic alcohols unique treatment (2)
supportive treatment
treatment similar to other toxic alcohols: fomepizole (4MP)
unique treatment: pyridoxine, thiamine
supportive treatment: bicarbonate four acidosis, dialysis for severe acidosis and/or high blood levels
Isopropyl alcohol
toxidrome compared to other toxic alcohols
symptoms (4)
treatment (2) and how differenent from other toxic alcohols
toxidrome compared to other toxic alcohols: ketosis /elevated osmolar gap WITHOUT anion gap or acidosis
symptoms: altered mental status plus hemorrhagic gastritis, pulmonary edema, hypotension
treatment: supportive care +/- hemodialysis
Tx difference: NO role for fomepizole or EtOH since metabolite less toxic than the toxin
Cocaine
similar toxidromes with key difference
Similar to anticholinergic toxidrome
cocaine: diaphoresis, dilated pupils
anticholinergic: skin dry instead of sweaty
cholinergic: pupils pinpoint instead of dilated
Toxicology pearls
bradycardia pneumonic (6)
tachycardia pneumonic (4)
Bradycardia
P Propranolol (beta blockers), poppies (opioids)
A Anticholinesterase drugs
C Clonidine, calcium channel blockers
E Ethanol, other alcohols
D Digoxin
Tachycardia
F Freebase (cocaine)
A Anticholinergics, antihistamines, amphetamines
S Sympathomimetics, solvent abuse
T Theophylline
Toxicology pearls
hyperthermia (4)
hypothermia (5)
Hyperthermia
N NMS, nicotine
A Antihistamines
S Salicylates, sympathomimetics, Serotonin syndrome
A Anticholinergics, antidepressants
Hypothermia
C Carbon monoxide
O Oral hypoglycemics, insulin
O Opioids
L Liquor
S Sedatives, hypnotics
Toxicology pearls
hypotension (5)
hypertension (6)
hypotension
C Carbon monoxide
O Oral hypoglycemics, insulin
O Opioids
L Liquor
S Sedatives, hypnotics
hypertension
C Clonidine, calcium channel blockers
R Reserpine (antihypertensive agents)
A Antidepressants, aminophylline
S Sedatives, hypnotics
H Heroin (opioids)
Toxicology pearls
hypoventilation (4)
hyperventilation (4)
Hypoventilation
S Sedatives, hypnotics
L Liquor
O Opioids
W Weed (marijuana)
Hyperventilation
P PCP, pneumonitis (chemical)
A ASA (salicylates)
N Noncardiogenic pulmonary edema
T Toxic metabolic acidosis
Toxicology paroles
Miosis (4)
Mydriasis
NMiosis
C Cholinergics, clonidine
O Opioids, organophosphates
P Phenothiazines, pilocarpine, pontine bleed
S Sedatives, hypnotics
Toxicology Pearls
Red Skin (2-3)
Blue Skin (2 + expand)
Red skin: Anticholinergics, boric acid, carbon monoxide
Blue skin: Cyanosis, methemoglobinemia, (nitrates, nitrites, aniline dyes, dapsone, phenazopyridine)
Toxicology Pearls - odors
Bitter almonds or “silver polish”
Mothballs
Garlic (3)
Wintergreen: Methyl salicylate
Carrots
Gasoline
Fruity (2)
Pears
Bitter almonds or “silver polish”: Cyanide
Mothballs: Camphor
Garlic: Arsenic, organophosphate, DMSO
Rotten eggs: Sulfur dioxide, hydrogen sulfide
Wintergreen: Methyl salicylate
Peanuts: Vacor (rat poison)
Carrots: Water hemlock
Gasoline: Hydrocarbons
Fruity: DKA, isopropanol
Pears: Chloral hydrate
Toxicology Pearls
Radioopaque drugs (5)
COINS
C Chloral hydrate, Cocaine packets
O Opiate packets
I Iron, (Heavy metal: Pb, As, Hg)
N Neuroleptic agents
S Sustained release products, enteric coated preparations
Toxicology pearls
noncardiogenic pulmonary edema
MOPS
M Meprobamate, methadone
O Opioids
P Phenobarbital, propoxyphene
S Salicylates
Toxicology pearls
multidose charcoal indications (4)
all bowel irrigation indications (2)
multidose charcoal indications: phenobarbital, sustained-release drugs, salicylates, theophylline
all bowel irrigation indications: sustained-release drugs not absorbed by charcoal, body packing
Toxicology pearls
appropriate for dialysis (7)
Toxic alcohols (methanol, isopropyl alcohol, ethylene glycol), lithium, salicylate, theophylline, phenobarbital
Delayed-release toxicity - many, review
Delayed toxicity
– Acetaminophen
– Digoxin
– Ethylene glycol
– Heavy metals
– Methanol
– Mushrooms
– Narcotics
– Iron
– Salicylates
– Slow release compounds
Anticholinergics/antihistamine
classic cause of severe symptoms and other 2 parts of this drugs toxidrome
EKG changes
TCA -> also causes sodium channel blockade. CNS depression
EKG: tachycardia, QRS wide, dominant R’ in AVR
TCA overdose
treatment
decontamination?
Drug for EKG changes
Drug for ventricular dysrhythmia
decontamination: yes, multidose charcoal, whole bowel irrigation
Drug for EKG changes: bicarbonate
Drug for ventricular dysrhythmia: lidocaine
Barbiturates
toxidrome similar to
treatment (4)
toxidrome similar to opiates
treatment: charcoal, gastric lavage, dialysis, urinary alkalinization
Beta-blocker/CCB
treatment (3-4)
unexpected’s systemic toxicity from this form
treatment: insulin/D5, glucagon, intralipids, calcium for CCB
unexpected’s systemic toxicity from this form: timolol eye drops
Carbon monoxide poisoning
mechanism
lab abnormality to suspect associated toxidrome
SaO2 and PaO2 level
delayed sequela
CO has 250 times the affinity for 02 and inhibits the release of oxygen from hemoglobin (why there is not significant cyanosis; O2 present but bound)
severe metabolic acidosis should suggest associated cyanide
SaO2 and PaO2 level: often normal
delayed: neuropsychiatric syndrome, HBO may prevent
Caustic ingestion
acid necrosis type
alkali necrosis type
Which is worse and why?
Predictive value of oropharyngeal burns with alkali
Acid: coagulation
alkali: liquefaction
alkali since liquefaction necrosis facilitates progression whereas eschar stops progression of coagulation necrosis
predictive value: none
Caustic ingestions
dilute?
Hydrofluoric acid treatment
solid alkali treatment
dilute: generally not as this can induce vomiting
Hydrofluoric acid treatment: magnesium citrate and milk
solid alkali treatment: dilution with water or milk
consider endoscopy
Clonidine
mechanism
toxidrome (3)
mimics? Toxidrome
treatment (3+1?)
mechanism: alpha adrenergic agonist
toxidrome: hypotension, bradycardia, AMS
mimics? Opiate overdose
treatment: fluids, atropine, pressers, naloxone may be helpful
Cyanide
odor
signature lab abnormality
other sx (2+) PaO2 and SaO2 levels
medication -induced cause
treatment principle and medication
Bitter almonds
large AG metabolic acidosis
altered mental status,CV collapse
normal
nitroprusside
induce methemoglobinanemia with hydroxocobalamin (or amyl nitrate, sodium nitrate/thiosulfate etc)
Digoxin toxicity
electrolyte abnormality?
signature EKG abnormality and most common
Antidote, acute and chronic
contraindicated hyperkalemia treatment
Hyperkalemia, hyponatremia (from inhibition of the Na-K pump)
AV blocks, PVCs
Digibind 10 and 6 vials; 20 if severe
calcium (increases toxicity)
Psychedelics - mechanism
hydrocarbons - often cause
gastric emptying?
Serotonin 5HT2 agonist
aspiration pneumonitis
no except when CHAMP
Camphor
Halogenated (carbon tet, PVC, vinyl chloride)
Aromatic (benzene, toluene, xylene)
Metals (leaded gas)
Pesticides
Hydrogen fluoride
mechanism
physical exam caveat
treatment
hydrogen sulfide treatment
Potent inorganic acid used in glass etching
May have deep injuries despite normal appearing skin
calcium gluconate gel, titrate to pain
hydrogen sulfide treatment: use methylene blue for MetHgb; simllar mech to CO
Intractable seizures classic tox cause and tx
Iron poisoning effects (3) and timing
diagnosis
treatment (2)
INH overdose, B6 - pyridoxine
G.I. bleed, inhibits aerobic metabolism, CV collpase/ARF
immediate and delayed phases
4 hour iron level; deferoxamine
Lead poisoning
timing, effective age classic symptom (+ others)
Chronic, children
peripheral neuropathy leading to rest drop, also: ha, encephalopathy, belly pain
Lithium tox
diagnosis
treatment (3+)
Mercury from thermometer toxic?
Symptoms plus a positive level (actual # not reliable)
aggressive hydration, dialysis, lavage, kayexalate
Mercury from thermometer toxic? NO
MAOI inhibitors
mechanism
toxic complication types (2) and drugs for 2nd type
Inhibits breakdown of catecholamines (norepi, epi, serotonin)
hypertensive crisis: with amphetamines, wine, cheese, fava beans
serotonin syndrome/severe hypothermia: meperidine and dextromethorphan
Methhemoglobinemia
mechanism
signature finding and blood color
classic causes
PaO2 level?
Antidote
MetHgb unable to bind O2
hypoxia unresponsive to oxygen; chocolate brown
causes: nitrates, benzocaine, dapone, pyridium
PaO2: normal
methylene blue
Mushroom toxicity
timing Pearl
specific for pictured species
Time from ingestion to symptom onset helps determine risk of significant toxicity
–Symptoms within 2 hours of ingestion indicate benign course if only one type of mushroom ingested
–Symptoms delayed more than 6 hours indicate a toxic ingestion with risk of hepatic and renal failure
Amanita Phalloides: initial G.I. symptoms in 12 hours, then latent, then liver and renal failure in 1 to 2 days
Neuroleptics
side effect categories (5)
treatment (3)
Dystonia, Tardive dyskinesia, Akathesia, anticholinergic,Quinidine like (prolonged QT)
benztropine/Cogentin, Benadryl, benzodiazepines
Neuroleptic malignant syndrome
timing
symptoms (3)
lab clue
treatment (3+)
Subacute onset
AMS, hyperthermia, leadpipe rigidity
elevated CK
fever control, benzodiazepines, dantrolene, bromocriptine, paralysis
Naloxone - duration of action
do non-sulfonylureas cause hypoglycemia?
Metformin complication
sulfonylureas antidote when severe
30 to 60 minutes
no
lactic acidosis
octreotide
Organophosphates mechanism of actions (2)
Toxidrome pneumonic
Inhibit cholinesterases; cholinergic toxidrome and nicotinic effects
cholinergic: SLUDGE + killers Bs
Nicotinic: weakness, fasciculations, respiratory failure
Killer “B”s – Bradycardia, Bronchospasm, Bronchorrhea
S – Salivation
L – Lacrimation
U – Urination
D – Diarrhea
G – Gastrointestinal upset
E – Emesis
Tox, Rotary nystagmus =
toxidrome for toxic plants
deadly nightshade, Henbane, jimsonweed
foxglove, Oleander, Lily of the Valley
tobacco/cigarettes
PCP
anticholinergic
digitalis toxidrome
Pictures - side 1 Jimsonweed, side 2 Foxglove
cholinergic
Salicylates
classic dyad
other symptoms (3)
treatment (2)
product with high amount of salicylate
Anion gap metabolic acidosis, respiratory alkalosis
other symptoms: tinnitus, pulmonary edema, hypoglycemia
urinary alkalinization, dialysis
oil of Wintergreen
Serotonin syndrome
timing
symptoms (with underlying categories)
treatment (2)
Acute
hyperthermia, altered mental status, myoclonus
cooling, cyproheptadine
Easiest way to distinguish from NMS is the acuity
–CNS (altered mental status, coma, seizures)
–Autonomic (hyperthermia, tachycardia, hypertension)
–Neuromuscular (myoclonus, hyperkinesia)
Strychnine mechanism/syndrome
Blocks inhibition of postsynaptic brainstem glycine receptors and spinal cord motor neurons
Results in CNS hyperstimulation
TCA overdose
symptom categories (3)
Anticholinergic, CNS, cardiovascular
Anticholinergic effects
–Flushed skin, dry mouth, mydriasis, decreased bowel sounds, urinary retention
CNS effects
–Drowsiness, confusion, ataxia, delirium, seizures, coma
Cardiovascular effects
–Hypotension, tachycardia, wide QRS, V-tach, torsades
–Right axis deviation (negative S in I, positive R in aVR)
-xabans; best test to assess activity
Pradaxa reversal
Thrombin time
praxabind
