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Toxicology Flashcards

1
Q

What to consider in kids pulled from a housefire??

What signs and symptoms would you see?

A

carbon monoxide, cyanide poisoning
CO: altered mental status +/- cyanosis despite normal pulse ox +/- flu like symptoms if chronic exposure
measure with co-oximeter, treat with 100% non-rebreather, hyperbaric O2
cyanide: headache, dizziness, fast heart rate, shortness of breath, and vomiting. Followed by seizures, slow heart rate, low blood pressure, loss of consciousness, and cardiac arrest

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2
Q

Which medications are potentially life threatening to a 10kg toddler following the ingestion of a single dose?

A 
Sulfonylureas
Propranolol
Clonidine
Calcium channel blockers 
Quinidine (class 1a anti-arrhythmic) 
Disopyramide (antiarrhythmic, Na-channel blocker)
Flecainide (class 1c anti-arrhythmic) 
Chlorpromazine (antipsychotic)
Clozapine (atypical antipsychotic)
Cyclic antidepressants
Hydroxychloroquine (antimalarial) 
Chloroquine (antimalarial)
Buprenorphine (opioid)
Methadone
Diphenoxylate/atropine (lomotil)
Methyl salicylate (wintergreen essential oil)
Camphor (evergreen oil)
Benzocaine (orogel)
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3
Q

What three antidotal drugs should be considered in the resuscitation of the comatose child?

A

oxygen
glucose
naloxone

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4
Q

What basic 5 elements go into the assessment of a toxidrome?

A 
Mental status
Vital signs
pupil size and reactivity
skin color and moisture
bowel sounds
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5
Q

How can you distinguish an anticholinergic toxidrome from a sympathomimetic toxidrome?

A

Both have delirium, psychosis, seizures, increased HR, BP, temperature and pupil size.

In anticholinergic poisoning, the pt has sluggishly reactive pupils, absent bowel sounds and flushed but DRY skin.
Sympathomimetic patients are more likely to be agitated.

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6
Q

What common drugs or intoxicants are poorly absorbed by activated charcoal?

A

ineffective: alcohol, iron, lithium

poorly effective: hydroxycarbons, metals

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7
Q

What are indications for activated charcoal?

A
  • substance known to bind well
  • intact or protected airway (intubated)
  • within 60 minutes of ingestion
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8
Q

List possible indications for whole-bowel irrigation

A 
ingestion of metals, lithium
ingestion of sustained release medications
ingestion of patches
massive overdoses
concretions of pills
body packers or stuffers
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9
Q

Lipid emulsions should be considered (in consultation with a toxicologist) after what ingestions?

A 
bupivacaine
verapamil
beta-blockers
some TCAs
chlorpromazine
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10
Q

What factors predict adequate removal of a poison by hemodialysis?

name 5 examples

A
  • small volume of distribution
  • little protein binding
  • water soluble
  • low molecular weight
  • low endogenous clearance
  • single compartment kinetics

ie: ethylene glycol, lithium, methanol, salicylate, theophylline

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11
Q

Describe the rationale behind urinary alkalinization, what are potential pitfalls?

A

adminitering sodium bicarb or acetate to raise the urine pH to 8 so that renally excreted toxicants, weak acids, are converted to their ionized form within the proximal tubules and not reabsorbed distally (ion trapping). Used in cases like salicylate, phenobarb poisoning, rhabdomyolysis

pitfalls: inhibited in the presence of hypokalemia, associated with pulmonary and cerebral edema, fluid administration to be monitored carefully

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12
Q

Describe the pathophysiology of acetaminophen poisoning

A

After acute overdoses of >150mg/kg/day, the typical metabolism expends all glutathione and results in p450 cytochrome oxidase metabolism and N-acetyl-p-benzoquine. The latter metabolite is toxic to hepatocytes and causes centrilobular liver necrosis.

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13
Q

What are the 4 stages of acetaminophen poisoning?

A

1 (30 minutes-24hrs) often asymptomatic, occasionally nausea, vomiting, diaphoresis, pallor
2 (24-48hrs) nausea, vomiting, RUQ pain, enzymitis
3 (72-96 hrs) fulminant hepatic failure with jaundice, thrombocytopenia, prolonged PTT, hepatic encephalopathy, renal failure, cardiomyopathy
4 resolution

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14
Q

What is the antidote for acetaminophen overdose and how does it work?

A

N-acetylcysteine (NAC)
it replenishes and substitutes for depleted glutathione stores
best benefit if given within 8 hrs of ingestion, IV over 21 hrs
risk of anaphylaxis

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15
Q

What is the approach to acute salicylate poisoning?

When to start advanced care?

A 
Activated charcoal
IV fluids
Urinary alkalization (mild alkalemia will reduce access to the brain)

Avoid intubation or at least mimic resp alkalosis (resp acidemia increases transit to brain)

Hemodialysis if metabolic acidosis, pulmonary edema, severe renal impairment, coma or seizures, liver impairment, level >70mg/dL

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16
Q

How does iron produce toxicity? What does it manifest as?

A

GI stage: vomiting, diarrhea, hypotension (mucosal irritant)

Quiescent stage: stop vomiting and labs worsen

Multiorgan failure with GI hemorrhage and shock (inhibitor of oxidative phosphorylation in the mitochondria)

occasionally 4-6 weeks later gastric scarring with pyloric obstruction

deferoxamine treatment if symptomatic or levels 350-500 can induce hypotension and vin rose pee
no mode of iron excretion (aside from bleeding)

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17
Q

How much iron is toxic? What are the ranges and expected toxicity?

A 
dose ingested: toxicity
20-60mg/kg : mild gastrointestinal symptoms
60-100mg/kg : moderate toxicity
100-200mg/kg : serious toxicity
>200mg/kg : possibly lethal
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18
Q 
How much iron is present in the following commonly available preparations?
ferrous sulphate
ferrous gluconate
ferrous fumarate
Feosol elixir
chewable vitamins
infant liquid vitamins
A 
ferrous fumarate: 105mg (32% 325mg tab)
ferrous sulphate: 65mg (20% 325mg tab)
ferrous gluconate: 40mg (12% 325mg tab)
Feosol elixir: 44mg/5mL
chewable vitamins: 4-18mg
infant liquid vitamins: 10mg/mL
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19
Q

What is the antidote for iron poisoning?

Risks?

A

Deferoxamine, an iron chelator
5-15mg/kg/hr

associated with pulmonary fibrosis and ARDS

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20
Q

List the major toxicities of cyclic antidepressants

A
  • dysrhythmia (sodium channel blockers in cardiac conduction system)
  • seizures
  • alpha-1 adrenergic blockade
  • inhibition of norepinephrine reuptake
  • anticholinergic toxicity
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21
Q

What electrocardiographic findings correlate wtih potential toxicity from cyclic antidepressants?

A

QRS complex > 0.1 seconds
prolonged QTc for age
R wave height greater than 3 mm for age

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22
Q

What treatment to consider for ventricular dysrhythmia with prolonged QRS interval?

A

consider drug-induced dysrhythmias and give sodium bicarbonate! it has been shown to narrow the QRS and improve function
many agents that cause v-tach in overdose block the fast sodium channels

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23
Q

What ingestions can cause a brady-dysrhythmia and how to treat?

A

beta blockers
calcium channel blockers
digitalis-containing compounds
clonidine

treat as per PALS: atropine, ephinephrine, pacing
beta blockers -> glucagon, calcium, insulin, lipid emulsions
calcium channel blockers -> calcium, insulin/glucose, lipids
digitalis-containing compounds -> digoxin-specific Fab

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24
Q

How do you treat poison-induced seizures?

Name two special considerations in specific poisoning of cyclic antidepressants and isoniazid

A

Benzodiazepines 1st line
Barbituates (phenobarbital) 2nd line

in cyclic antidepressant overdose DO NOT give IV phenytoin as cardiovascular effects may be complicated

in isoniazid overdose, they need PYRIDOXINE

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25
Describe the findings in a clonidine overdose
``` miosis coma apnea bradycardia hypotension ... can mimic opioid ingestion, however clonidine kids often transiently respond to stimulation ```
26
Hallucinations or psychosis are prominent in which drugs of abuse?
- anticholinergics (antihistamines, Jimsonweed) - dissociatives (PCP, ketamine, dextromethorphan) - hallucinogens (LSD, psilocybin, mescaline) - sympathomimetics (amphetamines, cocaine, MDMA, bath salts, synthetic cannabinoids) - withdrawal from ethanol or sedative-hypnotics
27
Why should neuroleptics be cautiously used in drug-induced agitation?
they lower the seizure threshold, may compound cardiovascular toxicity, may limit ability to dissipate heat use benzos benzos benzos
28
Name 7 hyperthermic syndromes in toxicology
1) sympathomimetic 2) anticholinergic 3) neuroleptic malignant syndrome 4) malignant hyperthermia 5) serotonin syndrome 6) uncoupling oxidative phosphorylation (salicylate) 7) acute withdrawal
29
What findings characterize serotonin syndrome?
autonomic hyperactivity increased neuromuscular tone (LEs especially) hyperreflexia CNS depression
30
What are bath salts?
synthetic canthiones, related to khat has similar features to amphetamine overdose notable for prolonged agitation, aggressive and violent behaviour, hallucinations, paranoia, seizures
31
How is the osmolar gap calculated? | What is normal
osmolar gap= measured osmolality - calculated osmolality calculated osmolality= 2(Na) + BUN + glucose Normal gap -7 to 10 mOsm
32
List causes of a large osmolar gap
``` acetone ethanol glycols isopropanol magnesium mannitol methanol renal failure severe ketoacidemia severe lactic acidemia ```
33
What are symptoms of TCA overdose? What is the treatment? What should you NEVER give?
Present with altered mental status, anticholinergic toxicity, seizures, wide-complex tachycardias (QRS >100msec). Treat with NaHCO3, secure airway, activated charcoal if <2hrs. Do not give: - procainamide (worsens cardiac delay) - physostigmine (increases seizures) - dopamine (ass' w/ vent dysrhythmias)
34
What is the antidote of choice for beta-blocker toxicity?
Glucagon
35
How is the osmolar gap calculated? | What is normal?
2{Na}+BUN+glucose | -7 to 10 mOsm
36
List potential causes of an osmolar gap
- acetone - ethanol - glycols - isopropanolol - magnesium - mannitol - methanol - renal failure - severe ketoacidemia - severe lactic acidemia
37
How is alcohol metabolized?
According to zero order kinetics, typically it decreases by 15mg/dL/hr
38
What are the toxic metabolites of ethylene glycol and methanol? What tissues do they damage? How to treat
methanol -> formic acid, toxic to the retina ethylene glycol -> glycolic and oxalic acids, toxic to the kidneys alcohol dehydrogenase is responsible for the dangerous transformation, therefore keep it busy with ethanol or fomepizole adjunctive treatments are folic acid for formic acid pyridoxine and thiamine for glycolic acids
39
What characteristics of hydrocarbon ingestion make them prone to aspiration? What's the clinical presentation?
- low viscosity - low surface tension - high volatility Children may cough, gag or sputter at the time. Gradually pneumonitis may develop, usually within 6hrs and 98% within 24hrs.
40
Which hydrocarbons are notable for systemic toxicity?
``` CHAMPs Camphor Halogenated hydrocarbons (carbon tetrachloride, tricholoethane) Aromatic hydrocarbons (benzene, toluene) Metal-containing hydrocarbons Pesticide-containing hydrocarbons ``` CNS depression, seizures, hepatotoxicity, nephrotoxicity, bone marrow toxicity
41
What are the clinical manifestations of organophosphate or carbamate insecticide poisoning?
1) Muscarinic effects (pre&post ganglionic parasympathomimetic) DUMBELS or SLUDGE with killer B's 2) Nicotinic effects (preganglionic sympathomimetic) tachycardia 3) Nicotinic effects (neuromuscular endplate) muscle fasciculations and weakness 4) CNS system effects depressed consciousness and seizures DUMBELS: diarrhea, diaphoresis, urination, myosis, bradycardia and bronchorrhea, lacrimations, salivation SLUDGE B's: salivation, lacrimation, urination, diarrhea, GI cramping, emesis, bronchorrhea, bradycardia, bronchospasm
42
What is the treatment for organophosphate or carbamate poisoning?
Atropine; repeat dose every 5 minutes with doubling (targets muscarinic effects) END POINT OF THERAPY IS THE DRYING OF SECRETIONS **PULMONARY Pralidoxime (2-PAM) for organophosphates only, dislodges the aged acetylcholine esterase inhibitor (it regenerates active acetylcholinesterases) Benzodiazepine
43
What toxins would you consider for hemodialysis?
alcohols salicylates theophylline lithium NO digoxing, NO TCAs (large volume of distribution)
44
How do you calculate an anion gap? What is the normal range?
AG= [Na] - [Cl] - [HCO3] | normally <11
45
What is the antidote for acetaminophen
NAC
46
What is the antidote for aspirin
NaHCO3 & hemodialysis
47
What is the antidote for carbamate
atropine and diazepam | not pralidoxime
48
What is the antidote for warfarin
vitK FFP
49
What is the antidote for hydrofluoric acid
Calcium, magnesium
50
What is the antidote for isoniazid
pyridoxine
51
What is the antidote for TCAs
NaHCO3
52
What is the antidote for CO
oxygen | hyperbaric oxygen
53
What is the antidote for beta blockers
glucagon, calcium, insulin, lipid emulsions
54
What is the antidote for calcium channel blockers
glucagon, insulin, calcium, intralipid
55
What is the antidote for heavy metals
chelators (BAL, EDTA)
56
What is the antidote for iron
Defuroximine
57
What is the antidote for cyanide
hydroxycobalamine
58
How can you differentiate bradycardic intoxications from digoxin, clonidine, beta-blockers and calcium channel blockers ?
digoxin: hyperkalemia, arrhythmias in atria and ventricle, AV block, give Fab fragments clonidine: looks like opioid with coma, pinpoint, resp depression. Supportive care beta-blockers: hypoglycemia, treat with IVF, pressors, glucagon, calcium, insulin... ECMO calcium-channel blockers: inhibits insulin release therefore hyperglycemia... ECMO
59
What is the suffix for sulfonylureas? What is the mechanism of action? What is the antidote in intoxications?
-ide, like glipizide increases insulin release from the pancreas Rx Octreotide (somatostatin analogue) and 2nd line glucagon
60
What is the differential diagnosis for a wide osmolar gap?
(ShARP) ¤ Sugar (mannitol,sorbitol) ¤ Alcohols(Ethanol, methanol, ethylene glycol, isopropyl) ¤ Renal Failure ¤ Pseudo-hyponatremia (hyperlipidemia, hyperproteinemia)
61
Name drugs that are readily removed by dialysis
``` STUMBLED ¤ Salicylates ¤ Theophylline/Caffeine ¤ Uremia ¤ Methanol ¤ Barbiturates ¤ Lithium ¤ Ethylene Glycol ¤ Depakote (Valproic Acid) ```
62
Name indications for hyperbaric oxygen therapy in carbon monoxide poisoning
̈ Neuro symptoms: Syncope, Coma, Seizure, Altered Mental Status/Confusion ̈ Acidosis ̈ COHgB >25% ̈ COHgB>20% in pregnancy
63
What are indications for urine drug screening?
``` No absolute indications, only relative indications ¤ Child abuse ¤ Acute psychosis NYD ¤ Altered LOC NYD ¤ Drug packer ```
64
Which people should drink charcoal quickly?
``` These People Should Drink Charcoal Quickly Theophylline Phenobarbital Salicylates Dapsone Carbamazepine Quinine ```

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