Transcript Toxicology Board Review I

Toxicology Board Review II
Ted Melnick, MD
January 2, 2008
1. Which statement about monoamine oxidase
inhibitor (MAOI) overdose is TRUE?
A. The tyramine reaction typically starts 8-10
hours after ingestion of foods high in
tyramine.
B. Once an irreversible MAOI has been
stopped, a 2-week “washout” period is
necessary before MAO activity returns.
C. Use of epinephrine and norepinephrine are
contraindicated in patients with an MAOI
overdose.
D. For severe hypertension, metoprolol is
consdered first-line therapy and should be
given in 5 mg boluses every 10 min until the
MAP is decreased by 25-30%.
Promes #23-4
1.
A.
B.
C.
D.
Which statement about monoamine oxidase
inhibitor (MAOI) overdose is TRUE?
The tyramine reaction typically starts 8-10 hours
after ingestion of foods high in tyramine. 15-90
minutes
Once an irreversible MAOI has been stopped, a 2week “washout” period is necessary before MAO
activity returns.
Use of epinephrine and norepinephrine are
contraindicated in patients with an MAOI overdose.
Norepi is preferred pressor in overdose
For severe hypertension, metoprolol is consdered
first-line therapy and should be given in 5 mg
boluses every 10 min until the MAP is decreased
by 25-30%. Unopposed alpha,
phentolamine/nitroprusside for BP control
Promes #23-4
Irreversibly block MAO causing accumulation of
norepi and serotonin in presynaptic terminals
MAOIs
• Replaced by SSRI due to toxicity but still used
in refractory cases
• Tyramine (dietary amine): aged meats,
cheeses, wine, fava beans causes release of
• 90 minutes after tyramine: HA, HTN,
tachycardia
• Hyperthermic syndrome: meperidine,
dextromethorpan are contraindicated with
MAOI, can cause severe hyperpyrexic
reaction
2. Which of the following statements about
barbiturates and barbiturate overdose is
TRUE?
A. Barbituric acid, the parent compound for all
barbiturates, is the strongest sedative of all
barbiturates.
B. Higher lipid solubility allows more rapid
transit of barbiturates across the blood-brain
barrier.
C. Longer-acting barbiturates are more lipid
soluble but are more protein bound than
short-acting barbiturates.
D. Multidose activated charcoal is
recommended for all barbiturate overdoses.
Promes #23-7
2. Which of the following statements about
barbiturates and barbiturate overdose is
TRUE?
A. Barbituric acid, the parent compound for all
barbiturates, is the strongest sedative of all
barbiturates. No CNS depressant activity
B. Higher lipid solubility allows more rapid transit
of barbiturates across the blood-brain barrier.
C. Longer-acting barbiturates are more lipid
soluble but are more protein bound than shortacting barbiturates. Less soluble and bound->smaller volume of distribution
D. Multidose activated charcoal is recommended
for all barbiturate overdoses. All need charcoal
multidose only in long acting
Promes #23-7
Barbiturates
• Management guided by duration of effect
• Short acting: Pentobarbital, hepatic
degradation
• Long acting: Phenobarbital, Renal excretion –
dialyzable
• Miosis, hypotension, CNS depression
• Cutaneous bulla = bad prognosis
• Rx: supportive care-intubation, activated
charcoal, alkalinize urine, dialysis
3. Which of the following is an accepted
indication for the use of flumazenil?
A. None--should never be used in the
ED.
B. Unresponsive patients with a
suspicion of benzo overdose.
C. The need to reverse the effects of
benzos given for therpeutic
procedures.
D. Gamma-hydroxybutyrate (GHB)
overdose.
Promes #23-8
3. Which of the following is an accepted
indication for the use of flumazenil?
A. None--should never be used in the ED.
Only if known to not be benzo user/abuser
B. Unresponsive patients with a suspicion of
benzo overdose. Lower seizure threshold
with coingestion, e.g., TCAs
C. The need to reverse the effects of benzos
given for therpeutic procedures.
D. Gamma-hydroxybutyrate (GHB) overdose.
Works on all benzos, ineffective in other
sedative hypnotics like GHB and barbs
Promes #23-8
Flumazenil
• Benzo antagonist
• Not effective in overdose
• Intractable seizures in chronic users,
epileptics, or seizure causing co-ingestant
• Contraindicated in elevated ICP or head
injury
• Short acting-0.2 mg IV q1min to response,
max dose 3 mg
4. Which of the following statements about
cocaine is TRUE?
A. Cocaine has no antiarrhythmic effect on
cardiac conduction.
B. Cocaine accelerates conduction of nerve
impulses via fast sodium channels
activation in the cell membrane.
C. Neuromuscular blocking agents may have a
long duration of effect in patients who have
ingested cocaine.
D. Neuroleptics like haloperidol and droperidol
are very effective at calming the agitation or
psychosis of cocaine-intoxication and
should be considered second-line therapy
after benzodiazepines.
Promes #23-11
4. Which of the following statements about cocaine is
TRUE?
A. Cocaine has no antiarrhythmic effect on cardiac
conduction. Type 1A quinidine effect cause QRS
widening and QTc prolongation
B. Cocaine accelerates conduction of nerve impulses
via fast sodium channels activation in the cell
membrane. In neural tissue
C. Neuromuscular blocking agents may have a long
duration of effect in patients who have ingested
cocaine.
D. Neuroleptics like haloperidol and droperidol are
very effective at calming the agitation or psychosis
of cocaine-intoxication and should be considered
second-line therapy after benzodiazepines. Cause
hyperthermia, dysrhythmia, lower seizure
threshold, benzo’s only!
Promes #23-11
Cocaine
• Blocks presynaptic uptake of
dopamine, serotonin, and norepi
• Sympathomimetic syndrome
• HTN, tachy, seizure, dilated pupils,
hyperthermia, agitation
• Unopposed alpha when giving only betablockers
• Keywords: abruptio placentae, fetal
prematurity, status epilepticus, strokes, MI,
rhabdo
• Cardiac ischemia: ASA, nitro, benzo
5. When comparing acute ingestions of digoxin, ßblockers, and Ca-channel blockers, which of the
following contrasts is INCORRECT?
A. Ca-channel blocker overdoses often present with
mild hyperglycemia, while ß-blocker overdoses
usually present with euglycemia or hypoglycemia.
B. Patients suffering a Ca-channel blocker overdose
often have a normal mental status even when
bradycardic, in contrast to patients with digoxin or
ß-blocker overdoses.
C. Patients with acute digoxin overdose are generally
hyperkalemic, while patients with Ca-channel
blocker overdose are generally slightly
hypokalemic.
D. Digoxin and Ca-channel blocker overdoses can
present with tachydysrhythmias, which are
exceedingly rare in ß-blocker overdoses.
Promes #23-14
5. When comparing acute ingestions of digoxin, ßblockers, and Ca-channel blockers, which of the
following contrasts is INCORRECT?
A. Ca-channel blocker overdoses often present with
mild hyperglycemia, while ß-blocker overdoses
usually present with euglycemia or hypoglycemia.
CCB antagonize pancreatic islet cells
B. Patients suffering a Ca-channel blocker overdose
often have a normal mental status even when
bradycardic, in contrast to patients with digoxin or
ß-blocker overdoses.
C. Patients with acute digoxin overdose are generally
hyperkalemic, while patients with Ca-channel
blocker overdose are generally slightly
hypokalemic.
D. Digoxin and Ca-channel blocker overdoses can
present with tachydysrhythmias, which are
exceedingly rare in Promes
ß-blocker
overdoses. Dig only
#23-14
Nodal blockers and Digoxin
• Digoxin:
– Inhibits Na-K ATPase pump
– Acute overdose: SVT, AV-block, brady, ventricular
dysrhythmias; n/v, AMS
– Chronic overdose: eldery with CRI; GI symptoms,
weakness, AMS, seizure, dysrhythmias
– Antidote: Digoxin-specific Fab/digibind
• Indications: ventricular dysrhythmia, refractory
bradydysrhythmia, K+>5.5
• Dose based on level and pt weight, 5-10 vials if unknown
– Don’t give Calcium
Nodal blockers and Digoxin
• Beta-blocker
– Hypotension, bradycardia, AV block, coma
– Antidote = glucagon bolus and gtt, insulin, glucose
– Other Rx: atropine, epinephrine for hypotension,
pacer
– Propanolol causes sudden CV collapse
• Ca-channel Blocker
–
–
–
–
Leading cause of death from cardiovascular drugs
Bradycardia, hypotension, conduction delay
Antidote = calcium, insulin, glucose
Other Rx: fluids, pacer, pressors, glucagon
6. With respect to hydrocarbon ingestions,
which chemical property of
hydrocarbons has the GREATEST
effect on the risk of an aspiration?
A.
B.
C.
D.
Volatility.
Viscosity.
Flash point.
Surface tension.
Promes #23-16
6. With respect to hydrocarbon ingestions,
which chemical property of
hydrocarbons has the GREATEST
effect on the risk of an aspiration?
A. Volatility. Ability to vaporize
B. Viscosity. Aspiration if low
C. Flash point. No effect, temp gas
ignites
D. Surface tension. Yes, but lesser role
Promes #23-16
Hydrocarbons
• Commonly abused: glue, propellants,
gasoline
– Sniffing: directly from can
– Bagging: from plastic bag
– Huffing: sprayed onto rag
• Aspiration pneumonitis – coughing,
dyspnea, do not induce vomiting, 4-6 hr
delay on CXR
Hydrocarbons
• GI decontamination only in CHAMP
–
–
–
–
–
Camphor
Halogenated (carbon tet, PVC, vinyl-Cl)
Aromatic (benzene, toluene, xylene)
Metals (Pb)
Pesticides
• Discharge only if asymptomatic for 6 hours
and clear CXR
7. A 38-year-old farm worker presents to the ED with
hypersalivation, urinary incontinence, and muscle
weakness, after being in a recently “sprayed” field.
He has prominent wheezing and is producing
copious amounts of clear sputum. Which of the
following statements is TRUE of the treatment for
this condition?
A. Atropine should be administered as 1 mg IV every
5 minutes until muscle weakness has resolved.
B. Supportive care is the only appropriate treatment
for this condition.
C. Pralidoxime will regenerate cholinesterase
molecules if given any time after exposure.
D. Atropine and pralidoxime work synergistically to
treat this condition.
Promes #23-18
7. Which of the following statements is TRUE
of the treatment for this condition?
A. Atropine should be administered as 1 mg IV
every 5 minutes until muscle weakness has
resolved. Until muscarinic effects resolve
B. Supportive care is the only appropriate
treatment for this condition. Atropine and
pralidoxime
C. Pralidoxime will regenerate cholinesterase
molecules if given any time after exposure.
Only if given early
D. Atropine and pralidoxime work
synergistically to treat this condition.
Promes #23-18
Organophosphates
• Pesticides
• Inhibit acetylcholinesterase
• Muscarinic effects: SLUDGE + pinpoint pupils
–
–
–
–
–
–
Salivation
Lacrimation
Urination
Diarrhea
GI upset
Emesis
8. Which of the following vitamins is
CORRECTLY paired with the symptoms
associated with a large ingestion of that
vitamin?
A. Vitamin B1: reddening and itching of the
face, neck, and chest.
B. Vitamin B2: abdominal pain, polyuria,
constipation, and lethargy.
C. Vitamin C: gout and/or nephrolithiasis.
D. Vitamin D: no significant toxicity.
Promes #23-20
8. Which of the following vitamins is
CORRECTLY paired with the symptoms
associated with a large ingestion of that
vitamin?
A. Vitamin B1: reddening and itching of the
face, neck, and chest. Niacin not thiamine,
rx with benadryl
B. Vitamin B2: abdominal pain, polyuria,
constipation, and lethargy. Riboflavin,
nontoxic
C. Vitamin C: gout and/or nephrolithiasis.
D. Vitamin D: no significant toxicity.
Hypercalcemia
Promes #23-20
Vitamins
• Vitamin A/D: hypercalcemia, blurred
vision, pseudotumor cerebri; charcoal, iv
fluid, prednisone, lasix
• Vitamin K: hemolytic anemia,
cardiovascular collapse with rapid iv
infusion
• Vitamin B6: sensory axonal neuropathy
with chronic overdose
9. Which statement about cyanide poisoning is
CORRECT?
A. Clinically, cyanosis can be seen before
frank signs of respiratory failure occur.
B. Cyanide has a weaker affinity for
methemoglobin than normal hemoglobin.
C. Sodium thiosulfate allows the body to turn
cyanide into a less toxic molecule.
D. Cyanide binds hemoglobin more avidly than
oxygen, impairing oxygen delivery to the
tissues.
Promes # 23-21
9. Which statement about cyanide poisoning is
CORRECT?
A. Clinically, cyanosis can be seen before
frank signs of respiratory failure occur.
Cyanide interferes with oxidation at tissue
level O2 sat remains normal, hypoxia after
resp arrest
B. Cyanide has a weaker affinity for
methemoglobin than normal hemoglobin.
Higher
C. Sodium thiosulfate allows the body to turn
cyanide into a less toxic molecule.
D. Cyanide binds hemoglobin more avidly than
oxygen, impairing oxygen delivery to the
tissues. No effect on hemoglobin
Promes # 23-21
10. A 26-year-old psychiatric patient attempted
suicide by swallowing 20 Clinitest tablets
(containing sodium hydroxide) and
“chasing” it with drain cleaner (containing
potassium hydroxide). Of the following
treatment options, which is the MOST
appropriate?
A. Administration of activated charcoal.
B. Nasogastric (NG) tube placement and
dilution with large amounts of water.
C. Neutralization with a weak acid via NG tube.
D. Immediate gastrointestinal consultation for
endoscopic evaluation.
Promes #23-24
10. Of the following treatment options, which is
the MOST appropriate?
A. Administration of activated charcoal. Not
well adsorbed & limits visualization on EGD
B. Nasogastric (NG) tube placement and
dilution with large amounts of water.
Exothermic reaction may result
C. Neutralization with a weak acid via NG tube.
NG by endoscopist in acids only,
exothermic reaction with neutralization
D. Immediate gastrointestinal consultation for
endoscopic evaluation.
Promes #23-24
Caustics
• Usually unintentional and peds <6 yo
• Alkalis have greater potential for proximal
esophageal injury
• Necroses: alkali=liquefactive-full thickness,
acid=coagulative-eschar limits burn
• Oropharyngeal burns are not predictive of
esophageal injury
• Check upright CXR for free air
• Steroids may decrease strictures but increase
infection risk, controversial
11. Which of the following characteristics
imporves a substance’s ability to be
cleared from the blood stream by
hemodialysis?
A.
B.
C.
D.
Small volume of distribution.
Highly protein bound.
Large molecular weight.
Low pKa.
Promes #23-26
11. Which of the following characteristics
imporves a substance’s ability to be
cleared from the blood stream by
hemodialysis?
A.
B.
C.
D.
Small volume of distribution.
Highly protein bound. Not bound
Large molecular weight. Small weight
Low pKa. pKa has no effect
Promes #23-26
Hemodialysis
• Can dialyze:
– Alcohols, lithium,
salicylates, theophylline,
barbiturates
• Can’t dialyze:
– CN, TCA, iron,
benzodiazepines,
phenothiazines,
hallucinogens
12. Which of the following statements concerning
hallucinogens is TRUE?
A. Patients with symptomatic phenycyclidine (PCP)
ingestions should have its excretion enhanced by
acidification of the urine.
B. Jimson weed can be ingested or smoked and can
cause delirium, mydriasis, tachycardia, dry mouth,
dry skin, and urinary retention.
C. Prolonged psychosis following lysergic acid
diethylamide (LSD) ingestion occurs in over 40% of
people who use the drug.
D. Urine tests are useful in distinguishing acute
marijuana usage from usage in the recent past.
Promes #23-29
12. Which of the following statements concerning
hallucinogens is TRUE?
A. Patients with symptomatic phenycyclidine (PCP)
ingestions should have its excretion enhanced by
acidification of the urine. Increases excretion but
also causes rhabdo, not recommended
B. Jimson weed can be ingested or smoked and can
cause delirium, mydriasis, tachycardia, dry mouth,
dry skin, and urinary retention.
C. Prolonged psychosis following lysergic acid
diethylamide (LSD) ingestion occurs in over 40% of
people who use the drug. 5%
D. Urine tests are useful in distinguishing acute
marijuana usage from usage in the recent past.
Days if acute, 2 weeks if chronic
Promes #23-29
Hallucinogens
• LSD, mushrooms, mescaline
• Serotonin antagonism
• Psychosis, anxiety, sympathomimetic
signs
– Tachy, hyperthermia, mydriasis
• Rx: sedation, benzos, haldol-may lower
seizure threshold
13. An 80-year-old female presents
following ingestion of a full bottle of
quinine. Which of the following
potential complications is associated
with quinine toxicity?
A.
B.
C.
D.
Pancytopenia.
Noncardiogenic pulmonary edema.
Hyperkalemia.
Sodium channel blockade.
Promes #23-33
13. An 80-year-old female presents
following ingestion of a full bottle of
quinine. Which of the following
potential complications is associated
with quinine toxicity?
A.
B.
C.
D.
Pancytopenia. No
Noncardiogenic pulmonary edema. No
Hyperkalemia. Hypokalemia
Sodium channel blockade.
Promes #23-33
Quinine
• Most toxic antibiotic
• Antimalarial
• Cause dysrhythmias, cardiovascular
collapse
– increased QRS, increased QT
• Ocular toxicity, hypoglycemia
• Bicarb for prolonged QRS
• Epi is pressor of choice
14. You are called to the resuscitation room to
examine a 34-year-old factory worker
rescued from an industrial plant fire. He is
profoundly hypotensiveand suddenly
becomes apneic. Following airway
management, empiric therapy with which of
the following agents is MOST likely to
benefit this patient?
A.
B.
C.
D.
Oxygen, 100%
Methylene blue and oxygen.
Sodium thiosulfate and oxygen.
Amyl nitrate, sodium nitrite, and oxygen.
Promes #23-34
14. Following airway management, empiric
therapy with which of the following agents is
MOST likely to benefit this patient?
A. Oxygen, 100% Beneficial, sodium
thiosulfate too
B. Methylene blue and oxygen. Antidote for
methemoglobinemia
C. Sodium thiosulfate and oxygen.
D. Amyl nitrate, sodium nitrite, and oxygen.
Nitrites induce methemoglobinemia, but
potentiates coexisting carboxyhemoglobinemia in setting of smoke inhalation
Promes #23-34
15. A 14-month-old child presents after swallowing 2 of
his grandmother’s glyburide pills approximately 3
hours prior to arrival. The patient is currently alert
and playful. Which of the following statements is
TRUE concerning the management of this patient?
A.
B.
C.
D.
The patient is safe for discharge as symptoms
should have developed by 3 hours postingestion.
Prophylactic glucagon is indicated for glyburide
ingestion in a patient without diabetes.
Octreotide would not be useful in refractory
hypoglycemia secondary to sulfonylurea poisoning.
The patient should be admitted and monitored for
up to 24 hours as hypoglycemia may be delayed in
onset.
Promes #23-37
15. Which of the following statements is TRUE
concerning the management of this patient?
A.
B.
C.
D.
The patient is safe for discharge as symptoms
should have developed by 3 hours postingestion.
delayed
Prophylactic glucagon is indicated for glyburide
ingestion in a patient without diabetes. May lack
efficacy due to depleted glycogen, EMS
Octreotide would not be useful in refractory
hypoglycemia secondary to sulfonylurea poisoning.
Useful, inhibit insulin release by pancreatic ß-cells
The patient should be admitted and monitored for
up to 24 hours as hypoglycemia may be delayed in
onset.
Promes #23-37
Sulfonylureas
• Work by increasing insulin prodcution
• Since increase secretion and action of
insulin in response to sugar/food,
feeding/sugar infusions exacerbate the
problem.
• Toxicity can last as long as 72 hours
• Octreotide 50 µg SC Q6 x24 hours