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USMLE Step 3 > Emergency Medicine/Toxicology > Flashcards

Emergency Medicine/Toxicology Flashcards

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USMLE® Step 1 flashcards
1
Q

What is the most important step for an acute change in mental status of unclear etiology (e.g. after suicide attempt)?

A
  • antidotes (e.g. naloxone, dextrose, thiamine)

- On a CCS case, also give O2 and saline while checking tox screen (all at same time)

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2
Q

When do I answer “gastric emptying?”

A

the answer is almost ALWAYS wrong, only useful in 1st hour after OD (removes ~50% of pills); you can NEVER do this when caustics (acids and alkalis) have been ingested

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3
Q

Is ipecac ever the right answer?

A

It seems like likely not (and especially not in pt w/ AMS and kids)

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4
Q

When can intubation and lavage be performed?

A

rarely; only done if pt has ingested the substance w/i last 1-2 hours and there is NO response to naloxone, thiamine, and dextrose

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5
Q

When do I give charcoal?

A

just give it, no harm; will help in most OD cases

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6
Q

What is the “overdose case menu” in CCS OD cases?

A
  • specific antidote if etiology clear
  • tox screen
  • charcoal
  • CBC, BMP, U/A
  • psych consult if OD result of suicide attempt
  • O2 for CO poisoning or any dyspneic patient
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7
Q

What is the antidote for acetaminophen?

A

N-acetyl cysteine

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8
Q

What is the antidote for ASA?

A

bicarbonate to alkalinize the urine

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9
Q

What is the antidote for benzodiazepines?

A

do NOT give flumazenil; may precipitate a SZ

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10
Q

What is the antidote for carbon monoxide?

A

100% O2; hyperbaric in some cases

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11
Q

What is the antidote for digoxin?

A

digoxin-binding antibodies (in severe disease i.e. CNS and cardiac abnormalities)

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12
Q

What is the antidote for ethylene glycol?

A

fomepizole or ethanol

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13
Q

What is the antidote for methanol?

A

fomepizole or ethanol

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14
Q

What is the antidote for methemoglobinemia?

A

methylene blue

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15
Q

What is the antidote for neuroleptic malignant syndrome?

A

bromocriptine, dantrolene

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16
Q

What is the antidote for opiates?

A

naloxone

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17
Q

What is the antidote for organophosphates?

A

atropine, pralidoxime

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18
Q

What is the antidote for tricyclic antidepressants?

A

bicarbonate protects the heart

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19
Q

What is the clinical course of acetaminophen OD?

A
  • 1st 24 hours: N/V, which resolve

- 48-72 hrs: hepatic failure

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20
Q

For how long is N-acetyl cystine useful to prevent liver toxicity from acetaminophen OD?

A

24 hours; after that, it is useless and there is no specific tx to prevent/reverse toxicity

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21
Q

How can you give NAC in acetaminophen OD pt who is vomiting?

A

NAC IV

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22
Q

What blood level of acetaminophen is toxic? Fatal?

A

10 g; 15 g (lower if underlying liver disease or alcohol abuse)

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23
Q

What physical exam findings are present in ASA/salicylate overdose?

A

hyperventilation but NO DYSPNEA (stimulant to brainstem), tinnitus, +/- confusion, fever, seizures, coma

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24
Q

What lab findings do you see in ASA/salicylate OD?

A

metabolic acidosis w/ elevated anion gap, respiratory alkalosis (precedes metabolic acidosis), renal insufficiency (ASA directly toxic to kidneys), elevated PT (ASA interferes with Vit K-dependent clotting factors)

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25
Q

What do you order in ASA/salicylate OD pt?

A
  • CBC
  • BMP
  • ABG
  • PT/INR/PTT
  • salicylate (ASA) level
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26
Q

Tx for ASA/salicylate OD?

A
  • alkalinize the urine with D5W w/ 3 amps of bicarbonate
  • charcoal
  • dialysis in severe cases
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27
Q

What substances does alkalinization of the urine help facilitate excretion of?

A
  • salicylates (ASA)
  • TCAs
  • phenobarbital
  • chlorpropamide (sulfonylurea used to treat T2DM)
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28
Q

Tx for benzodiazepine OD?

A

Let the patient sleep! Benzos by themselves are not fatal. The OD will pass. Do not administer flumazenil in the ED - you do not know who has chronic dependency and you do not want to precipiate a withdrawal and SZs.

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29
Q

What are the presenting sxs of CO poisoning?

A

SOB, lightheadedness/HA, disorientation, metabolic acidosis from tissue hypoxia

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30
Q

How does digoxin poisoning most commonly present?

A

GI disturbance (N/V, diarrhea, pain), +/- pt seeing “yellow halos” around objects, blurred vision, arrhythmias, encephalopathy

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31
Q

What lab abnormality is seen in digoxin poisoning?

A

hyperkalemia (poisoning of Na+/K+ ATPase)

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32
Q

What lab abnormality is common to both ethylene glycol and methanol OD?

A

metabolic acidosis with increased anion gap

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33
Q

What organ system does ethylene glycol OD particularly affect?

A

kidney (renal insufficiency from direct toxicity, hypocalcemia from precipitation of oxalic acid w/ Ca2+, kidney stones)

Also causes rapid and deep breathing (Kussmaul’s respirations), N/V, slurred speech, ataxia, nystagmus, lethargy

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34
Q

What organ system does methanol OD particularly affect?

A

eyes (visual disturbance, retinal hyperemia from toxicity of formic acid)

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35
Q

How are ethylene glycol and methanol OD treated?

A
  • fomepizole (antidote of choice; inhibitor of ADH)

- dialysis to remove them from the body before they are metabolized into the toxic metabolite

36
Q

Physiologically, what happens in methemoglobinemia?

A

hemoglobin is locked in an oxidized state that will not allow it to pick up oxygen

37
Q

How does methemoglobinemia present?

A

cyanosis, SOB, dizziness, HA, confusion, SZs

38
Q

What drugs can precipitate methemoglobinemia?

A

nitrates, anesthetics, dapsone, other oxidants, any of the drugs ending in -caine (lidocaine, benzocaine, bupivacaine), nitroglycerin

39
Q

Dx of methemoglobinemia?

A
  • normal pO2 on ABG with chocolate-brownish blood (oxidized blood)
  • methemoglobin level
40
Q

Tx of methemoglobinemia?

A

100% O2, methylene blue restores the hemoglobin to its normal state

41
Q

What will usually be in the history of a patient with neuroleptic malignant syndrome?

A

ingestion of neuroleptic meds (e.g phenothiazines)

42
Q

Lab abnormalities in NMS?

A

CPK and K+ can be elevated

43
Q

Physical exam findings in NMS?

A

muscle rigidity

44
Q

What is usually in history of pt with malignant hyperthermia?

A

h/o anesthetic use

45
Q

Tx of malignant hyperthermia?

A

dantrolene

46
Q

Tx of heat stroke?

A

physical removal of heat from body (spray patient with water and fan patient in air conditioned room or use ice baths/packs); do NOT infuse iced saline into body - this can stop the heart

47
Q

Why do people die in opiate OD?

A

death from respiratory depression

48
Q

Mechanism in organophosphate poisoning?

A

inhibition of acetylcholinesterase

49
Q

What should you look for in hx with organophosphate poisoning?

A
  • crop duster exposed to insecticides

- nerve-gas attack

50
Q

What are presenting sxs in organophosphate poisoning?

A

salivation, lacrimation, urination, diarrhea, wheezing from bronchospasm, bradycardia, skin flushing, miosis, garlic-like odor on clothes

51
Q

Tx of organophosphate poisoning?

A
  • best initial tx: atropine
  • most effective tx: pralidoxime
  • remove the clothes and wash the rest off the patient
52
Q

Death from TCA overdose occurs from what?

A

seizures, arrhythmias

53
Q

If you suspect TCA OD in a patient, what is the first step?

A

EKG –> if widened QRS, give bicarbonate (otherwise, don’t)

54
Q

What are the physical exam findings in TCA OD?

A

dilated pupils, dry mouth, dry skin, constipation, urinary retention (anticholinergic effects)

55
Q

Presenting sxs of black widow spider bite?

A

abdominal pain, rigidity, hypocalcemia, pain WITHOUT tenderness

56
Q

Tx of black widow spider bite?

A

antivenin

57
Q

Presenting sxs of brown recluse spider?

A

local necrosis, bullae, dark lesions

58
Q

Tx of brown recluse spider bite?

A

debride the wound

59
Q

What is the 1st step in a burn patient?

A

100% O2! (most common cause of death is CO poisoning)

60
Q

After 100% O2 administration, what do you do next for a burn pt?

A

look for hoarseness, wheezing, stridor, burns inside the nose or mouth - if none, give fluids (4 mL LR or NS for each % w/ a 2nd or 3rd degree burn for each kilogram)

61
Q

What is the most common cause of death later on for a burn patient?

A

infection

62
Q

How does hypothermia kill?

A

arrhythmias (J waves of Osborn, look like ST elevation, on EKG)

63
Q

How does acute angle closure glaucoma present?

A

red eye, fixed midpoint pupil

64
Q

Tx of acute angle closure glaucoma?

A 
pilocarpine drops (to constrict pupil)
-other therapies = acetazolimide (decreases production of aqueous humor), prostaglandin analogues (latanoprost, travoprost), beta blockers topically (timolol), alpha agonists (apraclonidine)
65
Q

How does retinal detachment present?

A

sudden loss of vision “like a curtain coming down”

66
Q

Tx of retinal detachment?

A
  • consult ophthalmology, perform dilated retinal exam

- reattach by: tilting head back, reattach w/ surgery, cryotherapy, by injecting expansile gas into eye

67
Q

Presentation of conjunctivitis?

A
  • viral: bilateral watery discharge, itchy eyes

- bacterial: unilateral purulent discharge, eyelids stuck together

68
Q

Dx of conjunctivitis?

A

clinical

69
Q

Tx of conjunctivitis?

A

topical Abx (if bacterial) - Erythromycin ointment

70
Q

Presentation of uveitis?

A

photophobia

71
Q

Dx of uveitis?

A

slit lamp exam (leukocytes in anterior chamber)

72
Q

Tx of uveitis?

A

antimicrobial for viral or bacterial; steroids for non-infectious

73
Q

Presentation of corneal abration?

A

h/o trauma, most commonly from contact lenses

74
Q

Dx of corneal abrasion?

A

fluorescein stain picks up on damaged cornea

75
Q

Tx of corneal abrasion?

A

NO specific tx; do NOT patch abrasions caused by contact lenses

76
Q

How do calculate an anion gap?

A

Na - [HCO3 + Cl-] (normal = 12, range 8-16)

77
Q

Dx of CO poisoning?

A

CO-oximetry

78
Q

Dx of organophosphate poisoning?

A

RBC cholinesterase (but hard to perform)

79
Q

Sxs of PCP intoxication?

A

disorientation, restlessness, tachycardia, hypertension, b/l vertical nystagmus

80
Q

Tx of PCP intoxication?

A
  • low-stim environment, metabolic and hemodynamic control
  • if agitation or SZ –> benzos
  • if aggression –> Haloperidol
81
Q

Sxs of lead poisoning?

A

anorexia, decreased activity, irritability, vague abd pain, insomnia, neurocognitive defects

82
Q

Dx of lead poisoning?

A

CBC, serum iron and ferritin, retic ct, blood lead level

83
Q

Tx of dry chemical burns with powder?

A

Brush off first, then rinse with low-pressure water x 15-30 min

84
Q

Tx of hypothermia?

A
  • if hypoventilation –> intubation
  • if hypotension –> fluids
  • then, active rewarming with warm IV fluids
85
Q

Cause of scombroid?

A

improperly stored seafood (histidine –> histamine!)

86
Q

Sxs of scombroid?

A

flushing, throbbing HA, palpitations, abd cramps, diarrhea, skin erythema, oral burning

USMLE Step 3 (7 decks)

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