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Medical Emergencies > Toxicology > Flashcards

Toxicology Flashcards

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USMLE® Step 1 flashcards
1
Q

outline

A
  • basic approach
  • toxidromes
  • decontamination
  • diagnostics
  • acetaminophen basics (APAP)
  • observation
  • toxicology consultation
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2
Q

General approach

A
  • ABCs
  • history
  • physical examination
  • labs, imaging
  • diagnosis, antidotes
  • disposition
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3
Q

REASSES

A

-frequently!!

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4
Q

history

A
  • what, when, how, much, why?
  • Rx. OTC. herbals, supplements, vitamins
  • talk to family, friends, EMS
  • pill bottles, needles, beer cans, suicide note
  • call pharmacy
  • comorbidities
  • allergies, medical problems
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5
Q

physical examination

A
  • vital signs: BP, HR, RR, temp, O2 sat
  • mouth- odors, mucous membranes
  • pupils
  • breath sounds
  • bowel sounds
  • skin
  • urination/defecation
  • neurologic exam
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6
Q

essential laboratory tests

A
  • electrolytes:
  • hyponatremia – lithium intox from DI, amitriptyline
  • hypokalemia – theophylline, B2 agonist, acidosis
  • glucose- BB, caffeine, theophylline – can cause hyoglycemia
  • propanol, insulin, salcylates – can cause hyperglycemia
  • BUN and creatinine- renal
  • LFTs- tylenol, arsenic, ethanol, iron, valproic acid
  • CK- rhabdo, rigidity, arrhythmias - PCP, cocaine, amphetamines
  • urinalysis, urine drug screen- hemoglobinuria, myoglobinuria, crystalluria
  • Etoh, alcohol screen
  • acetaminophen, salicylates
  • specific drug levels
  • pregnancy tests
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7
Q

prolonged QRS

A
  • TCAs (tricyclic antidepressant)
  • phenothiazines
  • calcium channel blockers
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8
Q

sinus bradycardia/AV block

A
  • beta blockers, calcium channel blocker
  • TCAs
  • digoxin
  • organophosphates
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9
Q

ventricular tachycardia

A
  • cocaine, amphetamines
  • chloral hydrate
  • theophylline
  • digoxin
  • TCAs
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10
Q

acetaminophen **

A

antidote- N-acetylcysteine

  • usually IV
  • common overdose with pediatrics
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11
Q

organophosphates **

A

antidote- atropine (anticholinergic)

  • pupils dilated, lacrimation, vomiting (everything coming out)
  • chemicals, hazmat
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12
Q

anticholinergic **

A

-antidotes- physostigmine

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13
Q

benzodiazepines **

A

-antidote- flumazenil

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14
Q

beta blockers**

A
  • antidote- glucagon

- beta blockers are BP medications -> BP will be too low

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15
Q

calcium channel **

A

-antidote- calcium

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16
Q

carboxyhemoglobin **

A

antidote- 100% O2

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17
Q

opioids

A
  • antidote- naloxone (narcan)
  • IV, up nose
  • fentanyl
  • pale, pinpoint pupils, altered
  • decompensate
  • oxycodone
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18
Q

salicylate (ASA)**

A

-antidote- alkalization

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19
Q

TCAs ** (tricyclic antidepressants)

A
  • antidote- sodium bicarbonate

- respiratory distress

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20
Q

warfarin**

A

-antidote- FFP, vitamin K

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21
Q

diagnosis

A
  • may not identify ingested substances
  • provide ABCs and supportive care
  • give antidote when appropriate
  • call regional poison control center
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22
Q

unconscious unresponsive patient in the EM…

A
  • ABCs
  • blood work
  • urinalysis (catheter)
  • call friends, family, pharmacy, neighbors, primary MD
  • just by look at a pill you can google it
  • be skeptical if patient is lying (especially suicidal)
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23
Q

establish a pattern to his symtpoms

A
  • toxic syndrome

- aka TOXIDROME

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24
Q

toxidrome

A

not every drug fits into a broad based category

  • lots of meds have unique effects not easily grouped
  • 5 basic toxidromes:
  • sympathomimetic
  • optiate
  • anticholinergic
  • cholinergic
  • sedative hypnotic
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25
Q

toxidromes: sympathomimetic

A
  • cocaine
  • methamphetamine/amphetamines
  • ecstasy (MDMA)
  • ADHD meds like Ritalin, Adderall
  • ephedrine
  • caffeine
  • excessive sympathetic stimulation involving epinephrine, norepinephrine, and dopamine
  • excessive stimulation of alpha and beta adrenergic system
  • tachycardia
  • arrhthmias
  • hypertension
  • ICH
  • confusion with agitation
  • seizures
  • rhabdomyolysis- renal failure can result
26
Q

sympathomimetic treatment

A
  • supportive care- monitor airway, diagnose ICH, rhabdo
  • IVF for insensible loses and volume repletion
  • Benzos!!!!
  • BP management if severe
  • CNS excitation -> behavioral agitation -> cardiac excitation ->
27
Q

toxidrome: opiate

A

opiate- derived directly from the opium poppy

  • morphine and codeine
  • much broader class of agents that are capable of producing opium like effects or of binding to opioid receptors
  • deadly- respiratory, cardiac arrest
  • heroin
  • methadone
  • hydrocodone
  • oxycodone
  • fentanyl
28
Q

risks of opiates

A
  • coma
  • miosis
  • respiratory depression
  • peripheral vasodilation
  • orthostatic hypotension
  • flushing (histamine)
  • bronchospasm
  • pulmonary edema
  • seizures
29
Q

opioid treatment

A
  • competitive opioid antagonist- naloxone
  • goal of return of spontaneous respirations sufficient to ventilate the patient appropriately
  • may have to re-dose as opiates may act longer than antagonist
  • there are other longer acting opioid antagonists such as nalmefene and naltrexone but these are not often used
30
Q

toxidrome: anticholinergic

A
  • ACh receptors are either nicotinic or muscarinic
  • the anticholinergic drugs just block the muscarinic receptors (SLUGEM)
  • some have argued that the anticholinergic poisoning syndrome should be called the antimuscarinic poisoning syndrome because you do not see anti-nicotinic symptoms
31
Q

what does wrong with anticholinergics

A
  • CNS muscarinic blockage:
  • confusion
  • agitation
  • myoclonus
  • tremor
  • picking movements
  • abnormal speech
  • hallucinations
  • coma
  • peripheral muscarinic effects:
  • mydriasis
  • anhidrosis
  • tachycardia
  • urinary retention
  • Ileus
32
Q

anticholinergics treatment

A
  • supportive care- IVF to replace insensible losses from agitation, hyperthermia
  • benzos to stop agitation
  • physotigmine:
  • induces cholinergic effects
  • short acting
  • may help with uncontrollable delirium
  • do not use if ingestion not known -> danger with TCAs
33
Q

toxidrome: cholinergic

A
  • D- diarrhea
  • U- urination
  • M- miosis
  • BBB- bradycardia, bronchorrhea, bronchospasm
  • E- emesis
  • L- lacrimation
  • S- salivation
  • S- salivation
  • L- lacrimation
  • U- urination
  • D- diaphoresis
  • G- gastrointestinal upset- vomiting, diarrhea
  • E- eye- miosis
34
Q

toxidrome- cholinergic treatment

A
  • antagonize muscarinic symptoms- atropine
  • stop aging of enzyme blockage- 2-PAM
  • prevent and terminate seizures- diazepam
  • supportive care
35
Q

toxidrome- sed-hypnotic

A

different agents have different mechanisms

-may interfere in the GABA system

36
Q

sed-hypnotic- what goes wrong

A
  • CNS depression
  • lethargy
  • can induce respiratory depression
  • can produce brady cardia or hypotension
37
Q

sed-hypnotic treamtent

A
  • supportive care
  • be wary of the benzo “antidote” flumazenil
  • is an antagonist at the benzo receptor
  • RARELY INDICATED
  • if seizures develop either because of benzo withdrawal, a co-ingestant or metabolic derangements, have to use 2nd line agents, barbiturates, for seizure control
38
Q

agitated, pupils 8 mm, sweaty, HR 140s, BP 230/130

A

-sympathomimetic

39
Q

unarousable, RR 4, pupils pinpoin

A

-opiate

40
Q

confused, pupils 8mm, flushed, dry skin, no bowel sounds, 100 cc output with foley (not urinating a lot)

A

-anticholinergic

41
Q

vomiting, urinating uncontrollably, HR 40, Pox 80% from bronchorrhea, pupils 2mm

A

-cholinergic

42
Q

lethargic HR 67, BP 105/70, RR 12, pupils midpoint

A

-sedative hypnotic

43
Q

basic approach

A
  • airway, breathing, circulation
  • establish IV, O2 and cardiac monitor
  • consider coma cocktail- D50, Narcan
  • evaluate history and a thorough physical exam
  • look at vitals, pupils, neuro, skin, bowel sounds
  • gives you hints regarding the general class of toxins
  • guides your supportive care
  • draw blood/urine for testing
  • time to consider decontamination options
44
Q

ordering diagnostic studies

A
  • acid base status
  • renal function
  • liver function
  • cardiac conduction- EKG
  • drug levels- based on history or clinical findings
  • any toxin specific findings- CK for cocaine, etc.
45
Q

EKG

A
  • evaluate QRS and QTC presence of blocks, rhythm

- QTc > 450 and a QRS > 100 can be concerning for toxin induced (eg TCAs) cardiac abnormalities

46
Q

specific toxins

A
  • acetaminophen- tylenol
  • salicylates- aspirin
  • tricyclic antidepressants (TCA)
47
Q

acetaminophen (apap)

A
  • max dose- 4g/day for adults
  • 90 mg/kg day kids
  • peak serum levels- 4 hours after overdose
  • toxicity- 140mg/kg acute ingestion*****
  • direct hepatocellular toxicity (liver)*
  • can also have renal damage and pancreatitis
48
Q

stages of tylenol toxicity

A
  • 1 (0-24 hours): n / v, but most asymptomatic
  • 2 latent stage (24-48 hours): subclinical increase in ast/alt/bilirubin
  • 3- hepatic stage (3-4days): liver failure, ruq pain, vomiting, jaundice, coagulopathy, hypoglycemia, renal failure, metabolic acidosis
  • IV recovery stage (4days-2weeks): resolution of hepatic dysfunction
  • dont really need to know
49
Q

need 4 hour level (peak) and N-acetylcysteine (NAC)

A
  • Dx- 4 hour level compared to the Rumack and Matthews nomogram
  • 150ug/ml at 4 hours
  • Rx- NAC 140mg/kg** then 70mg/kg every 4 hours for 17 doses
  • we have PO and IV dosing
  • only useful for one time ingestion (not chronic ingestion)
  • if time of ingestion unknown, drawl level immediately and again at 2-4 hours
  • labs- LFTs (liver function-> bilirubin), coags, lytes, aspirin, ETOH, tox screen
50
Q

N-acetylcysteine (NAC) indications

A
  • ingestion with potential toxicity
  • late presentations with potential or ongoing toxicity
  • chronic overdose with evidence of hepatic damage
51
Q

Acetaminophen (APAP) levels

A
  • if your patient is toxic on the nomogram- start NAC
  • if your patient does not have a known time of ingestion- start NAC
  • if your patient took multiple rounds of APAP- start NAC
  • if you have any question about the history…start NAC
52
Q

Tylenol overdose disposition

A
  • admit if…
  • known toxicity / potential toxic levels
  • lab evidence of hepatic damage
  • unknown time of ingestion and sx consistent with toxicity
  • unknown ingestion time with measurable acetaminophen levels
53
Q

salicylates (asa)

A
  • aspirin
  • weak acid, rapidly absorbed
  • messes up acid base balance
  • enteric coated has delayed absorption
  • toxic dose- 160 mg/kg
  • lethal dose 480 mg/kg
  • mixed respiratory alkalosis- metabolic acidosis
  • stimulates respiratory drive causing hyperventilation, but limits ATP production -> metabolic acidosis
54
Q

salicylates symptoms

A
  • tachypnea, tachycardia, hyperthermia
  • resp alkalosis-metabolic acidosis
  • altered serum glucose
  • AG metabolic acidosis (MUDPILES)
  • dehydration (vomiting, tachypnea, sweating)
  • Abd pain/ n/v
  • tinnitus, hearing loss
  • lethargy, seizures, altered mental status
  • noncardiogenic pulmonary edema
55
Q

evaluation of ASA overdose

A
  • lytes, ABG, LFTs, CBC, preg test, urine pH
  • bicarbonate, CO2 levels -> acid base levels
  • serum salicylate levels (toxicity at 25mg/ dl)
  • toxicity correlates POORLY with levels
  • evaluation with DONE nomegram based on single ingestion of regular ASA at levels drawn 6 hrs after ingestion
  • underestimates toxicity in cases of severe acidemia or chronic ingestion
56
Q

therapy for ASA overdose

A
  • ABCs
  • activated charcoal
  • urinary alkalinization (start if serum level is greater than 35mg/dl)
  • 3 amps bicarbonate in 1 L D5W at 150 ml/hr
  • neutralize acid base imbalance
  • by increasing urinary pH to greater than 8, ASA gets trapped in tubes and cannot be reabsorbed
  • dialysis for severe acidemia, volume overload, pulmonary edema, cardiac or renal failure, seizures, coma levels > 100 mg/dl in acute ingestion, or > 60-80 mg/dl in chronic ingestion
57
Q

disposition for ASA overdose

A
  • pt gets charcoal and remain asymptomatic after 6-8hours = possible D/C
  • sustained release requires longer observation period
  • pts with toxic levels, symptomatic, or develop symptoms = admission
58
Q

TAC (tricyclic antidepressants)

A
  • leading cause of death by intentional overdose
  • blocks sodium channels
  • respiratory depression
  • death by cardiovascular dysrhythmias and cardiovascular collapse
  • most TCAs have anticholinergic effects- dry skin, blurry vision , hot
  • severe OD- hypotension, ,seizures, respiratory depression
  • in severe cases- ARDS, rhabdomyolysis, DIC
59
Q

treatment of TCA overdose

A
  • Get an EKG
  • Sodium Bicarbinate
  • Initial bolus of 2 amps
  • Drip 3 amps in 1 L D5W at 150 ml/hr
  • Titrate for serum pH of 7.45-7.5
  • IV fluids
  • Lidocaine for perisistent arrhythymias
60
Q

other tox labs

A
  • Strongly consider ASA on every overdose
  • Not as silent as APAP can be but initial signs can be subtle
  • Urine drug screen -Little benefit but makes consultants feel better
  • EtOH level - Poor form to miss something as common as too much beer
  • Specific drug or toxin levels as indicated:
  • Know what you are looking for and how to order it
  • There is no such thing as a comprehensive drug screen
61
Q

observation period

A
  • Normal labs, normal EKG, normal exam, no history of extended release drug
  • Approximately 6 hours
  • Extended release medications, buprorion, oral hypoglycemics involved
  • Depending on agent, 12-24 hours

Medical Emergencies (16 decks)

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