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Toxicology. UNC Emergency Medicine Medical Student Lecture Series. Objectives. General approach to the poisoned patient Toxidromes Specific antidotes Decontamination and enhanced elimination. General Approach . ABC’s History Physical examination Labs, imaging Diagnosis, antidotes

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UNC Emergency Medicine

Medical Student Lecture Series

  • General approach to the poisoned patient
  • Toxidromes
  • Specific antidotes
  • Decontamination and enhanced elimination
general approach
General Approach
  • ABC’s
  • History
  • Physical examination
  • Labs, imaging
  • Diagnosis, antidotes
  • Disposition
a irway
  • Airway obstruction can cause death after poisoning
    • Flaccid tongue
    • Aspiration
    • Respiratory arrest
  • Evaluate mental status and gag/cough reflex
  • Airway interventions
    • Sniffing position
    • Jaw thrust
    • Head-down, left-sided position
    • Examine the oropharynx
    • Clear secretions
    • Airway devices: nasal trumpet, oral airway
  • Intubation?
    • Consider naloxone first
b reathing
  • Determine if respirations are adequate
  • Give supplemental oxygen
  • Assist with bag-valve-mask
  • Check oxygen saturation, ABG
  • Auscultate lung fields
    • Bronchospasm: Albuterol nebulizer
    • Bronchorrhea/rales: Atropine
    • Stridor: Determine need for immediate intubation
c irculation
  • IV access
  • Obtain blood work
  • Measure blood pressure, pulse
  • Hypotension treatment:
    • Normal saline fluid challenge, 20 mL/kg
    • Vasopressors if still hypotensive
    • PRBC’s if bleeding or anemic
  • Hypertension treatment:
    • Nitroprusside, beta blocker, or nitroglycerin
  • Continuous ECG monitoring
    • Assess for arrhythmias, treat accordingly
supportive care
Supportive Care
  • Foley catheter
  • Rectal temperature
  • Accucheck, treat hypoglyemia
  • Coma cocktail
    • Thiamine: 100 mg IV, before dextrose
    • Dextrose: 50 grams IV push
    • Naloxone: 0.01 mg/kg IV
supportive care10
Supportive Care
  • Treat Seizures
    • Lorazepam 2 mg IV, may repeat as needed
    • Dilantin 10 mg/kg IV
  • Control agitation
    • Haldol 5-10 mg IM
    • Ativan 2-4 mg IM or IV
    • Geodon 20 mg IM
  • Think about trauma
  • What, when, how much, why?
  • Rx, OTC, herbals, supplements, vitamins
  • Talk to family, friends, EMS
  • Pill bottles, needles, beer cans, suicide note
  • Call pharmacy
  • Allergies, medical problems
physical examination
Physical examination
  • Vital signs: BP, HR, RR, T, O2 sat
  • Mouth: odors, mucous membranes
  • Pupils
  • Breath sounds
  • Bowel sounds
  • Skin
  • Urination/defecation
  • Neurologic exam
essential laboratory tests
Essential Laboratory Tests
  • Electrolytes
  • Glucose
  • BUN and creatinine
  • LFT’s, CK
  • Urinalysis, urine drug screen
  • Etoh, alcohol screen
  • Serum osmolality
  • Acetaminophen, salicylates
  • Specific drug levels
  • Pregnancy test
anion gap
Anion Gap
  • Na – (HCO3 + Cl)
  • Normal: 8-12 mEq/L
  • Causes:
    • Methanol
    • Uremia
    • DKA
    • Paraldehyde, phenformin
    • Iron, isoniazid, ibuprofen
    • Lithium, lactic acidosis
    • Ethylene glycol
    • Strychnine, starvation, salicylates
osmolar gap
Osmolar Gap
  • Calculated osmolality – measured osmolality
  • 2(Na) + glucose/18 + BUN/2.8
  • Normal = 285-290 mOsm/L
  • Gap > 10 mOsm/L suggests the presence of extra solutes:
    • Ethanol, methanol
    • Ethylene glycol, isopropyl alcohol
    • Mannitol, glycerol
  • Clinical Pearl: Anion gap acidosis with an osmolar gap should suggest methanol or ethylene glycol poisoning
  • Prolonged QRS
    • TCAs
    • Phenothiazines
    • Calcium channel blockers
  • Sinus bradycardia/AV block
    • Beta-blockers, calcium channel blockers
    • TCAs
    • Digoxin
    • organophosphates
  • Ventricular tachycardia
    • Cocaine, amphetamines
    • Chloral hydrate
    • Theophylline
    • Digoxin
    • TCAs
  • May not identify ingested substance(s)
  • Provide ABCs and supportive care
  • Give antidote when appropriate
  • Call regional poison control center
    • Carolinas Poison Center, Charlotte
    • 800-848-6946
  • Case-based
  • ICU admission
  • Period of observation
  • Psychiatric evaluation
cholinergic toxidrome
Cholinergic Toxidrome

Diarrhea Salivation

Urination Lacrimation

Miosis Urination

Bradycardia Defecation

Bronchospasm GI upset

Emesis Emesis



Salivation, sweating

  • Organophosphates
    • Irreversibly bind cholinesterases
  • Carbamate
    • Reversibly bind cholinesterases, poor CNS penetration
  • Muscarinic and nicotinic effects
  • Pesticides, nerve agents
    • Military personnel
    • Field workers, crop dusters
    • Truckers
    • Pest control, custodial workers
  • Antidote
    • Atropine for muscarinic effects
    • Pralidoxime reverses phosphorylation of cholinesterase






















Jimson weed

anticholinergic toxidrome
Anticholinergic Toxidrome
  • Dry mucus membranes (Dry as a bone)
  • Mental status changes (Mad as a hatter)
  • Flushed skin (Red as a beet)
  • Mydriasis (Blind as a bat)
  • Fever (Hot as a hare)
  • Tachycardia
  • Hypertension
  • Decreased bowel sounds
  • Urinary retention
  • Seizures
  • Ataxia
  • Opioids
    • Respiratory depression
    • Miosis
    • Hypoactive bowel sounds
  • Sympathomimetics
    • Hypertension
    • Tachycardia
    • Hyperpyrexia
    • Mydriasis
    • Anxiety, delirium

Clinical Pearl: Sweating differentiates sympathomimetic

and anticholinergic toxidromes

  • Acetaminophen N-acetylcysteine
  • Organophosphates Atropine, pralidoxime
  • Anticholinergic physostigmine
  • Arsenic, mercury, gold dimercaprol
  • Benzodiazepines flumazenil
  • Beta blockers glucagon
  • Calcium channel block calcium
  • Carboxyhemoglobin 100% O2
  • Cyanide nitrite, Na thiosulfate
  • Digoxin digoxin antibodies
  • Ethylene glycol fomepizole, HD
  • Heparin protamine
  • Iron deferoxamine
  • Isoniazid pyridoxime
  • Methanol fomepizole, HD
  • Methemoglobin methylene blue
  • Opioids naloxone
  • Salicylate alkalinization, HD
  • TCA’s sodium bicarbonate
  • Warfarin FFP, vitamin K
principles of decontamination
Principles of Decontamination
  • External
    • Protect yourself and others
    • Remove exposure
    • Irrigate copiously with water or normal saline
    • Don’t forget your ABC’s
  • Internal
    • Patient must be fully awake or intubated
    • Most common complication is aspiration
    • Very little evidence for their use
  • Skin
    • Protect yourself and other HC workers
    • Remove clothing
    • Flush with water or normal saline
    • Use soap and water if oily substance
    • Chemical neutralization can potentiate injury
    • Corrosive agents injure skin and can have systemic effects
  • Eyes
    • remove contact lens
    • Flush copiously with water or normal saline
    • Use local anesthetic drops
    • Continue irrigation until pH is normal
    • Slit lamp and fluorescein exam
  • Inhalation
    • Give supplemental humidified oxygen
    • Observe for airway obstruction
    • Intubate as necessary
gi decontamination
GI Decontamination
  • Syrup of ipecac
    • Within minutes of ingestion
    • Aspiration, gastritis, Mallory-Weiss tear, drowsiness
    • Rarely, if ever, given in ED
  • Gastric lavage
    • Does not reliably remove pills and pill fragments
    • Used 30-60 minutes after ingestion
    • Useful after caustic liquid ingestion prior to endoscopy
    • Not used for sustained release/enteric coated ingestions
    • Perforation, nosebleed, vomiting, aspiration
  • Recent studies suggest that activated charcoal alone is just as effective as gut emptying followed by charcoal.
gi decontamination34
GI Decontamination
  • Activated charcoal
    • Limits drug absorption in the GI tract
    • Within 60 minutes of ingestion
    • Patient must be awake or intubated
    • Vomiting, aspiration, bezoar formation
    • Contraindication: bowel obstruction or ileus with distention
    • 1 gram/kg PO or GT
activated charcoal
Not good for:







Activated Charcoal
gi decontamination36
GI Decontamination
  • Cathartics
    • Hasten passage of ingestions or AC
    • Contraindications: obstruction or ileus
    • Severe fluid loss, hypernatremia, hyperosmolarity
    • 10% magnesium citrate 3ml/kg or 70% sorbitol 1-2 …./kg
  • Whole bowel irrigation
    • Large ingestions, SR or EC tablets, packers (ex. cocaine)
    • Contraindications: obstruction or ileus
    • Aspiration, nausea, may decrease effectiveness of charcoal
enhanced elimination
Enhanced Elimination
  • Urinary manipulation
    • Forced diuresis
    • Alkalinization
  • Repeat-dose activated charcoal
    • Very large ingestions of toxic substance
    • Sustained release and enteric coated preparations
      • Carbamazepine, phenobarbital, phenytoin
      • Salicylate, theophylline, digitoxin
  • Hemodialysis, Hemoperfusion
  • Peritoneal dialysis, Hemofiltration
enhanced elimination38
Enhanced Elimination
  • Does the patient need it?
    • Severe intoxication with a deteriorating condition despite maximal supportive care
    • Usual route of elimination is impaired
    • A known lethal dose or lethal blood level
    • Underlying medical conditions that can increase complications
specific toxins
Specific Toxins
  • Acetominophen
  • Salicylates
  • Tricyclic Antidepressants (TCA)
acetominophen apap
Acetominophen (apap)

Magic number to remember is 140

  • Max dose:
    • 4g/day adults
    • 90 mg/kg day kids
  • Peak serum levels: 4 hours after overdose
  • What are the three methods of APAP metabolism?
    • Glucuronidation (90% normal thru pathway)
    • Sulfonation
    • P450 mixed oxidase enzymes (5% nl thru pathway)
acetominophen apap41
Acetominophen (apap)
  • Toxicity
  • 140mg/kg acute ingestion
  • Direct hepatocellular toxicity with centrolobular distribution (hepatic vein)
  • Can also have renal damage and pancreatitis
stages of tylenol toxicity
Stages of Tylenol Toxicity
  • I (0-24hrs): n/v, but most asymptomatic
  • II latent stage (24-48hrs): subclinical increase in ast/alt/bili
  • III hepatic stage (3-4dys): liver failure, ruq pain, vomiting, jaundice, coagulopathy, hypoglycemia, renal failure, metabolic acidosis
  • IV recovery stage (4dys-2wks): resolution of hepatic dysfunction
need 4 hour level and n acetylcysteine nac
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 ingestions)

Need 4 hour level andN-acetylcysteine (NAC)
acetominophen apap44
Acetominophen (apap)
  • If time of ingestion unknown, draw level immediately and again at 2-4 hours.
  • Labs: LFTs, coags, lytes, aspirin, ETOH, tox screen
nac indications
NAC indications
  • Ingestions with potential toxicity
  • Late presentations with potential or ongoing toxicity
  • Chronic overdose with evidence of hepatic damage
tylenol overdose disposition
Tylenol Overdose Disposition
  • 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.
salicylates asa
Salicylates (asa)
  • Weak acid, rapidly absorbed
  • 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
  • Oil of wintergreen, 1ml = 1400mg
salicylates symptoms
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

Salicylates Symptoms
evaluation of asa overdose
Evaluation of ASA Overdose
  • Lytes, ABG, LFTs, CBC, preg.test, urine PH
  • 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
therapy for asa overdose
Therapy for ASA Overdose
  • ABC’s
  • Activated charcoal
  • Urinary alkalinization (start if serum level is greater than 35mg/dl)
    • 3 amps bicarbinate in 1 L D5W at 150 ml/hr
  • 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 > 100mg/dl in acute ingestion, or > 60-80 mg/dl in chronic ingestion
disposion for asa overdose
Disposion for ASA Overdose
  • Pt gets charcoal and remain asymptomatic after 6-8 hours = Possible D/C
  • Sustained release requires longer observation period
  • Pts with toxic levels, symptomatic, or develop symptoms = Admission
tca tricyclic antidepressants
TCA (Tricyclic Antidepressants)
  • Leading cause of death by intentional overdose
  • Blocks sodium channels
  • Death by cardiovascular dysrhythymias and cardiovascular collapse
  • Most TCA’s have anticholinergic effects
    • Dry skin, blurry vision, hot
  • Severe OD: hypotension, seizures, respiratory depression
  • In severe cases: ARDS, rhabdomyolisis, DIC
get an ekg

What do you see?

Prolonged QRS, sinus tachycardia, “tall R in R” – tall R wave in lead aVR

treatment of tca overdose
Treatment of TCA Overdose
  • 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
  • AVOID Class Ia drugs (procainimide quinidine)
thank you

Thank You!

Any Questions?

  • Poisoning & Drug Overdose, California Poison Control System. KR Olson, 3rd edition, Appleton & Lange, 1999.
  • Emergency Medicine Board ReviewSeries. L Stead, Lippincott Williams & Wilkins, 2000.
  • Emergency Medicine, A comprehensivestudy guide. Tintinalli, 6th edition, McGraw Hill, 2004.