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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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Toxicology l.jpg


UNC Emergency Medicine

Medical Student Lecture Series

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  • General approach to the poisoned patient

  • Toxidromes

  • Specific antidotes

  • Decontamination and enhanced elimination

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General Approach

  • ABC’s

  • History

  • Physical examination

  • Labs, imaging

  • Diagnosis, antidotes

  • Disposition

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  • 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

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  • 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

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  • 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

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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

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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

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REASSESS. . . frequently

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  • 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

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Physical examination

  • Vital signs: BP, HR, RR, T, O2 sat

  • Mouth: odors, mucous membranes

  • Pupils

  • Breath sounds

  • Bowel sounds

  • Skin

  • Urination/defecation

  • Neurologic exam

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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

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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

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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

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  • 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

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  • 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

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  • Case-based

  • ICU admission

  • Period of observation

  • Psychiatric evaluation

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Cholinergic Toxidrome

Diarrhea Salivation

Urination Lacrimation

Miosis Urination

Bradycardia Defecation

Bronchospasm GI upset

Emesis Emesis



Salivation, sweating

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  • 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

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Jimson weed


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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

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  • Opioids

    • Respiratory depression

    • Miosis

    • Hypoactive bowel sounds

  • Sympathomimetics

    • Hypertension

    • Tachycardia

    • Hyperpyrexia

    • Mydriasis

    • Anxiety, delirium

      Clinical Pearl: Sweating differentiates sympathomimetic

      and anticholinergic toxidromes

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  • 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

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  • 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

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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

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  • 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

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  • 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

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  • Inhalation

    • Give supplemental humidified oxygen

    • Observe for airway obstruction

    • Intubate as necessary

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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.

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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

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Not good for:







Activated Charcoal

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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

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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

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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

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Specific Toxins

  • Acetominophen

  • Salicylates

  • Tricyclic Antidepressants (TCA)

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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)

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Acetominophen (apap)

  • Toxicity

  • 140mg/kg acute ingestion

  • Direct hepatocellular toxicity with centrolobular distribution (hepatic vein)

  • Can also have renal damage and pancreatitis

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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 l.jpg

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)

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Acetominophen (apap) nomogram

  • If time of ingestion unknown, draw level immediately and again at 2-4 hours.

  • Labs: LFTs, coags, lytes, aspirin, ETOH, tox screen

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NAC indications nomogram

  • Ingestions with potential toxicity

  • Late presentations with potential or ongoing toxicity

  • Chronic overdose with evidence of hepatic damage

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Tylenol Overdose Disposition nomogram

  • 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.

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Salicylates (asa) nomogram

  • 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

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Tachypnea, tachycardia, hyperthermia nomogram

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

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Evaluation of ASA Overdose nomogram

  • 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

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Therapy for ASA Overdose nomogram

  • 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

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Disposion for ASA Overdose nomogram

  • 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

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TCA (Tricyclic Antidepressants) nomogram

  • 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

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GET AN EKG nomogram

What do you see?

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

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Treatment of TCA Overdose nomogram

  • 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)

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Thank You! nomogram

Any Questions?

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References nomogram

  • 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.