Intro to Emergency Toxicology

Author: Cheryl Hunchak MD, CCFP(EM), MPH, Lecturer, University of Toronto

Date Created: March 2011

Global Health Emergency Medicine Teachi ng Modules by GHEM is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Lecture Outline

Bedside approach to the patient with suspected overdose/intoxication

Universal antidotes Principles of decontamination Toxidrome recognition and management Cases

Learning Objectives

Develop a structured bedside approach to the intoxicated patient in the ED

Apply universal antidotes when appropriate Feel comfortable choosing appropriate

decontamination strategies Feel confident recognizing and managing

patients with classic toxidromes

What constitutes a poisoning?

Whenever an exposure to a substance adversely affects the function of any system within the body

Major Routes of Poisonings

Inhalation

Ingestion

Injection

Cutaneous exposures

Case 1

An 18 year old woman is brought to the ED by her parents. She has been unresponsive for 8 hrs and has the following vital signs: HR 105 RR 10 BP 90/60 Temp 34.5

How should you proceed?

Bedside Approach to Suspected Intoxication

ABC Oxygen, monitors, IV access Full set of vitals including O2 sat Gather history and collateral information Check glucose* Disability : GCS, pupils Detailed physical exam Drugs: Consider universal antidotes Decontamination Draw Labs Specific antidotes and care

“ABCDDDDD”

What history would you like to know?

History

Often difficult to obtain COLLATERAL very important

Family, friends Careful body search re bottles, powders, etc Patient’s occupation, hobbies Prior psychiatric history Prescription medications

History

Drug(s) or substance taken/exposed to Number of tablets, dosage per tablet Estimated time since ingestion Type of preparation (sustained release?) Chance of caustic ingestion? Co-ingestions (alcohol, etc)

The plot thickens…

The patients’ parents tell you that she has been very stressed at school. They found an empty pill bottle in the house but do not know what was inside. They found her unconscious in her room 8 hours ago. There were no other substances/exposures noted.

Physical Exam….after the ABCs

Completely undress the patient

Carefully search belongings

General observation Odours, powders, track marks Agitation, confusion, obtundation

Detailed Physical Exam

Neuro GCS, extremity tone, tremors, fasiculations Detailed exam if possible

Eyes Pupil size and reactivity Nystagmus, excessive lacrimation

Skin Cyanosis, flushing, diaphoresis, dryness Signs of injury/trauma

Physical Exam

CVS Rate, rhythm, peripheral pulses

Lungs Bronchorrhea, bronchoconstriction

GI Bowel sounds Bladder size Rigidity/tenderness

Drugs:Universal Antidotes

Thiamine 100 mg IV/IM/PO

Oxygen Nasal / face mask

Naloxone 0.4 mg IV/IM/ETT

Glucose 1 ampule IV D50W

“TONG”

Universal Antidotes

Thiamine: administer if appear malnourished or known alcohol/drug abuse

Glucose: administer if no immediate access to glucometer or confirmed hypoglycemia

Order in which glucose & thiamine given no longer felt to be important

Naloxone

Competitive opioid antagonist

0.4 mg IV/IM/ETT titrated to effect

T ½ = 30 mins

Consider for patients with RR < 12

Naloxone

Can safely give 6-10 mg over <10 minCan precipitate acute withdrawal in chronic opiate usersAcute opiate withdrawal is not life threatening BUT can cause aspiration Observe patients for 2-3 hrsMay require re-dosing or infusion

What universal antidotes would you consider giving this patient?

Case 1

An 18 year old woman is brought to the ED by her parents. She has been unresponsive for 8 hrs and has the following vital signs: HR 105 RR 10 BP 90/60 Temp 34.5

How should you proceed?

What labs would you consider drawing for this patient?

What next?

Decontamination Principles

Activated charcoal Orogastric lavage Whole bowel irrigation Urine alkalinization Syrup of Ipecac

Activated Charcoal

Adsorbs substances from the gut Establishes concentration gradient that

favours movement into the intestinal lumen, enhancing excretion by defecation

Can intercept entero-hepatic circulation

What makes charcoal “activated”?

Charcoal prepared from vegetable matter ‘‘Activated’’ by heating at high temperature

in stream of oxidizing gas (steam, CO2, air) or with activating agent (phosphoric acid, zinc chloride)

Creates complex internal pore structure which increases surface area from 2–4 m2/g to >1500 m2/g

Activated Charcoal

Most effective within 1 hr ingestion 1 g/kg OR 10:1 charcoal : dose ingested

Administer whichever is larger Given in slurry of water, coke, juice PO/NG

Activated Charcoal

Indications: Ingestion within 1 hr Airway protected

Contraindications: Known/suspected GI perforation/obstruction GCS <8 or declining rapidly (risk of aspiration) Known ingestion of substance that charcoal

does NOT adsorb

Multi-dose Activated Charcoal

Repeated use of activated charcoal to enhance elimination ingested toxins

Ideal for toxins with long t ½, small volume of distribution, reduced gut motility, bezoar formation

Theophylline, phenobarbitol, quinine, carbamazepine

Improves clearance rates comparable to hemodialysis

Orogastric Lavage

Intubate patient Place in left lateral decubitus position Head tilted 20 degrees downward Insert 40F orogastric tube (24F peds) Ideal length measured from chin to xiphoid Instill 200 cc body-temp fluids repeatedly

until fluid clear

Orogastric Lavage Indications

Life-threatening ingestions Pills able to fit through orogastric tube holes Ingestion within 1 hr

Contraindications Non-life threatening ingestions Pills known to be too big for holes of tube Caustic ingestions No ability to intubate patient Ingestions where lung toxicity>>GI toxicity

Whole Bowel Irrigation

Instillation of large volumes of polyethylene glycol in osmotically balanced electrolyte solutions

Promotes rapid, mechanical elimination of ingested toxins

Whole Bowel Irrigation

Intubate patient Infuse polyethylene glycol through NG tube

at: 2L/hr adults 1 L/hr children > 6 years 0.5 L/hr children < 6 years

Infuse until rectal fluid clear

Whole Bowel Irrigation

Indications Ingestion of sustained release drugs Ingestion of substances that charcoal cannot

adsorb (HAILL) Drugs ingested by body packers/stuffers

Contraindications Known or suspected bowel obstruction Inability to intubate patient Ingested toxin known to cause diarrhea

Syrup of Ipecac

Induces short-lived vomiting Peripherally and centrally acting

90% patients vomit within 20 mins Typical vomiting < 5X and < 2 hrs 30 mL PO (adults) 15 mL PO (peds 1-12 years)

Syrup of Ipecac

Indications Very recent ingestion (<1hr) Toxin known not to cause decreased LOC Toxin known not to fit through OG tube

Contraindications Ingestion > 1 hr ago Toxin known to cause decreased LOC/seizure Caustics, hydrocarbons, TCAs

Urinary Alkalinization

Infusion of sodium bicarbonate to raise urinary pH to enhance clearance of toxins excreted by kidneys

1-2 mEq/kg NaHCO3 IV push 3 ampules of NaHCO3 in 850 cc of D5W at

1.5X maintenance fluid rate

Urinary Alkalinization

Target urinary pH 7.5-8.5

Monitor electrolytes q2-4hrs (re hypokalemia)

For ASA, phenobarbitol, INH, quinolone OD

What decontamination strategy would you choose for this patient?

a) Orogastric lavageb) Syrup of Ipecacc) Urinary decontaminationd) Activated charcoale) None of the above

What decontamination strategy would you choose for this patient?

a) Orogastric lavageb) Syrup of Ipecacc) Urinary decontaminationd) Activated charcoale) None of the above

Next issue:

What toxin did your patient take?

Common Toxidromes

Sedative-hypnotic

Anticholinergic

Cholinergic

Sympathomimetic

Opioid

Sedative-Hypnotic Toxidrome

CNS depression Slurred speech Ataxia

Coma/stupor Respiratory depression apnea Hypotension Hypothermia

Common Sedative-Hypnotics

Benzodiazepines Diazepam, lorazepam, etc

Barbituates Phenobarbitol

Case closed….

The patient’s sister shows up to the hospital very worried. The patient had admitted yesterday that she felt suicidal and today the sister could not find her bottle of phenobarbitol tablets that she takes for her seizure disorder.

Management priorities??

Sedative-hypnotic OD management

Airway management IV fluids ++ (warm)Warming as neededPressors as needed

Case 2

34 yo male found at home by wife Combative, agitated, confused Vitals: HR 108, BP 146/92, T 38.6, RR 20 Pupils round, 5mm bilat Skin dry, flushed Distended bladder palpable below umbilicus

Anticholinergic Toxidrome

Blind as a bat (mydriasis) Mad as a hatter (confused, decr. LOC) Red as a beet (flushed, vasodilation) Dry as a bone (dry skin/membranes) Hot as a hare (hyperthermia) Stuffed as a pipe (urinary/bowel retention)

Seizures, rhabdomyolysis, dysrhythmias Tachycardia is early, sensitive sign

Common Anticholinergics

Atropine, scopolamine Antidepressants (TCAs, SSRIs) Antihistamines Antipsychotics Antiparkinsonians Antispasmodics Amanita mushroom species

Anticholinergic Management

IV fluids Cooling (fluids, mist, fans) Sedation

Diazepam IV Prevents trauma, hyperthermia, rhabdomyolysis

Physostigmine 0.5 – 2 mg slow IV over 5 min **Not for TCA overdoses

Physostigmine

Reversible acetylcholinesterase inhibitor Crosses blood-brain barrier Reverses anticholinergic effects Shorter t ½ than most anticholinergic drugs

Physostigmine

Major side effects: Profound bradycardias, dysrhythmias Seizures

Indications Severe agitation and delirium not responsive to

benzodiazepines

Contraindications TCA overdose or Na channel blockade Asthma or known cardiac conduction abnormalities

TCA Overdose

IV fluids NaHCO3 IF:

QRS > 100 msecs R axis deviation terminal 40 msecs QRS Hypotension refractory to IV fluids Ventricular dysrhythmias

NaHCO3 1-2 mEq/kg IV push then infusion: Mix 3 amps of NaHCO3 into 850 cc D5W Run at 1.5X maintenance Monitor serum lytes, pH (max 7.55) Expect hypokalemia!

TCA Overdose

Case 3

15 yo girl from rural area brought to ED by family on bus

Found behind barn 6 hours prior Decreased LOC, drooling, tears streaming Covered in vomit and urine, feces HR 101, RR 16, BP 90/60, T 36.5

Cholinergic Toxidrome

SalivationLacrimationUrinationDefecationGI painEmesis

Muscarinic Effects

Cholinergic Toxidrome

Bradycardia Bronchorrhea Bronchospasm

Muscle fasiculations, miosis Seizures, resp failure, paralysis

“The Killer Bees”

Common Cholinergics

Organophosphate insecticides Diazinon, acephate, malathion, parathion

Carbamate insecticides

Systemic absorption by inhalation, ingestion, transdermal and transcorneal exposure

Organophosphate Poisoning

Bind irreversibly to acetylcholinesterase Allows accumulation of Ach at NMJ Cholinergic crisis causes central and

peripheral toxidrome Must give antidotes before permanent

binding of organophosphates to acetylcholinesterase (“ageing”)

Cholinergic Management

Decontamination and staff protection! 1:9 bleach : water

Airway management Atropine sulphate 2 mg IV/IM

Every 5-20 mins until tracheobronchial secretions dry up

Treats muscarinic symptoms Pralidoxime 2 g IV/IM infused over 5 min

Treats nicotinic symptoms Continue for 48 hrs if used

Fatal Pesticide Poisonings

258,000 deaths from pesticide self-poisonings worldwide each year

Accounts for 30% suicides worldwide Suicides in developing countries >>

developed countries likely explained by very high case fatality rates in developing countries

Case 4

26 yo male found on street by police No family present Eyes bloodshot, agitated, sweaty Uncooperative HR 126, BP 178/104, RR 20, T 38.5

Sympathomimetic Toxidrome

Mydriasis Diaphoresis Tachycardia Hypertension Hyperthermia

Seizures, rhabdomyolysis, MI, SAH

Common Sympathomimetics

Cocaine Amphetamines Khat (cathinone and cathine)

Sympathomimetic Management

IV fluids Cooling (fans, mist, fluids) Sedation: benzodiazepines Seizures: benzodiazepines, phenobarbitol HTN: benzodiazepines, nitroprusside Chest pain: ASA, nitroglycerin Avoid beta-blockers! Monitor for rhabdomyolysis

Case 5

42 yo female Found at home by daughter unresponsive

in bed HR 90, RR 6, GCS 6, T 36.3, BP 92/60 Pupils pinpoint

Opioid Toxidrome

Respiratory depression

CNS depression/coma

Miosis

Opioid Management

Naloxone IV/IM/SC/ETT/IN

Airway management

Take Home Points

Approach to Tox Patient at Bedside

ABC Oxygen, monitors, IV access Full set of vitals including O2 sat Gather history and collateral information Check glucose (if possible) Disability : GCS, pupils Detailed physical exam Drugs: Consider universal antidotes Decontamination Draw Labs Specific antidotes and supportive care

“ABCDDDDD”

4 Universal Antidotes

Thiamine Oxygen Naloxone Glucose

“TONG”

5 Decontamination Options

Activated charcoal Syrup of Ipecac Orogastric Lavage Whole Bowel Irrigation Urinary alkalinization

5 Decontamination Options

Activated charcoal Syrup of Ipecac Orogastric Lavage Whole Bowel Irrigation Urinary alkalinization

5 substances charcoal cannot adsorb

Hydrocarbons Alcohols Iron Lithium Lead

“HAILL”

5 Toxidromes

Sedative-Hypnotic Anticholinergic Cholinergic Sympathomimetic Opioid

Quiz Question 1

Which of the following is NOT considered a universal antidote? A) Dextrose B) Atropine C) Naloxone D) Thiamine E) Oxygen

Quiz Question 2

Why is it crucial to observe opiate-intoxicated patients who have been given naloxone for 2-3 hours in the ED? A) Naloxone can induce tachycardia B) Naloxone has a high incidence of anaphylaxis C) Naloxone can cause depressed level of

consciousness D) The half-life of naloxone is shorter than that of

the opiates it is reversing E) Naloxone can precipitate urinary retention

Quiz Question 3

A 50 kg female ingested 30 tablets of 500 mg of acetaminophen 45 minutes ago. What is the appropriate dose of activated charcoal that should be given? A) 50 g B) 100g C) 150g D) Charcoal is contraindicated E) Charcoal will not be effective

Quiz Question 4

Which drug overdoses are not likely to be improved by the use of urinary alkalinization as a decontamination strategy? A) Salicylates B) Phenobarbitol C) Isoniazid (INH) D) Quinolone E) Carbamates

Quiz Question 5

Which of the following symptoms are muscarinic manifestations of organophosphate overdose? A) Lacrimation B) Vomiting C) Miosis D) Muscle fasciculations E) All of the above

General References

Gunnell D, Eddleston M, Phillips MR, Konradsen F. The global distribution of fatal pesticide self-poisoning: Systematic review. BMC Public Health 2007; 7:357.

Tintinalli’s Emergency Medicine. 7th Ed. Tintinalli JE et al. 2011. McGraw-Hill Companies, Inc.

American Academy of Clinical Toxicology Position Statement and Practice Guidelines on the Use of Multi-Dose Activated Charcoal in the Treatment of Acute Poisoning. Clinical Toxicology.1999;37(6): 731–751.