Download Intro toToxicology - Global Emergency Health Medicine

Intro to Emergency Toxicology
Author: Cheryl Hunchak MD, CCFP(EM), MPH, Lecturer,
University of Toronto
Date Created: March 2011
Global Health Emergency Medicine Teaching 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:
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HR 105
RR 10
BP 90/60
Temp 34.5
 How should you proceed?
Bedside Approach
to Suspected Intoxication
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“ABCDDDDD”
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
What history would you like to
know?
History
 Often difficult to obtain
 COLLATERAL very important
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Family, friends
Careful body search re bottles, powders, etc
Patient’s occupation, hobbies
Prior psychiatric history
Prescription medications
History
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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
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Thiamine
Oxygen
Naloxone
Glucose
“TONG”
100 mg IV/IM/PO
Nasal / face mask
0.4 mg IV/IM/ETT
1 ampule IV D50W
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 min
 Can precipitate acute withdrawal in chronic
opiate users
 Acute opiate withdrawal is not life threatening
BUT can cause aspiration
 Observe patients for 2-3 hrs
 May 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:
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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
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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
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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
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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
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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 lavage
b) Syrup of Ipecac
c) Urinary decontamination
d) Activated charcoal
e) None of the above
What decontamination strategy
would you choose for this patient?
a) Orogastric lavage
b) Syrup of Ipecac
c) Urinary decontamination
d) Activated charcoal
e) 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
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Coma/stupor
Respiratory depression
Hypotension
Hypothermia
apnea
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 needed
 Pressors as needed
Case 2
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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
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Blind as a bat
Mad as a hatter
Red as a beet
Dry as a bone
Hot as a hare
Stuffed as a pipe
(mydriasis)
(confused, decr. LOC)
(flushed, vasodilation)
(dry skin/membranes)
(hyperthermia)
(urinary/bowel retention)
 Seizures, rhabdomyolysis, dysrhythmias
 Tachycardia is early, sensitive sign
Common Anticholinergics
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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
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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:
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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:
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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
Salivation
Lacrimation
Urination
Defecation
GI pain
Emesis
Muscarinic
Effects
Cholinergic Toxidrome
 Bradycardia
 Bronchorrhea
 Bronchospasm
“The Killer Bees”
 Muscle fasiculations, miosis
 Seizures, resp failure, paralysis
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 selfpoisonings 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
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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
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Mydriasis
Diaphoresis
Tachycardia
Hypertension
Hyperthermia
 Seizures, rhabdomyolysis, MI, SAH
Common Sympathomimetics
 Cocaine
 Amphetamines
 Khat (cathinone and cathine)
Sympathomimetic Management
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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
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ABC
Oxygen, monitors, IV access
Full set of vitals including O2 sat
Gather history and collateral information
Check glucose (if possible)
Disability : GCS, pupils
“ABCDDDDD”
Detailed physical exam
Drugs: Consider universal antidotes
Decontamination
Draw Labs
Specific antidotes and supportive care
4 Universal Antidotes
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Thiamine
Oxygen
Naloxone
Glucose
“TONG”
5 Decontamination Options
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Activated charcoal
Syrup of Ipecac
Orogastric Lavage
Whole Bowel Irrigation
Urinary alkalinization
5 Decontamination Options
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Activated charcoal
Syrup of Ipecac
Orogastric Lavage
Whole Bowel Irrigation
Urinary alkalinization
5 substances charcoal cannot adsorb
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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?
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A) Dextrose
B) Atropine
C) Naloxone
D) Thiamine
E) Oxygen
Quiz Question 2
 Why is it crucial to observe opiateintoxicated 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?
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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?
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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?
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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.