A standardized approach to the patient exposed to toxic substances will ensure optimal outcomes for the patient.

• BC Drug and Poison Information Centre at 604-682-5050 or 1-800-567-8911.

Common toxidromes include anticholinergic, cholinergic, opioid, sympathomimetic, and sedative-hypnotic:

• Anticholinergic – antihistamines, antipsychotics, TCAs, atropine, jimson weed, codeine, devil’s breath, morphine.
• Cholinergic – organophosphates (pesticides), physostigmine, nerve gas.
• Opioid – fentanyl, heroin.
• Sympathomimetic – cocaine, amphetamines, bath salts, ecstasy.
• Sedative-hypnotic – ethanol, benzodiazepines.

Focused history and physical examination:

• Ensure all team members are in appropriate PPE.

History:

• AMPLE history.
• Exposure details – type, concentration, volume, time course, single vs multiple exposures, polysubstance.
• Collateral information.

Physical:

• Full set of vital signs (including core temperature and glucose).
• Assess ABCs, skin, bowel/bladder functioning, and a basic neurological exam (mental status, pupils, tone, reflexes).
• Assess for common toxidromes:

*Cholinergic presentations can be muscarinic or nicotinic.

Mnemonics:

• • Cholinergic:
    • Muscarinic: “DUMBBELLS” – diarrhea/diaphoresis, urination, miosis, bradycardia, bronchorrhea/bronchospasm, emesis, lacrimation, lethargic, salivation.
    • Nicotinic: “Days of the Week” – mydriasis, tachycardia, weakness, tremors, fasciculations, seizures, somnolence.
  • Anticholinergic:
    • MAD as a hatter (delirium, hallucination).
    • HOT as a hare (hyperthermia).
    • BLIND as a bat (dilated pupils).
    • RED as a beet (flushed).
    • DRY as a bone (dry skin, urinary retention).
  • Investigations
    • CBC, BUN, creatinine, electrolytes, glucose, INR/PTT, LFTs, CK, osmolality, lactate, ABG/VBG, ASA, acetaminophen and EtOH levels, and ECG.
    • Based on assessment: serum drug levels, Ca²⁺, Mg²⁺, PO₄^3-, TSH, protein, albumin, ketones, HCG, co-oximetry, and imaging for radiopaque toxins or ingested drug packets.
• BC Drug and Poison Information Centre at 604-682-5050 or 1-800-567-8911.

Clinical Pitfalls

• Failure to recognize limitations of toxicology screen.
  • urine toxicology screens are often prone to false negatives and false positives.
  • some drugs may take days to metabolize and excrete through urine.
• Failure to obtain collateral information and confirm patient history from paramedics, police, patient family and friends, or medical records.
• Failure to appreciate that that the history provided by the patient with intentional ingestion may be unreliable.
• Failure to consult poison centre.

Approach to managing any toxic exposure:

• ABCDEFG: ABCs, Decontaminate, Enhanced Elimination, Find the Antidote, Get help (Poison Control).

ABCs

• Follow routine resuscitation.
• General supportive therapy.

Decontamination

• Ocular: saline irrigation to neutralize pH.
• Dermal (preferably conducted prior to entering the department): remove clothing, irrigate external surfaces, brush off toxic agents.
• Gastrointestinal: Consult poison control
  • Single-dose activated charcoal – rarely used – considered in ingestions of substances that absorb to activate charcoal up to 1h after ingestion.
  • Gastric lavage – no longer used.
  • Syrup of Ipecac – Not longer used.

Enhanced Elimination – Consult poison control.

• Multidose activated charcoal – considered in ingestions of substances with delayed dissolution (Concretions, bezoars, ER/SR formulations), or undergo enterohepatic recirculation. Same contraindications as single-dose activated charcoal.
• Whole bowel irrigation – considered in large doses of ER/SR medications, drug packers, metals. Contraindicated if evidence of gut hypoperfusion, bowel obstruction, or perforation.
• Surgery – for drug packers with obstruction or rupture.
• Lipid emulsification (IV lipid emulsion therapy) – for toxin-mediated cardiogenic shock from a lipid-soluble substance; examples include anesthetics, refractory BB/CCB cases, TCAs, Bupropion.
• Alkalization using Sodium Bicarbonate – allows weakly acidic substances such as salicylates, methotrexate, phenobarbital to be trapped in alkali urine and eliminated. Contraindicated in patients who cannot tolerate the volume or sodium load, are hypokalemic, or have renal insufficiency unless also being dialyzed.
• Hemodialysis is indicated for eliminating toxins that are of low molecular weight, have low protein binding, and high water-solubility such as methanol, ethylene glycol, carbamazepine, phenobarbital, lithium, and salicylates.

Examples of Specific Antidotal Therapy:

Consider the following:

• Dextrose – for all hypoglycemia.
  • Adult: 0.5-1.0 g/kg (1-2 mL/kg) IV of D50W
  • Child: 0.25 g/kg (2-4 mL/kg) IV of D25W
• Oxygen – for all hypoxic patients, except Paraquat (herbicide) exposures, where oxygen is harmful.
• Naloxone – for opioid toxidromes with airway/respiratory compromise. Consider in the undifferentiated comatose patient.
  • Adult: step-wise administration of 2 mg bolus IV; 1st dose 0.4 mg, 2nd dose 0.6 mg if there’s no response, 3rd dose with remaining 1 mg if there’s still no response.
  • Child: 0.01 mg/kg initial bolus IV.
  • Maintenance infusion may be required for repeat respiratory suppression.
• Thiamine – for prevention or treatment of Wernicke’s encephalopathy.
  • 100 mg IV/IM for prevention.
  • 500 mg IV for treatment.
  • Note: withholding dextrose until after administration of thiamine to avoid precipitating or worsening Wernicke’s encephalopathy is unsupported by evidence and may be significantly harmful to patients who are hypoglycemic.

1. General approach to drug poisoning in adults.
   Levine, M. (Jul 19, 2021).
   – UpToDate. www.uptodate.com/ [Internet]

   
   

2. Hoffman R., Howland M., Lewin L., Goldfrank L., & Flomenbaum N. (eds) Goldfank’s Toxicologic Emergencies. McGraw Hill. (March 21, 2019)

   
   

3. Toronto Notes 2020: Comprehensive Medical Reference and Review.
   36^th Toronto Notes for Medical Students, Inc; 2020. p. 228-232.

   
   

4. Walls R., Hockerberger R., & Gausche-Hill M. (eds) Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9^th ed. Philadelphia, PA: Elsevier; 2018.

   
   

1. Video: ‘Approach to the Poisoned Patient’

   Matthew Zuckerman (2018)

   Youtube.com

   
   

2. Podcast: ‘General Approach to the Poisoned Patient‘

   Thomas, A. CRACKCast E147 (2018)

   Canadiem.org