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Introduction to Toxicology

Introduction to Toxicology. Richard W. Stair, MD. Toxicology - Generally Speaking. 4 million potentially toxic exposures annually fewer than 1% reaching hospital are fatal if arrive in deep coma, mortality 13-35% 25% of suicide attempts are via drug OD

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Introduction to Toxicology

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  1. Introduction to Toxicology Richard W. Stair, MD

  2. Toxicology - Generally Speaking • 4 million potentially toxic exposures annually • fewer than 1% reaching hospital are fatal • if arrive in deep coma, mortality 13-35% • 25% of suicide attempts are via drug OD • leading fatal exposures: analgesics, TCA, psychotropics, street drugs, CV agents, alcohols

  3. Routes of Exposure • Ingestions 79% • Dermal 7% • Ophthalmologic 6% • Inhalation 5% • Bites and Stings 3% • Injection 0.3%

  4. Initial Assessment - ABC’s • Airway with C spine protection • Breathing • Circulation • Disability • Exposure

  5. Toxic History • Patient story correct about 50% • Remember the P’s • Paramedics • parents • pals • physicians • pharmacist

  6. Toxic History • AMPLE history • A age , allergies • M medications • P past medical history • L last meal • E events leading to condition

  7. Information Gathering • Physical Exam • Poison Control Centers • Evaluating Toxicity - SATS • S substance • A amount • T time of exposure • S symptoms • Diagnostic tests

  8. Physical Exam - Toxidromes • Anticholinergic • Cholinergic • Sympathomimetic • Opioid • Torsion Head and Neck Syndrome • Phencyclidine Syndrome

  9. Anticholinergic • Dry as a bone • Red as a beet • Blind as a bat • Hot as hades • Mad as a hatter

  10. Cholinergic • DUMBELS • Defecation • Urination • Miosis • Bronchospasm • Excessive salivation • Lacrimation • Seizures

  11. Sympathomimetic • Convulsions • hyperthermia • tachycardia • hypertension • psychosis • mydriasis • MIMIC ANTICHOLINERGIC, BUT NOT DRY

  12. Opioid • Pinpoint pupil • Hypoventilation • Coma • Hypotension • Bradycardia • Hypothermia

  13. Torsion Head and Neck • Dysphonia • Oculogyric Crisis • Rigidity • Tremor • Torticollis

  14. Phencyclidine • Miosis • Rotatory nystagmus • Combativeness

  15. Odors as Clues to Toxins • Acetone acetone, acidosis • Alcohol not with ethylene glycol • Bitter Almonds cyanide • Hemp (burnt rope) marijuana • Garlic arsenic • Rotten eggs disulfiram, H2SO4

  16. 7 major mechanisms • 1. Interfere with O2 transport or utilization • 2. Depress or stimulate CNS • 3. Effect on autonomic nervous system • 4. Effect on lungs • 5. Effect on heart and vasculature • 6. Local damage • 7. Effects liver or kidneys

  17. Tox Management • As always, ABC’s • Coma cocktail • Removal of exposure • Prevention of Absorption/ Decontamination/ Enhancement of Elimination • Antidotes • Ancillary Tests

  18. Coma cocktail • Useful challenge in unresponsive patients • Consists of glucose, thiamine and naloxone • Beware of suddenly combative patients • NOT flumazenil

  19. Removal of Exposure • Environmental control • Removing contaminated clothing • Removal of pill bottles

  20. Decontamination • Many traditional treatments by the wayside • forced emesis • lavage • Must weigh risks and benefits • Charcoal most commonly used • limitations

  21. Why adsorption of toxins if early prevents toxin from entering circulation gut dialysis sustained release formulations Why Not too late too risky too useless Charcoal - Why and Why Not

  22. Charcoal Doesn’t Bind……. • C caustics and corrosives • H heavy metals • A alcohols • R rapidly absorbed/active agents • C chlorine or iodine • O others insoluble in water • A aliphatics and poorly absorbed hydrocarbons • L laxatives

  23. Charcoal - Contraindications • Agents from previous list • Loss of protective reflexes and/or unstable • Substances causing rapid depression of consciousness or early seizures • infants less than 6 months • ingested foreign body • neurologically impaired • absent bowel sounds

  24. But if Charcoal Indicated • 1g/kg initial dose • multiple doses for enterohepatic circulation • digitalis, INH, NSAIDS, phenytoin, salicylates, TCA • multiple doses for “gut dialysis” • phenobarbital, dapsone, salicylates, quinine, theophylline, carbamazepine

  25. Whole Bowel Irrigation • Simply washing out intestines of toxin • PEG solutions at 2L/hr (40cc/kg/hr) • Used to remove long acting and sustained release preparations, body packers and stuffers, and some toxins poorly absorbed by charcoal (ex: iron) • Contraindicated if hematemesis, ileus, obstruction, perforation, peritonitis

  26. Enhanced Elimination • Alkalinization (no acidification) • Hemodialysis • Hemoperfusion

  27. Antidotes • Relatively small handful of antidotes for vast number of toxins • Good supportive management first • See list

  28. Ancillary testing • Directed toxicology • EKG and cardiac monitoring • Acid base status, osmolar gaps • CXR if unarouseable or hypoxic

  29. Safety • Responsible for safety of patient, other patients and families, and staff • Often have agitation, psychosis, and violence in association with toxic exposure or underlying psychosocial disorder • Swift and sure physical restraint • Judicious use of chemical restraint

  30. Disposition • Admission • Psychiatry • Home

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