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Poisoning, Emergency Medicine

Basics

Description

- Intentional: - Depression - Suicide - Homicide - Recreational drug abuse

- Respiratory: - Tachypnea, bradypnea, apnea - Inability to protect airway

- Vital signs: - Varies depending on toxic substance - Hyperthermia, hypothermia - Tachycardia, bradycardia - Hypertension, hypotension

- Cholinergic: - Secretory overdrive (salivation, lacrimation, urination, diaphoresis) - Miosis - Bronchospasm, wheezing

- Serum osmol gap: - Calculate osmol gap if elevated anion gap acidosis from potential toxic alcohol. - Most sensitive early in poisoning - Normal osmol gap does not completely rule out toxic alcohol ingestion. - Calculated osmolality = 2(Na+) + glucose/18 + BUN/2.8 + ethanol (in mg/dL)/4.6. - Osmol gap = measured osmolality " calculated osmolality. - Use mnemonic ME DIE A when osmol gap >10: - Methanol - Ethanol - Diuretics (mannitol, glycerin, sorbitol) - Isopropyl alcohol - Ethylene glycol - Acetone

- Search for clues at scene: - Pills/pill bottles - Drug paraphernalia - Witnesses - Transport all drugs and pill bottles for identification.

- Restrain uncooperative patients for patient and health care giver protection. - Consider comorbid conditions: - Trauma - Medical illness - Environmental exposure

- ABCs: - Endotracheal intubation as needed for airway protection, oxygenation, ventilation, and orogastric lavage - Supplemental oxygen for hypoxia - Pulse oximetry - Cardiac monitor - IV access

- Hypotension: - Administer 0.9% normal saline IV fluid bolus. - Trendelenburg - Vasopressors for persistent hypotension

- Multiple-dose activated charcoal: - Theophylline - Carbamazepine - Phenobarbital

- Urinary alkalinization: - Hemodialysis/hemoperfusion: - Lithium - Salicylates - Theophylline - Toxic alcohols - Valproate

- Antidotes: - Acetaminophen: N-acetylcysteine - Anticholinergic: Physostigmine - Benzodiazepines: Flumazenil - ²-blockers: Glucagon - Calcium-channel blockers: Calcium chloride/gluconate, insulin - Carbon monoxide: Oxygen, hyperbaric oxygen - Coumadin: Vitamin K1 - Cyanide: Cyanide antidote kit, hydroxocobalamin - Digoxin: Digibind - Ethylene glycol: Ethanol, 4-methylpyrazole - Iron: Deferoxamine - Isoniazid: Pyridoxine (vitamin B6) - Methanol: Ethanol, 4-methylpyrazole - Methemoglobinemia: Methylene blue - Opiates: Naloxone - Organophosphates: Atropine, pralidoxime - Tricyclic antidepressants: NaHCO3

  • Poisoning may be intentional or unintentional.
  • Patients with change in mental status without clear cause should have poisoning (intoxication, overdose) considered in differential diagnosis.

Etiology

  • Intentional:DepressionSuicideHomicideRecreational drug abuse
  • Unintentional (accidental):Common cause in childrenTherapeutic error (e.g., double dose)Recreational drug experimentation
  • Accidental ingestions " typically young children (1 " 5 yr)
  • Consider child abuse if inconsistent or suspicious history.

Diagnosis

Signs and Symptoms

  • Neurologic:LethargyAgitationComaHallucinationsSeizures
  • Respiratory:Tachypnea, bradypnea, apneaInability to protect airway
  • Cardiovascular:DysrhythmiasConduction blocks
  • Vital signs:Varies depending on toxic substanceHyperthermia, hypothermiaTachycardia, bradycardiaHypertension, hypotension

Selected Toxidromes (seePoisoning, Toxidromes)

  • Anticholinergic:Altered mental status (confusion, delirium, lethargy)Dry skin and mucous membranesFixed dilated pupilsTachycardiaHyperthermiaFlushingUrinary retention
  • Cholinergic:Secretory overdrive (salivation, lacrimation, urination, diaphoresis)MiosisBronchospasm, wheezing
  • Opiate:CNS and respiratory depressionMiosis
  • Sympathomimetic:CNS excitationSeizuresTachycardiaHypertensionDiaphoresis

Essential Workup

  • A complete set of vital signs, including core temperature
  • A complete physical exam, including eyes, skin, odors

Diagnosis Tests & Interpretation

Lab

  • Electrolytes, BUN/creatinine, glucose
  • Calculate anion gap: Na + (Cl + HCO3):Normal anion gap: 8 " 12Use mnemonic A CAT MUD PILES for elevated anion gap acidosis:Alcoholic ketoacidosisCyanide, carbon monoxideAspirin, other salicylatesTolueneMethanol, metforminUremiaDiabetic ketoacidosisParaldehyde, phenforminIron, isoniazidLactic acidosis from other causesEthylene glycolStarvation ketosis
  • Serum osmol gap:Calculate osmol gap if elevated anion gap acidosis from potential toxic alcohol.Most sensitive early in poisoningNormal osmol gap does not completely rule out toxic alcohol ingestion.Calculated osmolality = 2(Na+) + glucose/18 + BUN/2.8 + ethanol (in mg/dL)/4.6.Osmol gap = measured osmolality " calculated osmolality.Use mnemonic ME DIE A when osmol gap >10:MethanolEthanolDiuretics (mannitol, glycerin, sorbitol)Isopropyl alcoholEthylene glycolAcetone
  • Pregnancy test
  • Acetaminophen level for suicidal ingestions
  • Toxicology screen

Imaging

  • ECG for dysrhythmias or QRS/QT changes
  • CT of head for altered mental status not clearly due to toxin
  • Chest radiograph if suspected aspiration or pneumonia

Differential Diagnosis

  • Causes of altered mental status
  • Intracranial mass, bleeding
  • Infection, sepsis
  • Endocrine abnormalities
  • Hypothermia
  • Hypoxia
  • Metabolic abnormalities
  • Psychogenic

Treatment

Pre-Hospital

  • Search for clues at scene:Pills/pill bottlesDrug paraphernaliaWitnessesTransport all drugs and pill bottles for identification.
  • Restrain uncooperative patients for patient and health care giver protection.
  • Consider comorbid conditions:TraumaMedical illnessEnvironmental exposure
  • Pre-hospital administration of activated charcoal may optimize decontamination if prolonged transport time.

Initial Stabilization/Therapy

  • ABCs:Endotracheal intubation as needed for airway protection, oxygenation, ventilation, and orogastric lavageSupplemental oxygen for hypoxiaPulse oximetryCardiac monitorIV access
  • Hypotension:Administer 0.9% normal saline IV fluid bolus.TrendelenburgVasopressors for persistent hypotension
  • Bradycardia:
  • If altered mental status, administer coma cocktail: Thiamine, D50W (or Accu-Chek), naloxone

Ed Treatment/Procedures

  • Decontamination:See Poisoning, Gastric Decontamination.Prevents systemic absorption of ingested toxin
  • Orogastric lavage:Consider in potentially lethal ingestions without known antidote within 1 hr of ingestion.Protected airway essential prior to lavage
  • Activated charcoal:Most effective within a few hours of most toxic ingestionsContraindicated if caustic ingestion, unprotected airway, or bowel obstructionDrugs not effectively bound to charcoal: Metals (borates, bromide, iron, lithium), alcohols, potassium
  • Whole-bowel irrigation:Polyethylene glycol (Colyte, GoLytely) evacuates bowel without causing electrolyte disturbances.Consider in toxins not well adsorbed by charcoal (e.g., iron and lithium), body packers/stuffers, sustained-release ingestions.Contraindicated if bowel obstruction, perforation, or hypotension
  • Enhanced elimination:Enhances removal of systemically absorbed toxin
  • Multiple-dose activated charcoal:TheophyllineCarbamazepinePhenobarbital
  • Urinary alkalinization:
  • Hemodialysis/hemoperfusion:LithiumSalicylatesTheophyllineToxic alcoholsValproate
  • SeizuresTreat initially with diazepam or lorazepam.For persistent seizures, consider phenobarbital.Phenytoinnot indicated in toxicologic seizures:Indicated only if seizures secondary to idiopathic epilepsy, post-traumatic, or status epilepticus
  • Antidotes:Acetaminophen: N-acetylcysteineAnticholinergic: PhysostigmineBenzodiazepines: Flumazenil ²-blockers: GlucagonCalcium-channel blockers: Calcium chloride/gluconate, insulinCarbon monoxide: Oxygen, hyperbaric oxygenCoumadin: Vitamin K1Cyanide: Cyanide antidote kit, hydroxocobalaminDigoxin: DigibindEthylene glycol: Ethanol, 4-methylpyrazoleIron: DeferoxamineIsoniazid: Pyridoxine (vitamin B6)Methanol: Ethanol, 4-methylpyrazoleMethemoglobinemia: Methylene blueOpiates: NaloxoneOrganophosphates: Atropine, pralidoximeTricyclic antidepressants: NaHCO3

Medication

  • Activated charcoal slurry: 1 " 2 g/kg PO
  • Dextrose: D50W 1 amp: 50 mL or 25 g (peds: D25W 2 " 4 mL/kg) IV
  • Diazepam: 5 " 10 mg (peds: 0.2 " 0.5 mg/kg) IV every 10 " 15 min
  • Lorazepam: 2 " 6 mg (peds: 0.05 " 0.1 mg/kg) IV every 10 " 15 min
  • Naloxone (Narcan): 0.4 " 2 mg (peds: 0.1 mg/kg) IV or IM initial dose
  • Thiamine (vitamin B1): 100 mg (peds: 50 mg) IV or IM

Follow-Up

Disposition

Admission Criteria

  • Altered mental status
  • Cardiopulmonary instability
  • Suicidal
  • Lab abnormalities
  • Potential for decompensation from delayed acting substance

Discharge Criteria

  • Psychiatrically clear
  • Detoxified
  • Hemodynamically stable

Issues for Referral

  • Patients with unintentional (accidental) poisoning require poison prevention counseling.
  • Patients with intentional (e.g., suicide) poisoning require psychiatric evaluation.
  • Consider substance abuse referral for patients.

In general, treating the mother is also the best treatment strategy for the fetus.

Follow-Up Recommendations

  • Consider substance abuse referral for patients with recreational drug abuse.
  • Patients with unintentional (accidental) poisoning require poison prevention counseling.
  • Patients with intentional (e.g., suicide) poisoning require psychiatric evaluation.

Pearls and Pitfalls

  • Do not forget to consider nontoxicologic etiologies for altered mental status.
  • Do not rely on the urine drug screen to make a diagnosis: It only provides screening tests for a limited number of drugs.
  • Call a toxicologist or a poison center for help: 800-222-1222.

Additional Reading

  • Erickson TB, Thompson TM, Lu JJ. The approach to the patient with an unknown overdose. Emerg Med Clin North Am. 2007;25(2):249 " 281.
  • Levine M, Brooks DE, Truitt CA, et al. Toxicology in the ICU: Part 1: General overview and approach to treatment. Chest. 2011;140(3):795 " 806.
  • Mycyk MB. Poisoning and drug overdose. In: Longo D, Fauci A, Kasper D, et al., eds. Harrisons Principles of Internal Medicine. 18th ed. New York, NY: McGraw Hill; 2012:e50.1 " e50.16.
  • Wills B, Erickson T. Drug- and toxin-associated seizures. Med Clin North Am. 2005;89:1297 " 1321.

See Also (Topic, Algorithm, Electronic Media Element)

  • Poisoning, Antidotes
  • Poisoning, Gastric Decontamination
  • Poisoning, Toxidromes

Codes

ICD9

  • 971.1 Poisoning by parasympatholytics (anticholinergics and antimuscarinics) and spasmolytics
  • 977.9 Poisoning by unspecified drug or medicinal substance
  • 977.9 Poisoning by unspecified drug or medicinal substance
  • 977.9 Poisoning by unspecified drug or medicinal substance
  • 971.0 Poisoning by parasympathomimetics (cholinergics)
  • 971.2 Poisoning by sympathomimetics [adrenergics]
  • 969.6 Poisoning by psychodysleptics (hallucinogens)
  • 965.00 Poisoning by opium (alkaloids), unspecified

ICD10

  • T44.3X1A Poisoning by oth parasympath and spasmolytics, acc, init
  • T65.91XA Toxic effect of unspecified substance, accidental (unintentional), initial encounter
  • T65.91XA Toxic effect of unspecified substance, accidental (unintentional), initial encounter
  • T65.91XA Toxic effect of unspecified substance, accidental (unintentional), initial encounter
  • T44.1X1A Poisoning by oth parasympath, accidental, init
  • T65.92XA Toxic effect of unspecified substance, intentional self-harm, initial encounter
  • T44.901A Poisn by unsp drugs aff the autonm nervous sys, acc, init
  • T65.93XA Toxic effect of unspecified substance, assault, initial encounter
  • T40.901A Poisoning by unsp psychodyslept, accidental, init
  • T65.94XA Toxic effect of unsp substance, undetermined, init encntr
  • T40.601A Poisoning by unsp narcotics, accidental, init

SNOMED

  • 216593002 Accidental poisoning by anticholinergics (disorder)
  • 75478009 Poisoning (disorder)
  • 75478009 Poisoning (disorder)
  • 75478009 Poisoning (disorder)
  • 235453002 selective decontamination of the digestive tract (procedure)
  • 61356009 Poisoning by parasympathomimetic drug (disorder)
  • 67329000 Administration of antidote (procedure)
  • 72431002 Accidental poisoning (disorder)
  • 410061008 Intentional poisoning (disorder)
  • 45536007 poisoning by sympathomimetic drug (disorder)
  • 269736006 Poisoning of undetermined intent (disorder)
  • 85975005 Poisoning by psychodysleptic (disorder)
  • 11196001 Poisoning by opiate AND/OR related narcotic (disorder)
  • 271982007 Intentional self poisoning (disorder)