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Anticholinergic Toxicity

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Anticholinergic Toxicity, Anticholinergic Poisoning, Anticholinergic Symptoms, Anticholinergic, Anticholinergic Syndrome, Anticholinergic Reaction

  • Causes
  1. Medications
    1. See Anticholinergic Medications
    2. Antihistamines
    3. Tricyclic Antidepressants
    4. Parasympatholytic medications
      1. Atropine
      2. Scopolamine
      3. Hyoscyamine
  2. Toxins
    1. Incapacitating Agents (e.g. BZ)
    2. Botulism (or infant bolulism)
      1. Foodborne Illness or Wound Infection
    3. Ingested items
      1. Jimsonweed
      2. Amanita muscaria mushrooms
  • Symptoms
  • Mnemonic (antimuscarinic)
  1. Hot as a hare (Hyperthermia)
  2. Dry as a bone (Dry Skin)
  3. Red as a beet (Flushed)
  4. Blind as bat (Mydriasis)
  5. Mad as a hatter (Delirium)
  • Symptoms
  • Complete List (antimuscarinic)
  1. Altered Level of Consciousness
    1. Speech may be soft spoken, or a mumbling Word Salad
    2. Hallucinations
    3. Delirium
    4. Coma
  2. Seizures
  3. Sinus Tachycardia (may approach 150 bpm in adults)
  4. Hypertension
  5. Hyperthermia (typically low grade fever)
  6. Dry Skin
    1. Examine axilla and groin (where dryness is uncommon)
    2. Contrast with Sympathomimetic Toxicity in which skin is diaphoretic
  7. Dry Mouth
    1. Speech may sound muffled as if cotton balls are in mouth
  8. Mydriasis with Blurred Vision
  9. Decreased bowel sounds
  10. Constipation
  11. Urinary Retention
  • Labs
  1. See Unknown Ingestion
  2. See Altered Level of Consciousness
  3. Creatine Kinase (CK)
    1. Monitor for Rhabdomyolysis with serial measurements
  1. Exclude contraindications to Physostigmine (esp. Tricyclic Antidepressant Overdose)
    1. Bradycardia
    2. Intraventricular conduction delay (Wide QRS)
    3. AV Nodal block
    4. Terminal R (wide R Wave >3 mm) in AVR (suggests Sodium channel blockade, seen in TCA Overdose)
  • Management
  1. Agitation may require treatment
    1. See Sedation in Excited Delirium
    2. Preferred sedation agents
      1. Benzodiazepines
      2. Dexmedetomidine (Precedex)
      3. Propofol could also be used (short course)
    3. Avoid Physical Restraints
      1. Risk of worsening Rhabdomyolysis
    4. Avoid Antipsychotics (e.g. Haloperidol)
      1. Risk of upsetting Temperature Regulation (with worsening hyperthermia)
  2. Control hyperthermia
    1. Monitor Temperature
      1. Consider Temperature-sensing Foley Catheter
    2. Other measures refractory to Benzodiazepines and other sedatives
      1. Paralysis could be considered (rare cases)
  3. Intravenous Fluids
  4. Antidote: Physostigmine
    1. See Physostigmine for dosing and contraindications
    2. Repeat dosing may be needed (lasts only 30 minutes)
    3. Consider Physostigmine in cases of Altered Level of Consciousness and signs of Anticholinergic Toxicity
      1. Physostigmine will transiently reverse Anticholinergic effects and aid diagnosis in unclear cases
    4. Review contraindications before administration
      1. Obtain EKG prior to administration
        1. Exclude Bradycardia, intraventricular conduction delay or AV Nodal block
        2. Avoid in Tricyclic Antidepressant Overdose (risk of Asystole)
      2. Contraindicated in uncontrolled Asthma or Wheezing
      3. Contraindicated in Seizure disorder
      4. Contraindicated in Bowel Obstruction
  5. References
    1. Claudius and Levine in Majoewsky (2012) EM:Rap 12(5): 7
  • References
  1. Orman and Hatten in Herbert (2016) EM:Rap 16(4): 6
  2. Swaminathan and Monas in Herbert (2020) EM:Rap 20(5):1