What are the options for symptom management in anticholinergic poisoning?

Symptom Management in Anticholinergic Poisoning

Physostigmine is the specific antidote for severe anticholinergic toxicity and should be administered for significant central nervous system effects or life-threatening peripheral manifestations. 1

Initial Assessment and Stabilization

• Secure airway, breathing, and circulation as the first priority in anticholinergic toxicity 1
• Obtain vital signs, with particular attention to temperature, heart rate, and blood pressure 1
• Perform focused neurological assessment to evaluate level of consciousness and presence of agitation 1
• Obtain ECG to assess for QRS prolongation or dysrhythmias 1
• Discontinue the precipitating anticholinergic agent immediately 1

First-Line Interventions

• Provide supportive care including IV fluids for hydration 1
• Administer benzodiazepines for agitation and seizure control 2, 1
  • Midazolam 0.05–0.1 mg/kg or diazepam 0.2 mg/kg in fractionated doses until desired effect 2
• Consider activated charcoal if recent oral ingestion and airway is protected 1
• Implement external cooling measures for hyperthermia 2, 1
• Treat prolonged QRS or dysrhythmias with sodium bicarbonate 2, 1

Specific Antidotal Therapy: Physostigmine

• Physostigmine is indicated for severe anticholinergic toxicity with significant central nervous system effects (agitated delirium, hallucinations) or life-threatening peripheral manifestations 1, 3
• Adult dosing: 1-2 mg IV slowly over 5 minutes, may be repeated after 10-30 minutes if needed 1, 4
• Pediatric dosing: 0.02 mg/kg IV (maximum 0.5 mg/dose) 1
• Duration of action is relatively short (45-60 minutes), so repeated doses may be necessary 3, 5
• For persistent symptoms, continuous IV infusion of physostigmine may be considered at 0.5-1 mg/hour (0.02-0.03 mg/kg/hour for pediatric patients) 6, 7

Management of Specific Complications

Central Nervous System Effects

• For agitated delirium not responsive to benzodiazepines, administer physostigmine 1, 8
• Dramatic reversal of central anticholinergic symptoms can be expected within minutes after IV physostigmine administration 3, 4

Cardiovascular Effects

• Monitor for tachycardia and mild hypertension 2
• Continuous cardiac monitoring should be performed for at least 6 hours after symptom resolution 1

Hyperthermia

• Implement external cooling measures 2, 1
• Avoid medications that may exacerbate hyperthermia 2

Urinary Retention

• Consider bladder catheterization if necessary 1

Special Considerations and Contraindications

• Physostigmine is contraindicated in patients with:

  • Cardiovascular disease 1
  • Asthma 1
  • Mechanical obstruction of intestines or urinary tract 1
  • History of seizures 1
  • Suspected tricyclic antidepressant overdose with QRS prolongation 1

• Anticholinergic toxicity may be worsened by antipsychotics due to their anticholinergic properties 2

• Patients receiving physostigmine have significantly lower rates of intubation compared to those receiving other treatments 1

• Avoid succinylcholine in patients requiring intubation as it may cause prolonged paralysis 1

Monitoring and Follow-up

• Perform serial neurological assessments to evaluate response to treatment 1
• Monitor for recurrence of symptoms due to the short duration of action of physostigmine 3, 5
• Continue cardiac monitoring for at least 6 hours after symptom resolution 1

Common Pitfalls

• Underdosing of physostigmine is common; larger doses than standard may be required in severe cases 1
• Failure to recognize the anticholinergic toxidrome (hot, dry, red skin; mydriasis; altered mental status; urinary retention; decreased bowel sounds) 2
• Administering antipsychotics for agitation, which may worsen anticholinergic toxicity 2