Anticholinergic toxicity

Background

• Meds
  • Atropine
  • Antihistamines
  • Antidepressants (SSRIs, TCAs)
  • Antipsychotics
  • Muscle relaxants
• Plants
  • Jimson weed (Devil's trumpet)
  • Amanita mushroom

Clinical Features

• Dry as a bone: anhidrosis (esp axillae, mouth)
• Hot as a hare: anhydrotic hyperthermia (may become severe w/ agitation)
• Red as a beet: cutaneous vasodilation
• Blind as a bat: nonreactive mydriasis (often delayed 12-24hr)
• Mad as a hatter: delirium; attention deficit; hallucinations; dysarthria; lethargy
• Full as a flask: urinary retention
• Tachycardia (HR 120-160) and decreased/absent bowel sounds

DDX

1. Sympathomimetic toxicity
   1. Red, dry skin and absent bowel sounds favors anticholinergic toxicity
2. Encephalitis
3. Head trauma
4. ETOH/sedative withdrawal
5. Neuroleptic Malignant Syndrome (NMS)
6. Acute psychotic disorder

Toxidrome Chart

Finding	Cholinergic	Anticholinergic	Sympathomimetic	Sympatholytic^	Sedative/Hypnotic
Example	Organophosphates	TCAs	Cocaine	Clonidine	ETOH
Temp	Nl	Nl / ↑	Nl / ↑	Nl / ↓	Nl / ↓
RR	Variable	Nl / ↓	Variable	Nl / ↓	Nl / ↓
HR	Variable	↑	↑ (sig)	Nl / ↓	Nl / ↓
BP	↑	↑	↑	Nl / ↓	Nl / ↓
LOC	Nl / Lethargic	Nl, agitated, psychotic, comatose	Nl, agitated, psychotic	Nl, Lethargic, or Comatose	Nl, Lethargic, or Comatose
Pupils	Variable	Mydriatic	Mydriatic	Nl / Miotic
Motor	Fasciculations, Flacid Paralysis	Nl	Nl / Agitated	Nl
Skin	Sweating (sig)	Hot, dry	Sweating	Dry
Lungs	Bronchospasm / rhinorrhea	Nl	Nl	Nl
Bowel Sounds	Hyperactive (SLUDGE)	↓ / Absent	Nl / ↓	Nl / ↓

^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan

Withdrawal from substances have the opposite effect

Disposition

• Consider d/c for pts w/ mild symptoms after 6hr obs if their symptoms resolve
• Admit if physostigmine was given (half-life of physo is often shorter than the ingested drug)

See Also

• Toxicology (Main)

Source

Tintinalli