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Anticholinergic toxicity
From WikEM
Contents
Background
Anticholinergic toxicity
- Medications
- Atropine
- Antihistamines
- Antidepressants
- Antipsychotics
- Muscle relaxants
- Anti-Parkinsonians
- 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
- ECG
- Sinus tachycardia
- QRS widening in some cases
Differential Diagnosis
- Sympathomimetic toxicity
- Red, dry skin and absent bowel sounds favors anticholinergic toxicity
- Encephalitis
- Head trauma
- ETOH/sedative withdrawal
- Neuroleptic Malignant Syndrome (NMS)
- 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 | Varriable | 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
Altered mental status and fever
- Infectious
- Sepsis
- Meningitis
- Encephalitis
- Cerebral malaria
- Other
- Neuroleptic malignant syndrome
- Serotonin syndrome
- Malignant hyperthermia
- Sympathomimetic toxicity (cocaine, amphetamine, ketamine)
- Anticholinergic toxicity
- Heat stroke
- Delirium tremens
- Hypothalamic stroke
- Pheochromocytoma
- Thyroid storm
Treatment
- GI decon
- Activated Charcoal may be effective even >1hr after ingestion (decreased GI motility)
- Sedation
- Decreases the risk of hyperthermia, rhabdo, traumatic injuries
- Benzos are agents of choice especially increase seizure threshold
- Conduction abnormalities (QRS prolongation)
- Sodium Bicarbonate
- Should be given at 2 mEq/kg
- Typically 2-3 amps of bicarb
- Begin continuous NaCO3 infusions if bolus effective
- Solution preparation = 1L D5W mixed with 3 ampules NaHCO3
- Run NaHCO3 solutions at 250 mL/hr
- Sodium Bicarbonate
- Cholinesterase inhibition
- Indicated for severe agitation or delirium (esp if unresponsive to benzos)
- Contraindicated in QRS>100 or Na blockade signs (R' in aVR)
- Relative contraindicated in asthma or ileus
- Physostigmine
- Crosses blood brain barrier, can be used to help make dx
- Dosing: 0.5-2mg IV over 5min
- Onset of action: 15-20min
- Side effects: bradycardia, dysrhythmias, cholinergic excess
- Always have atropine at the bedside for bradycardia or cholinergic excess
- Contraindicated in TCA toxicity, associated with cardiac arrest
Disposition
- Consider discharge for patients with 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)
