Author:
Patrick M.Whiteley
Description
- Central and peripheral cholinergic blockade
- Depending on the drug involved, antagonism occurs at muscarinic (most common), nicotinic, or both receptors
- Onset of activity: 15-60 min after ingestion
- Duration of effect: 2-24 hr
Etiology
- Many drugs contain anticholinergic properties:
- Mild at therapeutic doses
- Life threatening in overdose
- Anticholinergic substances:
- Antihistamines
- Belladonna alkaloids and synthetic congeners
- Antiparkinsonian drugs
- Cyclic antidepressants
- Antipsychotics (neuroleptics)
- Mydriatics
- Skeletal muscle relaxants (orphenadrine, cyclobenzaprine)
- Antispasmodics
- Mushrooms—Amanita muscaria, Amanita pantherina
- Plants—deadly nightshade, mand rake, henbane
- Jimson weed—smoked or ingested
Signs and Symptoms
History
- Onset and duration of symptoms
- Type and extent of ingestion/exposure
Physical Exam
- Classic toxidrome:
- General:
- Hyperthermia
- Altered mental status
- Ocular:
- Unreactive mydriasis
- Inability to accommodate
- Cardiovascular:
- Sinus tachycardia
- Dysrhythmias (rare except in massive ingestions)
- Hypotension/HTN
- Cardiogenic pulmonary edema
- Pulmonary:
- Tachypnea
- Respiratory failure
- GI:
- Decreased/absent bowel sounds
- Dysphagia
- Decreased GI motility
- Decreased salivation
- Genitourinary (GU):
- Integument:
- Decreased sweating
- Flushed skin
- Dry skin and mucous membranes
- CNS:
- Altered mental status
- Auditory or visual hallucinations
- Coma
- Seizures
Essential Workup
Diagnosis based on clinical presentation and an accurate history
Diagnostic Tests & Interpretation
Lab
- Urine toxicologic screen if clinically indicated
- Electrolytes, BUN, creatinine, and glucose
- CBC
- Creatine phosphokinase (CPK) if suspected rhabdomyolysis
- Urinalysis
- Acetaminophen and salicylate levels:
- Detects occult ingestion (e.g., Tylenol PM)
Imaging
ECG:
- Sinus tachycardia most common
- QRS prolongation
- AV blockade
- Bundle branch block pattern
- Dysrhythmias
Differential Diagnosis
- Sympathomimetic intoxication
- Withdrawal syndrome
- Acute psychiatric disorders
- Sepsis
- Thyroid disorder
Prehospital
Transport all pills/pill bottles involved in overdose for identification in ED
Initial Stabilization/Therapy
- Airway, breathing, and circulation (ABCs):
- Airway control essential
- Administer supplemental oxygen
- IV access
- Cardiac monitor and pulse oximetry
- Naloxone, thiamine, D50 (or Accu-Chek) if altered mental status
ED Treatment/Procedures
- Supportive care:
- IV rehydration with 0.9% NS
- Stand ard aggressive cooling measures for hyperthermia
- Use benzodiazepines for treatment of agitation:
- Avoid phenothiazines owing to anticholinergic effects
- Treat seizures with benzodiazepines and barbiturates
- Dysrhythmias:
- Use stand ard antidysrhythmics
- Avoid class Ia antidysrhythmic owing to the quinidine-like effect of many anticholinergic drugs
- Sodium bicarbonate boluses may reverse the quinidine-like effects
- Decontamination:
- Administer activated charcoal for oral ingestions if within 1 hr in patient that can protect airway
- Ocular lavage for eyedrop exposure
- Physostigmine (Antilirium):
- Reversible acetylcholinesterase inhibitor that crosses the blood-brain barrier
- Short-term reversal of both central and peripheral anticholinergic effects
- Indicated in the presence of peripheral anticholinergic signs and the following:
- Use with caution if prolonged QRS is present on ECG owing to risk of dysrhythmias (especially asystole), seizures, and cholinergic crises:
- Place on cardiac monitor
- Observe for cholinergic symptoms
- Contraindications:
- Cyclic antidepressant overdose (potentiates toxicity)
- Cardiovascular disease
- Asthma/bronchospasm
- Intestinal obstruction
- Heart block
- Peripheral vascular disease
- Bladder obstruction
Medication
- Activated charcoal: 1 g/kg PO
- Dextrose: 50-100 mL D50 (peds: 2 mL/kg of D25 over 1 min) IV; repeat if necessary
- Diazepam: 5-10 mg (peds: 0.2-0.5 mg/kg) IV every 10-15 min
- Dopamine: 2-20 mcg/kg/min IV with titration to effect
- Lorazepam: 2-4 mg (peds: 0.03-0.05 mg/kg) IV every 10-15 min
- Physostigmine: 0.5-2.0 mg (peds: 0.02 mg/kg) IV over 5 min; repeat if necessary in 30-60 min
- Phenobarbital: 10-20 mg/kg IV (loading dose); monitor for respiratory depression
- Thiamine (vitamin B1): 100 mg (peds: 50 mg) IV or IM
First Line
Lorazepam or Diazepam
Second Line
Physostigmine (use with caution and consult with medical toxicologist)
Disposition
Admission Criteria
ICU admission for moderate to severe anticholinergic symptoms (agitation control, temperature control, and observation for seizures or dysrhythmias)
Discharge Criteria
Mild and improving symptoms of anticholinergic toxicity after 6 hr of ED observation
Issues for Referral
- Substance abuse referral for patients with recreational anticholinergic abuse
- Patients with unintentional (accidental) poisoning require poison prevention counseling
- Patients with intentional (e.g., suicide) poisoning require psychiatric evaluation
Follow-up Recommendations
Appropriate psychiatric referral for intentional ingestions
ICD9
971.1 Poisoning by parasympatholytics (anticholinergics and antimuscarinics) and spasmolytics
ICD10
T44.3X1A Poisoning by oth parasympath and spasmolytics, acc, init
SNOMED