Rosen & Barkin's 5-Minute Emergency Medicine Consult (60 page)

• 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, mandrake, henbane
    
  • Jimson weed—smoked or ingested
    

DIAGNOSIS

• Onset and duration of symptoms
  
• Type and extent of ingestion/exposure
  

• Classic toxidrome:
  
  • “
    Mad as a hatter”
    —
    altered mental status
    
  • “
    Hot as a hare”
    —hyperthermia
    
  • “
    Red as a beet”
    —flushed skin
    
  • “
    Dry as a bone”
    —dry skin and mucous membranes
    
  • “
    Blind as a bat”
    —blurred vision secondary to mydriasis
    
• 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):
  
  • Urinary retention
    
• Integument:
  
  • Decreased sweating
    
  • Flushed skin
    
  • Dry skin and mucous membranes
    
• CNS:
  
  • Altered mental status
    
  • Auditory or visual hallucinations
    
  • Coma
    
  • Seizures
    

Diagnosis based on clinical presentation and an accurate history

• 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)
    

ECG:

• Sinus tachycardia most common
  
• QRS prolongation
  
• AV blockade
  
• Bundle branch block pattern
  
• Dysrhythmias
  

• Sympathomimetic intoxication
  
• Withdrawal syndrome
  
• Acute psychiatric disorders
  
• Sepsis
  
• Thyroid disorder
  

TREATMENT

Transport all pills/pill bottles involved in overdose for identification in ED.

• Airway, breathing, and circulation (ABCs):
  
  • Airway control essential
    
  • Administer supplemental oxygen.
    
  • IV access
    
  • Cardiac monitor and pulse oximetry
    
• Naloxone, thiamine, D
  ₅₀
  (or Accu-Chek) if altered mental status
  

• Supportive care:
  
  • IV rehydration with 0.9% NS
    
  • Standard 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 standard 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.
    
  • 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:
    
    • Seizures unresponsive to conventional therapy
      
    • Uncontrollable agitation
      
  • 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
      

• Activated charcoal: 1 g/kg PO
  
• Dextrose: 50–100 mL D
  ₅₀
  (peds: 2 mL/kg of D
  ₂₅
  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 μg/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 B
  ₁
  ): 100 mg (peds: 50 mg) IV or IM
  

Lorazepam or Diazepam

Physostigmine (use with caution and consult with medical toxicologist)

FOLLOW-UP

• ICU admission for moderate to severe anticholinergic symptoms (agitation control, temperature control, and observation for seizures or dysrhythmias)
  
• Any patient receiving physostigmine
  

Mild and improving symptoms of anticholinergic toxicity after 6–8 hr of ED observation

• 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.
  

Appropriate psychiatric referral for intentional ingestions

• Aggressively treat hyperthermia.
  
• Antipyretic medications are not effective in toxic hyperthermia.
  
• Use physostigmine cautiously and consult with medical toxicologist when available.
  

• Burns MJ, Linden CH, Graudins A, et al. A comparison of physostigmine and benzodiazepines for the treatment of anticholinergic poisoning.
  Ann Emerg Med
  . 2000;35:374–381.
  
• Ceha LJ, Presperin C, Young E, et al. Anticholinergic toxicity from nightshade berry poisoning responsive to physostigmine.
  J Emerg Med
  . 1997;15:65–69.
  
• Delaney KA. Anticholinergics and antihistamines (H1 antagonists). In: Ford MD, Delaney KA, Ling LJ, et al., eds.
  Clinical Toxicology
  . Philadelphia, PA: WB Saunders; 2001;472–477.
  
• Hidalgo HA, Mowers RM. Anticholinergic drug abuse.
  Ann Pharmacother
  . 1990;24:40.
  
• Patel RJ, Saylor T, Williams SR, et al. Prevalence of autonomic signs and symptoms in antimuscarinic drug poisonings.
  J Emerg Med
  . 2004;26(1):89–94.
  
• Reilly KM, Chan L, Mehta NJ, et al. Systemic toxicity from ocular homatropine.
  Acad Emerg Med
  . 1996;3:868–871.
  

CODES

971.1 Poisoning by parasympatholytics (anticholinergics and antimuscarinics) and spasmolytics

BASICS