How to manage atropine (antimuscarinic agent) eye drops induced delirium?

Management of Atropine Eye Drops Induced Delirium

Physostigmine is the first-line treatment for atropine eye drops induced delirium and should be administered promptly to reverse anticholinergic toxicity. 1, 2

Pathophysiology and Recognition

Atropine, an anticholinergic agent used in ophthalmic preparations, can cause delirium through:

• Blockade of muscarinic receptors in the central nervous system
• Systemic absorption through the nasolacrimal duct
• Increased risk in elderly patients even at therapeutic doses 3

Signs and symptoms of atropine-induced delirium include:

• Altered mental status and confusion
• Agitation and hallucinations
• Dry mucosa and flushed skin
• Hyperthermia
• Tachycardia
• Urinary retention
• Mydriasis

Treatment Algorithm

Step 1: Discontinue Atropine

• Immediately stop all atropine eye drops
• Remove any residual medication from the eye surface with saline irrigation

Step 2: Administer Physostigmine

• First-line treatment: Physostigmine 1-2 mg IV slowly over 5 minutes 4, 2
• Monitor for response (improvement in mental status, vital signs)
• May repeat dose after 10-30 minutes if symptoms persist
• Continue until symptoms resolve, with doses up to 4 mg in adults (0.5-1 mg in pediatric populations) 4

Step 3: Supportive Care

• Maintain hydration with IV fluids
• Control hyperthermia with cooling measures if present
• Monitor vital signs continuously
• Provide calm, well-lit environment with clear orientation cues
• Ensure adequate oxygenation

Step 4: For Severe or Refractory Cases

• For persistent symptoms, consider repeated doses of physostigmine (monitoring for cholinergic side effects)
• For severe agitation, consider benzodiazepines (diazepam 5-10 mg IV) 4
• For seizures, administer benzodiazepines rather than barbiturates 4

Step 5: Monitoring and Follow-up

• Continue monitoring for at least 24 hours after symptom resolution
• Be prepared for symptom recurrence as physostigmine's duration of action (1-2 hours) is shorter than atropine's 2

Special Considerations

Elderly Patients

• More susceptible to anticholinergic effects even at therapeutic doses 3
• May require lower doses of physostigmine (0.5-1 mg initially)
• Increased monitoring for adverse effects

Contraindications to Physostigmine

• Asthma
• Cardiovascular disease
• Mechanical obstruction of intestine or urinary tract
• Caution in patients taking cholinesterase inhibitors

Prevention of Recurrence

1. Use lowest effective concentration of atropine eye drops
2. Consider alternative mydriatics/cycloplegics in high-risk patients
3. Educate patients and caregivers about proper administration technique:
   • Apply gentle pressure to nasolacrimal duct for 1-2 minutes after instillation
   • Limit to one drop per administration
   • Wipe excess medication from cheek

Pitfalls to Avoid

1. Misdiagnosis: Atropine-induced delirium may be mistaken for stroke, primary psychiatric disorder, or other neurological conditions 2
2. Delayed treatment: Prompt recognition and administration of physostigmine can prevent need for intubation 1
3. Inadequate monitoring: Symptoms may recur as physostigmine's effect wears off 2
4. Excessive sedation: Avoid large doses of sedatives which may worsen respiratory depression 4

By following this approach, clinicians can effectively manage atropine eye drops induced delirium while minimizing complications and improving patient outcomes.