What is the acute management of suspected Datura (anticholinergic) poisoning?

Acute Management of Datura (Anticholinergic) Poisoning

Immediately secure the airway, administer benzodiazepines for agitation, provide aggressive supportive care with IV fluids and external cooling, and reserve physostigmine (1-2 mg IV slowly over 5 minutes in adults; 0.02 mg/kg IV in children, max 0.5 mg/dose) for severe cases with life-threatening central nervous system effects or refractory agitation that fails benzodiazepine therapy. 1, 2, 3

Initial Stabilization (First Priority)

Airway, breathing, and circulation take absolute priority over toxin identification or antidotal therapy. 4

• Secure the airway early if the patient has altered mental status, inability to protect airway, or severe agitation requiring sedation 1
• Obtain vital signs immediately: temperature (expect mild elevation <38.8°C but can be higher), heart rate (tachycardia), blood pressure (mild hypertension), and respiratory rate (tachypnea) 4, 1
• Perform focused neurological assessment for level of consciousness, agitation, delirium, hallucinations, and seizure activity 1
• Obtain ECG to assess for QRS prolongation or dysrhythmias, particularly if tricyclic antidepressant co-ingestion is suspected 1

Recognition of Anticholinergic Toxidrome

The classic presentation can be remembered as "hot as a hare, blind as a bat, dry as a bone, red as a beet, and mad as a hatter": 5

• Central effects: Agitated delirium, hallucinations, disorientation, incomprehensible speech, seizures, or coma 4, 6, 7, 8
• Cardiovascular: Tachycardia, mild hypertension 4, 1, 9
• Skin: Hot, dry, erythematous, flushed skin with absent sweating 4, 1, 7, 3
• Eyes: Mydriasis (markedly dilated, sluggish or fixed pupils) 4, 1, 7, 3, 8
• Gastrointestinal: Hypoactive or absent bowel sounds, dry mucous membranes 4, 1
• Genitourinary: Urinary retention 1, 2
• Respiratory: Tachypnea, decreased pharyngeal and bronchial secretions 4, 2

First-Line Management

Discontinue Exposure and Decontamination

• Remove any remaining plant material from the patient 4
• Activated charcoal (1 g/kg) may be considered if recent oral ingestion (<1-2 hours) AND the airway is protected (patient is alert or intubated), as gastrointestinal motility is decreased in anticholinergic poisoning 1, 8
• Do not induce vomiting due to risk of aspiration and rapid deterioration in mental status 4

Supportive Care

• Administer IV fluids for hydration and to prevent complications 1
• Benzodiazepines are first-line for agitation and seizure control: diazepam 5-10 mg IV (adults) or 0.2 mg/kg IV (children); alternatively midazolam 2-5 mg IV (adults) or 0.05-0.1 mg/kg IV (children) 1, 3, 8
• Treat hyperthermia aggressively with external cooling measures (ice packs, cooling blankets, misting with fans) as this significantly impacts morbidity 1
• Bladder catheterization for urinary retention 1
• Physical restraints may be necessary for violent agitation until adequate sedation is achieved, but chemical sedation with benzodiazepines is preferred 3, 8

Physostigmine: Specific Antidotal Therapy

Physostigmine is indicated for severe anticholinergic toxicity with significant central nervous system effects (severe delirium, hallucinations, seizures) or life-threatening peripheral manifestations, particularly when benzodiazepines fail to control agitation. 1, 5, 2, 3

Dosing

• Adults: 1-2 mg IV administered slowly over 5 minutes; may repeat after 10-30 minutes if needed 1, 2
• Pediatrics: 0.02 mg/kg IV (maximum 0.5 mg/dose) 1
• Dramatic reversal of anticholinergic symptoms occurs within 15-20 minutes if the diagnosis is correct 2, 3
• Duration of action is short (45-60 minutes), so repeat dosing or continuous infusion may be required 2

Contraindications to Physostigmine

Do not administer physostigmine in patients with: 1

• Cardiovascular disease or significant dysrhythmias
• Asthma or reactive airway disease
• Mechanical obstruction of intestines or urinary tract
• Gangrene
• Diabetes with vascular complications
• QRS prolongation >100 ms (suggests sodium channel blockade from tricyclic antidepressants) 1

Evidence for Physostigmine

• Patients receiving physostigmine have significantly lower rates of intubation compared to those receiving benzodiazepines alone 1
• Five cases of severe anticholinergic poisoning treated with physostigmine showed decreased agitation within 15-20 minutes with no adverse effects 3
• Common pitfall: Underdosing of physostigmine is frequent; larger or repeated doses may be required in severe Datura poisoning 1

Management of Specific Complications

Dysrhythmias and QRS Prolongation

• If prolonged QRS or ventricular dysrhythmias occur (suggesting co-ingestion of tricyclic antidepressants or other sodium channel blockers), administer sodium bicarbonate 1, 5
• Physostigmine is contraindicated in this scenario 1

Seizures

• Benzodiazepines remain first-line for seizure management 1
• Physostigmine may be considered for refractory seizures after benzodiazepines, if no contraindications exist 1

Severe Agitation Refractory to Benzodiazepines

• Physostigmine is the treatment of choice for severe, refractory agitation 1, 3
• Haloperidol has been used in combination with benzodiazepines but does not address the underlying pathophysiology 8

Monitoring and Disposition

• Continuous cardiac monitoring for at least 6 hours after symptom resolution 1
• Serial neurological assessments to evaluate response to treatment 1
• Observe for at least 6-24 hours as symptoms may recur when physostigmine wears off or if continued gastrointestinal absorption occurs 2, 8
• Most patients require hospitalization for observation and supportive care 6, 8

Critical Pitfalls to Avoid

• Never delay supportive care while attempting to identify the specific toxin; timely airway management and hemodynamic support take priority 4
• Never use physostigmine as first-line therapy; benzodiazepines and supportive care should be initiated first 1, 3
• Never administer physostigmine without obtaining an ECG first to rule out QRS prolongation 1
• Never assume a single dose of physostigmine will be sufficient; the short duration of action (45-60 minutes) often requires repeat dosing 2
• Avoid succinylcholine if intubation is required, as it may cause prolonged paralysis in the setting of anticholinergic crisis 1

Consultation

Contact a regional poison center (1-800-222-1222 in the United States) or medical toxicologist for expert guidance, particularly when considering physostigmine administration or managing severe cases. 4, 5

Prognosis

Prognosis is usually favorable with prompt recognition and appropriate supportive care. 6 Deaths are rare but can occur from severe hyperthermia, seizures, dysrhythmias, or respiratory failure if treatment is delayed 6, 9