What is the treatment for cholinergic overdose syndrome?

Treatment of Cholinergic Overdose Syndrome

The treatment of cholinergic overdose syndrome requires immediate administration of atropine as the primary antidote, followed by pralidoxime (2-PAM) in cases of organophosphate poisoning, along with supportive care including airway management and ventilatory support. 1, 2, 3

Clinical Presentation and Diagnosis

Cholinergic overdose syndrome results from excessive acetylcholine activity and presents with a constellation of symptoms that can be remembered using the mnemonic "SLUDGE":

• Salivation
• Lacrimation
• Urination
• Diarrhea
• Gastrointestinal distress
• Emesis

Additional symptoms include:

• Bradycardia
• Hypotension
• Miosis (pinpoint pupils)
• Bronchospasm and bronchorrhea
• Muscle fasciculations, weakness, or paralysis
• CNS effects (confusion, seizures, respiratory depression)

Treatment Algorithm

1. Immediate Interventions

• Airway management: Secure airway and provide oxygen
• Decontamination: Remove contaminated clothing and wash skin with soap and water in cases of external exposure
• Gastric lavage: Consider within 1 hour of ingestion for oral exposures 4

2. Pharmacological Management

First-Line Treatment: Atropine

• Dosing:

  • Adults: 2-4 mg IV initially 1
  • Repeat every 5-10 minutes until atropinization is achieved (secretions are inhibited)
  • Maintain atropinization for at least 48 hours

• Endpoint of atropine therapy: Drying of secretions, resolution of bronchospasm, and normalization of heart rate

• Important note: Atropine should not be given in the presence of significant hypoxia due to the risk of ventricular fibrillation 3

Second-Line Treatment: Pralidoxime (2-PAM)

• Indications: Only for organophosphate poisoning (not carbamate poisoning)

• Dosing:

  • Adults: 1000-2000 mg IV, preferably as an infusion in 100 mL normal saline over 15-30 minutes
  • If infusion not practical: Administer slowly over at least 5 minutes
  • May repeat 1000-2000 mg after one hour if muscle weakness persists
  • Additional doses every 10-12 hours as needed 3

• Alternative dosing strategy: Loading dose followed by continuous infusion to maintain therapeutic levels 3

3. Supportive Care

• Respiratory support: Mechanical ventilation may be required for respiratory failure
• Fluid resuscitation: For hypotension
• Seizure control: Benzodiazepines (not phenothiazines)
• Continuous monitoring: Vital signs, cardiac rhythm, oxygen saturation
• Temperature management: For hyperthermia

Special Considerations

Medications to Avoid

• Morphine
• Theophylline/aminophylline
• Reserpine
• Phenothiazine-type tranquilizers
• Succinylcholine (may cause prolonged paralysis) 3

Intermediate Syndrome

• May develop 24-96 hours after acute cholinergic crisis
• Characterized by respiratory paresis and weakness of facial, neck, and proximal limb muscles
• Requires prolonged monitoring of respiratory function 5

Central Anticholinergic Syndrome

This is the opposite of cholinergic syndrome and may occur during treatment with atropine. Signs include:

• Confusion, agitation, hallucinations
• Hyperthermia
• Dry skin and mucous membranes
• Urinary retention
• Tachycardia 6

Monitoring and Follow-up

• Monitor cholinesterase levels to guide therapy and follow recovery
• Observe for at least 24 hours after symptom resolution
• Be alert for delayed neuropsychological sequelae, which may persist for months 7

Prognosis

With prompt recognition and appropriate treatment, most patients with cholinergic overdose syndrome recover completely. However, mortality can be as high as 11% without proper treatment, primarily due to respiratory failure 2.