What are the signs and symptoms of organophosphate poisoning?

Signs and Symptoms of Organophosphate Poisoning

Organophosphate poisoning presents with a characteristic set of symptoms known as SLUDGE syndrome (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis), along with bronchorrhea, bronchospasm, and neurological manifestations including altered mental status, seizures, and muscle fasciculations. 1

Clinical Manifestations by System

Muscarinic Effects (Parasympathetic)

• Respiratory system:

  • Bronchorrhea (excessive respiratory secretions)
  • Bronchospasm
  • Shortness of breath
  • Wheezing
  • Respiratory failure (most common cause of mortality, 74.4% of cases) 2

• Gastrointestinal system:

  • Excessive salivation (70% of cases) 3
  • Nausea and vomiting
  • Abdominal cramps
  • Diarrhea
  • Involuntary defecation

• Cardiovascular system:

  • Bradycardia (can also see tachycardia in some cases)
  • Hypotension or hypertension

• Ocular effects:

  • Miosis (narrowed pupils) (73% of cases) 3
  • Blurred vision
  • Lacrimation (excessive tearing)

• Glandular effects:

  • Excessive sweating

• Urinary system:

  • Urinary incontinence

Nicotinic Effects (Sympathetic and Neuromuscular)

• Neuromuscular effects:

  • Muscle fasciculations (involuntary twitching)
  • Muscle weakness (68% of cases) 3
  • Progressive muscle paralysis
  • Respiratory muscle weakness leading to respiratory failure

• Sympathetic effects:

  • Tachycardia (49% of cases) 3
  • Hypertension
  • Mydriasis (dilated pupils, less common than miosis)

Central Nervous System Effects

• Altered mental status (54% of cases show lethargy) 3
• Anxiety and restlessness
• Seizures (22% of cases) 3
• Confusion
• Mental confusion
• Coma
• Respiratory depression due to central effects

Time-Based Classification of Symptoms

Acute Symptoms (within 24 hours)

• Initial cholinergic crisis with SLUDGE symptoms
• Respiratory symptoms are typically the earliest manifestations of vapor exposure 4
• Dermal exposure leads to early local muscle twitching, which can progress to fasciculation and weakness 4

Delayed Symptoms (24 hours to 2 weeks)

• Intermediate syndrome (occurs in approximately 19.1% of patients) 2
  • Characterized by proximal muscle weakness
  • Cranial nerve palsies
  • Respiratory muscle weakness requiring ventilation
  • Typically develops 24-96 hours after acute cholinergic crisis

Late Symptoms (beyond 2 weeks)

• Organophosphate-induced delayed polyneuropathy
• Peripheral neuropathy
• Long-term neuropsychiatric effects

Special Considerations

Pediatric Presentation

• Infants and young children may present with drowsiness rather than muscle twitching 1
• Some symptoms like drooling may be normal in young children and less reliable indicators 1

Route of Exposure Differences

• Inhalation exposure: Respiratory symptoms appear first, followed by systemic effects 4
• Dermal exposure: Local muscle twitching first, followed by progressive systemic effects 4
• Ingestion: Gastrointestinal symptoms predominate initially

Complications

• Respiratory failure (most common and serious complication)
• Aspiration pneumonia
• Seizures
• Intermediate syndrome
• Delayed polyneuropathy
• Cardiac complications including arrhythmias
• Septic shock in severe cases 2

Early recognition of these signs and symptoms is crucial for prompt diagnosis and treatment of organophosphate poisoning, as respiratory failure is the major cause of mortality in these cases.