What is the treatment for suspected cyanide poisoning?

Treatment for Suspected Cyanide Poisoning

Hydroxocobalamin is the first-line treatment for suspected cyanide poisoning and should be administered immediately without waiting for confirmatory testing. 1, 2

Clinical Recognition of Cyanide Poisoning

Signs and Symptoms

• Early manifestations:

  • Altered mental status (confusion, disorientation)
  • Headache, anxiety
  • Tachypnea/hyperpnea
  • Mydriasis (dilated pupils)
  • Hypertension (early)

• Late manifestations:

  • Coma or seizures
  • Bradypnea/apnea
  • Hypotension and cardiovascular collapse
  • Severe lactic acidosis

Diagnostic Indicators

• Plasma lactate concentration ≥8 mmol/L strongly correlates with cyanide poisoning 2, 3
• In smoke inhalation victims, lactate ≥10 mmol/L is indicative (higher threshold due to carbon monoxide contribution) 4

Treatment Algorithm

1. Immediate Actions

• Ensure rescuer safety first - use proper protective equipment when handling victims 1
• Administer 100% oxygen via non-rebreathing mask or ventilation with a mask and non-return valve system 1
• Do not delay treatment to obtain confirmatory testing 2

2. Antidote Administration

• First-line antidote: Hydroxocobalamin 1, 2

  • Adult dose: 5 g IV initially, may repeat with second 5 g dose if needed
  • Pediatric dose: 70 mg/kg (maximum 5 g)

• If hydroxocobalamin unavailable: Sodium nitrite 1

  • Administer according to package instructions
  • Use with caution in smoke inhalation victims due to potential carbon monoxide co-exposure

• Adjunctive therapy: Sodium thiosulfate 1, 4

  • Should be administered following hydroxocobalamin or sodium nitrite
  • Enhances cyanide elimination but acts too slowly to be used alone

3. Supportive Care

• Airway management and ventilatory support as needed
• Cardiovascular support with fluids and vasopressors if hypotensive
• Correction of metabolic acidosis
• Seizure management if present

Special Considerations

Smoke Inhalation Victims

• Consider combined carbon monoxide and cyanide poisoning 2
• Hydroxocobalamin is preferred over sodium nitrite in these cases 1, 2
• Fixed dilated pupils should not preclude resuscitation efforts 1

Monitoring Treatment Efficacy

• Monitor acid-base status and lactate levels 2
• Be aware that hydroxocobalamin causes red discoloration of skin, urine, and may interfere with laboratory tests 2, 3

Safety Considerations

• Hydroxocobalamin has a favorable safety profile compared to other antidotes 3, 5
• Common side effects include chromaturia (red-colored urine) and pink skin discoloration 2, 3
• Rare cases of methemoglobinemia have been reported with hydroxocobalamin, though this is more common with nitrite-based treatments 6

Treatment Efficacy

• High success rates have been reported even in patients with fixed dilated pupils 1
• Early administration of antidotes is critical for improved outcomes
• In massive cyanide poisoning, continuous infusion of sodium thiosulfate should be considered in addition to hydroxocobalamin 3

Remember that cyanide poisoning is a medical emergency requiring immediate recognition and aggressive treatment. The window for effective intervention is narrow, so treatment should be initiated based on clinical suspicion rather than waiting for laboratory confirmation.