What is the treatment plan for someone with inhalation injuries, possible carbon monoxide (CO) poisoning, and suspected cyanide toxicity?

Treatment Plan for Inhalation Injuries with Suspected Carbon Monoxide and Cyanide Toxicity

For patients with inhalation injuries, suspected carbon monoxide poisoning, and possible cyanide toxicity, immediate administration of 100% oxygen and hydroxocobalamin is the recommended first-line treatment approach. 1

Initial Management

• Immediately administer 100% oxygen via non-rebreather mask or endotracheal tube to all patients with suspected inhalation injury, as this accelerates the elimination of carboxyhemoglobin (COHb), reducing its half-life from approximately 320 minutes on room air to about 74 minutes 2

• Secure airway, provide ventilatory support, and ensure circulatory stability as part of basic and advanced life support measures 1

• Obtain blood samples to measure carboxyhemoglobin levels, arterial blood gases, lactate levels, and complete blood count 2

• Elevated lactate levels (>8 mmol/L) strongly suggest cyanide poisoning in the context of smoke inhalation 1, 3

Cyanide Toxicity Management

• Administer hydroxocobalamin (Cyanokit) as the first-line antidote for suspected cyanide poisoning in smoke inhalation victims 1, 4

  • Adult dose: 5 g IV (10 g for cardiac arrest)
  • Pediatric dose: 70 mg/kg (maximum 5 g) 1

• Consider sodium nitrite (300 mg IV for adults) only if hydroxocobalamin is unavailable 1, 5

  • Use with extreme caution in patients with smoke inhalation due to risk of worsening hypoxia from methemoglobinemia 5

• Administer sodium thiosulfate (12.5 g IV for adults, 250 mg/kg for children) following hydroxocobalamin or sodium nitrite to enhance cyanide elimination 1, 6, 3

• Note: Hydroxocobalamin is chemically incompatible with sodium thiosulfate and should not be administered via the same IV line 6

Carbon Monoxide Poisoning Management

• Continue administration of 100% oxygen until carboxyhemoglobin levels normalize 2

• Consider hyperbaric oxygen therapy (HBOT) for patients with:

  • Loss of consciousness during or after exposure
  • Neurological deficits
  • Significant metabolic acidosis
  • COHb levels >25%
  • Pregnancy with any symptoms of CO poisoning 1, 2

• HBOT is not routinely recommended for all cases of smoke inhalation with CO poisoning, but should be evaluated on a case-by-case basis, considering patient stability, severity of poisoning, and availability of specialized equipment 1

Monitoring and Supportive Care

• Continuously monitor vital signs, oxygen saturation, cardiac rhythm, and mental status 1

• Monitor methemoglobin levels if sodium nitrite was administered 5

• Treat bronchospasm with bronchodilators if present 7

• Provide fluid resuscitation as needed, especially in patients with associated burns 1

• Consider intubation and mechanical ventilation for patients with respiratory distress, decreased level of consciousness, or significant upper airway edema 7

Special Considerations

• For pregnant patients, HBOT is strongly recommended regardless of carboxyhemoglobin levels due to fetal vulnerability to carbon monoxide 2

• In children, adjust dosing of hydroxocobalamin and sodium thiosulfate based on weight, and be vigilant for methemoglobinemia if sodium nitrite is used 1, 5

• For patients with G6PD deficiency, use sodium nitrite with extreme caution due to increased risk of hemolytic crisis 5

• In patients with both thermal burns and inhalation injury, prioritize airway management and treatment of systemic toxicity before addressing burn wounds 1

Follow-up Care

• All patients should receive clinical follow-up 1-2 months after exposure to assess for delayed neurological sequelae 2

• Patients with persistent neurological symptoms should be referred for formal neuropsychological evaluation 2

• Ensure the source of exposure has been identified and eliminated before discharge to prevent re-exposure 2

Common Pitfalls to Avoid

• Do not delay oxygen therapy while awaiting laboratory confirmation of CO poisoning 2

• Do not withhold hydroxocobalamin in suspected cyanide poisoning while waiting for confirmatory tests 4, 8

• Remember that COHb levels may be normal or low if several hours have elapsed since exposure, so clinical suspicion should guide treatment 2

• Be aware that cyanide can interfere with hemoglobin testing, potentially causing inaccurate results 4

• Avoid administering sodium nitrite in patients with suspected concurrent carbon monoxide poisoning when possible, as it can worsen tissue hypoxia 5, 3