What is the treatment for carbon monoxide poisoning?

Treatment of Carbon Monoxide Poisoning

The immediate treatment for carbon monoxide poisoning is administration of 100% normobaric oxygen while awaiting confirmation of diagnosis, followed by consideration of hyperbaric oxygen therapy for severe cases. 1

Initial Management

• Administer 100% normobaric oxygen immediately to any person suspected of having CO poisoning, even before laboratory confirmation 1, 2
• Oxygen therapy accelerates the elimination of carboxyhemoglobin (COHb), reducing its half-life from approximately 320 minutes on room air to about 74 minutes on 100% oxygen 1
• Confirm diagnosis with laboratory measurement of COHb levels, especially for patients being considered for hyperbaric oxygen therapy 1
• Assess for severe metabolic acidosis or elevated lactate in patients exposed to CO from house fires, as this may indicate concomitant cyanide poisoning requiring specific treatment with hydroxocobalamin 1

Hyperbaric Oxygen Therapy (HBOT) Indications

• Consider HBOT for patients with:

  • Loss of consciousness during or after exposure 1
  • Neurological deficits 1
  • Ischemic cardiac changes 1
  • Significant metabolic acidosis 1
  • COHb levels >25% 1
  • Pregnant women with any symptoms of CO poisoning 1

• HBOT further reduces COHb elimination half-life to approximately 20 minutes 1

• HBOT should ideally be initiated within 6 hours of exposure for maximum benefit 2

• Treatment at 3.0 atmospheres absolute (atm abs) is common practice, and persistently symptomatic patients may benefit from up to three treatments 1

Special Considerations

• For intentional CO poisoning:

  • Perform toxicology screening to assess for coingestions, present in up to 44% of cases 1
  • Check blood alcohol levels in cases with disproportionate mental status changes 1
  • Arrange mandatory psychiatric follow-up due to high risk of subsequent suicide 1

• For patients with burns and CO poisoning, evaluate HBOT on a case-by-case basis, considering patient stability, burn severity, and equipment availability 1

Common Pitfalls and Caveats

• Do not rely solely on COHb levels to determine treatment, as they correlate poorly with symptoms or prognosis 1, 3
• COHb levels may be normal or low if several hours have elapsed since exposure 1, 3
• Do not withhold oxygen therapy while awaiting laboratory confirmation 1
• Do not withhold HBOT solely because a patient appears clinically stable 1
• Ensure the CO exposure source is identified and eliminated before discharge to prevent re-exposure 1

Follow-up Care

• Schedule clinical follow-up 1-2 months after exposure for all patients with accidental CO poisoning to assess for delayed neurological sequelae 1, 2
• Refer patients not recovered to baseline functioning for formal neuropsychological evaluation 1
• Arrange appropriate cardiology follow-up for patients with evidence of cardiac damage 1
• Inform all patients about the risk of delayed neurological sequelae, which can include memory disturbance, depression, anxiety, calculation difficulties, vestibular problems, and motor dysfunction 1, 2