Carbon Monoxide Poisoning

Key Features

• Avidly binds to hemoglobin, which results in reduced oxygen-carrying capacity and altered delivery of oxygen to cells

Clinical Findings

• At low carbon monoxide levels (carboxyhemoglobin [COHb] 10–20%)

  • Headache

  • Dizziness

  • Abdominal pain

  • Nausea

• With somewhat higher levels (COHb 20–50%)

  • Confusion

  • Dyspnea

  • Syncope

• With high levels (COHb > 50–60%)

  • Hypotension

  • Coma

  • Seizures

• Permanent neurologic or neuropsychiatric deficits may develop in survivors of acute severe poisoning

Diagnosis

• Suspect in the setting of severe headache or acutely altered mental status, especially if multiple victims

• Diagnosis depends on

  • Specific measurement of the arterial or venous COHb saturation

  • However, the level may have declined if high-flow oxygen therapy has already been given

  • COHb levels do not always correlate well with clinical findings

• Routine arterial blood gas testing and pulse oximetry are not useful because they may give falsely normal PaO₂ or oxygen saturation levels

Treatment

• Remove victim from exposure

• Administer 100% oxygen by tight-fitting high-flow reservoir face mask or endotracheal tube

• Hyperbaric oxygen (HBO)

  • Can provide 100% oxygen in higher than atmospheric pressures, further shortening the half-life

  • May also reduce incidence of subtle neuropsychiatric sequelae

• Indications for HBO treatment after acute carbon monoxide exposure

  • Loss of consciousness

  • Metabolic acidosis

  • COHb > 25%

  • Age > 50 yr

  • Cerebellar findings on neurologic examination