#EMConf: Carbon Monoxide Poisoning

Where does it come from?

  • Burned carbon without enough oxygen to create carbon dioxide
  • Burning fuel (charcoal, wood, natural gas) with inadequate ventilation (think burning things for heat in small place)       

What does it do?

  • Binds Fe on Hb with 250x affinity than O2
  • Decreases ability of Hb to offload oxygen
  • Decreased carrying capacity + decreased offloading = decreased O2 to tissues
  • Other effects:
    • Inhibits proteins within electro transport chain decouples oxidative phosphorylation decreased ATP + free radicals
      • Half life longer than CO bound to Hb
    • Lipid peroxidation and Inflammation in brain with ultimate neuronal cell death
      • Continues after initial stabilization
      • Thought to be caused of delayed neurological sequale
    • Cardiac injury and dysfunction
      • CO similar to NO vasodilation
      • Global hypokinesis
      • Arrythmias
    • Greatest effects on brain and cardiovascular system

 Clinical: Variable

  • Headache most common
    • Dull, frontal, constant
  • “Flu-like” malaise, nausea, vomiting, dizziness
    • Often misdiagnosed as viral illness especially because peak time for space heaters is winter
  • Neurological
    • Confusion, ataxia, focal deficit, seizure, LOC, coma
  • Cardiovascular/ Respiratory 
    • CP, SOB, Hypotension, tachycardia, tachypnea, arrythmias, EKG changes
    • Pulse ox NOT reliable: machine detects COHb same as Hb with O2
      • Will be normal despite profound hypoxia at tissue level

 Treatment & Management

  • ABC’s
  • Remove source and Oxygen
    • Oxygen competitively inhibits CO and displaces from Hb
  • Half-Life of COHb on RA: 250-320 mins, NRB: 90 minutes
  • Hyperbarics
    • Half-life: 30 minutes
    • Best if done early (less than 6 hours)
    • Indications:
      • Carboxyhemoglobin >25%
      • Carboxyhemoglobin >20% and pregnant (? 15%)
      • LOC, seizure
      • Severe metabolic acidosis (pH <7.1)
      • Evidence of end organ ischemia (chest pain, EKG changes, AMS)
        • Greatest effects on CV, brain: if these affected  transfer