Carbon monoxide poisoning (quick pearls)

15 Jul


usually worse in the morning

improves as you leave the environment.

Often worse in winter

  • using heating elements such as natural gas, wood, or other fuels,
  • people spend more time inside with less ventilation.

Flu-like symptoms like headache, nausea, vomiting, and general malaise are often early symptoms.

Often many people in the household will have similar symptoms, which can mimic a viral syndrome again.


CO binds hemoglobin stronger than does oxygen,

shifting the oxyhemoglobin dissociation curve to the left so the blood hangs on to more oxygen and does not off-load it to the tissues

decreased oxygen delivery and thus tissue hypoxia.


  • carboxyhemoglobin level — venous VBG sampling is equal to arterial
  • Levels up to 10% can be seen at baseline, especially in smokers.
  • Correleation of symptoms with levels is not great
  • Pulse oxymetry is not reliable because carboxyhemoglobin and oxyhemoglobin share the same range of wavelengths picked up by standard pulse oximetry



oxygen, which decreases the half-life of COHb.

Hyperbaric oxygenation is still controversial with regard to ultimate benefit, but an option to consider.


Submitted by J. Stone.


References: (Maloney, G., Tintinalli’s Emergency Medicine, Chapter 217 Carbon Monoxide); picture


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