USMLE

Carbon Monoxide Poisoning

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Toxicology
  1. Cyanide Poisoning
  2. Tetrodotoxin
  3. Methanol Poisoning
  4. Ethylene Glycol Poisoning
  5. Ciguatoxin (Ciguatera Fish Poisoning)
  6. Spoiled Fish (Scombroid) Poisoning
  7. Carbon Monoxide Poisoning
  8. Amanita Phalloides

Summary

Carbon monoxide poisoning occurs when an individual inhales an excess amount of carbon monoxide. It is an odorless, tasteless, and colorless substance emitted from burning organic fuels and it can be very difficult to detect. Carbon monoxide has a much stronger affinity for hemoglobin than oxygen. It’s binding to one of hemoglobin’s binding sites can cause hemoglobin to bind even more tightly to oxygen, thereby reducing oxygen unloading at the tissues. It can also inhibit complex IV of the electron transport chain, although this is far less important than its role in the bloodstream. Clinical manifestations of carbon monoxide poisoning include headache, cherry-red skin, myocarditis, and bilateral globus pallidus lesions on MRI. Pulse oximetry will not be able to detect carbon monoxide poisoning since it cannot differentiate between oxyhemoglobin and carboxyhemoglobin, but a follow-on arterial blood gas will reveal very low blood oxygen content. In order to treat this condition, one must administer 100% oxygen or hyperbaric oxygen to help shift the hemoglobin-oxygen dissociation curve back to the right.