Run Time: 8 minutes
Author: Peter Bakes M.D.
- CO poisoning is one of the most common fatal accidental ingestions.
- Two main causes of CO poisoning are 1) SI – such as a car left running in closed space, which accounts for ⅓ of CO poisoning 2) Any tool/appliance that runs on fuel and produces CO from incomplete combustion of that fuel.
- Exposure to a CO level of 50-100 parts per million for a few hours is when patients start to feel symptomatic. Where as, a CO2 in ambient air is at 400 parts per million.
- Pathophysiology – CO has a 120 times higher affinity to hemoglobin than O2, CO causes functional anemia, CO causes lipid peroxidation, CO binds to cytochromes which inhibits energy production, and CO binds to myoglobin which decreases cardiac function.
- The classic clinical presentation of CO poisoning is flu-like illness with a low energy state. CO can also cause ataxia, cognitive problems, and cerebellar dysfunction due to its toxicity to the brain. It is one of the only diseases which causes headache and chest pain at the same time.
- In the ED test a carboxyhemoglobin level – greater than 20% is when the patient is in need of immediate treatment.
- In the ER patients are placed on an O2 non-rebreather, or in more severe cases can be placed in hyperbaric chamber.
- CO has a half-life of 4-6 hours in normal air with an O2 concentrations of 21%. With the non-rebreather the half-life is decreased to 60-90 minutes, and in a hyperbaric chamber the half-life is again decreased to 20-30 minutes.
- Patients are treated until they become asymptomatic. Patients further removed from the exposure may need neuro-psychiatric testing for prolonged cognitive problems caused by hypoxia and lipid peroxidation.
- Interestingly, families who believe they lived in a haunted house may have been exposed to toxic CO and experienced delusions and delayed manifestations when in the “haunted house”, but when leaving the house the family will begin to feel better.