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October 14, 2014 by dailybolusoflr
By Ryan Circh, MD
- CO binds hemoglobin 200x more tightly than oxygen.
- 85% will bind O2, the rest will dissolve in plasma.
- CO can inhibit cytochrome oxidase like cyanide (interfering with cellular metabolism).
- Endothelial damage, triggering an inflammatory response.
- CO can cause nitric oxide release resulting in vasodilation and hypotension.
- Hypoxia and hypotension can lead to MI, neuronal death, rhabdomyolysis.
- Flu-like symptoms
- Focal neuro deficits
- Typically around fall, winter months when heater use increased
- Ask about exposure to heaters, fires, or gas/propane-powered motors in closed spaces.
- Multiple family members may have varying degrees of similar symptoms.
- Consider CO poisoning in non-specific symptoms
- Ask about CO detectors in homes
- Pulse ox will be normal as COHb absorbs at the same wavelength
- COHb level from ABG/VBG, do not need arterial sample
- COHb doesn’t always correlate with symptoms or outcomes
- Labs may help give a clue to degree of poisoning: metabolic anion gap lactic acidosis
- Room air half-life 200 minutes, 100% FiO2 80 minutes
- Mild-moderate symptoms 100% facemask
- Severe inbutaion
- Extreme hyperbaric oxygen
- Indication for hyperbarics: ataxia, seizure, focal neuro deficits, chest pain, dyspnea, EKG changes, or COHb over 25%
- Pregnancy for COHb >15%