Carboxyhemoglobinemia
Although many references relate carboxyhemoglobin level to symptoms, this appears to be a myth. There is no validated relationship between carboxyhemoglobin levels and specific symptoms - Josh Farkas
HWN Suggests
Carbon Monoxide Poisoning: Common Questions and Dilemmas
Interpretation of COHb levels
- Normal (non-smoker, outside of urban area): 0.4-1.0%
- Urban-dweller: Up to 5%
- Heavy smoker: Up to 15%
- Mild poisoning: >10% without clinical signs/symptoms
- Moderate poisoning: >10% with minor clinical signs/symptoms (headache, lethargy, fatigue)
- Severe poisoning: >20-25% with loss of consciousness, confusion, or signs of cardiac ischemia
Articles of Interest
BC Emergency Medicine Network
For all symptomatic CO toxicity or those with documented high COHb levels, high flow normobaric O2 should be continued for 6-8 hours, or until the COHb level is within a normal range, i.e. 3% or less and the patient is completely symptom free. To facilitate this, a short stay admission may be indicated, sometimes in a step-down unit of the ED.
Carbon Monoxide Poisoning
CO poisoning should always be considered when multiple patients present to the ED from a single location with appropriate findings.
Carbon monoxide poisoning
Interpreting carboxyhemoglobin levels... Nonsmokers: 0-3%. Smokers: 0-10% (The upper limit isn't well defined, potentially extending as high as 15%?). Severe intoxication is usually associated with carboxyhemoglobin level > 25%.
CO Poisoning – Pearls and Management
Symptoms from CO toxicity can start when levels are as low as 5%, with impaired judgment and fine motor skills. As levels increase, symptoms ranging from headache (most common) and “flu-like” symptoms (fatigue, dizziness, nausea, and vomiting) develop, and can progress to neuro-cognitive impairment, with alterations in level of alertness, vision changes, memory impairment, and sensorimotor deficits.
CO Toxicity: A Potentially Elusive Diagnosis
Historical clues such as high risk exposure environments (garages, heaters) and multiple family members with the same symptoms can narrow the differential to CO poisoning.
Critical Cases - CO and Cyanide toxicity!
Labs demonstrate: pH 7.06 Lactate 12.4 COHb 48%.
Resources
StatPearls
Carboxyhemoglobin is the complex formed within red blood cells when hemoglobin is exposed to carbon monoxide, subsequently binding to hemoglobin with an affinity 200 times that of oxygen.
