09/02/2017: Lab Advisory: Hurricane Harvey – Clinical Guidance for Carbon Monoxide (CO) Poisoning

Dear Clinical and Public Health Laboratory Partners,

For your awareness, we would like share a CDC Heath Advisory reminding clinicians to consider carbon monoxide (CO) poisoning for people affected by Hurricane Harvey.

In the guidance, there are recommendations (#4 and #5 highlighted below) to perform COHgb testing when the diagnosis of CO poisoning is being considered.  The most common technology available in hospital laboratories for analyzing the blood is the multiple wavelength spectrophotometer, also known as a CO-oximeter. Venous or arterial blood may be used for testing. A fingertip pulse CO-oximeter can be used to measure heart rate, oxygen saturation, and COHgb levels in the field, but suspicion of CO poisoning should be confirmed with a COHgb level by CO-oximeter. A conventional two-wavelength pulse oximeter is not accurate when COHgb is present.

Clinicians are also reminded that an elevated carboxyhemoglobin (COHgb) level of 2% or higher for non-smokers and 9% or higher COHgb level for smokers strongly supports a diagnosis of CO poisoning. The COHgb level must be interpreted in light of the patient’s exposure history and length of time away from CO exposure, as levels gradually fall once the patient is removed from the exposure. In addition, carbon monoxide can be produced endogenously as a byproduct of heme metabolism. Patients with sickle cell disease can have an elevated COHgb level as a result of hemolytic anemia or hemolysis.

For more information, visit CDC’s Clinical Guidance for Carbon Monoxide (CO) Poisoning After a Disaster webpage.