Carbon monoxide test for poisoning
in the last 12 hours (max)
A carbon monoxide test is only meaningful if done within several hours after exposure as
carbon monoxide levels in the blood decline once the
person is removed from the source.
Recent exposure can be tested using a carboxyhemoglobin (COHb) test that directly measures carbon monoxide in blood samples.
Exposure to carbon monoxide can also be tested and measured indirectly by determining the percentage of
carbon monoxide exhaled in the breath.
Another carbon monoxide test method uses a pulse cooximeter. This test reads the percentage of gas in the blood
by shining a light through the finger nail.
Most pulse cooximeters are not accurate with carbon monoxide because they only measure the gas saturation of
hemoglobin (on the red blood cells), they do not measure the kind of gas they're saturated with. However, some
new pulse cooximeters are able to detect carbon monoxide saturation.
Although there are several carbon monoxide tests that can lead to and confirm a diagnosis of CO poisoning, the
presence of signs and symptoms
is also a factor and should not be ignored.
Other tests that may useful in determining the extent of carbon monoxide poisoning include measurement of other
arterial blood gases and pH; a complete blood count; measurement of other blood components such as sodium, potassium,
bicarbonate, urea nitrogen, and lactic acid; an electrocardiogram (ECG); cardiac enzyme studies, and a chest x ray.
In some cases, skin, mucous membranes, and finger/toe nails of a person with carbon monoxide poisoning may
become cherry red or bright pink. As this color change happens occasionally it is not a reliable carbon monoxide
test / indicator of poisoning.
Part of the carbon monoxide testing and diagnosis may also come from asking questions to detect [subtle] changes
in ability to think, remember, and process information.
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