Blood carbon monoxide & bull; hello healthy

Definition

What is the blood carbon monoxide test?

The carbon monoxide blood test is used to detect poisoning from inhaling carbon monoxide (CO), a colorless and odorless gas. This test measures the amount of hemoglobin that is attached to carbon monoxide. This amount is also called the carboxyhemoglobin level.

When a person inhales carbon monoxide, the gas combines with red blood cells which normally carry oxygen in body tissues and replace oxygen normally carried in the blood. As a result, less oxygen is carried to the brain and other body tissues. Carbon monoxide can cause poisoning and death.

Carbon monoxide is generated during combustion when there is not enough oxygen to stop combustion. The main sources of carbon monoxide are engine fumes (such as cars or boats), fires with inadequate ventilation (such as heating gas and fire smoke when cooking indoors), factories, and tobacco smoking.

When should I have a blood carbon monoxide test?

You need this test if your doctor suspects you have CO poisoning. Symptoms of carbon monoxide poisoning include:

• headache
• nausea
• dizzy
• limp
• diarrhea
• red skin and lips

Severe poisoning can result in nervous system symptoms such as:

• convulsions
• coma

Carbon monoxide poisoning is more difficult to identify in very young children than in adults. For example, a child with CO poisoning will only appear cranky and refuse to eat.

You may be able to undergo this test if you have been exposed to CO, especially if you inhaled fumes during a fire. You can also undergo this test if you have been in close proximity to a vehicle whose engine is running in an enclosed space for a long time.

Precautions & warnings

What should I know before taking a blood carbon monoxide test?

A person with symptoms and possibly exposure to carbon monoxide, for example someone who lives in a house with an old heating system and complains of constant headaches, should be tested for carbon monoxide poisoning.

A person with carbon monoxide poisoning should be kept away from places that are likely to be exposed to the gas and give respiratory oxygen before testing.

If carbon monoxide poisoning is suspected, other tests (such as the arterial blood gas (ABG) test) may be ordered to determine whether the symptoms are due to carbon monoxide poisoning or another disease that has the same symptoms.

Process

What should I do before taking the blood carbon monoxide test?

You don't need to prepare anything for this test. But you should not smoke before taking this test and make sure your doctor knows all medicines, herbs, vitamins and supplements you are taking. This includes the use of over-the-counter drugs and illegal drugs.

How is the blood carbon monoxide test process?

The medical personnel in charge of drawing your blood will:

• wrap an elastic band around your upper arm to stop blood flow. This makes the blood vessel under the bundle enlarge making it easier to insert the needle into the vessel
• clean the area to be injected with alcohol
• inject a needle into a vein. More than one needle may be required.
• Insert the tube into the syringe to fill it with blood
• untie the knot from your arm when enough blood is drawn
• attaching gauze or cotton to the injection site, after the injection is complete
• apply pressure to the area and then put a bandage on.

What should I do after taking the blood carbon monoxide test?

An elastic band is wrapped around your upper arm and will feel tight. You may not feel anything when you get the injection, or you may feel like you are stung or pinched.

Your doctor will also ask you to do these tests:

• toxicology screen
• chest x-ray
• pregnancy test in women, because exposure to CO puts the fetus at higher risk of developing problems

Your doctor may also ask you to have an MRI scan if you have symptoms of a nervous system problem.

If you have questions related to this test process, please consult your doctor for a better understanding.

Explanation of the test results

What do my test results mean?

The yield of carbon monoxide is reported as a percentage: the amount of carbon monoxide bound to hemoglobin divided by the total amount of hemoglobin (and then multiplied by 100). The higher the percentage, the higher the risk of carbon monoxide poisoning. With a value below 10%, a person may not show any symptoms of poisoning.

Normal scores on this list (called references range) only serves as a guide. Range this varies from laboratory to laboratory, and your laboratory may have different normal scores. Your laboratory report will usually contain how much range they use. Your doctor will also check your test results based on your health condition and other factors. This means if your test results go into range abnormal in this manual, it could be in your laboratory the score belongs to range normal.

The results of these tests are usually available immediately after the test.

Normal

Carbon monoxide
Not a smoker:	Less than 2% of total hemoglobin
Smoker:	4% –8% of total hemoglobin

High marks

High carbon monoxide in the blood is caused by carbon monoxide poisoning. Symptoms of carbon monoxide poisoning can become severe when carbon monoxide levels increase.

Symptoms related to carbon monoxide value
Percentage of total hemoglobin	Symptoms
20%–30%	Headache, nausea, vomiting, difficulty making decisions
30%–40%	Dizziness, muscle weakness, visual disturbances, confusion, and increased heart rate and breathing
50%–60%	Loss of consciousness
More than 60%	Seizures, coma, death

Compared to men, women and children can have severe symptoms of carbon monoxide poisoning even though carbon monoxide levels are low because women and children usually have fewer red blood cells.

Depending on your chosen laboratory, the normal range of the carbon monoxide blood test may vary. Discuss any questions you have about your medical test results with your doctor.