Arterial Blood Gas: Purpose, Procedure, and Side Effects

An Arterial blood gas or ABG test helps to measure oxygen and carbon dioxide levels in your blood.

It can also help to measure the acid-base or pH level of your body which is often in balance when you are healthy.

Moreover, you can get this test if you are in a hospital or have a serious injury or illness.

This test will give your doctor clues about how well your lungs, heart, and kidneys are working.

Furthermore, you will probably get other tests along with this one.

The cells in your body need oxygen to live.

When you breathe in i.e. inhale or breathe out, i.e. exhale, your lungs move oxygen into your blood and push carbon dioxide out.

This process is the gas exchange and is able to provide the oxygen that you need to survive.

However, if you are having a hard time breathing, your doctor may use arterial blood gas, or ABG test to figure out what the problem is.

Keep on reading to learn more about it in detail.

Arterial Blood Gas

The arterial blood gas test is the test that helps to measure certain things in your blood.

These are:

• oxygen
• carbon dioxide
• the pH of the blood

Many doctors also refer to it as blood gas analysis or blood gas test.

Your red blood cells have the ability to transport oxygen and carbon dioxide throughout your body and these are blood gases.

However, as blood passes through your lungs, oxygen flows into the blood while carbon dioxide flows out of the blood into the lungs.

The blood gas tests can help determine how well your lungs are able to move oxygen into the blood and remove carbon dioxide.

Who needs an Arterial Blood Gas Test?

Imbalances in the oxygen, carbon dioxide, and pH levels of your blood the presence of certain medical conditions.

These may include:

• kidney failure
• heart failure
• uncontrolled diabetes
•  hemorrhage
• chemical poisoning
• a drug overdose
• shock

Moreover, your doctor can also order this test when you are showing symptoms of the above conditions.

This test needs the collection of a small amount of blood from an artery.

Furthermore, it is a safe and simple procedure that takes only a few minutes to complete.

It is important to note that your doctor may ask for an ABG test to:

Check for severe breathing and lung problems like asthma, cystic fibrosis, chronic obstructive pulmonary disease, COPD, or obstructive sleep apnea.

They may also order this test to check how treatment for your lungs is working, and check whether you need extra oxygen or help with breathing.

Additionally, this test can help to check acid-base balance.

You can have too much acid in your body from kidney failure, a severe infection, specific toxic ingestions, or complications of diabetes, DKA.

Why is a Blood Gas Test done?

An arterial blood gas test provides a precise measurement of the oxygen and carbon dioxide in your body.

Moreover, this will help your doctor understand how well your lungs and kidneys are working.

This test is commonly used in a hospital setting. And it helps to determine the management of actually ill patients.

However, it does not have a significant role in a primary care setting.

But your doctor may use it in a pulmonary function lab or clinic.

Furthermore, your doctor may order this test if you are showing symptoms of oxygen, carbon dioxide, or a pH imbalance.

The symptoms can be:

• shortness of breath
• difficulty breathing
• nausea
• confusion

It is important to note that these symptoms can be the signs of certain medical conditions.

These include asthma, and chronic obstructive pulmonary disease, COPD.

Your doctor can also order a blood gas test if they suspect you are experiencing any of the following:

Lung disease, kidney disease, metabolic disease, and head or neck injuries that affect breathing.

Identifying imbalance in the pH and blood gas levels can also help your doctor to monitor treatment for certain conditions like lung and kidney disease

Moreover, your doctor may order this test along with other tests.

These can be blood glucose tests to check for blood sugar levels and a creatinine blood test to evaluate kidney function.

Are there any risks for an Arterial Blood Gas Test?

As the blood gas test does not require a large sample of your blood, it is a low-risk procedure.

However, it is important to make sure that you tell your doctor about existing medical conditions that may make you bleed more than expected.

Moreover, you should also tell them if you are taking any over-the-counter or prescription medications.

These can be blood thinners that can affect your bleeding.

Some of the possible side effects of a blood gas test are:

• bleeding or bruising at the puncture site
• feeling faint
• blood accumulating under the skin
• infection at the puncture site

Make sure to tell your doctor or seek medical advice if you experience unexpected or prolonged side effects.

Procedure for an Arterial Blood Gas Test

A blood gas test requires the collection of a small sample of blood.

Arterial blood can be obtained from the artery in your wrist, arm, or groin, or a preexisting arterial line if you are already hospitalized.

Moreover, a blood gas sample can be venous, from a vein or preexisting IV or capillary which will need a small prick to the help.

Your health care provider will first sterilize the injection site with an antiseptic.

Once they find an artery, they will insert a needle into the artery and draw blood.

You may feel a slight prick when the needle goes into your skin.

Arteries have more smooth muscle layers than veins, and some may find an arterial blood gas test more painful than blood draws from a vein.

After your doctor or technician removes the needles, they will hold pressure for a few minutes before putting a bandage over the puncture wound.

They will then analyze the blood sample by a portable machine or in an on-site laboratory.

Moreover, it is important to note that the sample must be analyzed within 10 minutes of the procedure to make sure of an accurate test result.

Interpreting the Results

The results of an arterial blood gas test can help your doctor to diagnose a different disease or determine how well certain treatment is working for a condition, including lung disease.

It also helps to show whether or not your body is compensating for the imbalance or not.

Moreover, due to the potential for compensation in some values that will cause the correction of other values, it is important that the person who interprets your results is a trained healthcare provider with experience in blood gas interpretation.

This test measures:

Arterial Blood pH

This indicates the number of hydrogen ions in the blood.

A pH of less than 7.0 is acidic and a pH greater than 7.0 is basic or alkaline.

A lower blood pH may indicate that your blood is more acidic and has higher carbon dioxide levels.

However, a higher blood pH can indicate that your blood is more basic and has a higher bicarbonate level.

Bicarbonate

It is a chemical that helps to prevent the pH of blood from becoming too acidic or too basic.

Partial Pressure of Oxygen

It helps to measure the pressure of oxygen dissolved in your blood.

Moreover, it helps to measure how well oxygen is able to flow from the lungs into the blood.

Partial Pressure of Carbon dioxide

This one helps to measure the pressure of carbon dioxide dissolved in your blood.

Furthermore, it helps to determine how well carbon dioxide is able to flow out of the body.

Oxygen Saturation

Oxygen saturation measures the amount of oxygen that hemoglobin carries in the red blood cells.

In general, normal values are:

• arterial blood pH: 7.38 to 7.42
• bicarbonate: 22 to 28 milliequivalents per liter
• the partial pressure of oxygen: 75 to 100 mm Hg
• the partial pressure of carbon dioxide: 38 to 42 mm Hg
• oxygen saturation: 94 to 100 percent

Your blood oxygen levels can also be lower if you live above sea level.

The normal values, however, will have a slightly different reference range if they are from a venous or capillary sample.

Moreover, abnormal results may be a sign of certain medical conditions.

These can be:

od pH	Bicarbonate	Partial pressure of carbon dioxide	Condition	Common causes
Less than 7.4	Low	Low	Metabolic acidosis	Kidney failure, shock, diabetic ketoacidosis
Greater than 7.4	High	High	Metabolic alkalosis	Chronic vomiting, low blood potassium
Less than 7.4	High	High	Respiratory acidosis	Lung diseases, including pneumonia or COPD
Greater than 7.4	Low	Low	Respiratory alkalosis	Breathing too fast, pain, or anxiety

Therefore, normal and abnormal ranges can vary depending on the lab as some use different measurements or methods to analyze blood samples.

Furthermore, you should always meet your doctor to discuss your test results in more detail.

They can help to tell if you need more testing and if you will need any treatment.

Wrapping it Up

Ab ABG or arterial blood test helps to measure oxygen, carbon dioxide, and pH imbalance of your blood.

In some cases, however, you may need an additional test. Therefore, make sure to discuss the results of the test with your doctor as they can help diagnose the condition and help plan the treatment you may need for a certain condition.