Arterial Gases: Purpose, Risks, Procedure and Results

Red blood cells carry oxygen and carbon dioxide throughout the body. These are known as arterial blood gases.

As blood passes through your lungs, oxygen flows into the blood, while carbon dioxide flows from the blood to the lungs.

The blood gas test can determine how well your lungs can move oxygen into the blood and eliminate carbon dioxide.

Imbalances in oxygen levels, carbon dioxide and blood pH can indicate the presence of certain medical conditions. These may include:

  • Renal insufficiency.
  • Heart failure.
  • Diabetes not controlled.
  • Hemorrhage.
  • Chemical poisoning
  • An overdose of drugs.

Your doctor may order a blood gas test when you show symptoms of any of these conditions. The test requires the collection of a small amount of blood from an artery. It is a safe and simple procedure that only takes a few minutes to complete.

Purpose

An Arterial Gas Test provides an accurate measurement of the levels of oxygen and carbon dioxide in your body. This can help your doctor determine how well your lungs and kidneys are working.

This is a test that is used most often in the hospital setting to determine the treatment of patients with acute illnesses. It does not have a very important role in primary care, but it can be used in a laboratory or pulmonary function clinic.

Your doctor may order a blood gas test if you show symptoms of an imbalance of oxygen, carbon dioxide, or pH. Symptoms may include:

  • Difficulty breathing.
  • Difficult breathing
  • Confusion.
  • Nausea.

These symptoms can be signs of certain medical conditions, such as asthma and chronic obstructive pulmonary disease (COPD).

Your doctor may also order a blood gas test if you suspect that you are experiencing any of the following conditions:

  • Lung disease.
  • Kidney disease
  • Metabolic disease
  • Head or neck injuries that affect breathing.

Identifying imbalances in blood pH and gas levels can also help your doctor control the treatment of certain conditions, such as lung and kidney diseases.

A blood gas test is often ordered along with other tests, such as a blood glucose test to check blood sugar levels and a blood test with creatinine to evaluate kidney function.

Risks

Since a blood gas test does not require a large sample of blood, it is considered a low risk procedure. However, you should always inform your doctor about existing medical conditions that may cause you to bleed more than expected.

You should also inform them if you are taking over-the-counter or prescription medications, such as blood thinners, that can affect your bleeding.

Possible side effects associated with the blood gas test include:

  • Bleeding or bruising at the puncture site.
  • Fainting.
  • Accumulation of blood under the skin.
  • Infection at the puncture site.

Tell your doctor if you experience unexpected or prolonged side effects.

Procedure – Arterial Gases

A blood gas test requires the collection of a small sample of blood. Arterial blood can be obtained from an artery in the wrist, arm or groin, or pre-existing arterial line if you are currently hospitalized.

A blood gas sample can also be venous, from a vein or a preexisting IV or capillary, which requires a small heel prick.

A technician called a phlebotomist will first sterilize the injection site with an antiseptic. Once they find an artery, they insert a needle into the artery and draw blood.

You may feel a small pinch when the needle comes in, but the test itself is not painful. After removing the needle, the technician will place a bandage over the wound by puncture.

The blood sample will then be analyzed by a portable machine or in a laboratory on site. The sample must be analyzed within 10 minutes after the procedure to ensure an accurate test result.

Results

The results of an Arterial Blood test can help your doctor diagnose various diseases or determine how well treatments work for certain conditions, including lung diseases.

It also shows if your body is compensating for the imbalance. Due to the possibility of compensation in some values ​​that will cause the correction of other values, it is essential that the person interpreting the result is a trained doctor, with experience in the interpretation of blood gases.

The test measures:

  • The pH of arterial blood measures the amount of hydrogen ions in the blood. A pH of less than 7.0 is called acid, and a pH greater than 7.0 is called basic or alkaline.
  • A lower blood pH may indicate that your blood is more acidic and has higher levels of carbon dioxide.
  • A higher blood pH may indicate that your blood is more basic and has a higher bicarbonate level;
    Bicarbonate is a chemical that helps prevent the pH of the blood from becoming too acidic or too basic.
  • Oxygen partial pressure is a measure of the pressure of dissolved oxygen in the blood. It determines how well oxygen can flow from the lungs to the blood.
  • The partial pressure of carbon dioxide is a measure of the pressure of dissolved carbon dioxide in the blood. Determines how well carbon dioxide can escape from the body.
  • Oxygen saturation is a measure of the amount of oxygen carried by hemoglobin in red blood cells.

In general, normal values ​​include:

  • PH of arterial blood: 7.38 to 7.42.
  • Bicarbonate: from 22 to 28 milliequivalents per liter.
  • Partial oxygen pressure : 75 to 100 mm Hg.
  • Partial pressure of carbon dioxide: 38 to 42 mm Hg.
  • Oxygen saturation: 94 to 100 percent.

Your blood oxygen levels may be lower if you live above sea level. Normal values ​​will have a slightly different reference range if they come from a venous or capillary sample.