What is an ABG Test?

The following are the different results of an ABG test and their explanations:

• Arterial blood pH: 7.38 -7.42 (normal range)

A pH level less than 7 is acidic and indicates a higher presence of carbon dioxide. A pH level higher than 7 is basic, indicating a higher presence of bicarbonate.

• Bicarbonates: 22 – 28 milliequivalents per litre

Bicarbonates are the pH regulators present in the blood.

• Partial pressure of oxygen: 75 – 100 mm Hg
• Partial pressure of carbon dioxide: 38 to 42 mm Hg
• Oxygen saturation: 94-100%

It measures the oxygen level in haemoglobins in the RBC of blood.

An ABG test is recommended by a doctor, especially for ICU patients having the following symptoms:

• Show signs of respiratory distress
• Show signs of kidney failure
• Any injuries in the head or neck region interrupting respiration
• A drug overdose
• Symptoms of pH imbalance like nausea and shortness of breath
• Show signs of COPD (Chronic obstructive pulmonary disease) or asthma

During an ABG test, the healthcare personnel will collect blood from the patient’s artery using a small needle. The blood is generally drawn from the wrist. It may also be collected from one’s groin or the inside of the elbow.

Anyone under oxygen therapy is requested not to breathe the room air for 20 minutes before collecting blood.

The acceptable range of ABG test results are as follows:

• Arterial blood pH: 7.38 – 7.42
• Bicarbonates: 22 – 28 milliequivalents per litre
• Partial pressure of oxygen: 75 – 100 mm Hg
• Partial pressure of carbon dioxide: 38 – 42 mm Hg
• Oxygen saturation: 94-100%

Collecting blood from an artery is more difficult than the veins because arteries have smooth walls and are located deeper with multiple nerve endings.

You may feel a sharp sting as the needle pierces through the artery. You may also feel dizzy, lightheaded, or nauseous during blood collection.

ABG is a relatively easy blood test. However, there is a risk of bruising, bleeding, or infection in critical patients.

In some cases, it may cause paraesthesia and numbing if any nerve around the artery gets damaged. It is advised to feel the pulse properly before piercing the needle and avoid multiple pricking.

The blood for the ABG test is generally drawn from the radial artery of the wrist. Sometimes, it is also drawn from the femoral artery, located in the groin area. The blood can be taken from the brachial artery as well, which is located on the inner side of the arm above the elbow joint.

The test will not be conducted on the arm if it is used for dialysis, nor if the puncture site is infected or inflamed.

The ABG test blood samples should be tested immediately within 10 minutes of blood collection and analysed either on the portable testing appliance or within the in-house laboratory.

The results are available within 15 to 20 minutes. But the doctors will also conduct other tests like blood sugar and creatinine tests along with ABG for accurate diagnosis of the medical condition, which takes longer.

ABG test is safe, but because the blood is collected from the artery, there is always a risk of damage.

You may feel lightheaded and dizzy during blood collection. You may also get bruising, bleeding, or feel pain at the site of the puncture. Press on the punctured area for 10 minutes to avoid bleeding.

In rare cases, it may injure the artery or the surrounding nerves, and cause blockage.

Consult our doctors for a free second opinion. Book an appointment today with our medical experts at Yashoda Hospitals to know more about the Arterial Blood Gas (ABG) Test.