Sanja Jelic, MD is board-certified in pulmonary disease, sleep medicine, critical care medicine, và internal medicine. She is an assistant professor và attending physician at Columbia University College of Physicians và Surgeons in New York, NY.

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The partial pressure of carbon dioxide (PaCO2) is one of several measures calculated by an arterial blood gases(ABG) thử nghiệm often performed on people with lung diseases, neuromuscular diseases, & other illnesses. PaCO2 specifically evaluates carbon dioxide (CO2) levels in the blood. The ABG kiểm tra also evaluates the partial pressure of oxygene (PaO2), bicarbonate (HCO3), & the pH cấp độ of blood.


Verywell/Cindy Chung

Purpose of Test

An ABG thử nghiệm assessing PaCO2 is useful for getting a glimpse of the body"s metabolic & respiratory state. It helps evaluate lung function & the effectiveness of oxygen therapy, & can determine the body"s pH or acid-base balance.

Every time you inhale, oxyren is brought into your lungs & delivered to the alveoli. This is where the transfer of oxyren inkhổng lồ và the removal of carbon dioxide from the blood occurs.

If the partial pressure of both oxygen và carbon dioxide are normal, the molecules will move from the alveoli into the blood & baông chồng as they should. Changes in that pressure can result in too little oxygen or the accumulation of too much carbon dioxide in the blood. Neither is considered optimal.

Having too much carbon dioxide is called hypercapnia, a condition common in people with late-stage chronic obstructive sầu pulmonary disease (COPD).

In contrast, too little CO2 can lead to lớn alkalosis, a condition where you have too many bases in your blood (CO2 is an acid).

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Carbon dioxide is in equilibrium with bicarbonate (HCO3) in the blood. When CO2 is elevated, it creates an acidic environment. In people with COPD who have serious breathing problems, the increased CO2 màn chơi can result in what is called respiratory acidosis. When this happens in late-stage COPD (when a person has severely weakened respiratory muscles), the condition may lead to respiratory failure.

Risks và Contraindications

An ABG kiểm tra is a standard blood draw usually performed on the radial artery in the wrist, the femoral artery in the groin, or the brachial artery in the arm. It is generally an uncomplicated procedure but can be painful given that arteries are located deeper in the body than veins. Swelling và bruising can sometimes occur.

Feeling lightheaded or fainting after the blood drawBlood buildup under the skin (hematoma)Excessive sầu bleeding


If you have sầu recently been on supplemental oxyren, your oxygen levels must remain consistent for trăng tròn minutes before taking the test.

Be sure khổng lồ tell your healthcare provider if you"ve been taking blood thinners (anticoagulants) such as warfarin or aspirin.

Interpreting Results

The normal range of partial pressure of carbon dioxideis between 35 & 45 millimeters of mercury (mmHg). If the value is higher than 45 mmHg, it"s indicative sầu that you have too much carbon dioxide in your blood. Under 35 mmHg, và you have too little.