Arterial Blood Gases

Arterial blood gases are measured using blood drawn from an artery, usually in the wrist. Blood is usually drawn from a vein, but venous blood is inaccurate for these measurements. Drawing blood from an artery, unfortunately, causes more discomfort.

Arterial blood gases are measured to determine the amount of oxygen dissolved in the blood (pO2), the percentage of hemoglobin saturated with oxygen (O2 sat), the amount of carbon dioxide dissolved in the blood (pCO2), and the amount of acid in the blood pH.

The oxygen measure may be used to determine whether a patient needs oxygen therapy. The carbon dioxide measure gives some idea of lung function and is especially important to know when starting oxygen therapy

Alpha-1-Antitrypsin Levels

A person suspected of having a genetic deficiency of this enzyme will undergo this test. Alpha-1-antitrypsin deficiencies can also cause liver disease in children, and the level may be measured for that as well. If the level is low, a genetic probe may be used to determine the cause.

Publication Review By: Stanley J. Swierzewski, III, M.D.; the Editorial Staff at

Published: 01 Jun 2000

Last Modified: 24 Jun 2013