An arterial blood gas (ABG) test is a medical procedure that measures the levels of oxygen, carbon dioxide, and other gases in a person's arterial blood. It provides important information about the patient's respiratory and metabolic status, acid-base balance, and overall oxygenation. The test involves drawing a blood sample directly from an artery, typically from the wrist or groin, and analyzing it for various parameters such as pH, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2), bicarbonate (HCO3-), and oxygen saturation (SaO2). ABG tests are commonly used to diagnose and monitor respiratory and metabolic disorders, assess the effectiveness of breathing support, and guide treatment decisions.