Final answer:
PO2 refers to the partial pressure of oxygen in the blood, which is measured using an arterial blood gas (ABG) test. The result is expressed in mm Hg and indicates the amount of oxygen present in the bloodstream.
Step-by-step explanation:
PO2 refers to the partial pressure of oxygen in the blood. It is a measurement that indicates the amount of oxygen present in the bloodstream. PO2 is typically obtained from an arterial blood gas (ABG) test, which involves taking a blood sample from an artery and measuring the oxygen levels. The result of the test is expressed in units of millimeters of mercury (mm Hg) and represents the pressure exerted by oxygen in the blood.