The<unk>  (A-a<unk> , is a measure of the difference between the<unk>  concentration of oxygen and the<unk>  concentration of oxygen. It is used in diagnosing the source of hypoxemia.
Alveolar-arterial gradient
Ventilation/perfusion ratio
Pulmonary compliance
Ventricular pressure
Arteriovenous oxygen difference
Alveolar gas equation
Airway resistance
Volumetric flow rate