The<unk>  is the method for calculating partial pressure of alveolar oxygen (PAO2). The<unk>  is used in assessing if the lungs are properly transferring oxygen into the blood. The alveolar air<unk>  is not widely used in clinical medicine, probably because of the complicated appearance of its classic forms. The partial pressure of oxygen (pO2) in the pulmonary alveoli is required to calculate both the alveolar-arterial gradient of oxygen and the amount of right-to-left cardiac shunt, which are both clinically useful quantities. However, it is not practical to take a sample of<unk>  from the alveoli in order to directly measure the partial pressure of oxygen. The<unk>  allows the calculation of the alveolar partial pressure of oxygen from data that is practically measurable. It was first characterized in 1946.
Alveolar gas equation
Nitrogen washout
Surfactant–albumin ratio
Alveolar pressure
Alveolar–arterial gradient
Arteriovenous oxygen difference
Oxygenation index
Ventilatory threshold