What is alveolar dead space?

Alveolar dead space is the difference between anatomical and physiologic dead space, representing the space of alveoli occupied by air that does not participate in alveolar ventillation (oxygen-carbon di oxide exchange). Anatomical dead space: the Airways of mouth, nose, pharynx, larynx, trachea, bronchi, and the broncheoles. Equipment dead space is the volume of equipment that occurs in rebreathing of gases. Physiologic dead space is the sum of the anatomic and alveolar dead spaces Its volume VD is determined by measuring the partial pressure of carbon di oxide in a sample of exhaled gas (PE) and with tidal volum e(VT) using the formula VD/VT =[ (PCo2-PECo2)/PaCo2