What is alveolar ventilation?

Alveolar ventilation refers to the total amount of gas inhaled or exhaled by alveoli per minute, which is the effective ventilation for direct gas exchange. In normal respiration, the airway above respiratory bronchioles only plays the role of gas conduction, and does not participate in alveolar gas exchange. It is regarded as dissecting invalid space or dead space. Part of the gas entering the alveoli is considered as alveolar ineffective space because there is no corresponding alveolar capillary blood flow to exchange gas with it. The anatomical ineffective space and alveolar ineffective space are collectively referred to as physiological ineffective space. This part of the gas that cannot be exchanged is called dead space ventilation, and alveolar ventilation can accurately reflect the increase or decrease of effective ventilation. The increase of physiological dead space volume can be seen in the decrease of pulmonary vascular bed, decrease of pulmonary blood flow or pulmonary vascular embolism caused by various reasons, reflecting the abnormality of ventilation function, decrease of alveolar ventilation, decrease of pulmonary ventilation volume and increase of physiological dead space volume.