Mathematically, VA is total ventilation minus anatomical dead space ventilation.

Its calculation requires exclusion of ventilation occurring in the anatomical dead space. However, differences in the exact way of measuring this space result in clinically significant different results and, therefore, debate remains about the true value of this measured parameter.Ĭopyright © 2023, StatPearls Publishing LLC. Anatomical dead space occurs naturally in areas of the lungs that dont come in contact with alveoli (like the trachea). Alveolar ventilation (VA the subscript ‘A’ denotes ‘alveolar’) is the amount of ventilation occurring in the alveoli in one minute.

Indeed, it may serve as a prognostic factor in patients with acute repository distress syndrome (ARDS) who require ventilation. The meaning of ANATOMICAL DEAD SPACE is the dead space in that portion of the respiratory system which is external to the alveoli and includes the air-conveying ducts from the nostrils to the terminal bronchioles. This phenomenon has clinical significance because, both in healthy and impaired lungs, properly calculating and accounting for this non-physiological space is important for the proper respiratory care of ventilated patients. This is therefore termed anatomical dead space as it serves no respiratory function. Anatomic dead space is an important phenomenon in respiratory physiology whereby, owing to the fact that upper airways do not function as locations for gas exchange, and because of the tidal nature of ventilation, there is always a fraction of the inspired air that does not perform a physiologic function of exchanging carbon dioxide for oxygen.

Anatomical dead space contains