"Physiologic dead space (VD): volume of inspired air that does not participate in gas exchange"
https://next.amboss.com/us/article/ZI0ZYh?utm_source=anki&utm_medium=anki&utm_campaign=anki&utm_term=physiologic%2Bdead%2Bspace&guid=N%253Bd%255B%255D_%2524%25293L&aid=ee320c7d-b512-4f0d-8562-e858e936fcc1&uid=Dwsf1OCna#Zd888f2bcb22b618871e9d9823cb00c87
current definition is misleading since not all lung volume that does not participate in gas exchange should not be included in physiologic dead space. Only the volume that is ventilated but does not exchange gases due to either anatomic constraints or lack of perfusion is counted. The total lung volume includes functional alveoli that do participate in gas exchange, residual volume, and other non-participatory spaces that are not part of the dead space.