150 ml-the conducting airways (trachea, right and left mainstem bronchi, and lobar and segmental bronchi) do not contain alveoli and therefore do not take part in pulmonary gas exchange. these structures constitute the anatomic dead space. in the adult, the anatomic dead space is approximately 1 ml/lb or 2 ml/kg. the anatomic dead space increases during inspiration because of the traction exerted on the conducting airways by the surrounding lung parenchyma. in addition, the anatomic dead space depends on the size and posture of the subject.
