<prompt> In an normal adult, the anatomical dead space is approximately:2.2 cckg1 cckg3 cckg1.5 cckg  <response>: Approximately 30 of each breath does not paicipate in alveolar gas exchange and is thus called dead space ventilation VDS. Dead space ventilation is made up of anatomic dead space and alveolar dead space. Anatomic dead space is the volume of air that fills the conducting airways trachea, bronchi, and bronchioles and is estimated at approximately 2.2 cckg. The combination of alveolar and anatomic dead space is called the physiologic dead space. The normal ratio between dead VDS space ventilation and tidal volume VT is 0.3. Ref: Slesinger T.L. 2011. Chapter 20. Blood Gases. In R.K. Cydulka, G.D. Meckler Eds, Tintinallis Emergency Medicine: A Comprehensive Study Guide, 7e. 