![]() ![]() It is normally very small (less than 5 mL) in healthy individuals. Alveolar dead space is the area in the alveoli that does get air to be exchanged, but there is not enough blood flowing through the capillaries for exchange to be effective. The ratio of physiologic dead space to tidal volume is usually about 1/3. The physiological dead space is equal to the anatomical dead space plus the alveolar dead space. Alveolar dead space is the volume of gas within unperfused alveoli (and thus not participating in gas exchange either) it is usually negligible in the healthy, awake patient. The deviation of the space-time geometry near the gravitating Earth from the flat space-time of the special theory of relativity can be gauged by the ratio Phi / c2 /c2, where Phi is the Newtonian gravitational potential at the Earths surface. Anatomic dead space is the volume of gas within the conducting zone (as opposed to the transitional and respiratory zones) and includes the trachea, bronchus, bronchioles, and terminal bronchioles it is approximately 2 mL/kg in the upright position. Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space. Alveolar dead space increases with tidal volume so that the sum of anatomical and alveolar ( physiological) dead space remains about 32 of tidal volume (Fig. Dead space is the volume of a breath that does not participate in gas exchange. shunt) are schematically represented, and the method for quantifying the fraction of alveolar ventilation wasted in alveolar dead space is described. ![]()
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