APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -Because anatomical dead space is approximately 150 mL, this dead space ventilation (VD) is roughly 150 mL ×15/min, or 2250 mL/min. Alveolar ventilation is calculated by the formula: VA= R(VT-VD) where R is respiratory rate, VT is tidal volume, and VD is dead space volume.

Detailed explanation-2: -Clearance of the anatomic dead space is believed to play a significant role in using nasal high-flow cannulas. It is believed that high nasal flow allows dead space to be cleared more rapidly and subsequently decreases the portion of dead space that is rebreathed, increasing alveolar ventilation.

Detailed explanation-3: -Anatomical dead space is the volume of air that is in the conducting zone of the lung. Physiological dead space is the combination of anatomical dead space plus alveolar dead space. Alveolar dead space is the volume of air that fills the gas exchanging regions of the lung but does not participate in gas exchange.

Detailed explanation-4: -This volume is considered to be 30% of normal tidal volume (500 mL); therefore, the value of anatomic dead space is 150 mL. Physiologic or total dead space is equal to anatomic plus alveolar dead space which is the volume of air in the respiratory zone that does not take part in gas exchange.