1. Schematic illustration of upper airway anatomical dead space volume (VD) during unidirectional breathing.
Schematic illustration of upper airway anatomical dead space volume (VD) during unidirectional breathing. A: The airway filled with CO2-containing gas (gray) at end exhalation during nose-in nose-out breathing. This amount of CO2-containing gas is recycled in the subsequent breath. B: The nasal and part of the pharyngeal cavity (white) filled with fresh gas at end exhalation during nose-in mouth-out breathing. The CO2-containing gas in the oral cavity (black) is not recycled into the lung since inhalation occurs only via the nasal cavity. From Reference 8, with permission.
Demet S Sulemanji et al. Respir Care 2014;59:
(c) 2012 by Daedalus Enterprises, Inc.