Define dead space in lungs9/21/2023 Reduced in pregnancy, obesity, severe obstruction or proximal (of trachea/bronchi obstruction) Relies on muscle strength and low airway resistance Relies on muscle strength, lung compliance (elastic recoil) and a normal starting point (end of tidal volume)Įxtra volume that can be expired below tidal volume, from normal quiet expiration to maximum expiration shallow breaths vs deep breathsĮxtra volume that can be inspired above tidal volume, from normal quiet inspiration to maximum inspiration V d V t = P A C O 2 − P e C O 2 P A C O 2 Ī common step is to then presume that the partial pressure of carbon dioxide in the end-tidal exhaled air is in equilibrium with that gas' tension in the blood that leaves the alveolar capillaries of the lung.Volume that enters and leaves with each breath, from normal quiet inspiration to normal quiet expirationĬhanges with pattern of breathing e.g. The original formulation by Bohr, required measurement of the alveolar partial pressure P A. The Bohr equation is used to quantify the ratio of physiological dead space to the total tidal volume, and gives an indication of the extent of wasted ventilation. It differs from anatomical dead space as measured by Fowler's method as it includes alveolar dead space. ![]() This is given as a ratio of dead space to tidal volume. ![]() The Bohr equation, named after Danish physician Christian Bohr (1855–1911), describes the amount of physiological dead space in a person's lungs. Not to be confused with the Bohr model or the Bohr effect.
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