physiologic dead space


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dead space

 
1. a space remaining in the tissues as a result of failure of proper closure of surgical or other wounds, permitting the accumulation of blood or serum.
2. the portions of the respiratory tract that are ventilated but not perfused by pulmonary circulation.
alveolar dead space the difference between anatomical dead space and physiologic dead space, representing the space in alveoli occupied by air that does not participate in oxygen–carbon dioxide exchange (alveolar ventilation). It varies in different parts of the lungs and under different conditions.
anatomical dead space the airways of the mouth, nose, pharynx, larynx, trachea, bronchi, and bronchioles.
equipment dead space the volume of equipment that results in rebreathing of gases.
physiologic dead space the sum of the anatomic and alveolar dead spaces; its volume (VD) is determined by measuring the partial pressure of carbon dioxide in a sample of exhaled gas (PECO2) and in the arterial blood (PaCO2) and (with tidal volume of VT) using the formula VD/VT = (PaCO2−PECO2)/PaCO2.

phys·i·o·log·ic dead space (VD),

the sum of anatomic and alveolar dead space; the dead space calculated when the carbon dioxide pressure in systemic arterial blood is used instead of that of alveolar gas in the Bohr equation; it is a virtual or apparent volume that takes into account the impairment of gas exchange because of uneven distributions of lung ventilation and perfusion.

physiologic dead space.

See dead space, def 2.

phys·i·o·log·ic dead space

(fizē-ŏ-lojik ded spās)
The sum of anatomic and alveolar dead space; the dead space calculated when the carbon dioxide pressure in systemic arterial blood is used instead of that of alveolar gas in the Bohr equation; it is a virtual or apparent volume that takes into account the impairment of gas exchange because of uneven distributions of lung ventilation and perfusion.

phys·i·o·log·ic dead space

(fizē-ŏ-lojik ded spās)
The sum of anatomic and alveolar dead space.