Dead space of the respiratory system refers to the space in which oxygen (O2) and carbon dioxide (CO2) gasses are not exchanged across the alveolar membrane in the respiratory tract. Anatomic dead space specifically refers to the volume of air located in the segments of the respiratory tract that are responsible for conducting air to the alveoli and respiratory bronchioles but do not take part in the process of gas exchange itself. These segments of the respiratory tract include the upper airways, trachea, bronchi, and terminal bronchioles.
Physiologic dead space (VDphys) is the sum of the anatomic (VDana) and alveolar (VDalv) dead space.
VDphys = VDana + VDalv (L)
Dead space ventilation (VD) is then calculated by multiplying VDphys by respiratory rate (RR).
VD = VDphys x RR (L/min)
Enghoff's equation compiles these variables with PaCO2, tidal volume (TV), and expired CO2 (PECO2). It is then implied that VDphys/VT is representative of the portion of a tidal volume that does not participate in gas exchange.
VDphys/VT = (PaCO2 - PECO2)/PaCO2
Registration Status:
Qualified
Permissible Values:
Data Type:
Number
Unit of Measure:
L/min
Ids:
Value
Code Name
Code
Code System
Code Description
Designations:
Designation:
CPET: Dead Space Ventilation
Tags:
Designation:
Dead Space Ventilation (L/min)
Tags:
Suggested Question Text
Designations:
Definition:
Dead space of the respiratory system refers to the space in which oxygen (O2) and carbon dioxide (CO2) gasses are not exchanged across the alveolar membrane in the respiratory tract. Anatomic dead space specifically refers to the volume of air located in the segments of the respiratory tract that are responsible for conducting air to the alveoli and respiratory bronchioles but do not take part in the process of gas exchange itself. These segments of the respiratory tract include the upper airways, trachea, bronchi, and terminal bronchioles.
Physiologic dead space (VDphys) is the sum of the anatomic (VDana) and alveolar (VDalv) dead space.
VDphys = VDana + VDalv (L)
Dead space ventilation (VD) is then calculated by multiplying VDphys by respiratory rate (RR).
VD = VDphys x RR (L/min)
Enghoff's equation compiles these variables with PaCO2, tidal volume (TV), and expired CO2 (PECO2). It is then implied that VDphys/VT is representative of the portion of a tidal volume that does not participate in gas exchange.
VDphys/VT = (PaCO2 - PECO2)/PaCO2