Model No. PS-2152
Interpretation of PFT Data
5
®
Interpretation of PFT Data
Total Flow vs. Time
Total Flow is the
net volume
of air that flows
out
from the lungs through
the Spirometer, equal to the total expired volume minus the total inspired
volume. View the graph of Total Flow vs. Time. Four specific lung
volumes and two lung capacities can be interpreted from this graph.
*
Tidal Volume (TV)
is the volume of one breath, or the amount of air
moved into and out of the lungs during quiet breathing (breathing without
effort).
Expiratory Reserve Volume (ERV)
is the amount of air moved out of the
lungs during a forced expiration, beyond the level of tidal expiration.
Inspiratory Reserve Volume (IRV)
is the amount of air moved into the
lungs during a forced inspiration, beyond the level of tidal inspiration.
Forced Expiratory Volume in One Second (FEV
1.0
)
is the volume of air
moved out of the lungs in the first second of a forceful expiration following
a maximal inspiration.
Inspiratory Capacity
(IC)
is the maximum amount of air that can be
inspired after a normal expiration (IC = TV + IRV).
Vital Capacity (VC)
is the maximum
movable
amount of air contained by
the lungs (VC = TV + IRV + ERV).
FEV
1.0
% =
FEV
1.0
÷
VC × 100% is a common comparison of FEV
1.0
to VC.
TV
ERV
IRV
FEV
1.0
IC
VC
1 sec.
*To measure these
quantities from the
graph in DataStudio,
click the Smart Tool
button:
If you are viewing
the data on the
Xplorer GLX
(without a
computer), select
Smart Tool or Delta
Tool from the Tools
menu.
