Adobe Systems
Physiology department
1
Respiratory system.

Adobe Systems
Physiology department
2
Lung ventilation, volumes, measurement
Principle: determination the air flow velocity from the measured pressure differences between the
inner and outer spirometer membranes, the volumes being calculated (PowerLab spirometry)
̶

Adobe Systems
Physiology department
3
Lung ventilation, volumes, measurement
̶Tidal volume (TV) – the volume of air that enters the lungs during each inspiration (or the volume
that is exhaled during every expiration).
̶Inspiratory reserve volume (IRV) – the maximal amount of additional air that can be drawn into the
lungs by determined effort after a normal inspiration at rest.
̶Expiratory reserve volume (ERV) – the additional amount of air that can be exhaled from the lungs
by determined effort after a normal expiration.
̶Residual volume (RV) – the volume of air still remaining in the lungs after the most forcible
expiration possible.
̶
V [l]
Vt (0,5 l)
IRV (2,5 l)
ERV (1,5 l)
RV (1,5 l)

Adobe Systems
Physiology department
4
Lung ventilation, volumes, measurement
Lung capacity:
̶VC = VT + IRV + ERV
̶TLC = VC + RV
̶FRC = ERV + RV
̶IC = IRV + VT
̶EC = ERV + VT
̶
Vt (0,5 l)
IRV (2,5 l)
ERV (1,5 l)
RV (1,5 l)
V [l]
Dynamic lung volumes:
̶VE
̶MMV
̶

Adobe Systems
Physiology department
5
Lung ventilation, volumes, measurement
Dynamic lung volumes
̶
V [l]
Time [s]
1 s
FEV1
―FVC – the maximum volume of air that can be exhaled after maximum inhale
―FEV1 – the volume of air exhaled with the greatest effort in 1 second after maximum inhale
―FEV1/FVC (%) – Tiffeneau index – around 0,8 (80 %)

Adobe Systems
Physiology department
6
Lung ventilation, volumes, measurement
1 s
V [l]
Time [s]
1 s
V [l]
Time [s]
FEV1
FEV1
FVC > FVC
Obstructive lung disease
(FVC=N; FEV1=↓)
―tracheal stenosis
―astma bronchiale
―CHOPN
―tumor
Restrictive lung disease
(FVC=↓; FEV1=N)
Pulmonary etiology
―pulmonary fibrosis
―lung resection
―pulmonary edema
―pneumonia
Extrapulmonary etiology
―ascites
―kyphoscoliosis
―burns
―high diaphragm condition

Adobe Systems
Physiology department
7
Maximal respiratory flow - volume curve (spirogram)
PEF
MEF75%
MEF50%
MEF25%
TLC
IRV
Vt
ERV
RV
IRC
VC
FRC
RV
•PEF – peek expiratory flow; the highest  speed of air flow at peak of exhale
•MEF – maximum expiratory flow rates at different FVC levels, which is still to be exhaled (75 %,
50 % and 25 % of FVC)
Principle: the measurement of the air flow velocity according to the speed of the turbine and the
volumes are calculated (Cosmed).

Adobe Systems
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Adobe Systems
Physiology department
9
Maximal respiratory flow - volume curve (spirogram)

Adobe Systems
Physiology department
10
Lung ventilation, volumes, measurement
V1
c1
V2=RV+V1
c2
Helium dilution method – residual volume