1. (bx•Qb)in Ubx QAWO (AWOx •QAWO)in AWO (bx•Qb)out
PPL
QAWO PA
(AWOx •QAWO)in VA
AWO VL
(bx•Qb)out
(a)
(b)
Figure 9.1 Models of the lungs (a) basic gas-transport unit of the pulmonary system. Here (x  Q) is the molar flow of X through the airway opening, AWO, and the pulmonary capillary blood network, b. Ubx is the net rate of molar uptake –that is, the net rate of diffusion of X into the blood. VD and VA are the dead-space volume and alveolar volume, respectively. (b) A basic mechanical unit of the pulmonary system. PA is the pressure inside the lung – that is, in the alveolar compartment. PPL and PAWO are the pressures on the pleural surface of the lungs and at the airway opening, respectively. VL is the volume of the gas space within the lungs, including the airways; QAWO is the volume flow of gas into the lungs measured at the airway opening.

2. pAWO
RAW
uL  qAWO
CstW pA
CstL
RAW uL
CstL
qAWO
pPL
pPL
pAWO pA
CstW
pBS
 pMUS +
pMUS
pBS
(a)
(b)
Figure 9.2 Models of normal ventilatory mechanics for small-amplitude, low-frequency (normal lungs, resting) breathing (a) Lung mechanical unit enclosed by chest wall. (b) Equivalent circuit for model in Figure 9.2(a).

3. Figure 9. 3 Pneumotachometer flow-resistance elements (a) Screen
Figure 9.3 Pneumotachometer flow-resistance elements (a) Screen. (b) Capillary tubes or channels.

4. Figure 9.4 Pneumotachometer for measurements at the mouth (a) Diameter adapter that acts as a diffuser. (b) An application in which a constant flow is used to clear the dead space.

5. Figure 9.5 Volume ranges of the intact ventilatory system (with no external loads applied). TLC, FRC, and RV are measured as absolute volumes. VC, IC, ERV and VT are volume changes. Closing volume (CV) and closing capacity (CC) are obtained from a single-breath washout experiment.

6. Rotational
displacement
sensor
Other signal
processing
Strip-chart
recorder
Counterweight
Kymograph
Bell PS VS TS
Water seal
Blood
flow
Uabs
One-way
valves
FS x
Mouthpiece
Soda-lime
canister VL
Ubs
Thermometer for
spirometer gas
temperature TL PA
QAWO
FA x
Spirometer
system
Pulmonary
system
Figure 9.6 A water-sealed spirometer set up to measure slow lung-volume changes. The soda-lime and one-way-valve arrangement prevent buildup of CO2 during rebreathing.

7. 100% O2
One-way
valves TS TL
FSN2 VL
Spirometer VS
FAN2 O2 + N2
Nitrogen
analyzer +
CO2
Figure 9.7 Diagram of an N2 washout experiment The expired gas can be collected in a spirometer, as shown here, or in a rubberized-canvas or plastic Douglas bag. N2 content is then determined off-line. An alternative is to measure expiratory flow and nitrogen concentration continuously to determine the volume flow of expired nitrogen, which can be integrated to yield an estimate of the volume of nitrogen expired.

8. ( dP ) M ( dP ) B P M
Shutter ( P - P )
closed M
atm P B
Figure 9.8 A pressure-type total-body plethysmography is used with the shutter closed to determine lung volume and with the shutter open to determine changes in alveolar pressure. Airway resistance can also be computed if volume flow of gas is measured at the airway opening. Because atmospheric pressure is constant, changes in the pressures of interest can be obtained from measurements made relative to atmospheric pressure.
Shutter
QAWO VL
QAWO PA TL NL
-QAWO
dQAWO
dPB PB
Shutter
open VB PB
Pump TB
(PB –Patm) NB
Calibration VP VP VP = PB
BPB PB

9. V L
TLC
Less stiff
Normal
TLC
Normal VC
FRC
Slope of linear approximation
to curve (static compliance)
Normal VC RV VT
TLC
Normal
FRC
FRC VC
Normal RV
Stiffer lung RV
PL = PAWO –PPL
Figure 9.9 Idealized statically determined expiratory pressure-volume relations for the lung. The positions and slopes for lungs with different elastic properties are shown relative to scales of absolute volume and pressure difference.

10. -QAWO VL  TLC (Expiration) VL < 0.8 TLC (PAWO –PA) (Inspiration)
Figure Idealized isovolume pressure-flow curves for two lung volumes for a normal respiratory system. Each curve represents a composite from numerous inspiratory-expiratory cycles, each with successively increased efforts. The pressure and flow values measured as the lungs passed through the respective volumes of interest are plotted and connected to yield the corresponding curves.

11. Maximal expiratory
Flow-volume (MEFV) curves
-QAWO
Effort independent
Normal
(Expiration)
(FVC - QAWOdt)
TLC
TLC
Reduced FVC
Normal FVC
Effort
independent 1 2 3 4
Time, s
Time vital capacity (TVC) spirograms
Figure 9.11 Alternative methods of displaying data produced during a forced vital capacity expiration. Equivalent information can be obtained from each type of curve; however, reductions in expiratory flow are subjectively more apparent on the MEFV curve than on the timed spirogram.

12. Figure 9.12 Essential elements of a medical mass spectrometer.

13. Figure 9.13 General arrangements of the components of an infrared spectroscopy system.

14. Figure 9.14 N2 analyzer employing emission spectroscopy.

15. Light
source
Readout
scale
Sample in A
Pressure
sensor D J F C E
Magnets B
Dumbbell-shaped
test body
Point of
suspension
(a)
(b)
Figure 9.15 Oxygen analyzers (a) Diagram of the top view of a balance-type paramagnetic oxygen analyzer. The test body either is allowed to rotate (as shown) or is held in place by counter torque, which is measured to determine the oxygen concentration in the gas mixture. (b) Diagram of a differential pressure and a magneto-acoustic oxygen analyzer (see text for descriptions).

16. Figure 9.16 Distributions of volume and gas species at RV and TLC for a vital-capacity inspiration of air or pure oxygen.

17. Conducting airway
filled with 100% O2
Well-mixed alveolar
compartment
Figure single-breath nitrogen-washout maneuver (a) An idealized model of a lung at the end of a vital-capacity inspiration of pure O2, preceded by breathing of normal air. (b) Single-breath N2-washout curves for idealized lung, normal lung, and abnormal lung. Parameters of these curves include anatomical dead space, slope of phase III, and closing volume.
(a)
Abnormal slope
>0.02/500 ml
FEN2
Normal slope
 0.02/500 ml
Ideal lung
Normal lung I II
III IV
Abnormal lung CV
750
1250
Expired volume, vS
(ml)
Anatomical dead space
volume, V' D
TLC
Lung volume, vL RV
(b)