1. Pulmonary spirometry. Lung volumes in Liters
Capacities
Volume 6
TLC IC VC 5
IRV 4
Lung Volume 3 TV 2
ERV
FRC 1 RV

3. 7 6 IC 5 FEV1 FVC 4 3 2 1 FVC 5 FEV 1 4 FEV1 FVC 4 5 80% or 0.8
Lung volume (liter) 3 2 1
1 second

4. 7 6 IC
FEV1
FVC 5 4
Lung volume (liter) 3 2 1
1 second

5. 1 2 3 4 5 6 7
FEV1 IC
FVC
1 second
Lung volume (liter)

6. 1 2 3 4 5 6 7
FEV1 IC
FVC
1 second
Lung volume (liter)

7. OLD
Normal
RLD 1 2 3 4 5 6 7
FEV1 IC
FVC
1 second
Lung volume (liter) 1 2 3 4 5 6 7
FEV1 IC
FVC
1 second
Lung volume (liter) 1 2 3 4 5 6 7
FEV1 IC
FVC
1 second
Lung volume (liter)
FVC
FEV 1
FEV1 5 4
80%
FVC
FEV 1
FEV1
FVC
FEV 1
FEV1 4 4
3.5 2
50%
86%

8. FEV 1 FVC RV FRC TLC Obstructive Lung Disease Restrictive Lung Disease

9. Which of the following letter choices represents the functional residual capacity?
(A) A
(B) B
(C) C
(D) D
(E) E
(F) F
(G) G

11. Spirometry Vol/Time 11 Volume (L) Time (s) 6 5 In normal circumstances
FEV1 should be ~80% of
total volume expired
FEV1/FVC ratio
4.5/5.5*100=~80%
Slope of the initial line
gives the flow rate
FEF25-75
FEV3 4
75%
Volume (L) 3
FEV2
Vital Capacity
FEV1
Volume time spirometry. The patient is
usually asked to make a full inspiratory effort,
filling their lungs to TLC. Then the patient is
asked to exhale as hard and long as possible into
a tube that leads to a reservoir in which the
exhaled volume is recorded. The volume of
exhalation is thus recorded over time. A normal
patient should be able to exhale 80% of their
FVC in 1 second, so their FEV1:FVC ratio
should be 0.8 (or 80%). Importantly with
spirometry results, the practitioner should
consult a predicted values table, this will give
you the expected range of lung parameters based
on the persons height, sex and weight. Deviation
from these predicted values will inform you of
the types of lung disease present.
The FEF25-75 is a flow rate, i.e. volume per unit
time. On this graph draw a straight line between
the 25% and 75% values for the FVC. The slope
of this line is the flow rate in L s-1 between 25%
and 75% of FVC. Flow rates are more accurately
measured with flow-volume spirometry. 2
From fully inspired state patient expels all air in their lungs as forcefully as possible
25% 1 1 2 3 4
Time (s)

13. What is the interpretation of this spirometry reading?
Dr Bullman is a 72 year old retired family practitioner, Caucasian origin and weighing 80 kg. He complained of having a cough for the last 5 years or so. However, during the last two months the cough had worsened and he was now producing copious amounts of sputum. He also complained of difficulty in climbing stairs, and felt constantly tired. He stated that he was on no medication. On questioning he revealed that he had smoked about 20 cigarettes a day for the last 40 years and continued to smoke. After a detailed history was taken and a physical examination, he agreed to undergo a baseline spirometry test. However, the test had to be repeated several times as each time, Dr Bullman started to cough during the procedure. On one occasion he almost fell off his chair with exhaustion. Eventually at the fourth attempt he managed to complete the test. The results are shown.
What is the interpretation of this spirometry reading?
A. Normal pattern
B. Obstructive pattern
C. Restrictive pattern
D. Combined pattern

14. Flow/Volume Spirometry
Normal pattern.
Obstructive lung
Disease.
Flow/Volume Spirometry
Volume time spirometers have been superseded by flow-volume spirometers in the clinic. The patient is
asked to complete the same maneuver, a maximum forced expiratory effort, but this time two parameters
are measured. The volume expired is measured, just like the volume-time spirometer. In addition, the tube
that the patient breathes through has a small turbine inside which measures the speed of the airflow
generated, i.e. flow rate. These two parameters are then displayed together, the flow rate (y-axis) along with
the volume expired (x-axis) – note no time axis – time is recorded as a dot every second that lapses.
Flow volume spirometry
curve. The patient is asked to
make a full inhalation before
recording begins. Recording
begins as soon as the patient then
makes their forced expiration.
The red line traces their effort
(upon exhalation move from left
to right). Initially flow rates are
high and the patient rapidly
reaches the fastest flow rate, i.e.
peak expiratory flow. As the
volume breathed out increases
(i.e. lung volume falls) the flow
rate falls; the total volume
exhaled is on the x-axis.
Eventually flow will stop when
the lungs are at the RV, and the red line contacts the x-axis (here at 5 L), this represents the total volume of
air exhaled, i.e. the FVC. The patient then inhales and flow now reverses (upon inhalation move right to
left), the rate of this flow is again measured against volume inhaled. The FEF’s can simply be measured
from the y-axis, so at 25% of FVC flow rate is ~6 Ls-1. The computer automatically marks a dot at 1 sec
intervals (only first second is shown on this graph), therefore we can measure FEV1 – simply read down
from the dot, e.g. here it is 4 L, of a VC of 5 L – i.e normal FEV1:FVC ratio.
Flow volume loops in
disease states. Left
panel, a restrictive lung
disease results in fall of
FVC and FEV1, in this
recording the 1 second
point is indicated on the
trace by the circle. The
FEV1 is the volume on the x
axis at this point. The
FEV1:FVC ratio is either
unaltered or slightly
enhanced. Obstructive lung
disease, right panel, shows
much slower flow rates and
a reduced PEF. The
expiratory flow curve also demonstrates a scooped out appearance. FVC can be reduced or unaffected,
however, the FEV1 and the FEV1:FVC ratio are both significantly reduced. Note that in 1 second the patient
has only managed to breath out 2.25 L of a 4 L FVC. With obstructive lung diseases inspiratory rates are
generally not affected, since expansion of the lung tissue holds airways open as the lungs fill. In contrast, a
restrictive lung
Disease.

16. 0/760
0/760
-- 4/756
-- 4/756
0/760
Transpulmonary pressure (PTP)

20. Ph HCO Pco2

21. 65-year-old patient comes in for an insurance physical that requires pulmonary function tests to ensure he does not have underlying restrictive or obstructive lung disease before the insurance company will cover him. The patient
has a 55-pack-year history of smoking. Laboratory
testing reveals an arterial carbon dioxide pressure of 40 mm Hg and his expired carbon dioxide pressure is 30 mm Hg. His physiologic dead space is determined to be L. What is the patient’s tidal volume?
(A) 0.01 L
(B) 0.05 L
(C) 0.1 L
(D) 0.5 L
(E) 1 L
(F) 5 L

22. B)Surface Tension Law of Laplace:
Pressure in alveoli is directly proportional to surface tension; and inversely proportional to radius of alveoli.
Pressure in smaller alveolus would be greater than in larger alveolus, if surface tension were the same in both.
Insert fig

23. VA = VE – Vd

25. THE PARITAL PRESSURE OF OXYGEN DECREASES AS
INSPIRED AIR COURSES THROUGH THE AIRWAYS

26. A Key Factor In The Amount Of Gas Exchange
Is The Partial Pressure Difference Across The Gas Exchange Barrier
a.k.a. the driving pressure
Across pulmonary capillaries
O2 partial pressure gradient
from alveoli to blood = 60 mm Hg
(100 –> 40)
CO2 partial pressure gradient from
blood to alveoli = 6 mm Hg
(46 –> 40)
Across tissue capillaries
O2 partial pressure gradient from blood to tissue= 60 mm Hg
tissue cell to blood = 6 mm Hg

27. Gas Transport
The amount of gas that is transported across a surface can be calculated using Fick’s Law.
Vgas = (AD/T)*(P1-P2)
Diffusion through tissues is described by Fick's law (Figure 3-1). This states that the rate and volume of gas crossing through a sheet of tissue is proportional to the tissue area and the difference in gas partial pressure between the two sides, and inversely proportional to the tissue thickness. As we have seen, the area of the blood-gas barrier in the lung is enormous (50 to 100 square meters), and the thickness is only 0.3 µm in many places (Figure 1-1), so the dimensions of the barrier are ideal for diffusion. In addition, the rate of transfer is proportional to a diffusion constant, which depends on the properties of the tissue and the particular gas. The constant is proportional to the solubility of the gas and inversely proportional to the square root of the molecular weight (Figure 3-1). This means that CO2 diffuses about 20 times more rapidly than does O2 through tissue sheets because it has a much higher solubility but not a very different molecular weigh
A = area
D = diffusivity of substance
T = thickness
P1 = partial pressure in compartment 1
P2 = partial pressure in compartment 2

28. Is Complete Within ¼ Second
GAS EXCHANGE ACROSS THE PULMONARY
CAPILLARY
Is Complete Within ¼ Second
• at rest pulmonary transit time [¾
second] is more than that required to
complete gas exchange [¼ second].
• during exercise, despite increased
cardiac output, pulmonary transit time
remains > ¼ second & gas exchange is
complete.
• in pulmonary fibrosis, reduced gas
exchange is often seen in patients
during exercise. At rest, the additional
time spent in the capillary is sufficient
to compensate for the thickened barrier
O2 Transfer time
Blood coming into the pulmonary capillary bed spends only 0.75 seconds in contact with the alveolus, i.e.
only 0.75 s is available in which blood must go from a PO2 of 40 mm Hg to the alveolar level of 100 mm
Hg. However, the oxygenation of blood is easily achieved within this time. It takes only 0.25 s for blood to
become fully oxygenated and equilibrated with the alveolar PO2 of 100 mm Hg. The remaining time that
blood spends in the alveolar space, i.e. 0.5 s is called the capillary reserve time – if blood speeds up, e.g.
during exercise (increased cardiac output) then there is still plenty time to oxygenate blood since flow
generally will not go through the capillary in under 0.25 s.

30. pH, temperature and CO2 all right shift the curve
All of the above factors, singly, cause a right shift in the saturation curve and an increase in P50. In
combination the right-shift gets more pronounced. An easy way to remember it is that as a muscle works it
gets hot, acidic and produces CO2 – all of these factors then cause a right-shift in the saturation curve and
an increase in P50. Conversely an alkaline pH, a fall in CO2 and a fall in temperature all cause a left-shift in
the saturation curve and a decrease in P50.

31. Remember! Saturation is not O2 content24
100 22
Normal 15 g 100ml-1 20 80 18 16 60 14
O2 content ml 100 ml-1
% Hb saturation 12
100% 10 40 8
Anemia
An anemic patient can be fully saturated, have a normal PaO2 and still be weak due to poor oxygen carrying capacity.
Arterial PO2 is determined by the
diffusion of O2 across the alveolar/blood barrier – this is not affected in anemia, therefore PaO2 is normal.
The blood is fully saturated, i.e. all the binding sites for O2 are occupied – fully saturated.
However, the oxygen content is less since there are less O2 binding sites. A patient with 7.5 g/dl Hb has only half of the O2 binding sites of a patient with 15 g/dl Hb – and therefore can only carry half the oxygen.
So clinically, remember to only rely on saturation IF you know the patients Hb values are normal.
Anemic patient has e.g. half the Hb
and therefore can carry 0.5 times the O2 6 20 4 2
0 % 20 40 60 80
100
600
PO2 (mm Hg)