Pulmonary Physiology and
Lung Function Tests
Conor O’Dochartaigh
FRACP Teaching
24/10/07
Lung Function Testing (PFTs)
Spirometry (FV loop spirometry, dynamic lung
volumes)
Reversibility testing
Bronchial challenge testing
Static lung volumes (TLC, FRC)
Gas Transfer (DLCO, TLCO Transfer factor, KCO, )
Maximal respiratory pressures (Mouth
pressures)
CPEST (Cardiopulmonary exercise test)
General principles
Technical factors
– operator
– patient
within test repeatability
– confounding factors
Quality control – between test repeatability
Appropriate reference values
Spirometry
Measures the ability to move air rapidly
– Depends on nervous system, musc skel, skin
+ connective tissue, lungs, airways, inhaled
gas
How is the test done
Apparatus
– true spirometers - volume & time
– pneumotach, vane & hotwire anenometers flow
Method
– Full inspiration, forced maximal expiration
– Minimum 3 technically acceptable attempts
– within 5% repeatability FEV1 and FVC
Slow Vital Capacity may also be checked
Data generated
Volume time curve (spirogram)
– FEV1, FVC, Ratio
Flow volume loop
– Peak flow
– FVC
– FEF 25-75%
– MEF 75, 50, and 25
– Inspiratory flow data
NORMAL
Spirometry interpretation
Obstructive v. Restrictive
Mid flow obstruction
Shape of the FV loop
– Obstruction v. restriction
– Fixed large airway obstruction
– Variable airway obstruction
Extrathoracic
Intrathoracic
Airflow obstruction
Mild on left
Severe on right
Classification of COPD Severity
by Spirometry
Stage I: Mild
FEV1/FVC < 0.70
FEV1 > 80% predicted
Stage II: Moderate
FEV1/FVC < 0.70
50% < FEV1 < 80% predicted
Stage III: Severe
FEV1/FVC < 0.70
30% < FEV1 < 50% predicted
Stage IV: Very Severe
FEV1/FVC < 0.70
FEV1 < 30% predicted or
FEV1 < 50% predicted plus
chronic respiratory failure
True or False
Spirometry showing FEV1 < 80% of
predicted and FEV1/FVC ratio <70% is
diagnostic of COPD
COPD
ID: CSM4166
Weight(kg): 79.0
PB: 753
Spirometry Ref
4.86
FVC
3.38
FEV1
70.0
FEV1/FVC
3.11
FEF25-75%
9.02
PEF
Lung Volumes
TLC
RV
RV/TLC
FRC PL
ERV
VC
Resistance
Raw
sRaw
Diffusion
DLCO
DLCO /VA
VA
Date: 10/03/04
Height(cm): 184
Temp: 23
Pre
Pre Post
Meas % Ref Meas
4.48 92
(1.61) (48)
(36.0)
(0.35) (11)
5.43 60
Gender: Male
BMI: 23.33
Post
% Ref
Age: 62
Post
% Chg
Comments:The patient could not fully expire during to FVC or SVC, therefore the results for both vital
capacities may be underestimated. See attached FV loops
Pulmonary restriction
Scleroderma
ID: HLJ7135
Weight(kg): 61.0
PB: 753
Date: 04/08/04
Height(cm): 162
Temp: 22
Spirometry
FVC
FEV1
FEV1/FVC
FEF25-75%
PEF
Pre
Meas
(1.58)
1.13
71.0
0.71
4.92
Ref
2.52
1.69
69.0
1.90
5.15
Pre Post
% Ref Meas
(63)
67
Gender: Female
BMI: 23.24
Post
% Ref
37
96
Comments: Acceptable and repeatable results obtained.
Interpretation:
Post
% Chg
Age: 83
True or False?
A spirometry showing an FEV1< 80% of
predicted, FVC < 80% of predicted and
FEV1/FVC ratio of >70% is diagnostic of
Pulmonary Restriction.
Large Airway obstruction
Tracheal
– Fixed obstruction – expiratory and inspiratory
limitation
– Variable obstruction
Inspiratory limitation indicates extrathoracic
obstruction
Expiratory limitation indictaes intrathoracic
obstruction
Variable extrathoracic
Large airway obstruction
Fixed
Fixed Extrathoracic Obstruction PFT
ID: CLV3379
Weight(kg): 82.0
PB: 765
Spirometry
Ref
FVC
4.93
FEV1
3.94
FEV1/FVC
79
FEF25-75%
4.31
PEF
8.95
Lung Volumes
TLC
RV
RV/TLC
FRC PL
ERV
VC
Resistance
Raw
sRaw
Diffusion
DLCO
DLCO /VA
VA
Date: 22/03/01
Height(cm): 171
Temp: 25
Pre
Meas
5.48
3.45
(63)
3.26
(3.83)
Pre Post
% Ref Meas
111
88
Gender : Male
BMI: 28.04
Post
% Ref
Age: 30
Post
% Chg
76
(43)
Comments: All tests were done well with good patient effort and technique and results were acceptable and
reproducible.
Interpretation: Spirometry suggests obstructive pattern but flow loop consistent with fixed extrathoracic
obstruction. Lung volumes and gas transfer preserved, making bleomycin lung disease unlikely. Does this
subject have tracheal narrowing or an enlargedthyroid?.
Reversibility
How?
– Off inhalers
– Spiro
– Inhaled bronchodilator
– Check spiro again
Data
– Absolute and %predicted pre&post FEV1 &
FVC
Interpretation
Definition of significant response
– FEV1 inc. by 15% AND 200ml
– FEV1 or FVC inc. by 12% AND 200ml
What does reversibility mean?
– Reversible airflow obstruction
– Asthma
– COPD with reversibility
– COPD + asthma
Bronchodilator Response PFT
ID: AKC1991
Weight(kg): 96.0
PB: 745
Temp:
Pre
Spirometry Ref
FVC
5.71
FEV1
4.27
FEV1/FVC 74.0
FEF25-75% 4.19
PEF
10.27
Lung Volumes
TLC
RV
RV/TLC
FRC PL
ERV
VC
Resistance
Raw
sRaw
Diffusion
DLCO
DLCO /VA
VA
Date: 21/06/04
Height(cm): 189
21
Pre
Meas
6.05
3.74
62.0
(1.99)
10.19
Post
% Ref
106
88
(47)
99
Post
Meas
6.31
4.27
68
2.66
9.4
Gender: Male
BMI: 26.87
Post
% Ref
110
100
% Chg
4
14
63
91
33
-8
Age: 40
Comments: Acceptable and repeatable results obtained. Ventolin (2.5gm) was administered for bronchodilator
testing.
Interpretation:
Bronchodilator Response PFT
ID: AQA1519
Weight(kg): 47.0
PB: 734
Temp: 22
Spirometry Ref
FVC
2.54
FEV1
1.83
FEV1/FVC 73.0
FEF25-75%
2.26
PEF
5.15
Lung Volumes
TLC
RV
RV/TLC
FRC PL
ERV
VC
Resistance
Raw
sRaw
Diffusion
DLCO
DLCO /VA
VA
Date: 16/08/04
Height(cm): 153
Pre
Meas
1.83
(0.76)
(41.0)
(0.25)
2.36
Pre
% Ref
72
(41)
(11)
46
Post
Meas
2.66
1.17
(44.0)
(0.35)
3.64
Gender Female :
BMI: 20.08
Post
% Ref
105
64
Post
% Chg
45
54
(15.0)
71
41
54
Age: 63
Comments: Acceptable and repeatable results obtained. 2.5 mg of Ventolin was administered for 2 mins for
bronchodilator testing.
Interpretation: Clinical details provided: COPD, ex smoker ? reversibility. Spirometric lung volumes are
indicative of a very significant degree of airflow limitation with more profound flow limitation at mid and low lung
volumes. There is however a clinically important bronchodilator response.
Bronchial challenge testing Often used for asthma diagnosis
How?
– Off inhalers
– Check spirometry
– Inhale a bronchoprovocator (histamine,
methacholine, saline) at inc. concentrations
– measure spirometry after each inhalation
N.B. exercise as a bronchoprovocator
Bronchial challenge testing Data
PD20 = ‘Provocative Dose’ required to
produce a 20% drop in FEV1
– Histamine + if <4micromol
PC20 = ‘Provocative Concentration’
required to produce a 20% drop in FEV1
– Histamine + if <8mg/ml
PC20/PD20 also used for Methacholine
Hypertonic saline
Histamine Dose Response
ID: NDZ2751
Weight(kg): 81.5
PB: 7510
Histamine
Response
FVC
FEV1
FEV1/FVC
FEF25-75%
PEF
Pre
Meas
6.48
4.82
74
3.86
9.88
Date: 16/12/03
Height(cm): 182
Temp: 23
1
%
-3
-6
2
%
-2
-8
-9
-11
-16
-15
Gender: Male
BMI: 24.60
3
%
4
%
-4
-14
-31
-19
Age : 31
5
%
6
%
-14
-29
-45
-31
7
%
8
%
9
%
Post
Meas
6.30
5.02
80
4.62
10.03
Post
%
-3
2
20
1
Comments: Acceptable and repeatable results obtained. Histamine baseline Spirometry trials 5,6,7. Histamine
test was positive with PD20 =0.419. Ventolin (2.5 mg) was administered to release bronchoconstriction caused
during bronchoprovocation challenge.
Interpretation: Baseline spirometry, static lung volumes and transfer factor are within normal limits. Bronchial
challenge testing shows bronchoconstriction/airways hypersensitivity which is consistent with asthma in the
appropriate clinical context.
Bronchial challenge interpretation
Threshold for positive may vary centre to
centre
Indicates ‘Bronchial hyperresponsiveness’
Negative test virtually excludes asthma
False positives post-infection
Static lung volumes
Why?
– Measure residual volume (and therefore TLC)
How?
– Measure the FRC
– Plethysmography or Gas dilution
– Plethysmography (bodybox) preferred
measures poorly ventilated airspaces
2 types - volume-displacement & volume-constant
Lung volumes
Volume-constant body plethysmograph
Lung volumes - interpretation
True restriction - reduced TLC
Hyperinflation - high TLC
– Gas trapping - High RV, RV/TLC ratio
Neuromuscular disease -  TLC,
preserved or raised RV
COPD PFT
ID: BDD9943
Weight(kg): 65.0
PB: 754
Spirometry Ref
FVC
4.2
FEV1
3.1
FEV1/FVC
73.0
FEF25-75%
3.1
PEF
7.8
Lung Volumes
TLC
5.8
RV
2.0
RV/TLC
36.0
FRC PL
3.4
ERV
1.4
VC
4.2
Resistance
Raw
1.4
sRaw
4.6
Diffusion
DLCO
20.6
DLCO /VA
4.0
VA
6.3
Date: 23/06/04
Height(cm): 168
Temp: 21
Pre
Meas
(2.0)
(.8)
(37.0)
(.3)
(2.6)
Pre Post
% Ref Meas
(48.0)
(25.0)
(9.3)
(7.0)
(75.0)
(7.1)
(.3)
(2.4)
(162.0)
(346.0)
7.0
56.6
518.0
1243.0
14.7
3.1
(4.8)
71.0
78.0
(75.0)
Gender: Male
Race:
Post
% Ref
Age: 55
BMI: 23.03
Post
% Chg
(10.0)
(33.0)
(211.0)
(19.0)
(57.0)
Comments: The patient could not fully expire during forced and slow expiration, therefore the results were not
quite accurate, even though they were repeatable.
Interpretation: Stable lung function.
True or False
Transfer factor is a specific measure of
gas transfer at the alveolo-capillary
membrane
Transfer factor
Gas exchange by the lung depends on:
1. Ventilation of the airways and some air spaces by
bulk flow of gas;
2. Mixing and diffusion of gases in the alveolar ducts,
air sacs and alveoli;
3. Transfer of gases across the gaseous to liquid
interface of the alveolar membrane;
4. Mixing and diffusion in the lung parenchyma and
alveolar capillary plasma;
5. Chemical reaction with constituents of blood;
6. Circulation of blood between the pulmonary and
systemic vascular beds.
Transfer factor – How?
Inhale to TLC a gas mix containing known
concentrations of CO & He
Hold breath 10 sec
Exhale
– Discard dead space
– Collect ‘alveolar’ gas
Use He dilution to calculate VA & starting
Alveolar CO
DLCO – Data generated
Then DLCO is calculated from the
difference between ‘starting’ CO conc.,
and CO conc. after 10 sec in contact with
alveoli
Expressed in ml/mmHg/min
VA = TLC by single breath helium dilution
DLCO/VA = transfer coefficient (KCO)
DLCO - interpretation
DLCO ↓ by:
– Pulmonary vascular diseases
– Conditions affecting alveoli
– Cardiac diseases
– Anaemia
– Pregnancy
– Recent smoking
DLCO - interpretation
DLCO ↑ by
– Polycythaemia
– Pulmonary haemorrhage
– L to R shunt
– Exercise
KCO (DLCO/VA)
– Corrected for volume. Theoretical function of
the individual alveolus (??)
COPD PFT
ID: BDD9943
Weight(kg): 65.0
PB: 754
Spirometry Ref
FVC
4.2
FEV1
3.1
FEV1/FVC
73.0
FEF25-75%
3.1
PEF
7.8
Lung Volumes
TLC
5.8
RV
2.0
RV/TLC
36.0
FRC PL
3.4
ERV
1.4
VC
4.2
Resistance
Raw
1.4
sRaw
4.6
Diffusion
DLCO
20.6
DLCO /VA
4.0
VA
6.3
Date: 23/06/04
Height(cm): 168
Temp: 21
Pre
Meas
(2.0)
(.8)
(37.0)
(.3)
(2.6)
Pre Post
% Ref Meas
(48.0)
(25.0)
(9.3)
(7.0)
(75.0)
(7.1)
(.3)
(2.4)
(162.0)
(346.0)
7.0
56.6
518.0
1243.0
14.7
3.1
(4.8)
71.0
78.0
(75.0)
Gender: Male
Race:
Post
% Ref
Age: 55
BMI: 23.03
Post
% Chg
(10.0)
(33.0)
(211.0)
(19.0)
(57.0)
Comments: The patient could not fully expire during forced and slow expiration, therefore the results were not
quite accurate, even though they were repeatable.
Interpretation: Stable lung function.
Sclerorderma PFT
ID: ALE6999
Weight(kg): 81.0
PB: 767
Spirometry Ref
FVC
3.34
FEV1
2.46
FEV1/FVC 73.0
FEF25-75% 2.68
PEF
6.02
Lung Volumes
TLC
5.47
RV
2.11
RV/TLC
38.0
FRC PL
2.90
ERV
1.12
VC
3.34
Resistance
Raw
1.31
sRaw
3.80
Diffusion
DLCO
23.3
DLCO /VA
3.82
VA
Date:11/05/04
Height(cm): 169
Temp: 23
Pre
Meas
2.89
2.21
76.0
1.87
4.75
Pre Post
% Ref Meas
87
90
5.63
2.58
46.0
2.79
(0.31)
3.05
103
122
2.09
7.46
159
196
Gender: Female
BMI: 28.36
Post
% Ref
70
79
96
(27)
91
(9.80) (42.00)
2.1
55
4.66
Comments: Acceptable and repeatable results obtained.
Interpretation: No significant change since Nov 2001.
Post
% Chg
Age: 63
59 yo female smoker,
BMI = 24
Other patterns
Obesity
– Restrictive Spirometry and TLC, very reduced FRC,
reduced RV. DLCO only reduced in very gross obesity
Heart Failure
– Obstructive in Acute, Restrictive in Chronic with
decreased gas transfer
Neuromuscular
– Decreased FVC, lower when supine, decreased TLC,
preserved RV, preserved DLCO
Other tests to be aware of
Airways resistance (RAW) and conductance
– In the plethysmograph
Impulse oscillometry
Effort independent
Can identify site of obstruction
Maximal Inspiratory and Expiratory pressures
– Mouth pressures
– Musculoskeletal disorders
Q1
Which of the following spirometric parameters
is thought to represent the least effortdependent part of the expiratory flow volume
loop
a.
b.
c.
d.
e.
Peak expiratory flow (PEFR)
Forced Vital capacity
Forced expiratory volume in one second (FEV1)
FEV1/FVC ratio
Mid expiratory flow (FEF25-75%), aka Forced
expiratory flow between 25% and 75% of FVC
Q2
Preoperative lung function testing in a 55 year old man
with COPD shows a Forced Vital Capacity (FVC) of
2.0L (48% of predicted), and a Total Lung capacity
(TLC, measured by body plethysmography) of 9.3 L
(162%). Three months following lung volume reduction
surgery, what pattern of change can be expected in
these parameters?
a.
b.
c.
d.
e.
No change
FVC and TLC are both increased
FVC and TLC are both decreased
FVC is increased and TLC is decreased
FVC is decreased and TLC is increased
Q3
(2003) A 66-year-old man presents with progressive exertional dyspnoea.
His anthropometric indices are:
Hieght
175 cm
Weight
98 kg
Body Mass Index (BMI)
32 kg/m2
[18-25]
His lung function test results are:
Forced expiratory volume in one second (FEV1)
Forced vital capacity (FVC)
FEV1/FVC
Total Lung Capacity (TLC)
Residual Volume (RV)
Diffusing capacity for carbon monoxide
Corrected for volume (KCO)
1.72L
2.14L
80%
4.12 L
1.98L
(56% predicted)
(54% predicted)
(64% predicted)
(84% predicted)
4.9 ml/min/mmHg/L
(110% predicted)
Q3 contd
What is the most likely cause of this man’s
dyspnoea and lung function
abnormalities?
a. Obesity
b. Pulmonary fibrosis
c. Chronic obstructive pulmonary disease
d. Cardiac failure
e. Bilateral diaphragm paralysis
Q4
Disproportionately preserved peak
expiratory flow in Pulmonary fibrosis is
due to which of the following
mechanisms
a.
b.
c.
d.
e.
Increased pulmonary elastic recoil
Decreased pulmonary elastic recoil
Increased airways resistance
Decreased airways resistance
Impaired gas exchange
Q5
Which of the following apparatus used
for flow-volume spirometry does not
extrapolate volume from flow?
a.
b.
c.
d.
Vane anemometer
Hot wire anemometer
Pneumotachnograph
Water seal spirometer
Q6
This flow-volume loop was produced by a patient with
a history of Wegener’s Granulomatosis.
Q6 contd
The most likely cause of the abnormality is
a. Cyclophosphamide therapy
b. Asthma
c. Pulmonary fibrosis
d. Extrathoracic tracheal stenosis
e. Intrathoracic tracheal stenosis
END