Pulmonary Function Test

1. What exactly are PFTs?
•The term encompasses a wide variety of objective
methods to assess lung function. (Remember that the
primary function is gas exchange).
•Examples include:
–Spirometry
–Pulse oximetry
–Blood gases
–Lung volumes by helium dilution or body plethysmography
–Exercise tests
–Diffusing capacity
–Bronchial challenge testing

2. Spirometry
•Measurement of the pattern of air
movement into and out of the lungs during
controlled ventilatory maneuvers.
•Often done as a maximal expiratory
maneuver

3. Importance
•Patients and physicians have inaccurate
perceptions of severity of airflow
obstruction and/or severity of lung disease
by physical exam
•Provides objective evidence in identifying
patterns of disease

4. Silhouette of Hutchinson
Performing Spirometry
From
Chest,
2002

5. Indications
•Detect disease
•Evaluate extent and monitor course of
disease
•Evaluate treatment
•Measure effects of exposures
•Assess risk for surgical procedures

6. contraindications
•Chest or abdominal pain of any cause
•Oral or facial pain exacerbated by
mouthpiece
•Stress incontinence
•Dementia or confused state
•Within one month of Myocardial Infarction

7. To be avoided
•Smoking- 1 hour
•Alcohol- 4 hour
•Vigorous exercise -30 minutes
•Large meal – 2 hour
•Wearing tight clothes

8. •Tests should be performed when patients are
clinically stable and free from respiratory infection
• Patients should not have taken:
inhaled short-acting bronchodilators in the
previous six hours
long-acting bronchodilator in the previous 12
hours
sustained-release theophylline in the previous
24 hours

Preparation

9. Volume Measuring Spirometer

10. Flow Measuring Spirometer

11. Desktop Electronic Spirometers

12. Small Hand-held Spirometers

13. Weibel ER: Morphometry of the Human
Lung. Berlin and New York: Springer-
Verlag, 1963
The Airways
•Conducting zone: no
gas exchange occurs
–Anatomic dead
space
•Transitional zone:
alveoli appear, but are
not great in number
•Respiratory zone:
contain the alveolar
sacs

14. From
Netter
Atlas of
Human
Anatomy,
1989

15. Lung Volumes
IRV
TV
ERV
•4 Volumes
•4 Capacities
–Sum of 2 or
more lung
volumes
RV
IC
FRC
VC
TLC
RV

16. Tidal Volume (TV)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
•Volume of air
inspired and
expired during
normal quiet
breathing

17. Inspiratory Reserve Volume (IRV)
IRV
TV
ERV
•The maximum
amount of air
that can be
inhaled after a
normal tidal
volume
inspiration
RV
IC
FRC
VC
TLC
RV

18. Expiratory Reserve Volume (ERV)
IRV
TV
ERV
•Maximum
amount of air
that can be
exhaled from
the resting
expiratory level
RV
IC
FRC
VC
TLC
RV

19. Residual Volume (RV)
IRV
TV
ERV
•Volume of air
remaining in the
lungs at the end
of maximum
expiration
RV
IC
FRC
VC
TLC
RV

20. Vital Capacity (VC)
IRV
TV
ERV
•Volume of air that
can be exhaled
from the lungs
after a maximum
inspiration
•FVC: when VC
exhaled forcefully
•SVC: when VC is
exhaled slowly
•VC = IRV + TV +
ERV
RV
IC
FRC
VC
TLC
RV

21. Predicted Normal Values
 Age
 Height
 Sex
 Ethnic Origin
Affected by:

22. Terminology
•Forced vital capacity
(FVC):
–Total volume of air that can
be exhaled forcefully from
TLC
–The majority of FVC can be
exhaled in <3 seconds in
normal people, but often is
much more prolonged in
obstructive diseases
–Measured in liters (L)

23. FVC
•Interpretation of % predicted:
–80-120% Normal
–70-79% Mild reduction
–50%-69% Moderate reduction
–<50% Severe reduction
FVC

24. Terminology
•Forced expiratory volume
in 1 second: (FEV
1
)
–Volume of air forcefully
expired from full inflation
(TLC) in the first second
–Measured in liters (L)
–Normal people can exhale
more than 75-80% of their
FVC in the first second;
thus the FEV1/FVC can be
utilized to characterize
lung disease

25. FEV
1
•Interpretation of % predicted:
–>75% Normal
–60%-75% Mild obstruction
–50-59% Moderate obstruction
–<49% Severe obstruction
FEV
1
FVC

26. Terminology
•Forced expiratory flow 25-
75% (FEF
25-75
)
–Mean forced expiratory flow
during middle half of FVC
–Measured in L/sec
–May reflect effort
independent expiration and
the status of the small
airways
–Highly variable
–Depends heavily on FVC

27. FEF
25-75
•Interpretation of % predicted:
–>60% Normal
–40-60% Mild obstruction
–20-40% Moderate obstruction
–<10% Severe obstruction

28. Standard Spirometric Indicies
•FEV
1
- Forced expiratory volume in one second:
The volume of air expired in the first second of
the blow
•FVC - Forced vital capacity:
The total volume of air that can be forcibly
exhaled in one breath
•FEV
1/FVC ratio:
The fraction of air exhaled in the first second
relative to the total volume exhaled

29. Criteria for Normal
Post-bronchodilator Spirometry
•FEV
1
: % predicted > 80%
•FVC: % predicted > 80%
•FEV
1
/FVC: > 0.7

30. Spirometry Interpretation:
Obstructive vs. Restrictive
Defect
•Obstructive Disorders
–FVC nl or↓
–FEV1 ↓
–FEF25-75% ↓
–FEV1/FVC ↓
–TLC nl or ↑
•Restrictive Disorders
–FVC ↓
–FEV1 ↓
–FEF 25-75% nl to ↓
– FEV1/FVC N↑
– TLC ↓

31. SPIROMETRY
Flow Volume

32. Flow Volume Curve
•Standard on most desk-top spirometers
•Adds more information than volume
time curve
•Less understood but not too difficult to
interpret
•Better at demonstrating mild airflow
obstruction

33. Flow Volume Curve
Expiratory
flow rate
L/sec
Volume (L)
FVC
Maximum
expiratory flow
(PEF)
Inspiratory
flow rate
L/sec
RV
TLC

34. Flow-Volume Loop
•Illustrates maximum
expiratory and
inspiratory flow-
volume curves
•Useful to help
characterize disease
states (e.g.
obstructive vs.
restrictive)
Ruppel GL. Manual of Pulmonary Function Testing, 8
th

ed., Mosby 2003

35. Normal Trace Showing FEV
1
and
FVC
1 2 3 4 5 6
1
2
3
4
V
o
lu
m
e
, lite
r
s
Time, seconds
FVC5
1
FEV
1
= 4L
FVC = 5L
FEV
1
/FVC = 0.8

36. Three times FVC within 5% or 0.1 litre (100 ml)
Reproducibility - Quality of Results
V
o
l
u
m
e
,
l
i
t
e
r
s
Time, seconds

37. Spirogram Patterns
•Normal
•Obstructive
•Restrictive
•Mixed Obstructive and Restrictive

38. SPIROMETRY
OBSTRUCTIVE
DISEASE

39. Spirometry: Obstructive Disease
V
o
lu
m
e
, lite
r
s
Time, seconds
5
4
3
2
1
123456
FEV
1
= 1.8L
FVC = 3.2L
FEV
1
/FVC = 0.56
Normal
Obstructive

40. Flow Volume Curve Patterns
Obstructive and Restrictive
Obstructive Severe obstructive Restrictive
Volume (L)


E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e
E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e

E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e
Volume (L) Volume (L)
Steeple pattern,
reduced peak flow,
rapid fall off
Normal shape,
normal peak flow,
reduced volume
Reduced peak flow,
scooped out mid-
curve

41. Bronchodilator Reversibility Testing
•Provides the best achievable FEV
1

(and FVC)
•Helps to differentiate COPD from
asthma
Must be interpreted with clinical
history - neither asthma nor COPD
are diagnosed on spirometry alone

42. Bronchodilator Reversibility
Testing in COPD
Spirometry
•FEV
1
should be measured (minimum twice,
within 5%) before a bronchodilator is given
•The bronchodilator should be given by
metered dose inhaler through a spacer device
or by nebulizer to be certain it has been
inhaled
•The bronchodilator dose should be selected to
be high on the dose/response curve

43. Bronchodilator Reversibility Testing
in COPD
•An increase in FEV
1
that is both greater
than 200 ml and 12% above the pre-
bronchodilator FEV
1
(baseline value) is
considered significant
•It is usually helpful to report the absolute
change (in ml) as well as the % change from
baseline to set the improvement in a clinical
context

44. Figure 5.1-6.
Bronchodilator
Reversibility
Testing in COPD
GOLD
Report (2006)

46. SPIROMETRY
RESTRICTIVE
DISEASE

47. V
o
lu
m
e
, lite
r
s
Time, seconds
FEV
1
= 1.9L
FVC = 2.0L
FEV
1
/FVC = 0.95
123456
5
4
3
2
1
Spirometry: Restrictive Disease
Normal
Restrictive

48. Flow Volume Curve Patterns
Obstructive and Restrictive
Obstructive Severe obstructive Restrictive
Volume (L)


E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e
E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e

E
x
p
i
r
a
t
o
r
y

f
l
o
w

r
a
t
e
Volume (L) Volume (L)
Steeple pattern,
reduced peak flow,
rapid fall off
Normal shape,
normal peak flow,
reduced volume
Reduced peak flow,
scooped out mid-
curve

49. Mixed Obstructive and Restrictive
V
o
lu
m
e
, lite
r
s
Time, seconds
Restrictive and mixed obstructive-restrictive are difficult to diagnose by
spirometry alone; full respiratory function tests are usually required
(e.g., body plethysmography, etc)
FEV
1
= 0.5L
FVC = 1.5L
FEV
1
/FVC = 0.30
Normal
Obstructive - Restrictive

50. Spirometry - Quality Control
•Most common cause of inconsistent
readings is poor patient technique
 Sub-optimal inspiration
 Sub-maximal expiratory effort
 Delay in forced expiration
 Shortened expiratory time
 Air leak around the mouthpiece
•Subjects must be observed and
encouraged throughout the procedure

51. Troubleshooting
Examples - Unacceptable Traces

52. Unacceptable Trace - Poor Effort
V
o
l
u
m
e
,

l
i
t
e
r
s
Time, seconds
May be accompanied by a slow start
Inadequate sustaining of effort
Variable expiratory effort
Normal

53. V
o
l
u
m
e
,

l
i
t
e
r
s
Time, seconds
Unacceptable Trace – Stop Early
Normal

54. V
o
l
u
m
e
,

l
i
t
e
r
s
Time, seconds
Unacceptable Trace – Slow Start
Normal

55. V
o
l
u
m
e
,

l
i
t
e
r
s
Time, seconds
Unacceptable Trace - Coughing
Normal

56. V
o
l
u
m
e
,
l
i
t
e
r
s
Time, seconds
Unacceptable Trace – Extra Breath
Normal

57. EXAMPLE 1
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 4.0 L 3.2 3.2
FVC%(O/P) 80% 80%
FEV1 3.7L 2.9 2.9 +0%- 0ml
FEV1%(O/P) 78% 78%
FEV1/FVC% 90% 90%
PEF 3.51L/S 4.22L/S

58. EXAMPLE -2
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 2.8L 0.6
FVC%(O/P) 22%
FEV1 2.75L 0.5
FEV1%(O/P) 18.18%
FEV1/FVC% 84%
PEF 5.3L/S 1.6

59. EXAMPLE 2 cont
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 2.8L 0.6 1.6L
FVC%(O/P) 22% 57%
FEV1 2.75L 0.5 1.0L +100%-500ml
FEV1%(O/P) 18.18% 36.3%
FEV1/FVC% 84% 63%
PEF 5.3L/S 1.6 4.8

60. EXAMPLE 3
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 2.60L 1.60 1.63
FVC%(O/P) 62% 63%
FEV1 2.17L 1.32 1.34 1.5%-20ml
FEV1%(O/P) 61% 62%
FEV1/FVC% 83% 82%
PEF 5.85L/S 5.34 4.56

61. EXAMPLE 4
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 2.3L 1.8 1.8
FVC%(O/P) 78% 78%
FEV1 1.95L 0.75 0.75 +0-0ml
FEV1%(O/P) 38% 38%
FEV1/FVC% 41% 41%
PEF 3.10L/s 1.30L/S 1.34L/S

62. EXAMPLE 5
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 3.22L 1.69 1.82
FVC%(O/P) 52% 56%
FEV1 2.50L 1.15 1.19 +3%
FEV1%(O/P) 46% 48%
FEV1/FVC% 68% 66%
PEF 7.17L/S 4.48 4.41

63. EXAMPLE 6
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 2.75L 1.1 1.5
FVC%(O/P) 40% 54%
FEV1 2L 0.9 1.0 +11%-100ml
FEV1%(O/P) 31% 46%
FEV1/FVC% 81% 66%
PEF 3.7L/s 1.00L/s 3.20L/s

64. EXAMPLE 7
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 3.2L 1.54 2.3
FVC%(O/P) 48% 71%
FEV1 2.75L 0.95 1.94 +104%-
990ml
FEV1%(O/P) 34.5% 72%
FEV1/FVC% 61% 69%
PEF 4.50L/s 3L/s 3.70L/s

65. EXAMPLE 8
TEST PREDICTE
D
BROCHODILATOR CHANGE
BEFORE AFTER
FVC 3.2 L 2.55 2.75
FVC%(O/P) 79% 86%
FEV1 2.75L 1.95 2.3 +18%-
350ml
FEV1%(O/P) 70% 84%
FEV1/FVC% 76% 83%
PEF 4.5L/s 4.00L/s 4.40L/s

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