This document discusses spirometry testing for obstructive lung diseases such as COPD and asthma. It provides information on the different measures assessed during spirometry including FEV1, FVC, and FEF25-75. It describes how to interpret the results and what values indicate restrictive versus obstructive lung disease. Guidelines for pre- and post-bronchodilator spirometry are covered as well as how to assess for reversibility and bronchial hyperresponsiveness. The importance of spirometry for diagnosing and monitoring lung diseases like COPD and asthma is emphasized.

2. Spirometry of Obstructive
Lung Diseases
Gamal Rabie Agmy, MD, FCCP
Professor of Chest Diseases, Assiut University

3. Pulmonary Disorders Effects on
Pulmonary Function
Obstructive:
Any process that interferes with air flow either
into or out of the lungs.
Large or small airways.
Restrictive:
 Any process that interferes with the bellows
action of the lungs or chest wall.
 Reduced lung volumes.

4. Differential Diagnosis:
COPD and Asthma
COPD
Onset In mid-life
Symptoms slowly
progressive
Long smoking history
Dyspnea during exercise
Largely Irreversible
airflow limitation
Asthma
Onset early in life (often
childhood)
Symptoms vary from day to day
Symptoms at night/early
morning
Allergy, rhinitis, and/or eczema
also present
Family history of asthma
Largely reversible airflow
limitation

5. Inflammatory Cascade in
COPD & Asthma

6. Measures of Assessment and
Monitoring of Asthma
Asthma diagnosis criteria:
Repeated variability in well-performed
spirometic values (increase in FEV1 or FVC).
Positive bronchodilator (BD) responses
(increase in FEV1 or FVC ⩾12% and 200 mL
from baseline).
Positive methacholine challenge (20% fall in
FEV1 at a dose ⩽8 μg/mL).

7. Objective lung function
measurements in Asthma
Spirometry:
▫ Forced Expiratory Maneuvers.
Exhaled Nitric Oxide.
Peak Flows.

8. GOLD 2013: Diagnosis of COPD

Key Indicators to Consider COPD Diagnosis:
• SYMPTOMS
1
• Dyspnea-progressive (worsens over time and with exercise)
• Chronic cough
• Sputum
• HISTORY OF EXPOSURE TO RISK
FACTORS
2
3
• Tobacco smoke
• Smoke from home cooking/heating fuels
• Occupational dusts and chemical
• FAMILY HISTORY OF COPD
SPIROMETRY REQUIRED TO DIAGNOSE COPD
Presence of a post-bronchodilator FEV1/FVC < 0.70 confirms the presence of persistent airflow
limitation and thus of COPD.
Adapted from GOLD 2013

9. Simple Interpretation of
Pulmonary Function Tests
Gamal Rabie Agmy, MD, FCCP
Professor of Chest Diseases, Assiut University

11. Anatomy

Lungs comprised of


Airways
Alveoli
http://www.aduk.org.uk/gfx/lungs.jpg

12. The Airways



Weibel ER: Morphometry of the Human
Lung. Berlin and New York: SpringerVerlag, 1963
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

13. The Alveoli



Murray & Nadel: Textbook of Respiratory
Medicine, 3rd ed., Copyright © 2000 W. B.
Saunders Company
Approximately 300
million alveoli
1/3 mm diameter
Total surface area if
they were complete
spheres 80 sq.
meters (size of a
tennis court)

14. Mechanics of Breathing

Inspiration


Active process
Expiration
Quiet breathing: passive
 Can become active


15. Pulmonary Function Tests

Airway function





Simple spirometry
Forced vital capacity
maneuver
Maximal voluntary
ventilation
Maximal
inspiratory/expiratory
pressures
Airway resistance

Lung volumes and
ventilation




Functional residual
capacity
Total lung capacity,
residual volume
Minute ventilation,
alveolar ventilation,
dead space
Distribution of
ventilation

16. Pulmonary Function Tests


Diffusing capacity
tests
Blood gases and gas
exchange tests





Blood gas analysis
Pulse oximetry
Capnography
Cardiopulmonary
exercise tests
Metabolic
measurements



Resting energy
expenditure
Substrate utilization
Chemical analysis of
exhaled breath

17. 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)

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

19. Terminology

Forced expiratory volume
in 1 second: (FEV1)



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

20. FEV1

Interpretation of % predicted:





>75%
Normal
Mild
70-75%
Mod
50-69 %
Severe
35-49%
Very severe < 35%
FEV1
FVC

21. Terminology

Forced expiratory flow 2575% (FEF25-75)





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

22. FEF25-75

Interpretation of % predicted:
>60%
 40-60%
 20-40%
 <20%

Normal
Mild obstruction
Moderate obstruction
Severe obstruction

23. Acceptability Criteria
Good start of test
 No coughing
 No variable flow
 No early termination
 Reproducibility


24. Changes in Lung Volumes in
Various Disease States
Ruppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003

25. TLC
TLC < 80% of predicted value = restriction.
 TLC > 120% of predicted value =
hyperinflation.


26. Lung Volumes

27. Spirometry
Spirometry should be performed after the
administration of an adequate dose of a short
acting inhaled bronchodilator (e.g. 400 ᶙg
salbutamol) to minimize variability.
A post-bronchodilator FEV 1/FVC <0.70
confirms the presence of airflow limitation that
is not fully reversible.
Where possible, values should be compared to
age-related normal values to avoid overdiagnosis of COPD In the elderly.

28. Why Do We Need Spirometry
in COPD?
Spirometry is useful for:
Screen individuals at risk for pulmonary
disease.
Confirmation of COPD diagnosis.
Assessing severity of pulmonary dysfunction.
Guiding selection of treatment.
Assessing the effects of therapeutic
interventions.

29. Who Should Be Screened for
COPD?
Consider COPD, and perform spirometry, if any of these
indicators are present in an individual over age 40.
▫ Dyspnea that is progressive, usually worse with
exercise, and persistent.
▫ Chronic cough (may be intermittent and
unproductive).
▫ Chronic sputum.
▫ History of tobacco smoke exposure.
▫ Exposure to occupational dusts and chemicals.
▫ Risk factors.
▫ Exposure to smoke from home cooking and
heating fuels.

30. Spirometry Origin
Most basic of Pulmonary Function Tests
Clinical Tools Origin - Mid 1800' s
▫ John Hutchinson.
▫ Water-sealed spirometry to measure vital capacity
(VC).

31. Reasons for Performing
Spirometry
Diagnostic Purposes.
Monitoring Lung Disease.
Assessing Disability.

32. Spirometry
Spirometry with flow volume loops assesses the
mechanical properties of the respiratory system
by measuring expiratory volumes and flow rates.
▫ Maximal inspiratory and expiratory effort.
▫ At least 3 tests of acceptable effort are performed
to ensure reproducibility.

33. 21st Century Spirometry
Measurements of:
Forced Vital Capacity (FVC).
Forced Expiratory Volume in one second
(FEV1).
Forced Expiratory Volume in six seconds
(FEV6).
Forced Expiratory Flow over various Intervals
(FEFx).
Peak Expiratory Flow (PEF).

34. Definitions and Terms
FEV1 - forced expiratory volume 1 - the volume of
air that is forcefully exhaled in one second.
FEV6 - forced expiratory volume 6 - the volume of
air that Is forcefully exhaled in six seconds.
FVC- forced vital capacity- the volume of air that
can be maximally forcefully exhaled.
FEV1/FVC- ratio of FEV1 to FVC, expressed as a
percentage.

35. Definitions and Terms
FEV/FVC- ratio of FEV6 to FVC, expressed as a
percentage.
FEF25 -75 - forced expiratory flow - the average
forced expiratory flow during the mid (25 - 75%) portion
of the FVC.
PEF- peak expiratory flow rate - the peak flow rate
during expiration.

36. Spirometry
Flow volume loops provide a graphic illustration
of a patient's spirometric efforts.
Flow is plotted against volume to display a
continuous loop from inspiration to expiration.
The volume versus time curve is a an alternative
way of plotting spirometric results.
The overall shape of the flow volume loop is
important in Interpreting spirometric results.

37. Acceptability & Repeatability

38. Acceptability
At least three (3) acceptable maneuvers
Good start to the test.
No hesitation or coughing for the 1st second.
FVC lasts at least 6 seconds with a plateau of at
least 1 second.
No valsalva maneuver or obstruction of the
mouthpiece.
FIVC shows apparent maximal effort.

39. Repeatability
Repeatability criteria act as guideline to
determine need for additional efforts.
▫ Largest and 2nd largest FVC must be within 150
mL.
▫ Largest and 2nd largest FEV 1 must be 150 mL.
▫ PEF values may be variable (within 15%).
If three acceptable reproducible maneuvers are
not recorded, up to B attempts may be recorded.

40. Spirometry Value
Spirometry is typically reported in both absolute
values and as a predicted percentage of normal.
Normal values vary and are dependent on:
▫
▫
▫
▫
Gender,
Race,
Age, and
Height.

41. Reporting Standards
Largest FVC obtained from all acceptable efforts
should be reported.
Largest FEV1 obtained from all acceptable trials
should be reported.
May or may not come from largest FVC effort.
All other flows, should come from the effort with
the largest sum of FEV 1 & FVC.
PEF should be the largest value obtained from
at least 3 acceptable maneuvers.

42. Results Reporting
Example

43. Report Format
Report should also include:
▫
▫
▫
▫
▫
▫
Age on testing day.
Height (standing without shoes).
Weight (without shoes).
Gender.
Race or ethnic origin.
Technologist comment section.

44. FEV1 Results for Asthma

45. FEV 1 Severity Results for Asthma

46. At Risk for COPD
Spirometric classification of airflow limitation (in
patients with FEV1/FVC<0.70).
▫
▫
▫
▫
GOLD 1
GOLD 2
GOLD 3
GOLD 4
Adapted from GOLD 2013
(Mild; FEV1 ≥80% predicted).
(Moderate; 50% ≤FEV1 <80% predicted).
(Severe; 30% ≤FEV1 <50% predicted).
(Very severe; FEV1 <30% predicted).

47. Pre & Post Bronchodilator
Studies
B-Adrenergic aerosols are most common form
for testing.
Standardize.
▫ Drug.
▫ Dosage.
▫ Delivery Device.
Minimum of 15 minutes between pre and post
tests.

48. Pre & Post Bronchodilator
Studies: Withholding Medications

49. Pre & Post Bronchodilator
Studies: Interpretations
Determined based on improvement of FEV1.
Commonly expressed as Percent Change.
% Change = Post FEV 1 - Pre FEV1 x 100
Pre FEV1

50. Reversibility
Reversibility of airways obstruction can be
assessed with the use of bronchodilators.
> 12% increase in the FEV1 and 200 ml
improvement in FEV1
OR
> 12% increase in the FVC and 200 ml
improvement in FVC.

51. Spirometry

52. Asthma Challenge Testing
Spirometry can be used to detect the bronchial
hyperreactivity that characterizes asthma.
Increasing concentrations of histamine or
methacholine.
Patients with asthma will demonstrate
symptoms and produce spirometric results
consistent with airways obstruction at much
lower threshold concentration than normals.

53. Bronchial Provocation for Asthma

54. Spirometry
Indications — Diagnosis
 Evaluation of signs and symptoms
- SOB, exertional dyspnea, chronic cough
 Screening at-risk populations
 Monitoring pulmonary drug toxicity
 Abnormal study
- CXR, EKG, ABG, hemoglobin
 Preoperative assessment

55. Spirometry
Indications — Diagnosis
 Evaluation of signs and symptoms
- SOB, exertional dyspnea, chronic cough
 Screening at-risk populations
Smokers > 45yo
 Monitoring pulmonary drug toxicity & current)
(former
 Abnormal study
- CXR, EKG, ABG, hemoglobin
 Preoperative assessment

56. Spirometry
Indications — Diagnosis
 Evaluation of signs and symptoms
- SOB, exertional dyspnea, chronic cough
 Screening at-risk populations
 Evaluation of occupational symptoms
 Monitoring pulmonary drug toxicity
 Abnormal study
- CXR, EKG, ABG, hemoglobin
 Preoperative assessment

57. Spirometry
Indications — Prognostic
■ Assess severity
■ Follow response to therapy
■ Determine further treatment goals
■ Referral for surgery
■ Disability

59. 1-First Step, Check quality of the
test
1- Start:
*Good start: Extrapolated volume (EV) <
5% of FVC or 0.15 L
*Poor start: Extrapolated volume (EV)
≥5% of FVC or ≥ 0.15 L
2- Termination:
*No early termination :Tex ≥ 6 s
*Early termination : Tex < 6 s

60. 2- Look at …………FEV1/FVC
< N(70%)
Obstructive or Mixed
≥ N(70%)
Restrictive or Normal
3- Look at FEV1 To detect degree
Mild > 70%
Mod 50-69 %
Severe 35-49%
Very severe < 35%

61. 4- Postbronchodilator FEV1/FVC
> 70%
asthma
< 70%
COPD

62. 5- Reversibility test of FEV1
> 12%, 200 ml
Reversible (asthma)
< 12% ,200 ml
Ireversible (COPD)
6- Look at TLC
≥ 80-120% Pure
obstruction
< 80% Mixed

63. 2- Look at …………FEV1/FVC
< N(70%)
≥ N(70%)
Obstructive or Mixed
Restrictive or Normal
3- Look at FVC
≥ N(80%)
Normal or SAWD
4-Look at FEF25/75
> 50% Normal
< 50% SAWD
< N(80%)
Restrictive

64. Patterns of Abnormality
Obstructive low FEV1 relative to FVC, low PEF, low FEV1%FVC
R eco rd ed
Pred icted
SR
% Pred
0.56
3.25
-5.3
17
1.65
4.04
-3.9
41
FEV 1 % FV C
34
78
-6.1
44
PEF
2.5
8.28
-4.8
30
FEV
1
FV C
Restriction low FEV1 & FVC, high FEV1%FVC
R eco rd ed
FEV
1
FV C
FEV 1 % FV C
PEF
Pred icted
SR
% Pred
1.49
2.52
-2.0
59
1.97
3.32
-2.2
59
76
74
0.3
103
8.42
7.19
1.0
117 high PEF early ILD
low PEF late ILD

65. Patterns of Abnormality
Upper Airway Obstruction low PEF relative to FEV1
R eco rd ed
Pred icted
SR
% Pred
2.17
2.27
-0.3
96
2.68
2.70
0.0
99
81
76
0.7
106
PEF
2.95
5.99
-3.4
49
FEV 1 /PEF
12.3
FEV
1
FV C
FEV 1 % FV C
Discordant PEF and FEV1
High PEF versus FEV1 = early interstitial lung disease (ILD)
Low PEF versus FEV1 = upper airway obstruction
Concordant PEF and FEV1
Both low in airflow obstruction, myopathy, late ILD

66. Flow
Common FVL Shapes
Volume
Normal
Hesitation
Young or quitter
Knee
Poor effort
Coughing

67. 12
Asthma
Flow in L/s
10
concave FV curve
intrapulmonary airflow obstruction
8
6
4
2
0
0
1
2
3
4
5
Litres
6

68. Restrictive
12
F 19 yrs 1.64m
FVC 2.41 L -3.42 SR
FEV 2.41 L
-2.62 SR
FEV% 100
+2.23 SR
PEF 5.55L/s -2.00 SR
F/P 7.2
RT 116 ms
10
8
Flow in L/s
6
4
2
0
0
-2
-4
-6
-8
1
2
3
4
5
Litres
6

69. COPD
10
8
pressure dependent airways collapse
6
Flow in L/s
4
2
0
0
-2
-4
-6
1
2
3
4
5
Litres

70. Poorly co-ordinated start
EV = large
Rise Time = 496 ms
Irregular shape
Poorly repeatable
12
10
8
6
Flow in L/s
4
2
0
0
-2
-4
-6
-8
-10
1
2
3
4
5
6
Litres

71. Upper Airway Obstruction
6
Expiratory
Age 40 yrs
FVC 3.52 L
FEV1 3.0
L
0.74 SR
PEF 4.57 L/s
4
0.84 SR
-2.18 SR
FEV/PEF = 10.9
Flow in L/s
2
0
0
1
2
4
5
6
Volume in Litres
-2
-4
-6
3
Inspiratory
FEV1 in mls > 8
PEF in L/min

72. Upper Airway Obstruction
12
Male aged 62 Height 1.68m
10
R e co rd e d
SR
2.23
2.94
2.1 to 3.8
-1.4
FV C
3.40
3.71
2.7 to 4.7
-0.5
66
76
64 to 88
-1.5
P EF
2.85
7.81
5.8 to 9.8
-4.1
FEV 1 /P EF
13.1
FEV 1 % FV C
6
Flow in L/s
R an ge
FEV 1
8
P re d icte d
4
2
0
0
-2
-4
-6
1
2
3 4 5 6
Volume in Litres

73. Variable UAO
Inspiration
Expiration
+ve
-ve
-ve
Extra-thoracic UAO
worse on insp.
+ve
Intra-thoracic UAO
worse on exp.

74. Intra-thoracic UAO
12
Age 65 Female
FVC
2.97 L
FEV1
2.26 L
FEV1%
76%
PEF
3.4 L·s-1
F/P
11.1
10
Flo w in L /s
8
6
4
2
0
0
-2
-4
-6
-8
1
2
3
4
5
L ite rs
6
1.3 SR
0.6 SR
-0.1 SR
-2.5 SR
RT 455 ms

75. Upper Airway Obstruction
• Variable extrathoracic obstructions
1.
2.
3.
4.
vocal cord paralysis,
thyromegaly,
tracheomalacia, or
Neoplasm
• Large airways variable intrathoracic obstructions
1.
2.
tracheomalacia or
neoplasm
• Fixed obstruction
1.
2.
tracheal stenosis,
foreign body, or
3.
neoplasm.

76. Obstruction, Restriction, Mixed

77. Variable Extrathoracic Upper
Airway Obstruction

78. Fixed Upper Airway Obstruction

79. True Restrictive Disorders
Intraparenchymal
Interstitial
Infilterative
Chest Wall
Diffuse alveolar
Pleural
Skeletal
Neuromuscular
Reduced TLC.FRC,RV,VC and normal to high FEV1/FVC
DLVA,Dlcoc or both DLVc parynhymal If normal Chest wall or neuromuscular

80. Pseudorestrictive Disorders
Normally: IC/ERV=2-3/1
True restrictive: IC/ERV=<2/1
Pseudorestrictive: IC/ERV=6/1

81. Pseudorestrictive Disorders
Asthma is a disorder characterized by increased reactivity of the
airways. Patients with asthma have recurrent or persistent airflow
obstruction, which is reversible either spontaneously or with
appropriate therapy. An obstructive pattern is most often present,
recognized by reduced forced expiratory volume in 1 s (FEV1), and
FEV1 to forced vital capacity (FEV1/FVC) or FEV1/vital capacity
(VC) ratio. Patients may have normal spirometry between attacks.
In some patients, the FVC may be reduced due to air trapping,
resulting in pseudorestriction on spirometry in the presence of
increased or normal total lung capacity (TLC), increased functional
residual capacity (FRC) and increased residual volume (RV). We
have reported 12 asthmatic patients with reduced VC and no
increase in RV, i.e., a true restrictive impairment [Gill et al. Chest
2012)

82. Pseudorestrictive Disorders
Obesity:
*Early airway closure (low ERV & high RV)
*FRC is more reduced than TLC&VC
*Low FEF50% FEF75%, FEF25-75%,
,

83. Pseudorestrictive Disorders
Neuromuscular Disease:
*FRC normal
*IC&ERV decreased
*Decreased TLC
*Increased RV
*A-aO2 gradient normal
*MIP&MEP decreased

84. Pseudorestrictive Disorders
Asthma:
*FRC &TLC increased
*Improvement of FEV1&FVC with bronchodilators
*Positive bronchoprovacation test
*Increased diffusing capacity and DLco/VA

85. Pseudopseudorestrictive
Patients with obstructive diseases who do not
complete expiratory effort of FVC. This may
lead to a below normal FEV1 and FVC with
pseudonormalization of ratio.

86. Mixed Disorder
*Sarcoidosis
*Rhematoid
*Advanced IPF
*Bronchiectasis
*BOOP in smokers

87. Obstructive Pattern
■ Decreased FEV1
■ Decreased FVC
■ Decreased FEV1/FVC
- <70% predicted
■ FEV1 used to follow severity in COPD

88. Obstructive Lung Disease —
Differential Diagnosis
 Asthma
 COPD
- chronic bronchitis
- emphysema
 Bronchiectasis
 Bronchiolitis
 Upper airway obstruction

89. Restrictive Pattern
 Decreased FEV1
 Decreased FVC
 FEV1/FVC normal or increased

90. Restrictive Lung Disease —
Differential Diagnosis
 Pleural
 Parenchymal
 Chest wall
 Neuromuscular

91. Spirometry Patterns

92. Bronchodilator Response
 Degree to which FEV1 improves with inhaled
bronchodilator
 Documents reversible airflow obstruction
 Significant response if:
- FEV1 increases by 12% and >200ml
 Request if obstructive pattern on spirometry

93. Flow Volume Loop
 “Spirogram”
 Measures forced inspiratory and expiratory
flow rate
 Augments spirometry results
 Indications: evaluation of upper airway
obstruction (stridor, unexplained dyspnea)

94. Flow Volume Loop

95. Upper Airway Obstruction
 Variable intrathoracic obstruction
 Variable extrathoracic obstruction
 Fixed obstruction

96. Upper Airway Obstruction

97. Lung Volumes
 Measurement:
- helium
- nitrogen washout
- body plethsmography
 Indications:
- Diagnose restrictive component
- Differentiate chronic bronchitis from
emphysema

98. Lung Volumes – Patterns
 Obstructive
- TLC > 120% predicted
- RV > 120% predicted
 Restrictive
- TLC < 80% predicted
- RV < 80% predicted

99. Diffusing Capacity
 Diffusing capacity of lungs for CO
 Measures ability of lungs to transport inhaled gas
from alveoli to pulmonary capillaries
 Depends on:
- alveolar—capillary membrane
- hemoglobin concentration
- cardiac output

100. Diffusing Capacity
 Decreased DLCO
(<80% predicted)
 Increased DLCO
(>120-140% predicted)
 Obstructive lung disease
 Asthma (or normal)
 Parenchymal disease
 Pulmonary hemorrhage
 Pulmonary vascular
disease
 Polycythemia
 Anemia
 Left to right shunt

101. DLCO — Indications
 Differentiate asthma from emphysema
 Evaluation and severity of restrictive lung
disease
 Early stages of pulmonary hypertension

102. Bronchoprovocation
 Useful for diagnosis of asthma in the
setting of normal pulmonary function tests
 Common agents:
- Methacholine, Histamine, others
 Diagnostic if: ≥20% decrease in FEV1

103. PFT Patterns
 Emphysema
 Chronic Bronchitis
 FEV1/FVC <70%
 FEV1/FVC <70%
 “Scooped” FV curve
 “Scooped” FV curve
 TLC increased
 TLC normal
 Increased compliance
 Normal compliance
 DLCO decreased
 DLCO usually normal

104. PFT Patterns
 Asthma
 FEV1/FVC
normal or decreased
 DLCO
normal or increased
But PFTs may be normal  bronchoprovocation