Spirometry is a simple lung function test that measures how much air a person can exhale from their lungs after taking a deep breath. It can help diagnose and monitor conditions like asthma and COPD. The test involves blowing into a mouthpiece to measure exhaled volumes like FEV1 and FVC. The ratio of FEV1/FVC is used to identify obstructive or restrictive lung abnormalities. A reduced ratio below 70% indicates obstruction, while reduced volumes but a normal ratio suggest restriction. Spirometry is a valuable tool for physicians to assess respiratory conditions but should be interpreted along with clinical history and examination findings.

2. Simplifying
Spirometry Dr KUMAR UTSAV MD

3. CLINICIAN

4. WHY DO WE NEED SPIROMETRY…

5.  Spirometry is a method of assessing lung
function by measuring the volume of air the
patient can expel from the lungs after a
maximal inspiration.
 A simple and safe test that measures lung
function with a graphical display.
What is Spirometry?

6. spirometry is like the
ECG of lungs

7. Eur Respir J 2005; 25:587-588
Level of FEV1 as a predictor of all-cause
and cardiovascular mortality: an effect
beyond smoking and physical fitness?
J. Sunyer1 and C. S. Ulrik2
LUNG HEALTH STUDY

8. Chest. 2005;127:1952-1959
The Relationship Between Reduced Lung
Function and Cardiovascular Mortality
A Population-Based Study
Don D. Sin, MD, MPH, FCCP; LieLing Wu, MSc and S. F. Paul Man, MD
Every 10% decrease in FEV1 leads to –
14% Increase in all cause mortality
28% increase in Cardio-Vascular mortality
COPD is powerful independent risk
factor for Cardio-Vascular mortality
LUNG HEALTH STUDY

9. In fact, approximately 50% patients of COPD
have ischemic heart disease as the primary
cause of hospitalization.
COPD & CVD:
Chest. 2005;127:1952-1959
LUNG HEALTH STUDY

10. Why should every doctor know
about spirometry?
More than half of the population of India
suffer from respiratory disease or are the
potential patients of these diseases
Therefore any doctor involved in care of
asthma, COPD or pulmonary fibrosis should
understand the basics of pulmonary function
testing

11. Why do physicians not do
spirometry ?
 Don’t ever think about it
 Too busy
 Feel the test is complex
 Don’t know what to ask for in the spirogram
 Time consuming
 Not cost effective
 Results don’t affect treatment

12. Indications
 Diagnosis of obstructive & restrictive lung diseases
 To screen people at risk of pulmonary diseases
 To assess preoperative risk
 To assess prognosis
 To assess therapeutic interventions
 To assess patients as part of a rehabilitation program
 Epidemiologic surveys for pulmonary diseases

13. Contraindications:
 Within 6 weeks since the last
exacerbation.
 Recent MI less than 3-6 months
ago.
 Unstable angina in last 24 hours.
 Haemoptysis of unknown origin.
 Recent eye surgery less than 3-6
months.
 Abdominal surgery within last 3-6
months.
 Recent CVA less than 3-6 months.
 Diagnosis of Tuberculosis unless special
precautions used.
 Current chest infection or within in last 6
weeks.
 Current chest pain with no diagnosis.
 Pulmonary embolism (PE) within last 3-6
months.
 Ear infection.
 Spontaneous pneumothorax.
 Aortic aneurysm.

14. DONT’S
 Smoking (1 hour prior)
 Consumption of alcohol (4 hours prior)
 Vigorous exercise (30 minutes prior)
 Wearing tight clothes.
 Eating a substantial meal (at least 2 hours prior)
 Test should be performed when the patient is
clinically stable and free from infection.
 Drinking fluids containing caffeine (12 hours prior)

15. Withholding bronchodilators
(ARTP)
Inhaled bronchodilators Duration of
action (hours)
Short-acting 4 to 8
Long-acting 24
Anticholinergics 6
Oral short-acting bronchodilators 8
Sustained release β2
agonists 24
Theophylline
Twice-daily preparations 24
Once-daily preparations 48

16. Definitions
 Forced Expiratory Manoeuvre (FEM)
The patient takes a maximal deep breath , then blows out as hard as
possible until the lungs feel completely empty. From this the following
parameters are calculated:
 FEV1
Volume of gas expired from the lungs in the 1st
second of a FEM
 FVC
Total volume of gas expired from the lungs during a FEM
 FER
FEV1/FVC

17. Spirometric
Interpretation

18. Interpretation of Spirometry
Step 1. Look at the Flow-Volume loop
Step 2. Look at FEV1/FVC ratio
Step 3. Look at FVC
Step 4. Look at FEV1 >75%
Step 5. Look at FEF25-75%

23. Criteria for Normal
Post-bronchodilator Spirometry
 FEV1: % predicted > 80%
 FVC: % predicted > 80%
 FEV1/FVC: > 70

24. Two basic types of pulmonary function
abnormalities are described using the basic
spirometric parameters:
Obstructive and Restrictive

25. Obstructive defects
 FEV1/ FVC Ratio < 70%
 FEV1 <80%(Post bronchodilator)
Mechanism Airway damage and flow obstruction
+collapse of airways under forced expiration.
Causes
 COPD
 Asthma
 Bronchiectasis
 Cystic Fibrosis
 Sarcoidosis (endobronchial)
 Chronic extrinsic allergic alveolitis

26. Spirometry: Obstructive Disease
Time, seconds
Volume,liters
Time, seconds
5
4
3
2
1
1 2 3 4 5 6
FEV1 = 1.8L
FVC = 3.2L
FEV1/FVC = 0.56
Normal
Obstructive

27. Graphs: Obstructive Abnormality
Coving of the expiratory loop
towards lower lung volumes
Reduced forced expiratory volume
in the first second (FEV1)

28. Severity
Post bronchodilator
FEV1
(% of predicted value)
Mild airflow obstruction > 80%
Moderate airflow
obstruction
79-50%
Severe airflow obstruction <30 – 49%
V. Severe airflow
obstruction
<30%

29. Measuring Reversibility of Airflow
Obstruction
 To measure the degree of reversibility of airflow
obstruction, perform spirometry before and 10
to 15 minutes after administering a
bronchodilator by metered dose inhaler or
nebuliser
 Beta2
agonists (e.g. salbutamol) are generally
considered the benchmark bronchodilator

30. Obstructive with reversibility
 If you get a COPD picture (FEV1/FVC < 70% and
FEV1 <80%) but there is a good degree of
reversibility-
- If > 200ml, then more likely to be asthma than
COPD.
- If < 200ml, it could be a combination of
asthma and COPD or another diagnosis
too. (Go back to history, exam and other inv).

31. Spirometry For COPD

32. SYMPTOMS
chronic cough
shortness of breath
EXPOSURE TO RISK
FACTORS
tobacco
occupation
indoor/outdoor pollution
SPIROMETRY: Required to establish
diagnosis
GOLD 2018
sputum

33. GOLD 2018
Spirometry should be performed after the
administration of an adequate dose(400µg) of a short-
acting inhaled bronchodilator to minimize variability.
A post-bronchodilator FEV1/FVC < 0.70 confirms
the presence of airflow limitation.
Where possible, values should be compared to age-
related normal values to avoid over diagnosis of COPD in
the elderly.

34. GOLD
Classification of Severity of Airflow
Limitation in COPD*
In patients with FEV1/FVC < 0.70 -
GOLD 1: Mild FEV1 > 80% predicted
GOLD 2: Moderate 50% < FEV1 < 80% predicted
GOLD 3: Severe 30% < FEV1 < 50% predicted
GOLD 4: Very Severe FEV1 < 30% predicted
*Based on Post-Bronchodilator FEV1

35. Division of lung volumes in normal subjects
and patients with COPD
T L C
IC
F R C
R V
N o rm a l C O P D
R V
VOLUME
T L C
IC
F R C

36. Spirometry for Asthma

38. Restrictive defects
 FEV1/FVC Ratio normal i.e. >70%
 Both FEV1 & FVC reduced(But no text says below
what level)
Mechanism-Reduction in all lung volumes
and reduced lung compliance.
 Causes
 Intrinsic - Interstitial lung diseases
 Extrinsic - Kyphoscoliosis, Ankylosing spondylitis,
Muscular dystrophies, Diffuse pleural thickening

39. Spirometry: Restrictive Disease
Volume,liters
Time, seconds
FEV1 = 1.9L
FVC = 2.0L
FEV1/FVC = 0.95
1 2 3 4 5 6
5
4
3
2
1
Normal
Restrictive

40. Graphs: Restrictive Abnormality
Tall narrow graph
Reduced flow,
miniature graph

41. Categorisation of restriction.
VC or TLC- % predicted
 Normal ≥ 81
 Mild restriction 66 - 80
 Moderate restriction 51 - 65
 Severe restriction ≤ 50

42. Mixed Obstructive/Restrictive
 FEV1: % predicted < 80%
 FVC: % predicted < 80%
 FEV1 /FVC: < 70

43. Mixed Obstructive and Restrictive
Restrictive and mixed obstructive-restrictive are difficult to diagnose by
spirometry alone; full respiratory function tests are usually required (e.g.,
body plethysmography, etc)
Volume,liters
Time, seconds
FEV1 = 0.5L
FVC = 1.5L
FEV1/FVC = 0.30
Normal
Obstructive - Restrictive

44. FEV1/FVC ratio
(Post bronchodilator)
Normal
FEV1
Normal
spirometry
Normal FEV1 reduced
Look at FVC
Restrictive defect
FVC reduced
Reduced (<70%)
Obstructive
defect

45. Points to remember in interpretation
 It is impossible to diagnose a respiratory condition
using spirometry alone. History & exam very
important. Think about serial PEFRs, CXR etc too.
 If the clinical picture and spirometry findings don’t
quite fit together well, question the diagnosis.
 If the symptoms are out of keeping with the
spirometry results -question the diagnosis.

46. Conclusions
 Spirometry defines obstructive and restrictive lung
diseases
 Highly reproducible test
 Needs to be performed accurately to ensure useful
data
 Courses available to train operators
 Highly valuable in the clinical setting

48. spirometry is like the
ECG of lungs

49. Thank you

50. Complications
 Syncope, dizziness, light headedness
 Pneumothorax
 Chest pain
 Coughing
 Bronchospasm
 Contraction of infection

51. Severe COPD
A
a
A
a
A
a
A
a
Case 1

52. Case 2
Pulmonary Fibrosis (Asbestosis) A
A
A
A
a

53. Case 3
?Severe COPD (with reversibility)
But history very important in this one
A
a
A
a
A
a
A
a

54. Case 4
Bronchiectasis(but could easily be Asthma or COPD with
reversibility)
A
A
A
A
A
A

55. Case 5
Idiopathic Pulmonary Fibrosis
A
A

56. Case 6
Idiopathic Pulmonary Fibrosis

57. Case 7
A
a
A
a
Muscular dystrophy

59. Typical expiratory spirograms and flow-
volume loops
Volume
T im e
O b s tr u c t io n
Volume
T im e
R e s tr ic tio n
Volume
T im e
M ix e dFlow
V o lu m e
Flow
V o lu m e
Flow
V o lu m e
N o r m a l ( ? )
A b n o r m a l v e n t ila t o r y f u n c t io n
S p ir o m e tr y p e r f o r m e d