Pulmonary Function Test

1. DR. GIRISH JAIN
Dept. of Pulmonary Medicine,
Mahatma Gandhi Medical College , Jaipur

2. • Pulmonary function tests is a term used to indicate studies or
maneuvers that performed using standardized equipment to
measure lung function.
• Evaluates one or more aspects of the respiratory system
• – Respiratory mechanics
• – Lung parenchymal function/ Gas exchange
• – Cardiopulmonary interaction
INTRODUCTION

3. PFT INCLUDES:-
1. SPIROMETRY
2. DLCO
3. BODY PLETHYSMOGRAPHY
4. ABG

4. SPIROMETRY

5. Definition
Spirometry is a method of assessing lung function by
measuring the volume of air that patient can expel
from lungs after a maximal inspiration.
o physiological test that measures how an individual
inhales or exhales volumes of air as a function of
time.
• Measures VC, FVC, FEV1, PEFR.
• CAN’T MEASURE – FRC, RV, TLC.

6. John Hutchinson 1811-1861 A.D.
• Born - 1811
• Medical education in London
• M.R.C.S in 1836; M.D. in 1848
• Assistant Physician to the Hospital,
Brompton in 1850
• Invented the spirometer and the science
of spirometry
• Related vital capacity to height and
presented his work to Statistical Society and
Royal Medical and Surgical Society
1846, “On the capacity of the lungs” reported
on 2130 subjects in Medico-surgical
Transactions 29:137, London

7. Silhouette of Hutchinson Performing Spirometry
From
Chest,
2002

8. Types of Spirometers
o BELLOWS OR ROLLING SEAL - large and not very portable, and are used
predominantly in lung function laboratories. Require regular calibration with a 3-liter syringe
and are very accurate.
• ELECTRONIC DESKTOP SPIROMETERS are compact, portable, and usually quick
and easy to use. Real-time visual display and paper or computer printout. Require calibration
with the 3-liter syringe. They maintain accuracy over years and are ideal for primary care.
• Small, inexpensive HAND-HELD SPIROMETERS provide a numerical record but no
printout. Recent models allow pre-programming of patient details so that the spirometer also
gives percent predicted values. These are good for simple screening.

9. Spirometers
• Volume – displacement
 Water seal spirometer
 Dry rolling seal spirometer
 Bellows spirometer
• Flow sensing device
• Rotating vanes (Turbine)
• Pressure differential flow sensing spirometers
• Heated wire flow sensors
• Pitot tube flow sensors

10. Spirometer in the fifties..

11. Volume Measuring Spirometer

12. Flow Measuring Spirometer

13. NOW-Hand-held spirometer

14. Many types are available..
Spirobank
MicroLoop
SpiroPro
Simplicity
Datospir 70 SpiroStar

15. Pulmonary Function Parameters
• Total lung capacity (TLC)
• Vital capacity (VC)
• Inspiratory capacity (IC)
• Functional residual capacity (FRC)
• Inspiratory reserve volume (IRV)
• Expiratory reserve volume (ERV)
• Tidal volume (TV)
• Residual volume (RV)

17. -Tidal Volume (TV):
volume of air inhaled or
exhaled with each
breath during quiet
breathing
-Inspiratory Reserve
Volume (IRV):
maximum volume of
air inhaled from the
end-inspiratory tidal
position
-Expiratory Reserve
Volume (ERV):
maximum volume of
air that can be exhaled
from resting end-
expiratory tidal position

18. *Residual Volume (RV):
->Volume of air remaining in lungs after
maximium exhalation
->Indirectly measured (FRC-ERV) not by
spirometry
*Total Lung Capacity (TLC): Sum of all
volume compartments or volume of air in
lungs after maximum inspiration
*Vital Capacity (VC): TLC minus RV or
maximum volume of air exhaled from
maximal inspiratory level
*Inspiratory Capacity (IC): Sum of IRV and
TV or the maximum volume of air that can be
inhaled from the end-expiratory tidal position

19. Functional Residual
Capacity (FRC):
Sum of RV and ERV
or the volume of air
in the lungs at end-
expiratory tidal
position
Measured with
multiple-breath
closed-circuit
helium dilution,
multiple-breath
open-circuit nitrogen
washout, or body
plethysmography
(not by spirometry)

20. Indications for spirometry:-
• Diagnostic
• To evaluate symptoms, signs, or abnormal laboratory tests
• -Symptoms: dyspnea, wheezing, orthopnea, cough, chest pain
• -Signs: diminished breath sounds, overinflation,cyanosis, chest deformity, unexplained crepts
• -Abnormal laboratory tests: hypoxemia, hypercapnia, polycythemia,
• abnormal chest radiographs
• To measure the effect of disease on pulmonary function
• To screen individuals at risk of having pulmonary diseases
• -Smokers
• -Individuals in occupations with exposures to injurious substances
• -Some routine physical examinations
• To assess preoperative risk
• To assess prognosis (lung transplant, etc.)
• To assess health status before enrollment in strenuous physical activity programs

21. • Monitoring
• To assess therapeutic interventions
• -bronchodilator therapy
• -Steroid treatment for asthma, interstitial lung disease, etc.
• -Management of congestive heart failure
• To describe the course of diseases affecting lung function
• -Pulmonary diseases
• Obstructive airways diseases
• Interstitial lung diseases
• -Cardiac diseases
• Congestive heart failure
• -Neuromuscular diseases
• Guillain-Barre Syndrome
• To monitor persons in occupations with exposure to injurious agents
• To monitor for adverse reactions to drugs with known pulmonary toxicity

22. Contraindications
• Patients within 1 month of a myocardial infarction/Unstable cardiovascular status.
• Significant Chest or abdominal pain of any cause.
• Oral or facial pain may exacerbated by a mouthpiece.
• Stress incontinence, hernia.
• Dementia or confused state.
• Very ill or dyspnoeic patient.
• Hemoptysis of unknown origin.
• Pneumothorax, pulmonary embolism, severe infection.
• Thoracic/abdominal/cerebral aneurysms.
• Recent eye surgery/surgery of thorax or abdomen.
• Presence of acute disease process that may interfere with performance (e.g. Nausea,
vomiting, ac severe asthma}.
• history of stroke or severe head injury.

23. Complications of Spirometry
Nosocomial infections.
Syncope, dizziness, light headedness.
Chest pain, muscle cramps.
Paroxymal coughing.
Bronchospasm.
Oxygen desaturation due to interruption of oxygen
therapy.

24. Performing spirometry
 Spirometry can be performed at the bedside, physician’s
consulting room or a laboratory and must be recorded.
 Sitting is considered safe in order to prevent falling due
to syncope. However, in obese and pregnant subjects, the
standing position may be preferred. In children[more
than 4 yrs] seated position is preferred.

25. Preliminaries to Patient Testing
• Physical assessment
• Pulmonary history
• Instructions prior to testing
– Drink / drugs / chocolate / smoke
• Physical measurement
– Age, sex, height, weight

26. Subject should be asked to avoid :
Smoking 24 hours
Drinks containing caffeine
/ theobromines
12 hours
Chocolates 8 hours
Alcohol 4 hours
Heavy meal 2 hours
Exercise 30 minutes
Bronchodilators &
Bronchoconstrictors
 Short-acting bronchodilators, Anticholinergics- within previous
6 hours.
 Long-acting bronchodilators- within previous 12 hours.
 Slow release theophyllines- within previous 24 hours.

27. Precaution: while testing reversibility
*Patients should not use Bronchodilator in preceding hours- May cause
false negative test
-Short acting beta-2 agonist -6hours
-Long acting/oral beta 2 agonist-12 hours
-Slow release theophyllines- within previous 24 hours.

28. Patient Instructions
• Good seal around mouthpiece
• Take a few normal breaths in and out.
• Take a deep breath in, and then blow out as hard and as fast
as possible.
Remove nose ring & loose denture if any.

29. Test procedure
Three distinct phases to the FVC manoeuvre:
1) maximal inspiration;
2) ‘‘blast’’ of exhalation;
3) continued complete exhalation to the end of test (EOT).
Technician should demonstrate appropriate technique

30. 1. Maximal Inspiration;
Inhale rapidly and completely from functional residual capacity (FRC),
the breathing tube should be inserted into the subject’s mouth , making
sure the lips are sealed around the mouthpiece and that the tongue
does not occlude it, and then t FVC manoeuvre should be begun
without hesitation.
-Preceding inspiration should be fast and any pause at full inspiration
should be minimal (i.e. only for 1–2 s).
- inhalation should full before beginning forced exhalation

31. ‘2.‘Blast’’ of exhalation
The subject should prompted to ‘‘blast,’’ not just ‘‘blow,’’ air from their
lungs, and then subject should encouraged to fully exhale.
3.Continued complete exhalation to the end of test (EOT).
Throughout manoeuvre, enthusiastic coaching of the subject using
appropriate body language and phrases, such as ‘‘keep going’’, is
required.
If patient feels ‘‘dizzy’’manoeuvre should stopped, since syncope could
followed after procedure.
If testing undertaken on standing or in another position, this must be
documented on report.

32. Flow Volume Curve
Expiratory
flow rate
L/sec
Volume (L)
FVC
Maximum
expiratory flow
(PEF)
Inspiratory
flow rate
L/sec
RVTLC

33. Restrictive pattern
Normal
Obstructive pattern

34. Fixed obstruction:
constant airflow limitation on inspiration and expiration
so loop are flattened and look like rectangle -such as in
tumor, tracheal stenosis
Variable extrathoracic obstruction:
limitation of inspiratory flow, flattened inspiratory loop
expiratory flow is unimpaired—such as in vocal cord
dysfunction, unilateral vocal cord paralysis
Variable intrathoracic obstruction:
flattening of expiratory limb; as in malignancy or
tracheomalacia
Upper Airway Obstruction

35. Graph Showing FEV1 and FVC
1 2 3 4 5 6
1
2
3
4Volume,liters
Time, seconds
FVC5
1
FEV1 = 4L
FVC = 5L
FEV1/FVC = 0.8

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

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

38. Standard Spirometric Indicies
• FEV1 - 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
• FEV1/FVC ratio:
The fraction of air exhaled in the first second
relative to the total volume exhaled

39. FVC
• 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)

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

41. FEV1
• 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

42. FEV1
• Interpretation of % predicted:
– >75% Normal
– 60%-75% Mild obstruction
– 50-59% Moderate obstruction
– <49% Severe obstruction
FEV1 FVC

43. FEV1/FVC ratio:
Called as Tiffeneau-pinelli index
The fraction of air exhaled in the first second
relative to the total volume exhaled
80 or higher - Normal
79 or lower - Abnormal

44. FEF25-75
• Forced expiratory flow 25-
75% (FEF25-75)
– Mean forced expiratory flow
during middle half of FVC
– Measured in L/sec
– May reflect status of the
small airways
– Highly variable
– Depends heavily on FVC

45. FEF25-75
»Interpretation of % predicted:
»>80% Normal
»60-79% Mild obstruction
»40-59% Moderate obstruction
»<40% Severe obstruction

46. MAX. VOLUNTARY VENTILATION
Largest volume that can be breath per minute by
voluntary effort , as hard & as fast as possible.
N – 150-175 l/min.
Estimate of max. Ventilation available to meet increased
physiological demand.
Measured for 12 secs – extrapolated for 1 min.
 MVV = FEV1 X 35

47. Criteria for Normal
Spirometry
• FEV1: % predicted > 80%
• FVC: % predicted > 80%
• FEV1/FVC: > 0.7

48. Spirometry Interpretation: Obstructive vs.
Restrictive Defect
• Obstructive Disorders
– Characterized by a limitation of expiratory airflow so
that airways cannot empty as rapidly compared to
normal (such as through narrowed airways from
bronchospasm, inflammation, etc.)
– FVC nl or↓
– FEV1 ↓
– FEF25-75% ↓
– FEV1/FVC ↓
– TLC nl or ↑
Examples:
– Asthma
– Emphysema
– Cystic Fibrosis
• Restrictive Disorders
– Characterized by reduced lung
volumes/decreased lung compliance
- FVC ↓
– FEV1 ↓
– FEF 25-75% nl to ↓
– FEV1/FVC N↑
– TLC ↓
Examples:
– Interstitial Fibrosis
– Scoliosis
– Obesity
– Lung Resection
– Neuromuscular diseases
– Cystic Fibrosis

49. Normal vs. Obstructive vs. Restrictive
(Hyatt,
2003)

51. Spirometry: Obstructive Disease
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

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

53. Bronchodilator Reversibility Testing
• Provides the best achievable FEV1
(and FVC)
• Helps to differentiate COPD from
asthma
Must be interpreted with clinical
history - neither asthma nor COPD
are diagnosed on spirometry alone

54. Bronchodilator Reversibility
Testing in COPD
• FEV1 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

55. Bronchodilator Reversibility Testing
in COPD
•An increase in FEV1 that is both greater
than 200 ml and 12% above the pre-
bronchodilator FEV1 (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

56. Figure 5.1-6.
Bronchodilator
Reversibility
Testing in COPD

59. 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
Spirometry: Restrictive Disease
Normal
Restrictive

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

61. Mixed Obstructive and Restrictive
Volume,liters
Time, seconds
FEV1 = 0.5L
FVC = 1.5L
FEV1/FVC = 0.30
Normal
Obstructive - Restrictive

62. 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

63. Troubleshooting
Examples - Unacceptable Traces

64. Unacceptable Trace - Poor Effort
Volume,liters
Time, seconds
May be accompanied by a slow start
Inadequate sustaining of effort
Variable expiratory effort
Normal

65. Volume,liters
Time, seconds
Unacceptable Trace – Stop Early
Normal

66. Volume,liters
Time, seconds
Unacceptable Trace – Slow Start
Normal

67. Volume,liters
Time, seconds
Unacceptable Trace - Coughing
Normal

68. Volume,liters
Time, seconds
Unacceptable Trace – Extra Breath
Normal

69. SPIROMETRY‐Acceptability Criteria
Good start of test‐ without any hesitation
• No coughing / glottic closure
• No variable flow
• No early termination(> 6 sec)
• No air leak
• Reproducibility‐ The test is without excessive variability
The two largest values for FVC and the two largest values for
FEV1 should vary by no more than 150 ML

70. Bronchodilator Reversibility:
Spirometry recorded 15-20 minutes after administration of a short-acting beta-agonist, eg. 200-
400mcg of salbutamol/80-160micro g of ipratropium or both, is used to assess
bronchodilator reversibility.
Calculation of Bronchodilator Reversibility:
Calculation of % improvement=
FEV1(post-bronchodilator) – FEV1(prebonchodilator) x100
FEV1(prebonchodilator)
*A positive reversibility test shows an increase in FEV1 by more than 12% and at least by more
than 200ml in comparison to baseline values.
*This test shows no or partial reversibility in a majority of pts. With COPD

71. BRONCHODILATOR DOSE FEV1 BEFORE &AFTER
SALBUTAMOL 200-400mcg via LARGE
VOLUME SPACER
15 min
TERBUTALINE 500 mcg via TURBOHALER 15 min
IPRATROPIUM 160 mcg via SPACER
Usually 8 puffs of 20 mcg
45 min

72. In some cases of poorly treated persistent asthma, bronchodilator reversibility may not be
present, steroid reversibility can be demonstrated 2 weeks after a course of oral
prednisolone in a single daily dose of 1 mg/kg for 2 weeks.
Calculation of Steroid Reversibility:
Calculation of % improvement =
FEV1(post-steroid) – FEV1(presteroid) x100
FEV1(presteroid)
*Borderline NORMAL values should be interpreted with caution and should be used along with
clinical information to decide whether the report is normal or abnormal.

73. Steps in interpretation of spirometry
 Examine the flow volume curve
 Is it acceptable
 Is it reproducible
 Select the personal best
 Examine the FEV1/VC ratio
 Examine the FVC
 Examine the mid expiratory flow values
 Examine the response to bronchodilators

74. Interpretation of simple spirometry:-
1
4 3
2