2. INTRODUCTION
• To ‘’ Inspire’’ means to ‘’ Breath in’’ and ‘’Metric’’
means ‘’ Measurement’’. So ‘’Spirometry’’ simply
means ‘’ measurement of one’s breath’’.
• Sir Jhon Hutchinson invented the first spirometer to
measure the volume of air that can be forcefully
exhaled from the lungs after complete inflation for
which he coined the term ‘’vital capacity’’.
• Spirometry has become an important tool in the
evaluation of Respiratory Disease. It is simple and
inexpensive and used in Day to Day clinical Practice.
3. Clinical Application of Spirometry
• To identify or exclude a respiratory cause of
Dyspnoea.
• Provide objective assessment of lung function
that has been affected by a disease process
involving the lung parenchyma, airways,
interstitium, pulmonary vasculature, pleura,
chest wall, Diaphragm or components of
respiratory pump mechanism.
4. • Identify and Differentiate obstructive from
restrictive ventilatory defects.
• Establish persistant airflow limitation in
confirming the diagnosis and classifying the
severity of COPD.
• Establish reversibility or airway obstruction
and airway hyper-responsiveness in asthma
and other airway diseases.
5. • Screen and identify smokers at high risk.
• Prognostication, assesment and monitoring
the course of respiratory diseases( Asthma,
COPD, Bronchiectasis, ILD etc) and others
Neuromuscular disorders over time.
• Assesment of the efficacy of therapy(
bronchodilators) in obstructive lung diseases.
6. • Assesment and monitoring patients exposed to
noxious environmental agents or on drugs with
expected or known pulmonary toxicity.
• Disability assesment and evaluation of degree of
impairement.
• Pre- operative fitness evaluation by quantifying
lung function in patients scheduled for lung
resection, transplant or pulmonary interventions,
thoracic and cardiac surgeries, major upper
abdominal or orthopaedic surgeries or organ
transplantation.
7. • Detection of air trapping by slow vital
capacity(SVC) versus FVC manoevure.
• Clinical Research and derivation of reference
value or computation of prediction equation
8. Contraindication
• Recent myocardial infarction or arrhythmias.
• Aortic aneurysm.
• Recent cardiac, ocular or abdominal surgery.
• Pneumothorax
• Hemoptysis
• Severe thoracic, ocular or Abdominal pain that
may interfere with test performance.
• Stress incontinence
9. Time Interval to perform spirometry
ACTIVITY PERFORM SPIROMETRY AFTER INTERVAL
OF
Meals 2 hours
Exercise 30 minutes
Tea/ coffee/ aerated drink intake 6 hour
smoking 1-2 hour
Inhaled short acting beta agonist 4 hour
Inhaled long acting anti cholinergic 6 hour
Oral theophyllin 24 hour
11. SPIROMETRY- THE BASICS LUNG
VOLUMES AND CAPACITIES
• Tidal volume( TV) - The volume or air inhaled or exhaled
from the lungs during each breath during normal breathing
. Hence a normal quite breathing is also referred to as a
tidal breath. 500 ml
• Inspiratory Reserve volume ( IRV)- The maximal volume of
additional air that can be forcefully inhaled after the end of
normal inspiration during tidal breathing. 3000ml
• Expiratory Reserve volume (ERV)- The maximal volume of
additional air that can be forcefully exhaled after the end of
normal expiration during tidal breathing. 1500 ml
12. • Residual Volume (RV)- The volume of air
remaining in the lungs at the end of maximal
exhalation. This volume of air cannot be
measured by spirometry. It is calculated as
the difference between functional residual
capacity and expiratory reserve volume.1200
ml.
13. • Vital Capacity (VC)- The volume of air that can be
forcefully exhaled from the lungs after a maximal
inhalation or forcefully inspired into the lungs
after a maximal inhalation .VC = TV+ IRV + ERV.
5000 ml.
• Total Lung Capacity(TLC)- The volume of air
contained in the lungs at the end of a maximal
forced inspiration . It reflects the maximum size
of the lungs at full inflation. TLC = RV+ VC. (4 to 6
L).
14. • Functional Residual Capacity(FRC)- The
volume of air that remains in the lungs after
the end of normal exhalation. FRC= RV+ ERV
2500 ml
• Decrease-
• In supine position
• Obese patient
• Induction of anaesthesia by 16 to 20%
15. • Inspiratory Capacity(IC)- the maximum volume
of air that can be inhaled from the position of
end- expiration, IC= TV+ IRV(2400‐3800ml).
17. Variables measured during spirometry
• Force vital capacity(FVC)-
• The volume of air exhaled after expiration
with a maximal forced efforts, following a
maximal inspiration.
18. FEV1 (Forced Expiratory Volume in
One Second)
• The volume of air exhaled during the first
second of forced expiration from a position of
maximal inspiration.
• During the onset of forced expiration airway
gets compressed and flow tends to reach its
maximum value , manifested as a peak on the
expiratory limb on the flow volume curve.
19. • FEV1/ FVC- The fraction ( expressed as percentage ) of
the FVC exhaled during the first second of a forced
expiration.
• FEF 25%- 75%( Forced expiratory fow between 25% to
75% of FVC)- The forced expiratory flow rate during
the middle portion ( between 25% to 75% ) of the FVC
curve during the effort independent portion of the
curve. It is the sensitive index of narrowing in central
as well as peripheral airways in many obstructive lung
disease such as Asthma and COPD.
20. • FEF 75% - 85% - The forced expiratory flow
rate during 75% to 85% of the FVC curve . It
reflects the function of small airways.
• FIF 200-1200 –The forced inspiratory flow rate
during the one litre volume portion of the
inspiratory curve between 200 to 1200 ml
above residual volume . It provides
information about larger airway function.
21. • Maximum Voluntary Ventilation (MVV)-
• The largest minute ventilation achieved with efforts . In
this the subject asked to breath in and out as hard and fast
as possible. Ventilation continued for 12 seconds and the
volume is multiplied by 5 to calculate MVV. MVV is also
calculated by multiplying FEV1 by 35 .
• . It represented the strength of respiratory pump and
below mechanism ( chest wall and diaphragm) . It is the
useful screening test for neuromuscular disease and prior
to thoracic and upper abdominal surgery.
22. PEFR( peak expiratory flow rate )
• The maximal expiratory flow rate that can be sustained for
at least 20 miliseconds during the the forced expiratory
manoeuvre.
• It can also be measured by peak flow meter that are
separately available as peak flow meters as small and
compact handheld devices.
• PEFR is greately influenced by narrowing of larger airways.
• Diurnal variation in PFER >10% in adults suggestive of
asthma and an increase of >20% in PEFR after reversibility
testing is diagnostic of asthma.
• The subject should perform 3 attempts of each peak flow at
home morning and evening and record the peak flow value
for a week.
24. Withholding Medications
• Before performing spirometry, withhold:
• Short acting β2-agonists for 6 hours.
• Long acting β2-agonists for 12 hours.
• Ipratropium for 6 hours.
• Tiotropium for 24 hours.
• Optimally, subjects should avoid caffeine and
cigarette smoking for 30 minutes before performing
spirometry.
25. Performing Spirometry - Preparation
• Explain the purpose of the test and
demonstrate the procedure.
• Record the patient’s age, height and gender
and enter on the spirometer.
• Note when bronchodilator was last used.
• Have the patient sitting comfortably.
• Loosen any tight clothing.
• Empty the bladder beforehand if needed.
26. • Breath in until the lungs are full
• Hold the breath and seal the lips tightly
around a clean mouthpiece
• Blast the air out as forcibly and fast as
possible. Provide lots of encouragement
• Continue blowing until the lungs feel empty
27. • Watch the patient during the blow to assure
the lips are sealed around the mouthpiece.
• Check to determine if an adequate trace has
been achieved.
• Repeat the procedure at least twice more until
ideally 3 readings within 100 ml or 5% of each
other are obtained.
28. Spirometry - Possible Side Effects
• Feeling light-headed.
• Headache.
• Facial redness.
• Fainting: reduced venous return or vasovagal
attack (reflex).
• Transient urinary incontinence.
• Spirometry should be avoided after recent
heart attack or stroke.
29. TYPES OF SPIROMETRY
• Mainly Two types of lung function testing
equipments:-
• Volume sensing and flow sensing. Older
spirometer measure change in lung volume
directly via a closed circuit . Flow was
measured as a rate of change in volume per
unit time .
30. • Bellows spirometers: Measure volume; mainly
in lung function units.
• Electronic desk top spirometers: Measure flow
and volume with real time display.
• Small hand-held spirometers: Inexpensive and
quick to use but no print out.
35. Comparision of flow and volume
sensing spirometer
Flow sensing Volume sensing
Parameter measured flow volume
size Small and compact Large and bulky
cost Less expensive More expensive
Ease of disinfection easy difficult
Accuracy less difficult
Measurement affected by
humudity
Yes no
More suitable for Clinic institution
36. Recording and Reporting
• Spirometry is recorded numerically as well as graphically. Graphic
recording include:-
• Volume versus time.
• Flow versus volume.
• Visual inspection of flow – volume loops is essential not only
confirm quality of the procedure but also provide clues that aid the
diagnosis of various respiratory diseases.
• A small concave and scooped – out curve suggests
obstruction..whereas a normal looking curve with steep slope
suggest restriction.
• Small and flat curves either expiratory and inspiratory limbs or both
suggest upper airway obstruction.
45. Obstructive ventilatory defects
• It is characterized by expiratory flow limitation
which is represented by following changes;-
• Reduced FEV1
• Normal or reduced VC or FVC
• Reduced FEV1/FVC ratio
• Concavity of the expiratory limb of the flow
volume loop.
50. Bronchodilators reversibility (BDR)
Testing
• Bronchodilators reversibility testing measures
lung function prior to and after administration of
a fast and short acting bronchodilators to assess
reversibility of airflow obstruction.
• After performing baseline spirometry , the
manoeuver is repeated 15- 20 minutes after
adminstration of a short and fast acting
bronchodilators( 4 puff 100 μg salbutamol or 50
μg levosalbutamol) via pressurized meter dose
inhaler.
51. Bronchodilator Reversibility Testing
Bronchodilator Dose FEV1 before and
after
Salbutamol 200 – 400 μg via
large volume
spacer
15 minutes
Terbutaline 500 μg 15 minutes
Ipratropium 160 μg** via
spacer
45 minutes
53. • BDR (% improvement)=FEV1( Post
Bronchodilators)- FEV1(Baseline)#100
FEV1 ( baseline)
BDR is accepted to be present when an increase in
FEV1/FVC of 12% and 200 ml above the baseline
value.
BDR is usually to differentiate Asthma and Asthma –
COPD overlap syndrome from COPD.
54. Restrictive ventilatory Defect
• Restriction indicates a disease process causing
reduction in lung volume due to loss or destruction on
functional lung parenchyma and can occur various
disorder.
• The hallmark of a restrictive ventilatory defect is
reduction in total lung capacity.
• Restriction cannot be diagnosed spirometry alone but
may be suspected by the following feature on
spirometry:-
• Reduced FVC
• Normal or high FEV1 /FVC Ratio
• Relatively high PEFR
55. Diseases Associated with a Restrictive
Defect
Pulmonary Extrapulmonary
Fibrosing lung diseases Thoracic cage deformity
Pneumoconioses Obesity
Parenchymal lung
tumors
Neuromuscular disorders
Lobectomy or
pneumonectomy
Pregnancy
Fibrothorax
65. • Yes, PFTs are really wonderful but… They do
not act alone.
• They act only to support or exclude a
diagnosis.
• A combination of a thorough history and
physical exam, as well as supporting
laboratory data and imaging is helpful in
assesment for pt with pulmonary dysfunction.