Spirometry is a common test used to assess lung function by measuring how much air a person can inhale and exhale. A spirometer is used to measure lung volumes like vital capacity and flows like forced expiratory volume. Spirometry can help diagnose and monitor conditions like COPD and asthma by identifying obstructive or restrictive lung patterns. The test involves forceful inhalation and exhalation into a mouthpiece for at least 6 seconds while seated in front of the spirometer. Spirometry results are used to evaluate lung capacity, airflow limitation, and response to treatment over time.

1. Spirometry
By: Ahmed Sohail Kothawala

2. Spirometry - Introduction
• SPIROMETRY:- It is a method of assessing lung function by measuring
the total volume of air the patient can expel from the lungs after a
maximal inhalation.
-Simple method for studying pulmonary ventilation
• SPIROMETER:- Instrument used to perform spirometry.
• SPIROGRAM: It is the graphical representation of changes in lung
volume under different conditions of breathing
-Pulmonary volume and capacities vary according to height, age sex
and physical training
 All volumes and capacities
 Increase in males
 Decrease with age
 Increase with height
 Increase in athletes and physically active individuals

3. Functioning of the Spirometer
A typical basic spirometer consists of a drum inverted over a
chamber of water, with the drum counterbalanced by a weight. In
the drum is a breathing gas, usually air or oxygen; a tube connects
the mouth with the gas chamber. When one breathes into and out
of the chamber, the drum rises and falls, and an appropriate
recording is made on a moving sheet of paper.

4. Why Perform Spirometry?
• Determine your lung capacity
• Measure airflow obstruction to help make a definitive diagnosis
of COPD
• Confirm presence of airway obstruction
• Assess severity of airflow obstruction in COPD
• Decide how likely it is that inhaled medications may help with
your syntoms
• Monitor disease progression in COPD
• Assess one aspect of response to therapy
• Perform pre-operative assessment

5. How to perform spirometry?
• For this test, you'll sit in front of a machine and be fitted
with a mouthpiece.
• It's important that the mouthpiece fits snugly so that all the
air you breathe into the machine.
• You'll also wear a nose clip to keep you from breathing air
out through your nose.
• The patient is then instructed to inhale as much as possible
and exhale rapidly & forcefully for as long as flow can be
maintained. The patient should exhale for atleast 6 seconds

6. PULMONARY VOLUMES
 TIDAL VOLUME :
 Volume of air inspired
or expired with each
normal breath
• Value 500ml (0.5 L)
 INSPIRATORY
RESERVE VOLUME:
 Max extra volume of
air that can be inspired
over normal tidal
volume.
• Value 3000ml (2.5-
3 L) Spirogram

7. PULMONARY VOLUMES
 EXPIRATORY
RESERVE VOLUME:
 Max extra volume of
air that can be expired
forcefully after the
normal tidal expiration
• Value 1100ml.
 RESIDUAL VOLUME:
 Vol of air remaining l
in the lungs after the
most forceful
expiration
• Value 1200ml. Spirogram

8. PULMONARY CAPACITIES
 INSPIRATORY
CAPACITY:
 It is the max amount
of air that a person
can breath in.
 Tidal vol +insp res vol
 500+3000=3500ml.
 FUNCTIONAL
RESIDUAL CAPACITY
(FRC):
 Amount of air that
remains in the lung
after normal tidal
expiration
 ERV+RV
 1100+1200=2300ml.
Spirogram

9. PULMONARY CAPACITIES
•VITAL CAPACITY :
 Max vol of air expired
after max insp
 IRV+TV+ERV
 3000+500+1100
 4600ml (4.5-5L)
 TOTAL LUNG
CAPACITY:-
 Max vol to which the
lungs can be expanded
 IRV+TV+ERV+RV
 3000+500+1100+1200
 5800ml Spirogram

10. DYNAMIC FUNCTION TEST
 Forced Vital Capacity (FVC)
 Max vol of air expired forcefully and rapidly (as hard and
as far as possible) after a full inspiration.
 Forced Expiratory Volume in first sec
 it is the volume of air expired in the first sec during the
FVC maneuver
 FEV1/FVC
 Imp in differentiating obstructive and restrictive lung
diseases.

11. Obstructive & Restrictive Lung
Diseases
 Obstructive Airways Disease –
where your ability to breathe out quickly is affected by
narrowing of the airways, but the amount of air you can hold
in your lungs is normal.
 Examples: Asthma, COPD, Emphysema, Cystic Fibrosis
 Restrictive Lung Disease –
where the amount of air you can breathe in is reduced
because your lungs are unable to fully expand (such as in
pulmonary fibrosis)
 Examples: Obesity, Pleural effusion, Myasthenia Gravis

12. Obstructive Pattern VS
Restrictive Pattern
 Obstructive
 TLC Normal
 Normal or slight decreased
FVC
 Decreased FEV1
 FEV1/ FVC < 70% of
predicted
 Restrictive
 TLC Decreased
 FVC decreased
 Normal or slight decreased
FEV1
 FEV1/ FVC > 70% of
predicted

13. Disadvantages of Spirometry
 Feel Dizzy
 Feel lightheaded
 Feel tired
 coughing

14. THANK YOU