2. • Spirometry (meaning the measuring of
breath) is the most
common of the pulmonary function tests
(PFTs),
measuring lung function, specifically the
amount (volume)
and/or speed (flow) of air that can be inhaled
and exhaled.
•
3.
4. Indications:
• Spirometry is indicated for the following reasons:
to diagnose or manage asthma
to detect respiratory disease in patients presenting with symptoms of
breathlessness, and to distinguish respiratory from cardiac disease as the
cause
to diagnose and differentiate between obstructive lung
disease and restrictive lung disease
to follow the natural history of disease in respiratory conditions
to assess of impairment from occupational asthma
to identify those at risk from pulmonary barotrauma while scuba diving
to conduct pre-operative risk assessment before anaesthesia
or cardiothoracic surgery
to measure response to treatment of conditions which spirometry
detects
5. Contraindications:
• Hemoptysis of unknown origin
• Pneumothorax
• Unstable angina pectoris
• Recent myocardial infarction
• Thoracic aneurysms, abdominal aneurysms, cerebral aneurysms
• Recent eye surgery (within 2 weeks due to increased intraocular
pressure during forced expiration)
• Recent abdominal or thoracic surgical procedures
• Patients with a history of syncope associated with forced
exhalation.
• Patients with active tuberculosis should not be tested
6. MEASUREMENTS:
There are four lung volumes and four lung capacities.
A lung capacity consists of two or more lung volumes.
The lung volumes are:
1. Tidal volume (VT)
2. Inspiratory reserve volume (IRV)
3. Expiratory reserve volume (ERV)
4. Residual volume (RV).
The four lung capacities are:
1. Total lung capacity (TLC)
2. Inspiratory capacity (IC)
3. Functional residual capacity (FRC)
4. Vital capacity (VC).
7. 1. Tidal volume: It is the volume of air moved into or
out of the lungs during quiet breathing. Value: 500ml
2. Inspiratory reserve volume: It is the maximal
volume that can be inhaled from the end inspiratory
level(after the inspiration of a normal
tidal volume). Value: 3100 ml
3. Expiratory reserve volume: It is the maximal
volume of air that can be exhaled from the end expiratory
position(after the expiration of a normal
tidal volume). Value: 1200 ml
4. Residual volume: It is the volume of air remaining
in the lungs after a maximal exhalation. Value:
1200 ml
8. 1. Total lung capacity: It is the volume in the lungs at
maximal inflation or maximum amount of air that
can fill the lungs. Value: 6000 ml (TLC = TV + IRV +
ERV + RV).
2. Vital capacity: It is the total amount of air that can
be expired after fully inhaling. Value: 4800 ml (VC
= TV + IRV + ERV = approximately 80 percent TLC).
The value varies according to age and body size.
3. Inspiratory capacity: It is the maximum amount of
air that can be inspired. Value: 3600 ml (IC = TV +
IRV).
4. Functional residual capacity: It is the amount of
air remaining in the lungs after a normal
expiration. Value: 2400 ml (FRC = RV + ERV)
9.
10. Spirometer
• The spirometry test is performed
using a device called a spirometer,
which comes in several different
varieties. Most spirometers display
the following graphs, called
spirograms:
• a volume-time curve, showing
volume (liters) along the Y-axis and
time (seconds) along the X-axis
• a flow-volume loop, which
graphically depicts the rate of
airflow on the Y-axis and the total
volume inspired or expired on the
X-axis.
11. Parameters
• The most common parameters measured in spirometry
are
1. Vital capacity (VC),
2. Forced vital capacity (FVC),
3. Forced expiratory volume (FEV) at timed intervals of
0.5, 1.0 (FEV1), 2.0, and 3.0 seconds,
4. Forced expiratory flow 25–75% (FEF 25–75) and
5. Maximal voluntary ventilation (MVV),[5] also known as
Maximum breathing capacity.
* Functional residual capacity (FRC) cannot be measured
via spirometry, but it can be measured with
a plethysmograph or dilution tests (for example, helium
dilution test)
12. Forced vital capacity (FVC)
• Forced vital capacity (FVC) is the volume of air that can forcibly be blown
out after full inspiration, measured in liters.
• FVC is the most basic maneuver in spirometry tests.
• Forced expiratory volume in 1 second (FEV1)
• FEV1 is the volume of air that can forcibly be blown out in one second, after
full inspiration.
• Average values for FEV1 in healthy people depend mainly on sex and age.
• Values of between 80% and 120% of the average value are considered
normal.
• FEV1/FVC ratio (FEV1%)
• FEV1/FVC (FEV1%) is the ratio of FEV1 to FVC.
• In healthy adults this should be approximately 75–80%.
• Forced expiratory flow (FEF)
• Forced expiratory flow (FEF) is the flow (or speed) of air coming out of the
lung during the middle portion of a forced expiration.
• It can be given at discrete times, generally defined by what fraction remains
of the forced vital capacity (FVC).
• The usual intervals are 25%, 50% and 75% (FEF25, FEF50 and FEF75), or 25%
and 50% of FVC.
13. HOW IS THE TEST PERFORMED
• The patient is instructed to inhale as much as possible
and then exhale rapidly and forcefully for as long as
flow can be maintained. The patient should exhale for
at least six seconds. At the end of the forced
exhalation, the patient should again inhale fully as
rapidly as possible. The FVC should then be compared
with that inhaled volume to verify that the forced
expiratory manoeuvre did indeed start from full
inflation. The FVC and the FEV1 should be repeatable
to within 0.15 L upon repeat efforts unless the largest
value for either parameter is less than 1 L. In this case,
the expected repeatability is to within 0.1 L of the
largest value.
14.
15. Risks
• Spirometry is generally a safe test. You
may feel short of breath or dizzy for a
moment after you perform the test.
• Because the test requires some exertion, it
isn't performed if you've had a recent heart
attack or some other heart condition.
Rarely, the test triggers severe breathing
problems
16. • Measured (actual) spirometry values are
compared with predicted values- age , height,
weight & gender; expressed as a % of predicted
value.(>80% normal limits). During expiration
floating drum moves up , counter wt comes down ,
downward deflection on the graph. Inspiration
the drum moves down, counter wt comes up,
upward deflection on the graph. Spirometry test
–measured twice both before and after given a
bronchodilator. Improvement in measurements
means patient will respond well
