Lecture 2: Spirometer
Introduction
 Spirometry is the gold standard for COPD (Chronic
obstructive pulmonary disease) diagnosis
 Underuse leads to inaccurate COPD diagnosis
 Widespread uptake has been limited by:
 Concerns over technical performance of operators
 Difficulty with interpretation of results
 Lack of approved local training courses
 Lack of evidence showing clear benefit when
spirometry is incorporated into management
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Introduction
What is Spirometry?
Spirometry is a method of assessing lung
function by measuring the volume of air the
patient can expel from the lungs after a
maximal expiration.
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Introduction
Why Perform Spirometry?
 Measure airflow obstruction to help make a definitive
diagnosis of COPD
 Confirm presence of airway obstruction
 Assess severity of airflow obstruction in COPD
 Detect airflow obstruction in smokers who may have few or
no symptoms
 Monitor disease progression in COPD
 Assess one aspect of response to therapy
 Assess prognosis (FEV1) in COPD
 Perform pre-operative assessment
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Respiratory system
Respiratory system functions include gas exchange,
pH regulation, vocalisation, and protection from
foreign substances.
Respiration:
o Cellular respiration is the cellular mechanism of
energy conversion.
o External respiration is the exchange of gases
between atmosphere and cells. Includes
ventilation, gas exchange at lungs and cells, and
transport of gases in the blood
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Respiratory controls
Local controls
o ↑ blood CO2 = dilation of bronchioles
o ↑ alveolar O2 = vasodilation of bronchioles
Neural Controls
o Respiratory center in brain
o Stretch receptors
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Static lung volumes and capacities
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Static lung volumes and capacities
Dead space: the part of each breath that remains in the upper
respiratory tract does not exchange.
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Static lung volumes and capacities
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Dynamic Lung Volumes
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Calculating FVC
P. Jamel A. SMIDA
AJZ 205 “MECHANICAL MEDICAL DEVICES”
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Calculating FEV1.0
P. Jamel A. SMIDA
AJZ 205 “MECHANICAL MEDICAL DEVICES”
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Calculating FEF25-75
P. Jamel A. SMIDA
AJZ 205 “MECHANICAL MEDICAL DEVICES”
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Other volumes & capacities
Minute Respiratory Volume (MRV):
quantity of air moved into and out of the lungs in
one minute (TV x Respiratory rate)
Maximal Ventilatory Volume (MVV):
Maximal amount of air that a person can breathe in
or out in a short period of time, typically 10, 12, or
15 secs
Ventilation rate
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Spirometers
Apparatus used to:
Measure static & dynamic lung volumes/capacities
using a closed system
Registers the amount and rate of air moved into or
out of the lungs
Two main types:
1. Volume: records the amount of air exhaled or inhaled
within a certain time
2. Flow: measures how fast the air flows in or out as the
volume of air inhaled or exhaled increases
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Types of Spirometers
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
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Types of Spirometers
Volume Measuring Spirometer
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Types of Spirometers
Flow Measuring Spirometer
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Types of Spirometers
Desktop Electronic Spirometer
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Types of Spirometers
Small Hand-held Spirometers
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Volume Measuring Spirometer
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Volume Measuring Spirometer
Real time tracings record volume in relation to time
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Volume Measuring Spirometer
Advantages
Some are portable versions
Leak tests and calibrations are easy to perform
Many can produce flow/volume curves and loops
with the addition of special electronic or digital
circuitry.
Volume spirometers hold their calibration months
to years better than flow spirometers
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Volume Measuring Spirometer
Disadvantages
Not practical by hand to determine peak
expiratory flow or instantaneous volumes,
Coughs and submaximal efforts are not as
obvious
Some are heavy, cumbersome and may be prone
to fostering mold or bacterial growth if not cleaned
properly
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Flow Measuring Spirometer
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Flow Measuring Spirometer
 Measure how quickly air flows past a detector and
then derives the volume by electronic means.
 Records flow rate at brief intervals (30-300x/sec)
and use data to reconstruct the flow rate at each
point in time and volume (digitization).
 Tracings measure flow in relation to volume
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Flow Measuring Spirometer
Advantages
Computer can produce volume-time tracings
Tend to be lighter and more portable
Disposable, single-use flow sensors, available on
some flow spirometers eliminate the risk (low)
ofcross-contamination.
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Flow Measuring Spirometer
Disadvantages
No real-time or hard copy tracings
Reliance on electronic equipment
FEV1.0 cannot be calculated by hand unless the
time is indicated in seconds on a flow-volume
tracing
Some flow spirometers are more difficult to
calibrate and may lose their calibration over time if
not well maintained.
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Equipment Maintenance
 Most spirometers need regular calibration to
check accuracy
 Calibration is normally performed with a 3 litre
syringe
 Some electronic spirometers do not require
daily/weekly calibration
 Good equipment cleanliness and anti-infection
control are important; check instruction manual
 Spirometers should be regularly serviced; check
manufacturer’s recommendations
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Technical Specifications
 MEASUREMENT DEVICE
o Volume range, Accuracy
o Flow range, Accuracy
o Calibration method
 DISPLAYS
 PLOTS: Timed spirogram, Flow-volume loop
 DATA ANALYSIS
 HARD-COPYREPORT
 COMPUTER INTERFACE
 STERILIZING METHOD
 DISPOSABLE PARTS
 POWER REQUIREMENTS,
 STD List
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