Download Spirometry_for_A_P_II_Students

Spirometry in Primary Care
Global Initiative for Chronic Obstructive
Lung Disease (GOLD) 2008
What is Spirometry?
Spirometry is a method of
assessing lung function by
measuring the volume of air
the patient can expel
(expiration) from the lungs
after a maximal inspiration.
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
Spirometry – Additional Uses
• Make a diagnosis and assess severity in a
range of other respiratory conditions
• Distinguish between obstruction and
restriction as causes of breathlessness
• Screen workforces in occupational
environments
• Assess fitness to dive
• Perform pre-employment screening in certain
professions
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
Volume Measuring Spirometer
Flow Measuring Spirometer
Desktop Electronic Spirometers
Small Hand-held Spirometers
How to Perform Spirometry
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
Performing Spirometry - Preparation
1. Record the patient’s age, height and
gender and enter on the spirometer
2. Note when bronchodilator was last used
3. Have the patient sitting comfortably
4. Loosen any tight clothing
5. Empty the bladder beforehand if needed
6. Explain the purpose of the test and
demonstrate the procedure
Performing Spirometry
• 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
Performing Spirometry
• 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
Volume, liters
Reproducibility - Quality of Results
Time, seconds
Three times FVC within 5% or 0.1 litre (100 ml)
Spirometry - Possible Side Effects
• Feeling light-headed
• Headache
• Getting red in the face
• Fainting: reduced venous return or
vasovagal attack (reflex)
• Transient urinary incontinence
Spirometry should be avoided after
recent heart attack or stroke
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
Spirometry – Common Problems
 Inadequate or incomplete blow
 Lack of blast effort during exhalation
 Slow start to maximal effort
 Lips not sealed around mouthpiece
 Coughing during the blow
 Extra breath during the blow
 Glottic closure or obstruction of mouthpiece
by tongue or teeth
 Poor posture – leaning forwards
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
Additional Spirometric Indicies
• VC - Vital capacity:
A volume of a full breath exhaled in the patient’s
own time and not forced. Often slightly greater
than the FVC, particularly in COPD
• FEV6 – Forced expired volume in six seconds:
Often approximates the FVC. Easier to perform
in older and COPD patients but role in COPD
diagnosis remains under investigation
• MEFR – Mid-expiratory flow rates:
Derived from the mid portion of the flow volume
curve but is not useful for COPD diagnosis
Lung Volume Terminology
Inspiratory reserve
volume
Total
lung
capacity
Inspiratory
capacity
Tidal volume
Expiratory reserve
volume
Residual volume
Vital
capacity
Spirogram Patterns
• Normal
• Obstructive
• Restrictive
• Mixed Obstructive and Restrictive
Spirometry
Predicted Normal
Values
Predicted Normal Values
Affected by:
 Age
 Height
 Sex
 Ethnic Origin
Criteria for Normal
Post-bronchodilator Spirometry
• FEV1: % predicted > 80%
• FVC: % predicted > 80%
• FEV1/FVC: > 0.7
Normal Trace Showing FEV1 and FVC
FVC
Volume, liters
5
4
FEV1 = 4L
3
FVC = 5L
2
FEV1/FVC = 0.8
1
1
2
3
4
5
Time, seconds
6
SPIROMETRY
OBSTRUCTIVE
DISEASE
Obstructive Lung Disease
The Flow rates are reduced due to obstruction in
– the airways but the lung volumes are generally
OK.
Spirometry: Obstructive Disease
Volume, liters
5
4
Normal
3
FEV1 = 1.8L
2
FVC = 3.2L
1
FEV1/FVC = 0.56
1
2
3
4
5
Time, seconds
6
Obstructive
Spirometric Diagnosis of COPD
• COPD is confirmed by post–
bronchodilator FEV1/FVC < 0.7
• Post-bronchodilator FEV1/FVC
measured 15 minutes after 400µg
salbutamol or equivalent
SPIROMETRY
RESTRICTIVE
DISEASE
Restrictive Lung Diseases
With restrictive lung diseases there is a reduction
In lung volumes due to decreases in lung
compliance.
Criteria: Restrictive Disease
• FEV1: % predicted < 80%
• FVC: % predicted < 80%
• FEV1/FVC: > 0.7
Spirometry: Restrictive Disease
Normal
Volume, liters
5
4
3
Restrictive
2
FEV1 = 1.9L
FVC = 2.0L
1
FEV1/FVC = 0.95
1
2
3
4
5
Time, seconds
6
Mixed Obstructive/Restrictive
• FEV1: % predicted < 80%
• FVC: % predicted < 80%
• FEV1 /FVC: < 0.7
Volume, liters
Mixed Obstructive and Restrictive
Normal
FEV1 = 0.5L
Obstructive - Restrictive FVC = 1.5L
FEV1/FVC = 0.30
Time, seconds
Restrictive and mixed obstructive-restrictive are difficult to diagnose by
spirometry alone; full respiratory function tests are usually required
(e.g., body plethysmography, etc)
SPIROMETRY
Flow Volume
Flow Volume Curve
• Standard on most desk-top spirometers
• Adds more information than volume
time curve
• Less understood but not too difficult to
interpret
• Better at demonstrating mild airflow
obstruction
Flow Volume Curve
Maximum
expiratory flow
(PEF)
Expiratory
flow rate
L/sec
TLC
FVC
Inspiratory
flow rate
L/sec
Volume (L)
RV
Flow Volume Curve Patterns
Obstructive and Restrictive
Predicted versus actual
Severe obstructive
Volume (L)
Reduced peak flow,
scooped out midcurve
Restrictive
Expiratory flow rate
Expiratory flow rate
Expiratory flow rate
Obstructive
Volume (L)
Steeple pattern,
reduced peak flow,
rapid fall off
Volume (L)
Normal shape,
normal peak flow,
reduced volume
Spirometry: Abnormal Patterns
Restrictive
Time
Slow rise, reduced
volume expired;
prolonged time to
full expiration
Mixed
Volume
Volume
Volume
Obstructive
Time
Fast rise to plateau
at reduced
maximum volume
Time
Slow rise to reduced
maximum volume;
measure static lung
volumes and full PFT’s
to confirm
Some Spirometry Resources
• Global Initiative for Chronic Obstructive Lung
Disease (GOLD) - www.goldcopd.org
• Spirometry in Practice - www.brit-thoracic.org.uk
• ATS-ERS Taskforce: Standardization of
Spirometry. ERJ 2005;29:319-338
www.thoracic.org/sections/publications/statements
• National Asthma Council: Spirometry Handbook
www.nationalasthma.org.au