Spirometry in Primary Care
Dr Max Matonhodze FRCP (London) M A Med Ed (Keele)
Objectives
• Need for performing spirometry• Types of spirometers• Spirometric indices• Obstructive spirometry and severity scale• Practical tips• Quality control• Illustrative examples
COPD NICE guidance 2010
The presence of airflow obstruction should be confirmed by performing post-bronchodilator
spirometry. All health professionals involved in the care of people with COPD should have
access to spirometry and be competent in the interpretation of the results.
WHY?
• 3 million people are estimated to have COPD in UK
• 900 000 are diagnosed• 2 million are living with undiagnosed COPD• About 70% of COPD remain undiagnosed
Spirometry • Spirometry is the gold standard for 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
What is Spirometry?
Spirometry 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.
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
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
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
Totallung
capacity
Inspiratory reservevolume
Tidal volume
Expiratory reservevolume
Residual volume
Inspiratory 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 - 0.8, depending on age
Normal Trace Showing FEV1 and FVC
5
4
3
2
1
Volu
me,
lite
rs
1 2 3 4 5 6
Time, sec
FEV1 = 4LFVC = 5LFEV1/FVC = 0.8
FVC
SPIROMETRY
OBSTRUCTIVE DISEASE
Spirometry: Obstructive Disease
5
4
3
2
1
1 2 3 4 5 6
Time, seconds
Volu
me,
lite
rsNormal
FEV1 = 1.8LFVC = 3.2LFEV1/FVC = 0.56
Obstructive
Diseases Associated With Airflow Obstruction
• COPD• Asthma• Bronchiectasis• Cystic Fibrosis• Post-tuberculosis• Lung cancer (greater risk in COPD)• Obliterative Bronchiolitis
Spirometric Diagnosis of COPD
• COPD is confirmed by post–bronchodilator FEV1/FVC < 0.7 Plus
• FEV1 %pred >80%= Mild
• FEV1 %Pred 50-79% =moderate
• FEV1 % Pred 30-49% =Severe
• FEV1 %pred <30%= very severe
SPIROMETRY
RESTRICTIVE DISEASE
Criteria: Restrictive Disease
• FEV1: normal or mildly reduced
• FVC: < 80% predicted
• FEV1/FVC: > 0.7
Spirometry: Restrictive DiseaseVo
lum
e, li
ters
Time, seconds1 2 3 4 5 6
54
3
2
1
Restrictive
Normal
FEV1 = 1.9LFVC = 2.0LFEV1/FVC = 0.95
Diseases Associated with a Restrictive Defect
Pulmonary• Fibrosing lung diseases• Pneumoconioses• Pulmonary edema• Parenchymal lung tumors• Lobectomy or
pneumonectomy
Extrapulmonary• Thoracic cage deformity• Obesity• Pregnancy• Neuromuscular disorders• Fibrothorax
Mixed Obstructive/Restrictive
• FEV1: < 80% predicted
• FVC: < 80% predicted
• FEV1 /FVC: < 0.7
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
Expiratory flow rateL/sec
FVC
Maximum expiratory flow (PEF)
Inspiratory flow rate
L/sec
RVTLC
Volume (L)
Flow Volume Curve Patterns Obstructive and Restrictive
Obstructive Severe obstructive Restrictive
Volume (L)
Ex
pira
tory
flow
rate
Expi
rato
ry fl
ow ra
te
Exp
irato
ry fl
ow ra
te
Volume (L) Volume (L)
Steeple pattern, reduced peak flow, rapid fall
off
Normal shape, normal peak flow, reduced
volume
Reduced peak flow, scooped out mid-
curve
Spirometry: Abnormal Patterns Obstructive Restrictive Mixed
Time Time Time
Vo
lum
e
Volu
me
Volu
me
Slow rise, reduced volume expired;
prolonged time to full expiration
Fast rise to plateau at reduced
maximum volume
Slow rise to reduced maximum volume; measure
static lung volumes and full PFT’s to
confirm
PRACTICAL SESSION
Performing Spirometry
Spirometry Training• Training is essential for operators to learn correct performance
and interpretation of results
• Training for competent performance of spirometry requires a minimum of 3 hours
• Acquiring good spirometry performance and interpretation skills requires practice, evaluation, and review
• Spirometry performance (who, when and where) should be adapted to local needs and resources
• Training for spirometry should be evaluated
Obtaining Predicted Values
• Independent of the type of spirometer• Choose values that best represent the• tested population• Check for appropriateness if built into • the spirometer
Optimally, subjects should rest 10 minutesbefore performing spirometry
Performing Spirometry - Preparation1. Explain the purpose of the test and
demonstrate the procedure2. Record the patient’s age, height and gender
and enter on the spirometer3. Note when bronchodilator was last used4. Have the patient sitting comfortably5. Loosen any tight clothing 6. Empty the bladder beforehand if needed
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 100ml or 5% of each other are obtained
Reproducibility - Quality of Results
Volu
me,
lite
rs
Time, seconds
Three times FVC within 5% or 0.15 litre (150 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
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
Troubleshooting
Examples - Unacceptable Traces
Unacceptable Trace - Poor Effort
Volu
me,
lite
rs
Time, seconds
May be accompanied by a slow start
Inadequate sustaining of effort
Variable expiratory effortNormal
Unacceptable Trace – Stop Early
Volu
me,
lite
rs
Time, seconds
Normal
Unacceptable Trace – Slow Start
Volu
me,
lite
rs
Time, seconds
Unacceptable Trace - Coughing
Volu
me,
lite
rs
Time, seconds
Normal
Unacceptable Trace – Extra Breath
Volu
me,
lite
rs
Time, seconds
Normal
Spirometry
• Mrs PZ 47 yrs• FEV-1 = 0.8L (35% of pred)• FVC = 2.4L (85% of pred)• FEV-1/FVC Ratio = 30%
Spirometry
• Answer:
Spirometry
• Mr PY 83• FEV-1 =0.6L (28%pred)• FVC = 1.9 L (81% pred)• FEV-1/FVC ratio =31.5%
Spirometry
• Answer:
Spirometry
• Mr BY 63• FEV-1 = 1.6 L (63% pred• FVC = 2.1 L (67% pred)• FEV-1/FVC ratio = 76%
• Mr BY 63• FEV-1 = 1.6 L (63% pred• FVC = 2.1 L (67% pred)• FEV-1/FVC ratio = 76%
Spirometry
• Answer-
Spirometry
• Mrs TZ 56• FEV-1 =1.1L (41% pred)• FVC = 2.3 L (63%pred)• FEV-1/FVC ratio =48%
Spirometry
• Answer?
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;29:319-338www.thoracic.org/sections/publications/statements
• National Asthma Council: Spirometry Handbookwww.nationalasthma.org.au