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