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 (FEV 1 ) 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 β 2 -agonists for 6 hours Long acting β 2 -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

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

• FEV 1 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 • FEV 1 /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 • FEV 6 – 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 Tidal volume Expiratory reserve volume Residual volume Inspiratory capacity 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 • FEV 1 : % predicted > 80% • FVC: % predicted > 80% • FEV 1 /FVC: > 0.7

Normal Trace Showing FEV 1 and FVC FVC 5 4 3 2 1 FEV 1 = 4L FVC = 5L FEV 1 /FVC = 0.8

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 5 4 3 2 1 Normal FEV 1 = 1.8L

FVC = 3.2L

FEV 1 /FVC = 0.56

Obstructive 1 2 3 4 5 6 Time, seconds

Spirometric Diagnosis of COPD • COPD is confirmed by post– bronchodilator FEV 1 /FVC < 0.7

• Post-bronchodilator FEV salbutamol or equivalent 1 /FVC measured 15 minutes after 400µg

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

• FEV 1: % predicted < 80% • FVC: % predicted < 80% • FEV 1 /FVC: > 0.7

Spirometry: Restrictive Disease

5 4 3 2 1

Normal Restrictive FEV 1 = 1.9L

FVC = 2.0L

FEV 1 /FVC = 0.95

1 2 3 4 5

Time, seconds

6

Mixed Obstructive/Restrictive • FEV 1 : % predicted < 80% • FVC: % predicted < 80% • FEV 1 /FVC: < 0.7

Mixed Obstructive and Restrictive Normal Obstructive - Restrictive FEV 1 = 0.5L

FVC = 1.5L

FEV 1 /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

Expiratory flow rate L/sec TLC Inspiratory flow rate L/sec

Flow Volume Curve

Maximum expiratory flow (PEF) FVC RV Volume (L)

Flow Volume Curve Patterns Obstructive and Restrictive

Predicted versus actual

Obstructive Severe obstructive Restrictive Volume (L) Reduced peak flow, scooped out mid curve Volume (L) Steeple pattern, reduced peak flow, rapid fall off Volume (L) Normal shape, normal peak flow, reduced volume

Spirometry: Abnormal Patterns Obstructive Restrictive Mixed Time Slow rise, reduced volume expired; prolonged time to full expiration 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