spirometryprecoursebooklet210909

Provision of Spirometry in Primary Care

Stage One Training

Pre-Course Reading Material

- 1 -Copyright © 2008 Southend University Hospital, NHS Foundation Trustwww.southend.nhs.uk

Index

Spirometry

Background to Spirometry

How Do We Breathe?

What is Spirometry?

Definitions of Terms Used in Spirometry

Obstructive or Restrictive Disorders

Who Should We Be Testing?

Are There Patients We Should Not Test?

Definition of COPD

COPD, Smoking and Spirometry

Making a COPD Diagnosis

Spirometry & Asthma Diagnosis: Reversibility Testing

What Should We Do Before Performing a Test?

How to Perform Spirometry Tests for FEV¹ & FVC Measurements

What Are Acceptable Results?

What is the Right Spirometer For Me?

Infection Control

References

AppendicesAppendix 1 - Flow Chart for InterpretationAppendix 2 - QuizAppendix 3 - Case Studies


SPIROMETRY

Background to Spirometry

A number of disorders can cause detrimental changes in the lungs and airways. The most important effects are on the calibre of the airway and the elastic recoil of the lungs. Spirometry testing is valuable in the detection of some of these abnormalities associated with respiratory disorders.

Spirometry has been available for the last 40 years. However, the volume of air which a person inhales during a single deep breath was first measured in 1679. Hutchinson quantified this later in 1846 and defined Vital Capacity as ‘the greatest voluntary expiration following the deepest inspiration’. He designed the spirometer for this estimation. In 1915 Rohrer examined the relationship between the forces exerted by the respiratory muscles over the rate of airflow.


Spirometry is possibly the most common respiratory test performed in hospitals and in the community. However approximately 30% of GP practices do not have access to a spirometer.

The use is increasing since the introduction of the GMS contract in 2004. Predominantly it is practice nurses who perform the test, however many lack confidence in performing and interpreting the results.

Practitioners of Spirometry not only need good quality training but also need to perform the test regularly in their working environment. They need to be aware of the calibration and quality controls needed to maintain their equipment so that they can be sure that the tests they perform will produce accurate and precise results.

There are many different types of spirometers available and it is the manufacturer's responsibilities to ensure that their equipment meets the same criteria as others; however it is the person using the equipment who must ensure that these standards are maintained.

The performance of the test must reach certain criteria so that all patients' results, wherever they are tested, will be similar.

The Spirometry training will ensure that the vast majority of staff who perform these tests will produce reproducible results on any type of spirometer in any situation.

Spirometry provides doctors, nurses and other medical personnel with important and meaningful information to aid in the accurate diagnosis and monitoring of various respiratory diseases, and of differentiating between obstructive and restrictive diseases.

How Do We Breathe?

Breathing is important because your body needs the oxygen in the air you breathe to create the energy that keeps you alive.

When fresh air is breathed in through the nose and mouth, it is pulled through the windpipe or trachea and into the lungs. (You have two lungs, with the right lung being slightly larger than the left lung.) From the windpipe, the air moves through two large passageways, called the bronchi. A complex system of much smaller tubes, or bronchioles, branch out from your bronchi to carry oxygen to the "working parts" of the lungs — the millions of air sacs or alveoli. These small sacs (like tiny folded balloons) have very thin walls that are full of blood vessels. The walls are so thin that the oxygen in the air can pass through them to enter your bloodstream and travel to cells in all parts of your body.

When you breathe in, you are inhaling oxygen which is the “fuel” to make your body cells work. And when you breathe out, you are exhaling the bi-product of your body cells’ work – a


gas called carbon dioxide, which is often called "used" air. Carbon dioxide is exhaled with every breath you blow out of your lungs.

The respiratory tract is divided into two main parts: the upper respiratory tract, consisting of the nose, nasal cavity and the pharynx; and the lower respiratory tract consisting of the larynx, trachea, bronchi and the lungs.

The trachea, which begins at the edge of the larynx, divides into two bronchi and continues into the lungs. The trachea allows air to pass from the larynx to the bronchi and then to the lungs. The bronchi divide into smaller bronchioles which branch in the lungs forming passageways for air. The terminal parts of the bronchi are the alveoli. The alveoli are the functional units of the lungs and they form the site of gaseous exchange.


Breathing is usually automatic, controlled subconsciously by the respiratory centre at the base of the brain. Breathing continues during sleep and usually even when a person is unconscious. Sensory organs in the brain and in the aorta and carotid arteries monitor the blood and sense oxygen and carbon dioxide levels. Normally, an increased concentration of carbon dioxide is the strongest stimulus to breathe more deeply and more frequently. Conversely, when the carbon dioxide concentration in the blood is low, the brain decreases the frequency and depth of breaths. During breathing at rest, the average adult inhales and exhales about 15 times a minute.

Air is inhaled by the active contraction of the respiratory muscles. The major respiratory muscle is the diaphragm, a large muscular partition that separates the chest cavity from the abdominal cavity. It lies beneath the lungs and is dome shaped, with the apex of the dome in approximation with the lower portion of the lungs. During inhalation, the diaphragm contracts downward and away from the lungs, creating more space in the chest cavity. This lowers the pressure in the chest cavity relative to the pressure outside the body, and air moves into the lungs.

The diaphragm receives help from accessory muscles. The muscles in the neck that attach to the upper part of the sternum and clavicles, such as the sternocleidomastoid muscle, and the muscles between the ribs, called the intercostal muscles, increase the diameter of the chest wall, which helps lower the pressure in the chest. Intercostal muscles contract and shrink the chest wall during forced exhalation.

Inspiration (inhalation) is the process of taking air into the lungs. It is the active phase of ventilation because it is the result of muscle contraction. During inspiration, the diaphragm contracts and the thoracic cavity increases in volume. This decreases the intra-alveolar pressure so that air flows into the lungs. Inspiration draws air into the lungs.

Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle. During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intra-alveolar pressure. Expiration pushes air out of the lungs.


What is Spirometry?

It is the method of assessing lung function by measuring the volume of air that the patient is able to expel from the lungs after a maximal inspiration. It is a reliable method of differentiating between diseases with obstructive airways (eg: COPD and Asthma) and restrictive disorders such as Fibrotic Lung disease. It is the most effective way of determining the severity of COPD/Asthma etc. However there are other measures such as the MRC breathlessness score and Borg breathlessness score which may be useful to ascertain activity levels and the impact of breathlessness.

Definitions of Terms Used in Spirometry

FEV¹ = Forced Expiratory Volume in the First Second

The maximal volume of air which can be expired from the lungs in the first second of a forced expiration from the position of full inspiration:

Above 80% of predicted value based on age, height and gender is normal

All RESTRICTIVE and OBSTRUCTIVE defects will have reduced FEV¹

Grading for COPD (according to NICE guidelines)

50-80% Mild

30-49% Moderate

<30% Severe

FVC = Forced Vital capacity.

Normal subjects can expire to their FVC within 4.6 secs.

Patients with OBSTRUCTIVE defects will take significantly longer. If the maximum volume of FVC is completed in over 6 seconds, this indicates a possible obstructive defect. If it is completed in less than 2 seconds, this indicates a possible restrictive defect. If the blow terminates at 6 seconds and the FVC is still increasing, the FVC will be an underestimate.

Patients with RESTRICTIVE defect will have significantly reduced FVC and VC (Vital Capacity)

Patients with RESTRICTIVE defect will have significantly reduced FVC and VC (Vital Capacity).

Patients with OBSTRUCTIVE defects will have low or near normal FVC.


FEV¹/FVC Ratio

Normal is considered 70% of baseline (although this decreases with age so elderly patients could be considered normal if the FEV¹ %FVC is 65% of predicted)

Patients with OBSTRUCTIVE defects will have a reduced ratio.

Patients with RESTRICTIVE defects usually have normal or raised ratio.

Table 1 – Summary table of disease affecting Spirometry

Obstructive Ventilatory Defect

Effect on FEV¹ Effect on FVC Effect on FEV¹/FVCRatio (%)

Asthma( Normal if well)

or normal or

COPD

Emphysema

Cystic Fibrosis

Restrictive Ventilatory Defect

Effect on FEV¹ Effect on FVC Effect on FEV¹/FVCRatio (%)

Pulmonary Fibrosis

E.G.IPF

or

Sarcoidosis or

Kyphosciolosis or

Muscle weakness

E.G. MND/ Guillan-Barre

or

Obesity or Normal or


Obstructive and Restrictive Disorders

Spirometry results may be used to classify a patient's lung function into one of four different disease patterns or classifications of ventilatory function; Normal, Obstructive, Restrictive and Combined.

Normal Ventilatory Function:

Using the NICE/BTS guidelines a patient with an FEV¹ of greater than 80% would be deemed to have normal lung volumes and flow rates for a patient of their age, sex and height.

Obstructive Ventilatory Function

An obstructive disorder refers to any disease that causes narrowing of the airways. This could be the result of excessive mucus production, inflammation or bronchoconstriction or collapsing airways.

The obstructive pattern presents itself as reduced flow rates and the definitions of the most common disease are:

(NB –COPD is the new terminology used to describe Chronic Bronchitis and Emphysema.)

Chronic bronchitis

Chronic bronchitis is a chronic inflammatory condition in the lungs that causes the respiratory passages to be swollen and irritated, increases the mucus production and may damage the lungs. The symptoms are coughing and breathlessness, which will get worse over the years.The definition of chronic bronchitis is chronic cough or mucus reproduction for at least three months in two successive years when other causes have been excluded.

Emphysema

Emphysema is characterized by loss of elasticity (increased pulmonary compliance) of the lung tissue, from destruction of structures supporting the alveoli, and destruction of capillaries feeding the alveoli, owing to the action of alpha 1 antitrypsin deficiency. Thus the small airways collapse during exhalation, as alveolar collapsibility has increased. This impedes airflow and traps air in the lungs, as with other obstructive lung diseases. Symptoms include shortness of breath on exertion and later at rest, hyperventilation, and an expanded chest. It is often caused by exposure to toxic chemicals, including long-term exposure to tobacco smoke.


http://en.wikipedia.org/wiki/Pulmonary_compliance

http://en.wikipedia.org/wiki/Tobacco_smoking

http://en.wikipedia.org/wiki/Chemical_substance

http://en.wikipedia.org/wiki/Toxin

http://en.wikipedia.org/wiki/Hyperventilation

http://en.wikipedia.org/wiki/Capillary

http://en.wikipedia.org/wiki/Alveoli

Asthma

Asthma is a chronic condition involving the respiratory system in which the airways occasionally constrict, become inflamed, and are lined with excessive amounts of mucus, often in response to one or more triggers. These episodes may be triggered by such things as exposure to an environmental stimulant such as an allergen, environmental tobacco smoke, cold or warm air, perfume, pet dander, moist air, exercise or exertion, or emotional stress. In children, the most common triggers are viral illnesses such as those that cause the common cold. This airway narrowing causes symptoms such as wheezing, shortness of breath, chest tightness, and coughing. The airway constriction responds to bronchodilators. Between episodes, most patients feel well but can have mild symptoms and they may remain short of breath after exercise for longer periods of time than the unaffected individual. The symptoms of asthma, which can range from mild to life threatening, can usually, be controlled with a combination of drugs and environmental changes.

Restrictive Ventilatory Function

A restrictive disorder is one that may affect the lung tissue itself or the capacity of the lungs to expand and hold predicted volumes of air. This could be due to muscle weakness, fibrosis, scarring, physical deformity such as kyphoscoliosis or a patient with only one lung.

Combined Ventilatory Function

This pattern would exhibit features of both an obstructive and restrictive defect. An example of this could include Cystic fibrosis, which can cause excess mucus production and damage lung tissue.


http://en.wikipedia.org/wiki/Medication

http://en.wikipedia.org/wiki/Bronchodilators

http://en.wikipedia.org/wiki/Cough

http://en.wikipedia.org/wiki/Dyspnea

http://en.wikipedia.org/wiki/Wheezing

http://en.wikipedia.org/wiki/Symptom

http://en.wikipedia.org/wiki/Common_cold

http://en.wikipedia.org/wiki/Stress_(medicine)

http://en.wikipedia.org/wiki/Exercise

http://en.wikipedia.org/wiki/Allergen

http://en.wikipedia.org/wiki/Mucus

http://en.wikipedia.org/wiki/Inflammation

http://en.wikipedia.org/wiki/Lung

http://en.wikipedia.org/wiki/Respiratory_system

http://en.wikipedia.org/wiki/Condition

http://en.wikipedia.org/wiki/Chronic_(medicine)

Who Should We Be Testing?

Guidelines suggest we should consider screening all patients who may be at risk of COPD, including all smokers who are over the age of 35 years of age. However this may not be practical so you need to be able to identify those who may be a risk. ( Case finding)

To help here is a list of indicators you should look out for those have been identified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD 2003).

Key Indicators for Considering a Diagnosis of COPD

Dyspnoea: Progressive, slow, and often ignored. (worsens over time) Usually worse with exercise Persistent (present every day) Described by the patient as an: “Increased effort to breathe,” “Heaviness,” “air hunger,” or “gasping.”

Chronic cough: May be intermittent and may be unproductive.

Chronic sputum production: Any pattern of chronic sputum production may indicate COPD.

History of exposure to risk factors: Tobacco smoke. THE MOST IMPORTANT

Occupational dusts and chemicalsSmoke from home cooking and especially heating fuels.


Are There Patients We Should Not Test?

Before referring a patient for a Spirometry test you must always consider the relative contra-indications listed below, that pose a danger to the patient or the validity of

the results:1) Haemoptysis of unknown origin: the FVC manoeuvre may aggravate the underlying

condition

2) Pneumothorax3) Unstable cardiovascular status, recent* myocardial infarction, or pulmonary embolism:

FVC manoeuvre may worsen angina or cause blood pressure changes4) Thoracic, abdominal or cerebral aneurysms: danger of rupture due to increased thoracic

pressure

5) Recent* eye surgery: increased intraocular pressure

6) Acute disorders affecting test performance such as nausea or vomiting

7) Recent* thoracic or abdominal surgical procedures.

* The term 'recent' is not defined by any of the associations involved with Spirometry and it is

advisable to seek further advice if a patient presents with any of these symptoms before

proceeding with test.

The enclosed algorithm from NICE should help you to decide:


Definition of COPD

COPD is characterised by airflow obstruction. The airflow obstruction is usually progressive, not fully reversible and does not change markedly over several months. The disease is predominantly caused by smoking.

Think of the COPD diagnosis for patients who are:

Over 35 Smokers or ex-smokers Have any of these symptoms:

o Exertional breathlessnesso Chronic cougho Regular sputum productiono Frequent winter ‘bronchitis’o Wheeze

And have no clinical features of asthma (see table below)

Perform Spirometry if COPD seems likely

Airflow obstruction is defined as:FEV¹ < 80% predictedAnd FEV¹/FVC < 0.7

Spirometric reversibility testing is not usually necessary as part of the diagnostic process or to plan initial therapy

If still doubt about diagnosis consider the following pointers:

Asthma may be present if:o There is a >400 ml response to bronchodilatorso Serial peak flow measurements show significant diurnal or day-to-day

variability Clinically significant COPD is not present if FEV , and FEV¹/FVC ratio return to normal

with drug therapy Refer for more detailed investigations if needed

If still in doubt, make a provisional diagnosis If no doubt, diagnose COPD and startand start empirical treatment. treatment.

Reassess diagnosis in view of response to treatment


Clinical features differentiating COPD and Asthma

COPD Asthma

Smoker or ex-smoker Nearly all Possibly

Symptoms under age 35 Rare Common

Chronic productive cough Common Uncommon

Breathlessness Persistent and progressive Variable

Night-time waking with breathlessness and/or wheeze

Uncommon Common

Significant diurnal or day-to-day variability of symptoms

Uncommon Common


COPD, Smoking and Spirometry

The guidelines from the National Institute for Clinical Excellence (NICE) 2004 define COPD as characterised by airflow obstruction. The airflow obstruction is usually progressive, not fully reversible and does not change markedly over several months. COPD is a spectrum of disorders which include chronic bronchitis and emphysema. Approximately 900,000 people in England and Wales were identified as suffering from COPD in 1999. As many patients go undiagnosed, a more accurate figure would be at least twice this number. COPD is a major cause of mortality. In1999 there were 30,000 deaths from COPD, almost 20 times the number that died as a result of asthma.

The major cause of COPD is tobacco smoking. In susceptible individuals, smoking accelerates the normal age-related decline in lung function. Although smoking causes irreversible structural changes, cessation allows the rate of decline in lung function to return to that of a non-smoker.

Early identification of COPD enables targeting on smoking cessation advice and so may prevent progression of this potentially fatal disease.

Decline in lung function in smokers and non smokers

Early identification of COPD enables targeting of smoking cessation advice and so may prevent progression of this potentially fatal disease.


Making a COPD Diagnosis

How do you make a diagnosis of COPD? You should consider the diagnosis of COPD in patients aged over 35 years who smoke or have smoked, and have appropriate chronic symptoms of breathlessness, cough and sputum. The diagnosis is confirmed by demonstrating airflow obstruction using Spirometry. Peak flow meters, whilst excellent for monitoring asthma, are of limited value in COPD diagnosis as the readings may underestimate the extent of lung impairment.

NICE and all international guidelines recommend the use of Spirometry to confirm the diagnosis and assess the level of severity in COPD.


Spirometry and Asthma Diagnosis : Reversibility Testing

DIAGNOSIS IN ADULTS

The diagnosis of asthma is based on the recognition of a characteristic pattern of symptoms and signs and the absence of an alternative explanation for them. The key is to take a careful clinical history. In many cases this will allow a reasonably certain diagnosis of asthma, or an alternative diagnosis, to be made. If asthma does appear likely, the history should also explore possible causes, particularly occupational. Repeated assessment and measurement may be necessary before confirmatory evidence is acquired. Confirmation hinges on demonstration of airflow obstruction varying over short periods of time.

Spirometry, which is now becoming more widely available, is preferable to measurement of peak expiratory flow because it allows clearer identification of airflow obstruction, and the results are less dependent on effort.

Spirometry should be the preferred test where available (although some training is required to obtain reliable recordings and to interpret the results).

Of note, a normal spirogram (or PEF) obtained when the patient is not symptomatic does not exclude the diagnosis of asthma. Results from Spirometry are also useful where the initial history and examination leave genuine uncertainty about the diagnosis. In such cases, the differential diagnosis and approach to investigation is different in patients with and without airflow obstruction.

In patients with a normal or near-normal spirogram when symptomatic, potential differential diagnoses are mainly non-pulmonary; these conditions do not respond to inhaled corticosteroids and bronchodilators. In contrast, in patients with an obstructive spirogram the question is less whether they will need inhaled treatment but rather exactly what form and how intensive this should be.

Other tests of airflow obstruction, airway responsiveness and airway inflammation can also provide support for the diagnosis of asthma, but to what extent the results of the tests alter the probability of a diagnosis of asthma has not been clearly established, nor is it clear when these tests are best performed.

Spirometry is the preferred initial test to assess the presence and severity of airflow obstruction.

B2 & Corticosteroid Trials

A >400 ml improvement in FEV¹ to either β2 agonists or corticosteroid treatment trials strongly suggests underlying asthma. Smaller improvements in FEV¹ are less discriminatory and a decision on continuation of treatment should be based on objective assessment of symptoms using validated tools. Trials of treatment withdrawal may be helpful where there is doubt.

Assess FEV¹ (or PEF) and/or symptoms: before and after 400 mcg inhaled salbutamol in patients with diagnostic uncertainty and airflow obstruction present at the time of assessment


in other patients, or if there is an incomplete response to inhaled salbutamol, after either inhaled corticosteroids (200 mcg twice daily beclometasone equivalent for 6-8 weeks) or oral prednisolone (30 mg once daily for 14 days).

In adults, most clinicians would try a 6-8 week treatment trial of 200 mcg inhaled beclometasone (or equivalent) twice daily. In patients with significant airflow obstruction there may be a degree of inhaled corticosteroid resistance and a treatment trial with oral prednisolone 30 mg daily for two weeks is preferred.

Bronchodilator Reversibility Test

Pre and post bronchodilator reversibility testing is recommended.

A 15% or more change from baseline in FEV¹ and 200ml or more will confirm diagnosis.

Patients with airways obstruction

Tests of peak expiratory flow variability, lung volumes, gas transfer, airway hyper-responsiveness and airway inflammation are of limited value in discriminating patients with established airflow obstruction due to asthma from those whose airflow obstruction is due to other conditions. Patients may have more than one cause of airflow obstruction, which complicates the interpretation of any test. In particular, asthma and chronic obstructive pulmonary disease (COPD) commonly coexist.

Offer patients with airways obstruction and intermediate probability of asthma a reversibility test and/or a trial of treatment for a specified period: if there is significant reversibility, or if a treatment trial is clearly beneficial treat as asthma if there is insignificant reversibility and a treatment trial is not beneficial, consider tests for alternative conditions.

Patients without airways obstruction

In patients with a normal or near-normal spirogram it is more useful to look for evidence of airway hyper-responsiveness and/or airway inflammation. These tests are sensitive so normal results provide the strongest evidence against a diagnosis of asthma. In patients without evidence of airways obstruction and with an intermediate probability of asthma, arrange further investigations before commencing treatment.


What Should We Do Before Performing a Test?

Calibration

'A calibration check is the procedure used to validate that the device is within the calibration limits'

Calibration checks should be done at least on a daily basis, and if you suspect an error then a calibration check should be performed.

A syringe, usually of one or two litres volume, is attached to the equipment and this volume is injected into the equipment. The number of times this needs to be done per check is dependent on the manufacturer's instructions.

The amount measured should be within ±-3% of the volume of the syringe.

The syringe must also be checked regularly to ensure its own accuracy which must be maintained a level of ±15ml or ±O.5%. Dropped or damaged equipment should not be used until it is checked and repaired. This needs to be done using the manufacturer’s recommendations.

The syringe should be stored out of direct sunlight and from any heat sources. The temperature it is stored in should be the same as the spirometer is stored in.

The importance of doing this check regularly cannot be overstressed. Leaks can be picked up quickly. Problems with software can also be detected.

A log of all calibration checks should be kept and any problems recorded in this log and the action taken to correct any errors.

Quality Control

Quality control ensures that all aspects of the test procedure produce reliable and reproducible results.

There are two methods of quality control: 1. Mechanical 2. Physiological

Mechanical would be using a calibration syringe as described previously.

Physiological control is to use a member of staff or yourself with known normal values and test that person on a regular basis. There should be at least two members of staff tested in case of the absence of one person. The results of each test should be logged and compared against the previous tests. This will ensure accuracy, precision and reproducibility of tests.


How to Perform Spirometry Tests for FEV¹ and FVC Measurements

1. Once the equipment is set up for use, explain the purpose of the test to the patient and check for contra-indications.

2. For accurate results you should ascertain if the patient has avoided:a) Smoking for 24hrs prior to test b) Consuming alcohol for at least 4 hrs c) Vigorous exercise for at least 30 mins prior to test d) Eating a substantial meal for at least 2 hrs prior to test. e) Taking short or long acting bronchodilator drugs for the duration of their

action i.e. salbutamol for 4-6 hrs (If any deviation to the above it must be recorded.)

3. Ask the patient to sit in an upright position4. Instruct the patient to breathe in as deeply as possible through the mouth5. Ask patient to put a clean mouthpiece in their mouth 6. Ask the patient to blow out their breath as hard and as fast as they can into the

machine until they can blow out no longer. (Ensure that patient has exhaled until flow of air has ceased - this will vary greatly with patients. In a normal patient this could be between 5-6secs in a patient with COPD it could last a lot longer)

7. Ask the patient to remove the mouthpiece 8. A minimum of 30 seconds should be left between each test and at least THREE

technically acceptable tests should be recorded

9. Tests should be rejected if:a) The patient did not inspire to TLC (Total Lung Capacity)b) There was a leak at the mouth c) There is an obstructed mouthpiece due to tongue or false teeth d) There was a poorly co-coordinated start to manoeuvre e) There was a cough within the first second of the manoeuvre or later if it is

deemed to have interfered with the blow f) There was early termination of the blow g) The test was conducted with a sub maximal effort

10. In a technically correct test the curve should show:a) A Rapid rise at start of trace until peak flow is reachedb) A relatively smooth, continuous change in flow or volume until residual

volume is reached c) Reproducibility in shape between repeat tests (FEVl and FVC

measurements should not differ between tests more than 5%)

11. Operators should be aware that asthmatic patients may develop bronchoconstriction as a result of performing these tests. If this occurs the test should be terminated. Ensure a comment is made is on the report or chart


What are Acceptable Results?

The most common reason for inconsistent readings is patient technique. Errors may be detected by observing the patient throughout the test and by examining the traces.

Common problems are:

1) inadequate or incomplete inhalation2) cough3) slow start to the forced exhalation4) poor effort 5) early stoppage of the manoeuvre (trace stops abruptly)

Incomplete blow


What is the Right Spirometer for me?

There are many different types of spirometer with costs varying from £300 to over £3000.

The simplest hand-held spirometers produce FEV¹ and FVC readings, which you then need to compare with predicted normal values

More advanced spirometers produce traces (i.e. visual display or print-out) of the volume of air exhaled over time, the volume-time curve, so you can see how well the patient has carried out the manoeuvre. If your spirometer has a memory facility, you may also be able to store the trace.

Many electronic spirometers also display a flow-volume curve. You do not need this information to calculate FEV¹ and FVC values for your patient, so it is not necessary to use this facility when you are new to Spirometry.

Most spirometers calculate the percentage of the predicted normal values because they have reference data already programmed into them. You have to enter details of the patient’s sex, race, age and height.

Spirometers are designed for use in all types of lung disease and not just COPD.

Some spirometers will provide a report on lung function results including comments such as normal, obstructive and restrictive defects. They may also comment on severity of disease, though not necessarily corresponding to the NICE COPD classifications (i.e. actual FEV¹% predicted values need to be studied to provide the correct severity levels).

There are many spirometers we could choose from:


Dry Wedge Bellows

These consist of a square shaped bellows mounted in a box. It is solely for expiratory measurements. The patient blows into the machine and the bellows expand pushing a stylus upwards. The stylus moves across a pressure sensitive paper and makes a recording. The bellows are calibrated so the stylus moves the appropriate distance to record the correct volume on the chart paper. An electric motor drives the chart horizontally to give a record of volume against time. I believe only Vitalograph produces this type of equipment now.

It is big and bulky and cannot record inspiratory measurements. The recalibration requires specialist medical engineer and the inside cannot be cleaned.

It is a simple piece of equipment and is reliable and accurate.

Rotary Vein

The rotation of the vein interrupts light from two light emitting diodes and provides a digital count. The volume of air passing through the turbine is proportional to the total number of pulses generated and the flow is proportional to the frequency of the pulse generation.

These are difficult to calibrate and are not always accurate as they tend to under read at low flow rates. They are cheap and most are portable although care needs to be taken as they tend to be fragile.


Pneumotachograph

There are two types of pneumotachographs the Lily and the Fleisch. Both consist of a tube split in two parts by a differential transducer. The transducer can be made of wire mesh or capillary tubes. Basically the air flows down the tube in which the wire mesh or capillary tube causes a partial obstruction. The pressure beyond the obstruction is less than that immediately before it. The difference, which is the pressure drop across the resistance is a function of the rate of flow.

Most pneumotachs are easy to clean, light to hold and portable. They can be heated which prevents condensation. The results are accurate and reproducible and the equipment tends to be very reliable.

They need to be connected to an output drive to display trace, and technical problems are not uncommon if they are not heated.


Infection Control

Sterilisation and Disinfection

All parts of instruments that come into contact with the mucus membrane, or could potentially become contaminated with saliva, should be decontaminated.

Sterilisation

Definition: 'the complete destruction of all micro organisms and their spores, either by chemical or physical agents.

(ARTP Spirometry Handbook 2000)

The spirometer would need to be stripped down and the parts would need to be steamed at high temperature for 3 - 10 mins dependent on the temperature used.

Disinfection

Definition: 'the provision of freedom from infecting organisms: it is the destruction of potentially pathogenic micro organisms but not their spores.”

(ARTP Spirometry Handbook 2000 )

Several methods of disinfection are available. Probably the most common and convenient is the use of chlorine disinfectant tablets such as Actichlor. The parts of the spirometer that are not single patient use are soaked in a solution made up to manufacturers instructions for as long as recommended. They should then be rinsed and dried. This method is a good veridical agent and kills most micro organisms.

Another option is to steam the parts at temperatures lower 120°c but this is actually not as efficient as the above method.

All methods have advantages and disadvantages and the method used will depend on cost, effectiveness, suitability for the material or object being decontaminated, ease of use and availability.

Frequency of cleaning

'Best practice' would include daily, post session and weekly documented cleaning procedures.


Always follow the manufacturer's instructions.

Other Infection Control Procedures

Patients with a known infectious disease and who require Spirometry should preferably be tested at the end of the day on equipment that can be fully sterilised. If this is not possible strip the spirometer, replace mouthpieces, filters. Clean other areas with, for example “clini-wipes”

Immuno-comprised patients should be tested at the start of the day using freshly decontaminated equipment and accessories.

Bacterial filters should be used.

The wearing of gloves can cut down the risk of cross infection from bodily fluids.

Hand washing should be done between patients and use of a microbiological hand rub can be used to supplement this.


References

1. Gold 2003, Chronic Obstructive Pulmonary Disease National clinical guideline formanagement of chronic obstructive pulmonary disease in adults in primary andsecondary care. Thorax 2004; 59 (Suppl 1): 1–232

2. Survey of GPs and practice nurses. PMSI. Presented by Bellamy et al. at British Thoracic Society meeting Dec 1998

3. Burden of lung disease A statistics report from the British Thoracic Society. November 2001

4. Making Spirometry happen. Thorax 1994; 54 (53): A43

5. ARTP Spirometry Handbook produced by Association of Respiratory Technology and Physiology, 2000

6. British Thoracic Society (BTS) COPD Consortium April 2005

7. Thorax 2008;63(Suppl IV):iv1–iv121. doi:10.1136/thx.2008.097741 iv17


Appendices - Appendix 1

Flow Chart for Interpretation(using NICE/BTS guidelines)


Observe graph for abnormalities/technique

Measure FEV¹

FEV¹ reduced(Below 80% pred.)


Measure FEV¹/FVCratio

Ratio below 70%(can go as low as 65% in very elderly)

Ratio above 70%

Obstructive(may have a mixed defect)

REPORT GRADE OF OBSTRUCTION

(see attached definitions and values)

IF REVERSIBLITY TEST PERFORMED

15% OR MORE CHANGE IN FEV1 FROM BASELINE

AND

200 ML OR MORE

TO PROVE REVERSIBLITY

Suspect restrictive(? Need for further tests)

NORMAL(All but borderline obstructive/restrictive can be ruled out)

FEV¹(80% pred or above)

Appendix 2 - Spirometry Quiz

1) Who should be referred for spirometry testing? Answer

2) Which two are contra-indications to performing a spirometry test?

Answer

3) Define the terms FEV¹ and FVC

Answer

4) Which four things the patient should be asked to avoid prior to the spirometry test?

Answer

5) What are the categories for the NICE/BTS guidelines for categorising COPD?

Answer


6) What are the criteria for acceptability – What does this mean?How do you know if a spirometry result can be trusted?

Answer

7) When a post bronchodilator test is performed, what are the current criterion to prove reversibility (as per BTS/ARTP guidelines)

Answer

8) List the common problems which may cause inconsistentreadings due to patient technique errors

Answer

9) How often should you calibrate your spirometer and why?

Answer

10) A female patient aged 36yrs old attends your surgery and complains of shortness of breath and some wheeze. What tests would you consider in addition to the spirometry.

Answer


Appendix 3 - Case Studies

Case study 1

Amanda: Housewife 50yrs old

History: Attended GP’s surgery complaining of a recent onset of wheeze and shortness of breath. She is a smoker, smoking approximately 20 cigarettes a day for 30years.

Her height and weight are measured and she is 1.62m tall and weighs 57kg. She is not on any other medication. Her general health appears good but she says she gets so breathless walking up the stairs in her house and even the housework can be a chore on some days.

A Spirometry test is performed at the surgery.

Predicted Measured % Predicted

FEV¹ litres 2.51 1.31 52

FVC litres 3.31 2.88 87

FEV¹/FVC % 75 45

Technician’s commentsGood patient technique, results were acceptable and reproducible despite frequent cough.Patient had a cigarette 1 hour prior to test.

Spirometry repeated 15 mins after administration of bronchodilator (400 mcgs Salbutamol via a spacer)

Measured % Predicted %Change

FEV¹ litres 1.60 64 22

FVC litres 3.36 102 17

FEV¹/FVC % 48

ConclusionAmanda has abnormal FEV¹ (below 80%) and FEV¹/FVC ratio is below 70%. This indicates an obstructive pattern.

To grade this we would use the NICE/BTS guidelines. The FEV¹ is 52% of predicted and therefore moderate.

After administration of bronchodilator there is a 22% change. Using the ARTP/BTS guidelines for reversibility there is more than a 15% change and more than 200mls change in baseline FEV¹ so is therefore reversible.

This test would be reported a moderate obstructive pattern with reversibility.


Case study 2

David; Retired banker 77yrs old

History: Attended GP’s surgery complaining of a gradual onset of dyspnoea and cough over the past few months.

He smokes approximately 20cigarettes a day for 30years but gave up smoking 15years ago.

His height and weight are measured and he is 1.63m tall and weighs 65kg. He is on amiodarone for atrial fibrillation. He has a pet parrot.



FEV¹ litres 2.16 1.59 73

FVC litres 3.31 1.91 58

FEV¹/FVC % 69 83

Technician’s comments

Good patient technique, results were acceptable and reproducible

Conclusion

David has abnormal FEV¹ (below 80%) and FEV¹/FVC ratio is significantly raised (above 70%) . This is indicative of a restrictive defect .

Reversibility was not done.

Further lung function tests would be useful for this patient.


Case study 3

Rose: Cook, 49yrs old

History: Attended GP’s surgery complaining of a gradual but noticeable shortness of breath especially when she is working or walking with her family.

She smokes approximately 20 cigarettes a day for 25 years.

Her height and weight are measured and she is 1.85m tall and weighs 68kg. She is not on any other medication and there is no evidence of heart disease and no other symptoms apart from “ smokers cough”.



FEV¹ litres 3.89 0.80 20

FVC litres 5.34 3.56 67

FEV¹/FVC % 72 22

Technician’s comments

Good patient technique, results were acceptable and reproducible

Spirometry repeated 15 mins after administration of bronchodilator (400 mcgs Salbutamol via a spacer)

Measured % Predicted %Change

FEV¹ litres 0.90 23 3

FVC litres 3.61 67 0

FEV¹/FVC % 24

Conclusion

Rose has abnormal FEV¹ (below 80%) and FEV¹/FVC ratio is below 70%). This is indicative of an obstructive defect.

Reversibility was done but there was no significant reversibility.

This would be reported as per NICE/BTS guidelines as severe obstructive pattern seen with no reversibility

These results would confirm a diagnosis of COPD


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