Spirometry
Diana Hart NP MN(Hons)BA
Nurse Practitioner Respiratory
Diana Hart Nurse Practitioner 2008
Introduction
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What is spirometry
Objectives of spirometry
Terminology
Predicted Values
Volume Time and Flow Volume curves
International Standards and Guidelines
Contraindications
Test procedure
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Client-related problems
Assessing for reversibility
Interpretation
Reports
Care and Maintenance of equipment
Infection control
Calibration
Biological controls
Hands-on testing / questions
Evaluation
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Spirometry
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Conventionally, a spirometer is a device used to
measure timed expired and inspired volumes,
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From these we can calculate how effectively and
how quickly the lungs can be emptied and filled.
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Objectives of Spirometry
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Diagnosis
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Screening for persons at risk of having pulmonary disease.
Evaluating symptoms of respiratory impairment
Pre-op assessment
Pre-employment screening
Monitoring
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Occ Health: monitor those exposed to hazardous agents
Determine effectiveness of medication
Monitor for adverse reactions of other drugs e.g.
chemotherapy
Follow the course of disease – helps predict mortality and
morbidity.
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Disability and Impairment
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Assessing changes during respiratory rehab
Insurance risk
Employment/environmental risk
Research
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Large population studies - predicted (reference
equations),
Pharmaceutical trials
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Terminology
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VITAL CAPACITY (VC)
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Volume of air expired from a maximal inspiration
using a slow/relaxed technique.
Measured in Liters
FORCED VITAL CAPACITY
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Volume of air that can be forcibly expelled
following a maximal inspiration.
Measured in Liters
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FORCED EXPIRATORY VOLUME IN 1 sec. (FEV1)
z Volume of air blown out in the first one second of
an FVC maneuver.
z Measured in Liters.
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FEV1 / FVC Ratio
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This if the FEV1 expressed as a percentage of FVC
May be reported as FER [Forced Expiratory Ratio]
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PEF or PEFR
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FET - Forced expiratory time.
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Peak Expiratory Flow Rate
Recorded as Liters/sec (LPS) or Liters/minute (LPM)
Time taken to complete an FVC maneuver.
FEF25-75%
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Average expired flow over the middle half of the FVC
maneuver. An indication of small airways narrowing
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Predicted Values
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These values are derived from statistical analysis of
population studies of healthy individuals.
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Predicted equations for Spirometry are based on
age, sex, height, and in some cases weight.
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Weight and ethnicity should be noted on any report
as they may influence interpretation
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Selecting Predicted Values
NHANES 111 is the preferred reference equation set in
NZ.
Third National Health and Nutrition Examination Survery 1999
Am J Resir Crit Care Med 1999;159;179-187
ERS/ECCS (1993) would be the second choice
European Respiratory Society/European Community for Steel and Coal
1993
Eur Respir J 1993;6:Suppl 16
ECSC (1983) for third choice
European Community for Coal and Steel 1983
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All indices of ventilatory function should be reported at body
temperature and pressure saturated with water vapour (BTPS).
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If this is not done the results will be underestimated, because
when the patient blows into a ‘cold’ spirometer, the volume
recorded by the spirometer is less than that displaced by the
lungs.
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It is important to be able to view the graphs in
real-time as the patient performs each test. If you
can only view one graph in real time, then you would
choose the Flow/Volume graph. But both graphs should
be printed on any reports.
Volume (l)
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Baseline
Post BD1
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Flow (l/s)
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Baseline
Post BD1
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10 12 14 16 18 20
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Volume (l)
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Time (s)
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Volume Time Curve
Shows FEV1 and FVC
Flow Volume Curve
Shows PEF and FVC
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International Standards and
Guidelines
The American Thoracic Society (ATS) and the
European Respiratory Society (ERS) have set down
definitions, terminology, and standards for
spirometry measurement.
Standards are constantly being reviewed and revised
as knowledge and technology advances.
ANZRS: Professional body set up to serve
professional needs of scientists and technologists in
NZ and AUS.
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Summary of Standards
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A minimum of 3 technically satisfactory tests.
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A maximum of 8 attempts.
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The two best FVC and FEV1’s should have a variance of less
than 150mls.
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Exhaled for at least 6 seconds (adults) or reached a plateau on
the volume-time graph. (No change of volume for at least one
second.)
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Graph traces are smooth and free from irregularity
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Smooth take-off without hesitation
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Flow Chart re test acceptability
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Contraindications to Spirometry
Think about what questions you may need to ask, prior
to the test……
z Unstable angina
z Post MI (one week) or stroke
z Recent Pneumothorax
z Lack of coordination
z Mental confusion
z Lack of cooperation
z Recent surgery- eye, abdominal, thoracic
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Potential hazards
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Pneumothorax
Dizziness, light-headedness
Chest pain
Cough
Bronchospasm
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Test Procedure
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If your protocol demands that a slow VC is
measured, this should always be measured
prior to the FVC.
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Allow enough time between tests for patient
to recover.
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VC or SVC [Slow Vital Capacity]
Take a big breath in from the room, place your teeth and
lips over the mouthpiece, blow out steadily for as long as
you can. (minimum 6 seconds)
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FVC
[Forced Vital Capacity]
Take a big breath in from the room, place your teeth and
lips over the mouthpiece, blow out hard and fast, for as
long as you can. (minimum 6 seconds)
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Acceptability
Flow (l/s)
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Baseline
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Volume (l)
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Baseline
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10 12 14 16 18 20
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Volume (l)
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Time (s)
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Example of an acceptable test.
Smooth take-off without hesitation or coughing
Graphs smooth – no irregularity
1 sec plateau at end of test
Minimum 6 sec exhalation
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Patient related errors
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Inadequate inspiration or expiration
Poor mouth seal (air leakage)
Slow start to FVC
Premature termination
Coughing
Glottis closure
Teeth or tongue obstructing mouthpiece
Leak between lips and mouthpiece
Poor posture.
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Reversability
Evaluation of reversibility is a measure of the
response to a drug, and often require
withholding of bronchodilators prior to testing.
Significant improvement following
bronchodilator is indicated when there is a
12% improvement in FEV1 compared to the
baseline measurement, and a minimum of
200mls improvement.
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Interpreting the test
FVC, FEV1, and FEV1 / FVC ratio
form the basis for interpretation.
Inter-relationships of the above
measurements may also be of importance
diagnostically.
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Flow Chart
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Obstructive
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Restrictive
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Indicative of airways disease, affecting the
AIRWAYS.
Indicative of disease affecting the LUNG TISSUE.
Mixed obstructive/restrictive
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When both airways and lung tissue are affected.
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Obstructive Airways Disease
For obstruction, review the FEV1/FVC ratio first. If this is
less than Lower Limit of predicted, think obstruction,
and then observe the FEV1 to determine degree of
obstruction.
When FEV1/FVC is below the Lower Limit of Normal (LLN)…….
Mild :
FEV1 above LLN (>70% predicted)
Moderate : FEV1 40-60% predicted
Severe :
FEV1 < 40% predicted
Please check current guidelines for asthma and COPD as these
may change, depending on source.
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Normal vs Obstructive
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Restrictive Lung Disease
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For restriction, review the FEV1/FVC ratio first. If
this is normal, think restriction, and then observe
FVC to determine degree of restriction.
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When FEV1/FVC is normal
Mild :
FVC below LLN (>60% predicted)
Moderate : FVC 50-60% predicted
Severe :
FVC
< 50% predicted
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Please check current guidelines, as these may
change, depending on source
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Normal vs Restrictive
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Restrictive Lung Disease
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Affects the lung tissue
The inability of the lungs to expand. The
lungs are small because of:
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Fibrosis or scarring
Full inflation is not possible (disease of lung lining,
chest wall or abdomen.
Inspiratory respiratory muscles are weak
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Restrictive Lung Diseases
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z Ankylosing spondylitis
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Subdiaphragmatic Conditions
Ascites
Obesity
Asbestosis
Fibrosing Alveolitis
Malignant infiltration
Pleural Diseases
Effusions
Tumours
Pneumothorax
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Mixed Obstructive and Restrictive
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Both the airways and the lung tissue is involved.
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When FEV1 / FVC ratio is reduced and FVC is low.
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E.G a person with gas trapping and hyperinflation
will have a reduced FVC.
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An obese person with asthma may show a mixed
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Summary
Obstruction
Restriction
Mixed
FEV1
↓
↓ or normal
↓
FVC
↓ or normal
↓
↓
FEV1/FVC
↓
↑ or normal
↓
Diana Hart Nurse Practitioner 2008