Quality
Assurance
Accurate and reliable measurements of spirometry are very
important otherwise comparison with reference normal values is meaningless and
one would have no confidence that a given result or change in results over time
is real. Therefore, the practice of spirometry requires an ongoing program of
preventative maintenance and quality assurance:
- Regular cleaning.
- Calibration checks (consult your spirometer manual).
- Equipment maintenance to ensure that the spirometer
is operating correctly.
- Regular review to ensure ongoing test quality
A very useful and practical method of assessing the
overall performance of the spirometer is to regularly test a healthy subject
every week (‘biologic control’). Generally, a variation of more than 5% in FEV1
or FVC should alert you to a problem and the need to have your instrument
checked and serviced. Records should be kept of each calibration and the test
results from healthy subjects.
Ideally, regular calibration/validation is usually
performed with an accurate 3 litre syringe before each testing session.
Infection Control
Precautions must be taken to minimise any risk of
cross-infection via the spirometer. The use of low resistance barrier filters
significantly reduces the risk of cross-infection and also helps protect the
equipment. A new filter must be used for each patient. Re-useable mouthpieces
must be cleaned and disinfected between patients. In the case of disposable
mouthpieces, a new one must be used for each patient.
Criteria for Spirometer Performance
The American Thoracic Society (ATS)
www.thoracic.org/statements and European Respiratory Society (ERS)
www.ersnet.org/ers/
have published comprehensive guidelines on the minimum performance
specifications for spirometers.
