All measuring devices are susceptible to drifts (shocks, transport, wear and tear), which could falsify measurements and interpretation of tests. As such, we advise periodically checking the spirometer to confirm the validity of measurements performed.

Different methods for checking a respiratory function test:

Visual check:
Inspection of sensor, different connections (computer, power supply), external aspect of the spirometer. A simple means of checking the state of the device to detect wear and tear and malfunctions. However, this does not check device precision.
Time: about 1 min.

Functional check:
Performing a test (VC, FVC) with a known patient: to determine correct functioning of the spirometer. This does not, however, indicate precision of the device.
Time: about 5 min.

Check with calibration syringe:
The test is performed with the calibrating syringe, to check the precision of the volume measured. If the difference in volume is too great, the sensor should be calibrated.
Time: less than 5 min.
Frequency: once per day (ATS recommendation).
Average cost of a 3L calibration syringe: approx. 400 € before tax.

ATS recommandations for quality* control:

• Daily calibration check with a 3L syringe.
•  Keep a log of calibration results.
  
•  Keep traces of any sort of intervention necessary for correct functioning of the devices (repairs, etc.).
  
•  Note the date of updates or changes in software or computer equipment.
  

*Extract from European Respiratory Journal Volume 26 Number 2 «Standardisation of Spirometry».