Spirometry calibration

Question 1

define quality control

Answer 1

a series of checks to ensure that results generated are as accurate and precise as possible

-need to be good repeatability (during the test) and reproducability (between visits)

Question 2

What is calibration?

Answer 2

-comparing the measurements of two instruments, one with a known magnitude or correctness (standard device) against which you measure the other and correct if necessary

Question 3

What is verification?

Answer 3

checking an instrument and ensuring any error of measurement is within permissible limits

-spirometers have their calibration verified by injecting a known volume, 3L syringe is used

Question 4

What value is acceptable for verification?

Answer 4

+/- 3% of true volume

Question 5

Why do we calibrate a spirometer?

Answer 5

-Spirometers are precision instruments which have been calibrated by the manufacturer.​

-If the accuracy is not checked, then errors would go undetected.​

-Correct interpretation of spirometry can only be made if the results are accurate.​

-By performing spirometry to ARTP standards, you can have confidence in the results produced.​

Question 6

Describe the verification of calibration process

Answer 6

Use a 3 litre syringe.​

-it must read +/- 3% of true value i.e. between 2.91L – 3.09L.​

-Calibration should be verified every morning before each clinic session and again after every 4 hours of use.​

-Recheck if room temp changes by more than 5oC​

-A calibration log should be maintained (software or logbook)​

-Calibration syringe need to be checked YEARLY​

Question 7

What should you do if the verification of calibration is unsuccesful?

Answer 7

-return the spirometer to the manufacturer for recalibration

-can’t be used for testing until it can be successfully calibrated

Question 8

Why do some spirometers need calibration checks at different flows?

Answer 8

-low, middle and high flow rate are generated by applying different pressure to the calibration syringe

-checking each flow is getting the volume

Question 9

How do you chek the physiological control of a spirometer?

Answer 9

-perform 10 consecutive spirometry tests which should be reproducible and technically acceptable .​

• performed by the same operator at a similar time of day.​

-Add each of 10 FEV1, 10 RVC, 10 FVC, and 10 PEF together and divide by 10 to get average.​

-Work out 5% either side to represent normal variability and create acceptable operating range.​

-Check your own against the range at least weekly and log results.​

Not to be done instead of the calibration syringe but as an extra level of calibration

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Question 10

What needs to be included in the calibration log book?

Answer 10

-equiptment calibrated(model, serial number)
-date
-time
-temp
-operator
-syringe used
-was calibration check successful?