Respiratory
Division
Diagnostic Products
Spirometry
Spirometry made Simple
Accuracy
As with most diagnostic equipment, it is important for the professional to check the machine is functioning correctly. Periodic cleaning will reduce the risk of dirt and moisture causing malfunction, but the accuracy will need to be checked at regularintervals.
To check the accuracy of either VM device, the pointer on the Mini-Wright must be set at zero before each patient is tested, and a comparison made between the Mini-Wright and electronic PEF readings after a successful exhalation.
It is unlikely that both will be the same (the electronic reading will be more accurate), but they should differ by no more than 10%.
Faults in the patient’s technique are the most common reason for poor quality readings.
The main errors include:-
If any of these faults occur the results given will be incorrect and the patient will have to restart the process.
However, there may be some less obvious factors that affect the results given by any one patient. It is important to note in the records if, and at what time, any of the following have been taken:
Short-acting bronchodilators – within previous 6 hours
Long-acting bronchodilators – within the previous 12 hours
Slow release theophyllines – within the previous 24 hours
Before each patient begins the test, they should ensure that they are wearing loose clothing around the abdomen, as clothing can restrict full chest and abdominal expansion.
