Calibration and stability of Standard and Mini-Wright peak flow meters.

Periodic checks of peak flow meter (PFM) stability is essential to ensure meaningful application even when the PFMs are only used to measure the relative changes in patient peak flow rate. Calibration of PFMs becomes necessary, however, when peak flow readings are to be interpreted precisely. Techniques and flow systems which offer ease and accuracy in calibrating and/or checking PFMs were tested on Standard Wright and Mini-Wright PFMs. Individual Wright PFMs were found to be stable over a six-month testing period. The PFM readings varied from actual flow, however, and the variation from actual flow was greatest among the Mini-Wright PFMs.