New peak expiratory flow meters (PFMs) manufactured to a new European Standard are being introduced from September 1.
It has been known for some time that existing PFMs calibrated using the Wright scale can over-read in the mid-range by up to 30%.
This has not generally caused clinical problems, although in some cases the over-reading of the Wright scale may have falsely reassured patients and their healthcare professionals so that the appropriate corticosteroid therapy has not been prescribed.
The new European standard is based on absolute flow and should produce peak flow measurements similar to those obtained by conventional spirometry and a more accurate assessment of peak flow across the entire measurement range.
The Medicines Healthcare and products Regulatory Agency (MHRA) warns that the change has the potential to cause confusion, but should lead to improvements in diagnosis and treatment of pulmonary disease.
Practice nurses are advised:
Be aware that PFMs manufactured to EN 13826 will be available from September 1.
Be aware of the differences in peak flow readings between the old and the new PFMs.
Before prescribing or issuing a new EN 13826 PFM, check that a patient's personal best and treatment levels have been re-assessed on the new scale.
Further information from the MHRA website www.medical-devices.gov.uk