What is a Peak Flow Meter?
Peak flow meters play an important role in the management of asthma for a large number of patients, by indicating the how narrow or open the airways are. Peak flow readings are higher when patients are well, and lower when the airways are constricted.
The measurement of peak expiratory flow (PEF) was pioneered by Dr. B.M. Wright, who produced the first meter specifically designed to measure this index of lung function. Since the original design of instrument was introduced in the late 1950’s, and the subsequent development of a more portable, lower cost version (the Mini-Wright peak flow meter), other designs and copies have become available across Europe and the World.
How accurate are peak flow meters?
As a medical instrument, one would expect that all meters would be accurate; however scientists and medical researchers have noted that certain brands of peak flow meters give incorrect readings, when compared to reference testing standards, and suggested that there were two reasons for this:
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The meter’s design produced inaccurate readings.
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The meter’s scale was not as accurate as it could be
Many professionals use peak expiratory flow (P.E.F.) readings to aid decisions about treatment, and many patients rely on their peak flow meter to act as a marker for their disease – scientists became concerned that inaccurate readings may result in patients being treated less than optimally.
What does the European Standard (EN 23747) mean?
Since 1993, a group of European scientists have researched the problems and possible solutions, and in 2003, a new European Standard (EN 23747) for such instruments was published. The new standard sets minimum acceptable levels for accuracy, repeatability and general performance, and defines a new ‘scale’ for P.E.F. readings – thereby addressing the two major faults with the meters previously available. The new standard also has the advantage that readings are similar to those obtained from conventional spirometers, due to the new scale being based on ‘absolute’ airflows.
Peak flow meters that use the new ‘E.U.’ P.E.F. scale became available in 2004 and only designs that can confirm to the strict standards within the EN 23747 definition can claim to be compliant.
Certain brands of peak flow meter, previously thought to have acceptable accuracy, have not been able to meet the more stringent accuracy requirements of the new tests.
Patients and Healthcare Professionals using the Mini-Wright brand of peak flow meter can be reassured that this meter has already been shown to comply with the accuracy requirements.
When will the new peak flow meters be available?
New EU-Scale meters were introduced in the U.K. from 1st September 2004, as a replacement for the peak flow meters that are reimbursed through the Drug Tariff’s Specification 51. Wright-scaled meters will be phased out of use from this date onwards.
Within the rest of Europe, each country will decide when to change from the old scale to the new EU-Scale; new meters will be available throughout Europe from 2004 onwards.
The introduction of a new P.E.F. scale in Europe does not affect the United States or other countries, unless they have been using Wright-scale instruments. The American Thoracic Society (ATS) scale meter will remain unchanged.
Are Low range meters omitted from the EN 23747 standard?
The EN 23747 Standard has been welcomed by many, and will improve the value of P.E.F. readings in the diagnosis and management of asthma. Unfortunately, the new Standard has failed to recognise the value of ‘low range’ peak flow meters – those meters that have been requested by asthma professionals specifically for those with peak flow readings that never go above 400 l/min.
Our range of Mini-Wright Low Range peak flow meters complies with all aspects of the new EN 23747 Standard – with the exception that the upper limit of its readings will be 400 l/min. This device is suitable for children, the elderly, and those with severe asthma.
Multiple patient use – how do we protect against cross-infection?
The original use of the Mini-Wright meter was in chest clinics, measuring the lung function of multiple patients in Hospitals and Surgeries across the country. For over 20 years, the Mini-Wright has been the only peak flow meter to feature an integral one-way valve that prevents patients from inhaling through the meter during use.
More recently, we became the first company to validate multiple-patient cleaning instructions which provide recommendations for the use of the instrument by more than one patient.
The Mini-Wright is suitable for both single-patient use, and multiple-patient use, provided the respective cleaning instructions are followed. In addition, disposable cardboard one-way mouthpieces are available for other brands of peak flow meter (which do not have the inbuilt protection of the Mini-Wright design).
